We present a measurement of the free-streaming length of dark matter (DM) and subhalo abundance around 28 quadruple image strong lenses using observations from James webb space telescope mid-infrared instrument presented in Paper III of this series. We improve on previous inferences on DM properties from lensed quasars by simultaneously reconstructing extended lensed arcs with image positions and relative magnifications (flux ratios). Our forward modeling framework generates full populations of subhalos, line-of-sight halos, and globular clusters, uses an accurate model for subhalo tidal evolution, and accounts for free-streaming effects on halo abundance and concentration. Modeling lensed arcs leads to more-precise model-predicted flux ratios, breaking covariance between subhalo abundance and the free-streaming scale parametrized by the half-mode mass \ud835\udc5ahm. Assuming subhalo abundance predicted by the semianalytic model galacticus (\ud835\udc41-body simulations), we infer (Bayes factor of 10\u22361) \ud835\udc5ahm<10^(7.4)\u2062\ud835\udc40\u2299 (\ud835\udc5ahm <10^(7.2)\u2062\ud835\udc40\u2299), a 0.4 dex improvement relative to omitting lensed arcs. These bounds correspond to lower limits on thermal relic DM particle masses of 6.5 and 7.4 keV, respectively. Conversely, assuming DM is cold, we infer a projected mass in subhalos (10\u2076 <\ud835\udc5a/\ud835\udc40\u2299 <10^(10.7)) of 1.7^(+2.6)_(−1.2)×10\u2077\u2062\ud835\udc40\u2299 kpc\u207b² at 95% confidence. This is consistent with galacticus predictions (0.9×10\u2077\u2062\ud835\udc40\u2299 kpc\u207b²), but in mild tension with recent \ud835\udc41-body simulations (0.6×10\u2077\u2062\ud835\udc40\u2299 kpc\u207b²). Our results are among the strongest bounds on warm dark matter, and the most precise measurement of subhalo abundance around strong lenses. Further improvements will follow from the large sample of lenses to be discovered by Euclid, Rubin, and Roman.
", "doi": "10.1103/k2m5-kf6p", "issn": "2470-0010", "publisher": "American Physical Society", "publication": "Physical Review D", "publication_date": "2026-08-18", "series_number": "4", "volume": "114", "issue": "4", "pages": "043044" }, { "id": "authors:jgsrr-z1w61", "collection": "authors", "collection_id": "jgsrr-z1w61", "cite_using_url": "https://authors.library.caltech.edu/records/jgsrr-z1w61", "type": "article", "title": "JWST lensed quasar dark matter survey. III. Dark matter sensitive flux ratios and warm dark matter constraint from the full sample", "author": [ { "family_name": "Keeley", "given_name": "R.\u2009E.", "orcid": "0000-0002-0862-8789" }, { "family_name": "Nierenberg", "given_name": "A.\u2009M.", "orcid": "0000-0001-6809-2536" }, { "family_name": "Gilman", "given_name": "D." }, { "family_name": "Treu", "given_name": "T.", "orcid": "0000-0002-8460-0390" }, { "family_name": "Du", "given_name": "X.", "orcid": "0000-0003-0728-2533" }, { "family_name": "Gannon", "given_name": "C." }, { "family_name": "Mozumdar", "given_name": "P.", "orcid": "0000-0002-8593-7243" }, { "family_name": "Wong", "given_name": "K.\u2009C.", "orcid": "0000-0002-8459-7793" }, { "family_name": "Paugnat", "given_name": "H.", "orcid": "0000-0002-2603-6031" }, { "family_name": "Birrer", "given_name": "S.", "orcid": "0000-0003-3195-5507" }, { "family_name": "Malkan", "given_name": "M.", "orcid": "0000-0001-6919-1237" }, { "family_name": "Benson", "given_name": "A.\u2009J.", "orcid": "0000-0001-5501-6008", "clpid": "Benson-A-J" }, { "family_name": "Abazajian", "given_name": "K.\u2009N.", "orcid": "0000-0001-9919-6362" }, { "family_name": "Anguita", "given_name": "T.", "orcid": "0000-0003-0930-5815" }, { "family_name": "Bennert", "given_name": "V.\u2009N.", "orcid": "0000-0003-2064-0518" }, { "family_name": "Djorgovski", "given_name": "S.\u2009G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Hoenig", "given_name": "S.\u2009F.", "orcid": "0000-0002-6353-1111" }, { "family_name": "Kusenko", "given_name": "A.", "orcid": "0000-0002-8619-1260" }, { "family_name": "Larsson", "given_name": "H.\u2009R.", "orcid": "0000-0002-9417-1518" }, { "family_name": "Morishita", "given_name": "T.", "orcid": "0000-0002-8512-1404", "clpid": "Morishita-Takahiro" }, { "family_name": "Motta", "given_name": "V.", "orcid": "0000-0003-4446-7465" }, { "family_name": "Moustakas", "given_name": "L.\u2009A.", "orcid": "0000-0003-3030-2360", "clpid": "Moustakas-Leonidas-A" }, { "family_name": "Sheu", "given_name": "W." }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Stiavelli", "given_name": "M.", "orcid": "0000-0001-9935-6047" }, { "family_name": "Williams", "given_name": "D.", "orcid": "0000-0002-8386-0051" } ], "abstract": "We present the full sample of measurements of the warm dust emission of 31 strongly-lensed, multiply imaged quasars, observed with JWST MIRI multiband imaging, which we use to constrain the particle properties of dark matter. The strongly lensed warm dust region of quasars is compact and statistically sensitive to a population of dark matter halos down to masses of 10\u2076\u2062\ud835\udc40\u2299. The high spatial resolution and infrared sensitivity of MIRI make it uniquely suited to measure multiply imaged warm dust emission from quasars and thus to infer the properties of low-mass dark halos. In this work, we present image fluxes as well as dark matter sensitive warm dust flux ratios inferred from spectral energy distribution fitting. We then use these flux ratios to test for the presence of a warm dark matter turnover in the halo mass function. We use a forward modeling pipeline which explores dark matter parameters while also accounting for tidal stripping effects on subhalos, globular clusters, and complex deflector macromodels with \ud835\udc5a =1,\ud835\udc5a =3, and \ud835\udc5a =4 elliptical multipole moments. Adopting a comparable prior on the projected density of substructure to previous analyses, the data presented here provide a factor of 2 improvement in sensitivity to a turnover in the halo mass function. Assuming subhalo abundance predicted by the semianalytic model galacticus, we infer with a Bayes factor of 10\u22361, a half-mode mass \ud835\udc5ahm <10^(7.8)\u2062\ud835\udc40\u2299. If instead we use a prior from \ud835\udc41-body simulations, we infer \ud835\udc5ahm <10^(7.6)\u2062\ud835\udc40\u2299. This corresponds to a thermally produced dark matter mass of 5.6 (6.4) keV for the galacticus and \ud835\udc41-body priors, respectively. This is one of the strongest constraints to date on a turnover on the halo mass function, and the flux ratios and inference methodology presented here can be used to test a broad range of dark matter physics.
", "doi": "10.1103/53tj-sjlg", "issn": "2470-0010", "publisher": "American Physical Society", "publication": "Physical Review D", "publication_date": "2026-08-18", "series_number": "4", "volume": "114", "issue": "4", "pages": "043043" }, { "id": "authors:1aqtx-qwe32", "collection": "authors", "collection_id": "1aqtx-qwe32", "cite_using_url": "https://authors.library.caltech.edu/records/1aqtx-qwe32", "type": "article", "title": "Free-Streaming Length of Dark Matter from JWST Observations of 28 Strong Gravitational Lenses", "author": [ { "family_name": "Gilman", "given_name": "D.", "orcid": "0000-0002-5116-7287" }, { "family_name": "Nierenberg", "given_name": "A.\u2009M.", "orcid": "0000-0001-6809-2536" }, { "family_name": "Treu", "given_name": "T.", "orcid": "0000-0002-8460-0390" }, { "family_name": "Abazajian", "given_name": "K.\u2009N.", "orcid": "0000-0001-9919-6362" }, { "family_name": "Anguita", "given_name": "T.", "orcid": "0000-0003-0930-5815" }, { "family_name": "Bennert", "given_name": "V.\u2009N.", "orcid": "0000-0003-2064-0518" }, { "family_name": "Benson", "given_name": "A.\u2009J.", "orcid": "0000-0001-5501-6008", "clpid": "Benson-A-J" }, { "family_name": "Birrer", "given_name": "S.", "orcid": "0000-0003-3195-5507" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Du", "given_name": "X.", "orcid": "0000-0003-0728-2533" }, { "family_name": "Gannon", "given_name": "C.", "orcid": "0009-0009-0443-3181" }, { "family_name": "Hoenig", "given_name": "S.\u2009F.", "orcid": "0000-0002-6353-1111" }, { "family_name": "Keeley", "given_name": "R.\u2009E.", "orcid": "0000-0002-0862-8789" }, { "family_name": "Kusenko", "given_name": "A.", "orcid": "0000-0002-8619-1260" }, { "family_name": "Larsson", "given_name": "H.\u2009R.", "orcid": "0000-0002-9417-1518" }, { "family_name": "Malkan", "given_name": "M.", "orcid": "0000-0001-6919-1237" }, { "family_name": "Morishita", "given_name": "T.", "orcid": "0000-0002-8512-1404", "clpid": "Morishita-Takahiro" }, { "family_name": "Motta", "given_name": "V.", "orcid": "0000-0003-4446-7465" }, { "family_name": "Moustakas", "given_name": "L.\u2009A.", "orcid": "0000-0003-3030-2360", "clpid": "Moustakas-Leonidas-A" }, { "family_name": "Mozumdar", "given_name": "P.", "orcid": "0000-0002-8593-7243" }, { "family_name": "Paugnat", "given_name": "H.", "orcid": "0000-0002-2603-6031" }, { "family_name": "Sheu", "given_name": "W.", "orcid": "0000-0003-1889-0227" }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Stiavelli", "given_name": "M.", "orcid": "0000-0001-9935-6047" }, { "family_name": "Williams", "given_name": "D.", "orcid": "0000-0002-8386-0051" }, { "family_name": "Wong", "given_name": "K.\u2009C.", "orcid": "0000-0002-8459-7793" } ], "abstract": "The formation of gravitationally bound overdensities of dark matter (DM), or halos, is a generic prediction of theories with particle DM. We present a measurement of halo properties in 28 quadruple image strong lens systems recently observed by JWST, and use these observations to constrain the free-streaming length, \ud835\udf06FS, of DM, a quantity that depends on the DM particle mass and formation mechanism. We improve on previous lensing analyses by simultaneously reconstructing extended lensed arcs with image positions and relative magnifications, enhancing sensitivity to perturbations by halos. Our analysis rules out deviations from the predictions of cold dark matter (CDM) on scales above 10^(7.2)\u2062\ud835\udc40\u2299 and 10^(7.4)\u2062\ud835\udc40\u2299 for subhalo abundance predicted by cosmological \ud835\udc41-body simulations and semianalytic models, respectively. These bounds correspond to upper limits \ud835\udf06FS<6.0 kpc and \ud835\udf06FS <7.0 kpc, and lower limits on the mass of a spin–1/2 thermal relic DM particle \ud835\udc5atherm>7.4 keV and \ud835\udc5atherm >6.5 keV. Conversely, assuming a negligible free-streaming length, as predicted by CDM, we measure a projected mass in subhalos around elliptical galaxies 1.7^+(+2.6)_(−1.2)×10\u2077 M\u2299 kpc\u207b² at 95% confidence. These inferences confirm key predictions of the CDM paradigm.
", "doi": "10.1103/qckh-cqrd", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2026-08-18", "series_number": "8", "volume": "137", "issue": "8", "pages": "081004" }, { "id": "authors:xtjpv-hv513", "collection": "authors", "collection_id": "xtjpv-hv513", "cite_using_url": "https://authors.library.caltech.edu/records/xtjpv-hv513", "type": "article", "title": "Measurement of the Minimum Cold Dark Matter Halo Mass with Strong Gravitational Lensing", "author": [ { "family_name": "Nierenberg", "given_name": "A.\u2009M.", "orcid": "0000-0001-6809-2536" }, { "family_name": "Gilman", "given_name": "D.", "orcid": "0000-0002-5116-7287" }, { "family_name": "Treu", "given_name": "T." }, { "family_name": "Du", "given_name": "X.", "orcid": "0000-0003-0728-2533" }, { "family_name": "Gannon", "given_name": "C." }, { "family_name": "Paugnat", "given_name": "H.", "orcid": "0000-0002-2603-6031" }, { "family_name": "Birrer", "given_name": "S.", "orcid": "0000-0003-3195-5507" }, { "family_name": "Benson", "given_name": "A.\u2009J.", "orcid": "0000-0001-5501-6008", "clpid": "Benson-A-J" }, { "family_name": "Abazajian", "given_name": "K.\u2009N.", "orcid": "0000-0001-9919-6362" }, { "family_name": "Anguita", "given_name": "T.", "orcid": "0000-0003-0930-5815" }, { "family_name": "Djorgovski", "given_name": "S.\u2009G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Hoenig", "given_name": "S.\u2009F.", "orcid": "0000-0002-6353-1111" }, { "family_name": "Keeley", "given_name": "R.\u2009E.", "orcid": "0000-0002-0862-8789" }, { "family_name": "Kusenko", "given_name": "A.", "orcid": "0000-0002-8619-1260" }, { "family_name": "Larsson", "given_name": "H.\u2009R.", "orcid": "0000-0002-9417-1518" }, { "family_name": "Moustakas", "given_name": "L.\u2009A.", "orcid": "0000-0003-3030-2360", "clpid": "Moustakas-Leonidas-A" }, { "family_name": "Mozumdar", "given_name": "P.", "orcid": "0000-0002-8593-7243" }, { "family_name": "Sheu", "given_name": "W." }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Williams", "given_name": "D.", "orcid": "0000-0002-8386-0051" }, { "family_name": "Wong", "given_name": "K.\u2009C.", "orcid": "0000-0002-8459-7793" } ], "abstract": "We explore the lowest mass limit that can be placed on the halo mass function in cold dark matter (CDM) using 28 strong gravitational lenses. For this purpose, we study an extreme model in which the halo mass function and mass-concentration relation follow CDM, with a sharp cutoff at some mass scale, \ud835\udc5alow. Lensing provides a unique window into this quantity as it does not depend on the presence of baryons in dark matter halos and allows for the detection of low mass halos at cosmological distances, both in the lens galaxies and along the line of sight. Our model incorporates the effects of tidal stripping of subhalos, leading to the presence of many subhalos below a given model cutoff scale. We place an upper limit on the low-mass cutoff of the halo mass function of \ud835\udc5alow<10^(8.3) \u2062\ud835\udc40\u2299 at 10\u22361 odds using a prior for the normalization of the subhalo mass function from the semianalytic model galacticus and \ud835\udc5alow<10^(8.2) \ud835\udc40\u2299 at 10\u22361 odds using a prior from \ud835\udc41-body simulations. These limits are comparable to, or stronger than, existing constraints based on Milky Way satellite galaxies. Based on these results, we forecast more than an order of magnitude improvement with a sample of 200 quadruply imaged quasar lenses. This number represents a small subset of the thousands that are anticipated to be discovered by Rubin, Euclid, and Roman. Furthermore, with this larger sample of lenses we expect to directly constrain the normalization of the subhalo mass function, thereby eliminating a major source of uncertainty in our current measurements.
", "doi": "10.1103/jnjt-1ghp", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2026-08-11", "series_number": "7", "volume": "137", "issue": "7", "pages": "071001" }, { "id": "authors:brh3w-wvp17", "collection": "authors", "collection_id": "brh3w-wvp17", "cite_using_url": "https://authors.library.caltech.edu/records/brh3w-wvp17", "type": "article", "title": "Semi-Supervised Learning for Lensed Quasar Detection", "author": [ { "family_name": "Sweeney", "given_name": "David", "orcid": "0000-0002-7528-1463" }, { "family_name": "Krone-Martins", "given_name": "Alberto" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Tuthill", "given_name": "Peter" }, { "family_name": "Scalzo", "given_name": "Richard" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ducourant", "given_name": "Christine" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Teixeira", "given_name": "Ramachrisna" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" } ], "abstract": "Lensed quasars are key to many areas of study in astronomy, offering a unique probe into the intermediate and far universe. However, finding lensed quasars has proved difficult despite significant efforts from large collaborations. These challenges have limited catalogues of confirmed lensed quasars to the hundreds, despite theoretical predictions that they should be many times more numerous. We train machine learning classifiers to discover lensed quasar candidates. By using semi-supervised learning techniques we leverage the large number of potential candidates as unlabelled training data alongside the small number of known objects, greatly improving model performance. We present our two most successful models: (1) a variational autoencoder trained on millions of quasars to reduce the dimensionality of images for input to a dense neural network classifier that can make accurate predictions and (2) a convolutional neural network trained on a mix of labelled and unlabelled data via virtual adversarial training. These models are both capable of producing high-quality candidates, as evidenced by our discovery of GRALJ140833.73+042229.98. The success of our classifier, which uses only multi-band images, is particularly exciting as it can be combined with existing classifiers, which use other data than images, to improve the classifications of both models and discover more lensed quasars.
", "doi": "10.1093/mnras/stag445", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2026-04", "series_number": "4", "volume": "547", "issue": "4", "pages": "stag445" }, { "id": "authors:t6zg0-4m990", "collection": "authors", "collection_id": "t6zg0-4m990", "cite_using_url": "https://authors.library.caltech.edu/records/t6zg0-4m990", "type": "article", "title": "The nature of ASASSN-24fw's occultation: modelling the event as dimming by optically thick rings around a substellar companion", "author": [ { "family_name": "Shah", "given_name": "Sarang", "orcid": "0000-0003-1959-8439" }, { "family_name": "Marshall", "given_name": "Jonathan P", "orcid": "0000-0001-6208-1801" }, { "family_name": "del\u00a0Burgo", "given_name": "Carlos", "orcid": "0000-0002-8949-5200" }, { "family_name": "Hajdu", "given_name": "Gergely", "orcid": "0000-0003-0594-9138" }, { "family_name": "Rebollido", "given_name": "Isabel", "orcid": "0000-0002-4388-6417" }, { "family_name": "Pilecki", "given_name": "Bogumi\u0142", "orcid": "0000-0003-3861-8124" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Zeegers", "given_name": "Sascha T", "orcid": "0000-0002-8163-8852" }, { "family_name": "Reddy", "given_name": "Bacham Eswar", "orcid": "0000-0001-9246-9743" }, { "family_name": "Kemper", "given_name": "Francisca", "orcid": "0000-0003-2743-8240" }, { "family_name": "Kasliwal", "given_name": "Mansi M", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Karambelkar", "given_name": "Viraj", "orcid": "0000-0003-2758-159X", "clpid": "Karambelkar-Viraj" }, { "family_name": "Graham", "given_name": "Matthew J", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S G", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" } ], "abstract": "ASASSN-24fw, monitored by the All-Sky Automated Survey for SuperNovae, underwent a rapid and deep dimming event beginning in late 2024 and lasting until 2025 June. The pre-dimming spectral energy distribution indicates that ASASSN-24fw is an F-type main-sequence star with a persistent infrared excess, corresponding to a fractional luminosity of about 10 per cent. Public survey light curves show that the star is otherwise photometrically stable, implying that the dimming was caused by an external occulter. While long-duration stellar dimming events have become increasingly common in recent years, ASASSN-24fw is distinguished by a pronounced flat-bottomed light curve lasting nearly 200 d. We analyse this event using available photometric and spectroscopic data obtained during the dimming phase. Two independent light-curve models are applied. The first characterizes the multiple phases of the ingress structure, while the second model suggests that the occulter is a gas-giant companion, likely a brown dwarf, with a minimum mass of 3.42 M$_{\\rm {J}}$ and an extended ring system with a radial extent of approximately 0.17 au. Near-infrared spectra obtained during dimming show enhanced infrared excess and are consistent with an M8-type brown dwarf companion. Optical spectra reveal variable H$_{\\alpha }$ emission during the event. Post-dimming spectra show no evidence for ongoing accretion, suggesting that the H$\\alpha$ variability is associated with the occulter rather than the host star. We conclude that ASASSN-24fw represents a rare and unusual system, and that further observations are required to better constrain its stellar properties, circumstellar environment, and evolutionary history.
", "doi": "10.1093/mnras/staf2251", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2026-03", "series_number": "3", "volume": "546", "issue": "3", "pages": "staf2251" }, { "id": "authors:t0vsc-k4s10", "collection": "authors", "collection_id": "t0vsc-k4s10", "cite_using_url": "https://authors.library.caltech.edu/records/t0vsc-k4s10", "type": "article", "title": "An extremely luminous flare recorded from a supermassive black hole", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "McKernan", "given_name": "Barry" }, { "family_name": "Ford", "given_name": "K. E. Saavik", "orcid": "0000-0002-5956-851X" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Cantiello", "given_name": "Matteo" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-Andrew-J" }, { "family_name": "Ding", "given_name": "Yuanze", "orcid": "0000-0002-5770-2666", "clpid": "Ding-Yuanze" }, { "family_name": "Kasliwal", "given_name": "Mansi", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Koss", "given_name": "Mike", "orcid": "0000-0002-7998-9581" }, { "family_name": "Margutti", "given_name": "Raffaella", "orcid": "0000-0003-4768-7586" }, { "family_name": "Rose", "given_name": "Sam", "orcid": "0000-0003-4725-4481", "clpid": "Rose-Sam" }, { "family_name": "Somalwar", "given_name": "Jean", "orcid": "0000-0001-8426-5732", "clpid": "Somalwar-Jean-J" }, { "family_name": "Wiseman", "given_name": "Phil" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Veres", "given_name": "Patrik M.", "orcid": "0000-0002-9553-2987" }, { "family_name": "Bellm", "given_name": "Eric C.", "orcid": "0000-0001-8018-5348" }, { "family_name": "Chen", "given_name": "Tracy X.", "orcid": "0000-0001-9152-6224", "clpid": "Chen-Tracy-X" }, { "family_name": "Groom", "given_name": "Steven L.", "orcid": "0000-0001-5668-3507", "clpid": "Groom-Steven-L" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "Since their discovery more than 60 years ago, accreting supermassive black holes in active galactic nuclei (AGN) have been recognized as highly variable sources, requiring an extremely compact, dynamic environment. Their variability is related to several phenomena, including changing accretion rates, temperature changes, foreground absorbers and structural changes to the accretion disk. Spurred by a new generation of time-domain surveys, the extremes of black hole variability are now being probed. Here we describe the discovery of an extreme flare by the AGN J224554.84+374326.5, which brightened by more than a factor of 40 in 2018. The source has slowly faded since then. The total emitted ultraviolet and optical energy to date is ~1054 erg, which represents the complete conversion of approximately one solar mass into electromagnetic radiation. This flare is 30 times more powerful than the previous most powerful AGN transient. Very few physical events in the Universe can liberate this much electromagnetic energy. We discuss potential mechanisms, including the tidal disruption of a high-mass star (>30 M\u2299), gravitational lensing of an AGN flare or supernova, or a supermassive (pair-instability) supernova in the accretion disk of an AGN. We favour the tidal disruption of a massive star in a prograde orbit in an AGN disk.
\nThe Catalina Real-time Transient Survey (CRTS) carried out a public survey for optical transients between 2007 and 2019, discovering more than 16 000 transient candidates. Here, we present the spectra and highlight the results of the spectroscopic follow-up of CRTS extragalactic transients. As expected, we find that the bulk of these transients are normal supernovae. However, as we prioritized transients exhibiting unusual features or environments during our spectroscopic follow-up, we focus on the rarer types of transients. These objects include more than a dozen type-I superluminous supernovae and dozens of type-I and II supernovae that underwent circumstellar medium interactions. We highlight several specific supernovae, including a new analysis of SN 2008iy, a type-IIn which exhibited a bright pre-supernova outburst event similar to SN 2009ip and lasted more than 1800 d; CSS111225:140122+161705, a type-I supernova that showed an extreme 2.5 mag rebrightening event more than 200 d after its initial outburst; and SN 2009ny, a type-Ibn supernova that exhibited strong helium emission lines similar to SN 2002ao. We confirm our previous finding that numerous CRTS transients are associated with galaxies of extremely low luminosity. We discuss the difficulty in determining the origin of transients associated with outbursts in active galactic nuclei (AGNs), tidal disruption events, and type-IIn supernovae. As an example, we present CSS150120:110008+385352, a CRTS transient similar to CSS100217:102913+404220 that occurred within a quiescent AGN and peaked at M_V = −23.6.
", "doi": "10.1093/mnras/staf1716", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2025-12", "series_number": "2", "volume": "544", "issue": "2", "pages": "1373-1389" }, { "id": "authors:985q2-ndq40", "collection": "authors", "collection_id": "985q2-ndq40", "cite_using_url": "https://authors.library.caltech.edu/records/985q2-ndq40", "type": "article", "title": "QZO: A Catalog of 5 Million Quasars from the Zwicky Transient Facility", "author": [ { "family_name": "Nakoneczny", "given_name": "S. J.", "orcid": "0000-0003-2130-7143", "clpid": "Nakoneczny-Szymon-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Helou", "given_name": "G.", "orcid": "0000-0003-3367-3415", "clpid": "Helou-G" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bellm", "given_name": "E. C.", "orcid": "0000-0001-8018-5348" }, { "family_name": "Chen", "given_name": "T. X.", "orcid": "0000-0001-9152-6224", "clpid": "Chen-Tracy-X" }, { "family_name": "Dekany", "given_name": "R.", "orcid": "0000-0002-5884-7867", "clpid": "Dekany-Richard" }, { "family_name": "Drake", "given_name": "A.", "orcid": "0000-0003-0228-6594", "clpid": "Drake-Andrew" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Prince", "given_name": "T. A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Riddle", "given_name": "R.", "orcid": "0000-0002-0387-370X", "clpid": "Riddle-Reed" }, { "family_name": "Rusholme", "given_name": "B.", "orcid": "0000-0001-7648-4142", "clpid": "Rusholme-Benjamin" }, { "family_name": "Sravan", "given_name": "N." } ], "abstract": "Machine learning methods are well established in the classification of quasars (QSOs). However, the advent of light-curve observations adds a great amount of complexity to the problem. Our goal is to use the Zwicky Transient Facility (ZTF) to create a catalog of QSOs. We process the ZTF DR20 light curves with a transformer artificial neural network and combine different surveys with extreme gradient boosting. Based on ZTF g-band and Wide-field Infrared Survey Explorer (WISE) observations, we find 4,849,574 objects classified as QSOs with confidence higher than 90% (QZO). We robustly classify objects fainter than the 5σ signal-to-noise ratio (SNR) limit at g = 20.8 by requiring g < nobs/80 + 20.375. For 33% of QZO objects, with available WISE data, we publish redshifts with estimated error Δz/(1 + z) = 0.14. We find that ZTF classification is superior to the Pan-STARRS static bands, and on par with WISE and Gaia measurements, but the light curves provide the most important features for QSO classification in the ZTF data set. Using ZTF g-band data with at least 100 observational epochs per light curve, we obtain a 97% F1 score for QSOs. We find that with 3 day median cadence, a survey time span of at least 900 days is required to achieve a 90% QSO F1 score. However, one can obtain the same score with a survey time span of 1800 days and the median cadence prolonged to 12 days.
", "doi": "10.3847/1538-4357/adf4e4", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2025-10-10", "series_number": "1", "volume": "992", "issue": "1", "pages": "153" }, { "id": "authors:98e0f-scf03", "collection": "authors", "collection_id": "98e0f-scf03", "cite_using_url": "https://authors.library.caltech.edu/records/98e0f-scf03", "type": "article", "title": "Gaia GraL: Gaia gravitational lens systems. IX. Using XGBoost to explore the Gaia Focused Product Release GravLens catalogue", "author": [ { "family_name": "Petit", "given_name": "Q." }, { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979" }, { "family_name": "Slezak", "given_name": "E." }, { "family_name": "Krone-Martins", "given_name": "A.", "orcid": "0000-0002-2308-6623" }, { "family_name": "B\u0153hm", "given_name": "C.", "orcid": "0000-0002-5074-9998" }, { "family_name": "Connor", "given_name": "T.", "orcid": "0000-0002-7898-7664", "clpid": "Connor-Thomas" }, { "family_name": "Delchambre", "given_name": "L.", "orcid": "0000-0003-2559-408X" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Galluccio", "given_name": "L.", "orcid": "0000-0002-8541-0476" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Jalan", "given_name": "P.", "orcid": "0000-0002-0524-5328" }, { "family_name": "Klioner", "given_name": "S. A.", "orcid": "0000-0003-4682-7831" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "orcid": "0000-0002-3469-5133" }, { "family_name": "Mignard", "given_name": "F.", "orcid": "0000-0002-9525-6505" }, { "family_name": "Negi", "given_name": "V.", "orcid": "0000-0001-5824-1040" }, { "family_name": "Scarano Jr", "given_name": "S.", "orcid": "0000-0003-3739-4288" }, { "family_name": "Sebastian den Brok", "given_name": "J." }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976" }, { "family_name": "Teixeira", "given_name": "R.", "orcid": "0000-0002-6806-6626" }, { "family_name": "Vale-Cunha", "given_name": "P. H.", "orcid": "0000-0003-4459-0738" }, { "family_name": "Walton", "given_name": "D. J." }, { "family_name": "Wambsganss", "given_name": "J.", "orcid": "0000-0001-5055-7390" } ], "abstract": "Aims. Quasar strong gravitational lenses are important tools for putting constraints on the dark matter distribution, dark energy contribution, and the Hubble-Lemaître parameter. We aim to present a new supervised machine learning-based method to identify these lenses in large astrometric surveys. The Gaia Focused Product Release (FPR) GravLens catalogue is designed for the identification of multiply imaged quasars, as it provides astrometry and photometry of all sources in the field of 4.7 million quasars.
\nMethods. Our new approach for automatically identifying four-image lens configurations in large catalogues is based on the eXtreme Gradient Boosting classification algorithm. To train this supervised algorithm, we performed realistic simulations of lenses with four images that account for the statistical distribution of the morphology of the deflecting halos as measured in the EAGLE simulation. We identified the parameters discriminant for the classification and performed two different trainings, namely, with and without distance information.
\nResults. The performances of this method on the simulated data are quite good, with a true positive rate and a true negative rate of about 99.99% and 99.84%, respectively. Our validation of the method on a small set of known quasar lenses demonstrates its efficiency, with 75% of known lenses being correctly identified. We applied our algorithm (both trainings) to more than 0.9 million quadruplets selected from the Gaia FPR GravLens catalogue. We derived a list of 1127 candidates with at least one score larger than 0.75, where each candidate has two scores–one from the model trained with distance information and one from the model trained without distance information–and including 201 very good candidates with both high scores.
", "doi": "10.1051/0004-6361/202451690", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2025-04", "volume": "696", "pages": "A51" }, { "id": "authors:wm1q4-weq79", "collection": "authors", "collection_id": "wm1q4-weq79", "cite_using_url": "https://authors.library.caltech.edu/records/wm1q4-weq79", "type": "article", "title": "JWST Lensed quasar dark matter survey II: Strongest gravitational lensing limit on the dark matter free streaming length to date", "author": [ { "family_name": "Keeley", "given_name": "Ryan E.", "orcid": "0000-0002-0862-8789" }, { "family_name": "Nierenberg", "given_name": "A. M." }, { "family_name": "Gilman", "given_name": "D." }, { "family_name": "Gannon", "given_name": "C." }, { "family_name": "Birrer", "given_name": "S." }, { "family_name": "Treu", "given_name": "T.", "orcid": "0000-0002-8460-0390" }, { "family_name": "Benson", "given_name": "A. J.", "orcid": "0000-0001-5501-6008", "clpid": "Benson-A-J" }, { "family_name": "Du", "given_name": "X." }, { "family_name": "Abazajian", "given_name": "K. N.", "orcid": "0000-0001-9919-6362" }, { "family_name": "Anguita", "given_name": "T.", "orcid": "0000-0003-0930-5815" }, { "family_name": "Bennert", "given_name": "V. N." }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gupta", "given_name": "K. K.", "orcid": "0009-0007-9018-1077" }, { "family_name": "Hoenig", "given_name": "S. F." }, { "family_name": "Kusenko", "given_name": "A." }, { "family_name": "Lemon", "given_name": "C.", "orcid": "0000-0003-2456-9317" }, { "family_name": "Malkan", "given_name": "M." }, { "family_name": "Motta", "given_name": "V" }, { "family_name": "Moustakas", "given_name": "L. A.", "orcid": "0000-0003-3030-2360", "clpid": "Moustakas-Leonidas-A" }, { "family_name": "Oh", "given_name": "Maverick S. H." }, { "family_name": "Sluse", "given_name": "D." }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Wechsler", "given_name": "R. H." } ], "abstract": "This is the second in a series of papers in which we use JWST Mid Infrared Instrument multiband imaging to measure the warm dust emission in a sample of 31 multiply imaged quasars, to be used as a probe of the particle nature of dark matter. We present measurements of the relative magnifications of the strongly lensed warm dust emission in a sample of nine systems. The warm dust region is compact and sensitive to perturbations by populations of haloes down to masses ∼10\u2076 M\u2299\u2060. Using these warm dust flux-ratio measurements in combination with five previous narrow-line flux-ratio measurements, we constrain the halo mass function. In our model, we allow for complex deflector macromodels with flexible third- and fourth-order multipole deviations from ellipticity, and we introduce an improved model of the tidal evolution of subhaloes. We constrain a WDM model and find an upper limit on the half-mode mass of 10^(7.6)M\u2299 at posterior odds of 10:1. This corresponds to a lower limit on a thermally produced dark matter particle mass of 6.1 keV. This is the strongest gravitational lensing constraint to date, and comparable to those from independent probes such as the Ly α forest and Milky Way satellite galaxies.
", "doi": "10.1093/mnras/stae2458", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2024-12", "series_number": "2", "volume": "535", "issue": "2", "pages": "1652-1671" }, { "id": "authors:gp40x-tcd67", "collection": "authors", "collection_id": "gp40x-tcd67", "cite_using_url": "https://authors.library.caltech.edu/records/gp40x-tcd67", "type": "article", "title": "Black hole jets on the scale of the cosmic web", "author": [ { "family_name": "Oei", "given_name": "Martijn S. S. L.", "orcid": "0000-0002-0610-2644", "clpid": "Oei-Martijn-S-S-L" }, { "family_name": "Hardcastle", "given_name": "Martin J.", "orcid": "0000-0003-4223-1117" }, { "family_name": "Timmerman", "given_name": "Roland", "orcid": "0000-0001-9404-2612" }, { "family_name": "Gast", "given_name": "Aivin R. D. J. G. I. B.", "orcid": "0000-0002-8986-1573" }, { "family_name": "Botteon", "given_name": "Andrea", "orcid": "0000-0002-9325-1567" }, { "family_name": "Rodriguez", "given_name": "Antonio C.", "orcid": "0000-0003-4189-9668", "clpid": "Rodriguez-Antonio-C" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Calistro Rivera", "given_name": "Gabriela" }, { "family_name": "van Weeren", "given_name": "Reinout J.", "orcid": "0000-0002-0587-1660" }, { "family_name": "R\u00f6ttgering", "given_name": "Huub J. A.", "orcid": "0000-0001-8887-2257" }, { "family_name": "Intema", "given_name": "Huib T.", "orcid": "0000-0002-5880-2730" }, { "family_name": "de Gasperin", "given_name": "Francesco", "orcid": "0000-0003-4439-2627" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "When sustained for megayears (refs. 1,2), high-power jets from supermassive black holes (SMBHs) become the largest galaxy-made structures in the Universe3. By pumping electrons, atomic nuclei and magnetic fields into the intergalactic medium (IGM), these energetic flows affect the distribution of matter and magnetism in the cosmic web4,5,6 and could have a sweeping cosmological influence if they reached far at early epochs. For the past 50 years, the known size range of black hole jet pairs ended at 4.6–5.0 Mpc (refs. 7,8,9), or 20–30% of a cosmic void radius in the Local Universe10. An observational lack of longer jets, as well as theoretical results11, thus suggested a growth limit at about 5 Mpc (ref. 12). Here we report observations of a radio structure spanning about 7 Mpc, or roughly 66% of a coeval cosmic void radius, apparently generated by a black hole between 4.4^(+0.2)_(-0.7) and 6.3 Gyr after the Big Bang. The structure consists of a northern lobe, a northern jet, a core, a southern jet with an inner hotspot and a southern outer hotspot with a backflow. This system demonstrates that jets can avoid destruction by magnetohydrodynamical instabilities over cosmological distances, even at epochs when the Universe was 7 to 15\u207a\u2076\u208b\u2082 times denser than it is today. How jets can retain such long-lived coherence is unknown at present.
", "doi": "10.1038/s41586-024-07879-y", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2024-09-19", "series_number": "8030", "volume": "633", "issue": "8030", "pages": "537-541" }, { "id": "authors:h2012-2en81", "collection": "authors", "collection_id": "h2012-2en81", "cite_using_url": "https://authors.library.caltech.edu/records/h2012-2en81", "type": "article", "title": "NuSTAR Observations of Candidate Subparsec Binary Supermassive Black Holes", "author": [ { "family_name": "Saade", "given_name": "M. Lynne", "orcid": "0000-0001-7163-7015", "clpid": "Saade-M-Lynne" }, { "family_name": "Brightman", "given_name": "Murray", "orcid": "0000-0002-8147-2602", "clpid": "Brightman-Murray" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Connor", "given_name": "Thomas", "orcid": "0000-0002-7898-7664", "clpid": "Connor-Thomas" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "D'Orazio", "given_name": "Daniel J.", "orcid": "0000-0002-1271-6247", "clpid": "D'Orazio-Daniel-J" }, { "family_name": "Ford", "given_name": "K. E. S.", "orcid": "0000-0002-5956-851X", "clpid": "Foord-K-E-Saavik" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Haiman", "given_name": "Zolt\u00e1n", "orcid": "0000-0003-3633-5403", "clpid": "Haiman-Zolt\u00e1n" }, { "family_name": "Jun", "given_name": "Hyunsung D.", "orcid": "0000-0003-1470-5901", "clpid": "Jun-Hyunsung-D" }, { "family_name": "Kammoun", "given_name": "Elias", "orcid": "0000-0002-0273-218X", "clpid": "Kammoun-Elias" }, { "family_name": "Kraft", "given_name": "Ralph P.", "orcid": "0000-0002-0765-0511", "clpid": "Kraft-Ralph-P" }, { "family_name": "McKernan", "given_name": "Barry", "orcid": "0000-0002-9726-0508", "clpid": "McKernan-Barry" }, { "family_name": "Vikhlinin", "given_name": "Alexei", "orcid": "0000-0001-8121-0234", "clpid": "Vikhlinin-Alexei" }, { "family_name": "Walton", "given_name": "Dominic J.", "orcid": "0000-0001-5819-3552", "clpid": "Walton-Dominic-J" } ], "abstract": "We present an analysis of NuSTAR X-ray observations of three active galactic nuclei (AGN) that were identified as candidate subparsec binary supermassive black hole (SMBH) systems in the Catalina Real-Time Transient Survey based on apparent periodicity in their optical light curves. Simulations predict that close-separation accreting SMBH binaries will have different X-ray spectra than single accreting SMBHs. We previously observed these AGN with Chandra and found no differences between their low-energy X-ray properties and the larger AGN population. However, some models predict differences to be more prominent at energies higher than probed by Chandra. We find that even at the higher energies probed by NuSTAR, the spectra of these AGN are indistinguishable from the larger AGN population. This could rule out models predicting large differences in the X-ray spectra in the NuSTAR bands. Alternatively, it might mean that these three AGN are not binary SMBHs.
\nThe flux ratios of gravitationally lensed quasars provide a powerful probe of the nature of dark matter. Importantly, these ratios are sensitive to small-scale structure, irrespective of the presence of baryons. This sensitivity may allow us to study the halo mass function even below the scales where galaxies form observable stars. For accurate measurements, it is essential that the quasar’s light is emitted from a physical region of the quasar with an angular scale of milliarcseconds or larger; this minimizes microlensing effects by stars within the deflector. The warm dust region of quasars fits this criterion, as it has parsec-size physical scales and dominates the spectral energy distribution of quasars at wavelengths greater than 10 μm. The JWST Mid-Infrared Instrument is adept at detecting redshifted light in this wavelength range, offering both the spatial resolution and sensitivity required for accurate gravitational lensing flux ratio measurements. Here, we introduce our survey designed to measure the warm dust flux ratios of 31 lensed quasars. We discuss the flux-ratio measurement technique and present results for the first target, DES J0405-3308. We find that we can measure the quasar warm dust flux ratios with 3 per cent precision. Our simulations suggest that this precision makes it feasible to detect the presence of 107 M\u2299 dark matter haloes at cosmological distances. Such haloes are expected to be completely dark in cold dark matter models.
", "doi": "10.1093/mnras/stae499", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2024-05", "series_number": "3", "volume": "530", "issue": "3", "pages": "2960-2971" }, { "id": "authors:x195g-7m088", "collection": "authors", "collection_id": "x195g-7m088", "cite_using_url": "https://authors.library.caltech.edu/records/x195g-7m088", "type": "article", "title": "Gaia GraL: Gaia DR2 gravitational lens systems \u2013 VIII. A radio census of lensed systems", "author": [ { "family_name": "Dobie", "given_name": "Dougal", "orcid": "0000-0003-0699-7019" }, { "family_name": "Sluse", "given_name": "Dominique", "orcid": "0000-0001-6116-2095" }, { "family_name": "Deller", "given_name": "Adam", "orcid": "0000-0001-9434-3837" }, { "family_name": "Murphy", "given_name": "Tara", "orcid": "0000-0002-2686-438X" }, { "family_name": "Krone-Martins", "given_name": "Alberto", "orcid": "0000-0002-2308-6623" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Wang", "given_name": "Ziteng", "orcid": "0000-0002-2066-9823" }, { "family_name": "Wang", "given_name": "Yuanming", "orcid": "0000-0003-0203-1196" }, { "family_name": "B\u0153hm", "given_name": "C\u00e9line", "orcid": "0000-0002-5074-9998" }, { "family_name": "Djorgovski", "given_name": "S G", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Galluccio", "given_name": "Laurent", "orcid": "0000-0002-8541-0476" }, { "family_name": "Delchambre", "given_name": "Ludovic", "orcid": "0000-0003-2559-408X" }, { "family_name": "Connor", "given_name": "Thomas", "orcid": "0000-0002-7898-7664", "clpid": "Connor-Thomas" }, { "family_name": "den\u00a0Brok", "given_name": "Jakob Sebastiaan", "orcid": "0000-0002-8760-6157" }, { "family_name": "Do\u00a0Vale\u00a0Cunha", "given_name": "Pedro H", "orcid": "0000-0003-4459-0738" }, { "family_name": "Ducourant", "given_name": "Christine", "orcid": "0000-0003-4843-8979" }, { "family_name": "Graham", "given_name": "Matthew J", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Jalan", "given_name": "Priyanka", "orcid": "0000-0002-0524-5328" }, { "family_name": "Klioner", "given_name": "Sergei A", "orcid": "0000-0003-4682-7831" }, { "family_name": "Kl\u00fcter", "given_name": "Jonas", "orcid": "0000-0002-3469-5133" }, { "family_name": "Mignard", "given_name": "Fran\u00e7ois", "orcid": "0000-0002-9525-6505" }, { "family_name": "Negi", "given_name": "Vibhore", "orcid": "0000-0001-5824-1040" }, { "family_name": "Petit", "given_name": "Quentin", "orcid": "0009-0006-1067-7922" }, { "family_name": "Scarano", "given_name": "Sergio" }, { "family_name": "Slezak", "given_name": "Eric", "orcid": "0000-0003-4771-7263" }, { "family_name": "Surdej", "given_name": "Jean" }, { "family_name": "Teixeira", "given_name": "Ramachrisna", "orcid": "0000-0002-6806-6626" }, { "family_name": "Walton", "given_name": "Dominic J", "orcid": "0000-0001-5819-3552" }, { "family_name": "Wambsganss", "given_name": "Joachim", "orcid": "0000-0001-5055-7390" } ], "abstract": "We present radio observations of 24 confirmed and candidate strongly lensed quasars identified by the Gaia Gravitational Lenses working group. We detect radio emission from eight systems in 5.5 and 9 GHz observations with the Australia Telescope Compact Array (ATCA), and 12 systems in 6 GHz observations with the Karl G. Jansky Very Large Array (VLA). The resolution of our ATCA observations is insufficient to resolve the radio emission into multiple lensed images, but we do detect multiple images from 11 VLA targets. We have analysed these systems using our observations in conjunction with existing optical measurements, including measuring offsets between the radio and optical positions for each image and building updated lens models. These observations significantly expand the existing sample of lensed radio quasars, suggest that most lensed systems are detectable at radio wavelengths with targeted observations, and demonstrate the feasibility of population studies with high-resolution radio imaging.
", "doi": "10.1093/mnras/stad4002", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2024-03", "series_number": "4", "volume": "528", "issue": "4", "pages": "5880-5889" }, { "id": "authors:gb6gg-ek616", "collection": "authors", "collection_id": "gb6gg-ek616", "cite_using_url": "https://authors.library.caltech.edu/records/gb6gg-ek616", "type": "article", "title": "1100 days in the life of the supernova 2018ibb. The best pair-instability supernova candidate, to date", "author": [ { "family_name": "Schulze", "given_name": "Steve", "orcid": "0000-0001-6797-1889" }, { "family_name": "Fransson", "given_name": "Claes", "orcid": "0000-0001-8532-3594" }, { "family_name": "Kozyreva", "given_name": "Alexandra", "orcid": "0000-0001-9598-8821" }, { "family_name": "Chen", "given_name": "Ting-Wan", "orcid": "0000-0002-1066-6098" }, { "family_name": "Yaron", "given_name": "Ofer", "orcid": "0000-0002-0301-8017" }, { "family_name": "Jerkstrand", "given_name": "Anders", "orcid": "0000-0001-8005-4030" }, { "family_name": "Gal-Yam", "given_name": "Avishay", "orcid": "0000-0002-3653-5598" }, { "family_name": "Sollerman", "given_name": "Jesper", "orcid": "0000-0003-1546-6615" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" }, { "family_name": "Kangas", "given_name": "Tuomas", "orcid": "0000-0002-5477-0217" }, { "family_name": "Leloudas", "given_name": "Giorgos", "orcid": "0000-0002-8597-0756" }, { "family_name": "Omand", "given_name": "Conor M. B.", "orcid": "0000-0002-9646-8710" }, { "family_name": "Smartt", "given_name": "Stephen J.", "orcid": "0000-0002-8229-1731" }, { "family_name": "Yang", "given_name": "Yi", "orcid": "0000-0002-6535-8500" }, { "family_name": "Nicholl", "given_name": "Matt", "orcid": "0000-0002-2555-3192" }, { "family_name": "Sarin", "given_name": "Nikhil", "orcid": "0000-0003-2700-1030" }, { "family_name": "Yao", "given_name": "Yuhan", "orcid": "0000-0001-6747-8509", "clpid": "Yao-Yuhan" }, { "family_name": "Brink", "given_name": "Thomas G.", "orcid": "0000-0001-5955-2502" }, { "family_name": "Sharon", "given_name": "Amir" }, { "family_name": "Rossi", "given_name": "Andrea", "orcid": "0000-0002-8860-6538" }, { "family_name": "Chen", "given_name": "Ping", "orcid": "0000-0003-0853-6427" }, { "family_name": "Chen", "given_name": "Zhihao", "orcid": "0000-0001-5175-4652" }, { "family_name": "Cikota", "given_name": "Aleksandar", "orcid": "0000-0001-7101-9831" }, { "family_name": "De", "given_name": "Kishalay", "orcid": "0000-0002-8989-0542" }, { "family_name": "Drake", "given_name": "Andrew J.", "orcid": "0000-0003-0228-6594", "clpid": "Drake-Andrew-J" }, { "family_name": "Filippenko", "given_name": "Alexei V.", "orcid": "0000-0003-3460-0103" }, { "family_name": "Fremling", "given_name": "Christoffer", "orcid": "0000-0002-4223-103X", "clpid": "Fremling-Christoffer" }, { "family_name": "Fr\u00e9our", "given_name": "Laurane", "orcid": "0000-0003-3355-0079" }, { "family_name": "Fynbo", "given_name": "Johan P. U.", "orcid": "0000-0002-8149-8298" }, { "family_name": "Ho", "given_name": "Anna Y. Q.", "orcid": "0000-0002-9017-3567" }, { "family_name": "Inserra", "given_name": "Cosimo", "orcid": "0000-0002-3968-4409" }, { "family_name": "Irani", "given_name": "Ido", "orcid": "0000-0002-7996-8780" }, { "family_name": "Kuncarayakti", "given_name": "Hanindyo", "orcid": "0000-0002-1132-1366" }, { "family_name": "Lunnan", "given_name": "Ragnhild", "orcid": "0000-0001-9454-4639" }, { "family_name": "Mazzali", "given_name": "Paolo", "orcid": "0000-0001-6876-8284" }, { "family_name": "Ofek", "given_name": "Eran O.", "orcid": "0000-0002-6786-8774" }, { "family_name": "Palazzi", "given_name": "Eliana", "orcid": "0000-0002-8691-7666" }, { "family_name": "Perley", "given_name": "Daniel A.", "orcid": "0000-0001-8472-1996" }, { "family_name": "Pursiainen", "given_name": "Miika", "orcid": "0000-0003-4663-4300" }, { "family_name": "Rothberg", "given_name": "Barry", "orcid": "0000-0003-2283-2185" }, { "family_name": "Shingles", "given_name": "Luke J.", "orcid": "0000-0002-5738-1612" }, { "family_name": "Smith", "given_name": "Ken", "orcid": "0000-0001-9535-3199" }, { "family_name": "Taggart", "given_name": "Kirsty", "orcid": "0000-0002-5748-4558" }, { "family_name": "Tartaglia", "given_name": "Leonardo", "orcid": "0000-0003-3433-1492" }, { "family_name": "Zheng", "given_name": "WeiKang" }, { "family_name": "Anderson", "given_name": "Joseph P.", "orcid": "0000-0003-0227-3451" }, { "family_name": "Cassara", "given_name": "Letizia", "orcid": "0000-0001-5760-089X" }, { "family_name": "Christensen", "given_name": "Eric" }, { "family_name": "George Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Galbany", "given_name": "Llu\u00eds", "orcid": "0000-0002-1296-6887" }, { "family_name": "Gkini", "given_name": "Anamaria", "orcid": "0009-0000-9383-2305" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Gromadzki", "given_name": "Mariusz", "orcid": "0000-0002-1650-1518" }, { "family_name": "Groom", "given_name": "Steven L.", "orcid": "0000-0001-5668-3507", "clpid": "Groom-Steven-L" }, { "family_name": "Hiramatsu", "given_name": "Daichi", "orcid": "0000-0002-1125-9187" }, { "family_name": "Andrew Howell", "given_name": "D." }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "McCully", "given_name": "Curtis", "orcid": "0000-0001-5807-7893" }, { "family_name": "M\u00fcller-Bravo", "given_name": "Tom\u00e1s E.", "orcid": "0000-0003-3939-7167" }, { "family_name": "Paiano", "given_name": "Simona", "orcid": "0000-0002-2239-3373" }, { "family_name": "Paraskeva", "given_name": "Emmanouela" }, { "family_name": "Pessi", "given_name": "Priscila J.", "orcid": "0000-0002-8041-8559" }, { "family_name": "Polishook", "given_name": "David", "orcid": "0000-0002-6977-3146" }, { "family_name": "Rau", "given_name": "Arne" }, { "family_name": "Rigault", "given_name": "Mickael", "orcid": "0000-0002-8121-2560" }, { "family_name": "Rusholme", "given_name": "Ben", "orcid": "0000-0001-7648-4142", "clpid": "Rusholme-Benjamin" } ], "abstract": "Stars with zero-age main sequence masses between 140 and 260\u2006M\u2299 are thought to explode as pair-instability supernovae (PISNe). During their thermonuclear runaway, PISNe can produce up to several tens of solar masses of radioactive nickel, resulting in luminous transients similar to some superluminous supernovae (SLSNe). Yet, no unambiguous PISN has been discovered so far. SN 2018ibb is a hydrogen-poor SLSN at z\u2004=\u20040.166 that evolves extremely slowly compared to the hundreds of known SLSNe. Between mid 2018 and early 2022, we monitored its photometric and spectroscopic evolution from the UV to the near-infrared (NIR) with 2–10 m class telescopes. SN 2018ibb radiated > 3\u2005×\u20051051\u2006erg during its evolution, and its bolometric light curve reached > 2\u2005×\u20051044\u2006erg\u2006s−1 at its peak. The long-lasting rise of > 93 rest-frame days implies a long diffusion time, which requires a very high total ejected mass. The PISN mechanism naturally provides both the energy source (56Ni) and the long diffusion time. Theoretical models of PISNe make clear predictions as to their photometric and spectroscopic properties. SN 2018ibb complies with most tests on the light curves, nebular spectra and host galaxy, and potentially all tests with the interpretation we propose. Both the light curve and the spectra require 25–44 M\u2299 of freshly nucleosynthesised 56Ni, pointing to the explosion of a metal-poor star with a helium core mass of 120–130 M\u2299 at the time of death. This interpretation is also supported by the tentative detection of [Co\u202fII] λ 1.025 μm, which has never been observed in any other PISN candidate or SLSN before. We observe a significant excess in the blue part of the optical spectrum during the nebular phase, which is in tension with predictions of existing PISN models. However, we have compelling observational evidence for an eruptive mass-loss episode of the progenitor of SN 2018ibb shortly before the explosion, and our dataset reveals that the interaction of the SN ejecta with this oxygen-rich circumstellar material contributed to the observed emission. That may explain this specific discrepancy with PISN models. Powering by a central engine, such as a magnetar or a black hole, can be excluded with high confidence. This makes SN 2018ibb by far the best candidate for being a PISN, to date.
", "doi": "10.1051/0004-6361/202346855", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy & Astrophysics", "publication_date": "2024-03", "volume": "683", "pages": "A223" }, { "id": "authors:s572z-tab07", "collection": "authors", "collection_id": "s572z-tab07", "cite_using_url": "https://authors.library.caltech.edu/records/s572z-tab07", "type": "article", "title": "Strong gravitational lensing by AGNs as a probe of the quasar\u2013host relations in the distant Universe", "author": [ { "family_name": "Millon", "given_name": "Martin", "orcid": "0000-0001-7051-497X", "clpid": "Millon-Martin" }, { "family_name": "Courbin", "given_name": "Fr\u00e9d\u00e9ric", "orcid": "0000-0003-0758-6510", "clpid": "Courbin-Fr\u00e9d\u00e9ric" }, { "family_name": "Galan", "given_name": "Aymeric", "orcid": "0000-0003-2547-9815", "clpid": "Galan-Aymeric" }, { "family_name": "Sluse", "given_name": "Dominique", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-Dominique" }, { "family_name": "Ding", "given_name": "Xuheng", "orcid": "0000-0001-8917-2148", "clpid": "Ding-Xuheng" }, { "family_name": "Tewes", "given_name": "Malte", "orcid": "0000-0002-1155-8689", "clpid": "Tewes-Malte" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "The tight correlations found between the mass of supermassive black holes and the luminosities, stellar masses and velocity dispersions of their host galaxies are often interpreted as a sign of their co-evolution. Studying these correlations across redshift provides a powerful insight into the evolutionary path followed by the quasar and its host galaxy. While the mass of the black hole is accessible from single-epoch spectra, measuring the mass of its host galaxy is challenging as the active nucleus largely overshines its host. Here we present a technique to probe quasar–host relations beyond the local Universe with strong gravitational lensing, hence overcoming the use of stellar population models or velocity dispersion measurements, both prone to degeneracies. We study in detail one of the three known cases of strong lensing by a quasar to accurately measure the mass of its host and to infer a total lensing mass within the Einstein radius. The lensing measurement is more precise than any other alternative technique and compatible with the local scaling relation between the mass of the black hole and the stellar mass. The sample of such quasar–galaxy or quasar–quasar lensing systems should reach a few hundred with Euclid and the Rubin-Large Synoptic Survey Telescope, thus enabling the application of such a method with statistically significant sample sizes.
", "doi": "10.1038/s41550-023-01982-2", "issn": "2397-3366", "publisher": "Nature Publishing Group", "publication": "Nature Astronomy", "publication_date": "2023-08", "series_number": "8", "volume": "7", "issue": "8", "pages": "959-966" }, { "id": "authors:46n56-47e89", "collection": "authors", "collection_id": "46n56-47e89", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230328-706203600.24", "type": "article", "title": "Testing the Radio-selection Method of Dual Active Galactic Nuclei in the Stripe 82 Field", "author": [ { "family_name": "Gross", "given_name": "Arran C.", "orcid": "0000-0001-7681-9213", "clpid": "GrossArran-C" }, { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Myers", "given_name": "A. D.", "clpid": "Myers-Adam-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Steffen", "given_name": "Joshua L.", "orcid": "0000-0003-3299-9595", "clpid": "Steffen-Joshua-L" }, { "family_name": "Wrobel", "given_name": "J. M.", "orcid": "0000-0001-9720-7398", "clpid": "Wrobel-Joan-M" } ], "abstract": "We test the merger-induced dual active galactic nuclei (dAGNs) paradigm using a sample of 35 radio galaxy pairs from the Sloan Digital Sky Survey Stripe 82 field. Using Keck optical spectroscopy, we confirm 21 pairs have consistent redshifts, constituting kinematic pairs; the remaining 14 pairs are line-of-sight projections. We classify the optical spectral signatures via emission line ratios, equivalent widths, and excess of radio power above star formation predicted outputs. We find six galaxies are classified as LINERs and seven are AGN/starburst composites. Most of the LINERs are retired galaxies, while the composites likely have AGN contribution. All of the kinematic pairs exhibit radio power more than 10\u00d7 above the level expected from just star formation, suggestive of a radio AGN contribution. We also analyze high-resolution (0.\u20333) imaging at 6 GHz from the NSF's Karl G. Jansky Very Large Array for 17 of the kinematic pairs. We find six pairs (two new, four previously known) host two separate radio cores, confirming their status as dAGNs. The remaining 11 pairs contain single AGNs, with most exhibiting prominent jets/lobes overlapping their companion. Our final census indicates a dAGN duty cycle slightly higher than predictions of purely stochastic fueling, although a larger sample (potentially culled from VLASS) is needed to fully address the dAGN fraction. We conclude that while dAGNs in the Stripe 82 field are rare, the merger process plays some role in their triggering and it facilitates low to moderate levels of accretion.", "doi": "10.3847/1538-4357/acb646", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2023-03-01", "series_number": "1", "volume": "945", "issue": "1", "pages": "Art. No. 73" }, { "id": "authors:st18n-2bd60", "collection": "authors", "collection_id": "st18n-2bd60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230215-30605800.9", "type": "article", "title": "A Highly Magnified Gravitationally Lensed Red QSO at z = 2.5 with a Significant Flux Ratio Anomaly", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-Eilat" }, { "family_name": "Rusu", "given_name": "Cristian E.", "orcid": "0000-0003-4561-4017", "clpid": "Rusu-Cristian-E" }, { "family_name": "Chen", "given_name": "Geoff C.-F.", "orcid": "0000-0002-2580-6321", "clpid": "Chen-Geoff-C-F" }, { "family_name": "Chan", "given_name": "James Hung-Hsu", "orcid": "0000-0001-8797-725X", "clpid": "Chan-James-Hung-Hsu" }, { "family_name": "Spingola", "given_name": "Cristiana", "orcid": "0000-0002-2231-6861", "clpid": "Spingola-Cristiana" }, { "family_name": "Stacey", "given_name": "Hannah", "orcid": "0000-0002-8999-9636", "clpid": "Stacey-Hannah" }, { "family_name": "McKean", "given_name": "John", "clpid": "McKean-John" }, { "family_name": "Berghea", "given_name": "Ciprian T.", "orcid": "0000-0001-5538-5903", "clpid": "Berghea-Ciprian-T" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-Daniel" }, { "family_name": "Urrutia", "given_name": "Tanya", "orcid": "0000-0001-6746-9936", "clpid": "Urrutia-Tanya" }, { "family_name": "Lacy", "given_name": "Mark", "orcid": "0000-0002-3032-1783", "clpid": "Lacy-Mark" }, { "family_name": "Secrest", "given_name": "Nathan J.", "orcid": "0000-0002-4902-8077", "clpid": "Secrest-Nathan-J" }, { "family_name": "O'Meara", "given_name": "John M.", "orcid": "0000-0002-7893-1054", "clpid": "O'Meara-John-M" } ], "abstract": "We present the discovery of a gravitationally lensed dust-reddened QSO at z = 2.517, identified in a survey for QSOs by infrared selection. Hubble Space Telescope imaging reveals a quadruply lensed system in a cusp configuration, with a maximum image separation of \u223c1\u2033.8. We find that, compared to the central image of the cusp, the neighboring brightest image is anomalous by a factor of \u223c7\u201310, which is the largest flux anomaly measured to date in a lensed QSO. Incorporating high-resolution Very Large Array radio imaging and submillimeter imaging with the Atacama Large Millimeter/submillimeter Array, we conclude that a low-mass perturber is the most likely explanation for the anomaly. The optical through near-infrared spectrum reveals that the QSO is moderately reddened with E(B \u2212 V) \u2243 0.7\u20130.9. We see an upturn in the ultraviolet spectrum due to \u223c1% of the intrinsic emission being leaked back into the line of sight, which suggests that the reddening is intrinsic and not due to the lens. The QSO may have an Eddington ratio as high as L/L_Edd \u2248 0.2. Consistent with previous red QSO samples, this source exhibits outflows in its spectrum, as well as morphological properties suggestive of it being in a merger-driven transitional phase. We find a host galaxy stellar mass of log M\u22c6/M_\u2299 = 11.4, which is higher than the local M_BH versus M\u22c6 relation but consistent with other high-redshift QSOs. When demagnified, this QSO is at the knee of the luminosity function, allowing for the detailed study of a more typical moderate-luminosity infrared-selected QSO at high redshift.", "doi": "10.3847/1538-4357/aca093", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2023-01-20", "series_number": "1", "volume": "943", "issue": "1", "pages": "Art. No. 25" }, { "id": "authors:zr9he-c2023", "collection": "authors", "collection_id": "zr9he-c2023", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230206-9587900.11", "type": "article", "title": "A Light in the Dark: Searching for Electromagnetic Counterparts to Black Hole-Black Hole Mergers in LIGO/Virgo O3 with the Zwicky Transient Facility", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "McKernan", "given_name": "Barry", "orcid": "0000-0002-9726-0508", "clpid": "McKernan-Barry" }, { "family_name": "Ford", "given_name": "K. E. Saavik", "orcid": "0000-0002-5956-851X", "clpid": "Ford-K-E-Saavik" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-Daniel" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Coughlin", "given_name": "Michael", "orcid": "0000-0002-8262-2924", "clpid": "Coughlin-Michael-W" }, { "family_name": "Burdge", "given_name": "Kevin B.", "orcid": "0000-0002-7226-836X", "clpid": "Burdge-Kevin-B" }, { "family_name": "Bellm", "given_name": "Eric C.", "orcid": "0000-0001-8018-5348", "clpid": "Bellm-Eric-C" }, { "family_name": "Helou", "given_name": "George", "orcid": "0000-0003-3367-3415", "clpid": "Helou-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-Ashish-A" }, { "family_name": "Masci", "given_name": "Frank J.", "orcid": "0000-0002-8532-9395", "clpid": "Masci-Frank-J" }, { "family_name": "Purdum", "given_name": "Josiah", "orcid": "0000-0003-1227-3738", "clpid": "Purdum-Josiah-N" }, { "family_name": "Rosnet", "given_name": "Philippe", "orcid": "0000-0002-6099-7565", "clpid": "Rosnet-Philippe" }, { "family_name": "Rusholme", "given_name": "Ben", "orcid": "0000-0001-7648-4142", "clpid": "Rusholme-Benjamin" } ], "abstract": "The accretion disks of active galactic nuclei (AGNs) are promising locations for the merger of compact objects detected by gravitational wave (GW) observatories. Embedded within a baryon-rich, high-density environment, mergers within AGNs are the only GW channel where an electromagnetic (EM) counterpart must occur (whether detectable or not). Considering AGNs with unusual flaring activity observed by the Zwicky Transient Facility (ZTF), we describe a search for candidate EM counterparts to binary black hole (BBH) mergers detected by LIGO/Virgo in O3. After removing probable false positives, we find nine candidate counterparts to BBH mergers during O3 (seven in O3a, two in O3b) with a p-value of 0.0019. Based on ZTF sky coverage, AGN geometry, and merger geometry, we expect \u22483(N_(BBH)/83)(f_(AGN)/0.5) potentially detectable EM counterparts from O3, where N_(BBH) is the total number of observed BBH mergers and f_(AGN) is the fraction originating in AGNs. Further modeling of breakout and flaring phenomena in AGN disks is required to reduce our false-positive rate. Two of the events are also associated with mergers with total masses >100 M_\u2299, which is the expected rate for O3 if hierarchical (large-mass) mergers occur in the AGN channel. Candidate EM counterparts in future GW observing runs can be better constrained by coverage of the Southern sky as well as spectral monitoring of unusual AGN flaring events in LIGO/Virgo alert volumes. A future set of reliable AGN EM counterparts to BBH mergers will yield an independent means of measuring cosmic expansion (H\u2080) as a function of redshift.", "doi": "10.3847/1538-4357/aca480", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2023-01-10", "series_number": "2", "volume": "942", "issue": "2", "pages": "Art. No. 99" }, { "id": "authors:626s7-x5a92", "collection": "authors", "collection_id": "626s7-x5a92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230817-224044768", "type": "monograph", "title": "Data-Driven Approaches to Searches for the Technosignatures of Advanced Civilizations", "author": [ { "family_name": "Lazio", "given_name": "Joseph", "clpid": "Lazio-J-W" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Cutler", "given_name": "Curt", "orcid": "0000-0002-2080-1468", "clpid": "Cutler-C-J" }, { "family_name": "Howard", "given_name": "Andrew", "orcid": "0000-0001-8638-0320", "clpid": "Howard-A-W" } ], "abstract": "Humanity has wondered whether we are alone and about the existence of \"others\" for millennia. The discovery of life elsewhere in the Universe, particularly intelligent life, would have profound scientific, cultural, and societal effects, comparable to those of recognizing that the Earth is not the center of the Universe and that humans (Homo sapiens) evolved from previous species. \n\nThe past two decades have witnessed rapid growths in both the fields of extrasolar planets and data-driven astronomy. In a relatively short interval, we have seen a change from knowing of no extrasolar planets to now knowing far more potentially habitable extrasolar planets than there are planets in the Solar System. In approximately the same interval, astronomy has transitioned from a relatively data-starved field into one in which extensive sky surveys can generate 1 quadrillion bytes (= 10\u00b9\u2075B = 1PB) or more of data. \n\nThe Data-Driven Approaches to Searches for the Technosignatures of Advanced Civilizations study at the W. M. Keck Institute for Space Studies was intended to revisit searches for evidence of alien technologies in light of these two developments. Experts from around the world, in a variety of disciplines, gathered for a week to assess what new kinds of searches might be able to be undertaken. \n\nOf particular value for the search for technosignatures is that a data-driven approach may be able to mitigate biases, particularly unknown ones. Data-driven searches, being able to process volumes of data much greater than a human could, and in a reproducible manner, can identify anomalies\u2014data\nthat are inconsistent with a larger sample\u2014that could be clues to the presence of technosignatures. \n\nWhile the focus of the study was identifying technosignatures from other civilizations, it was recognized that there are other intelligent species on this planet, even if they do not employ technologies capable of being detected over interstellar distances. Learning from how various species have interacted, or coopted interactions, may provide clues for how to search for extraterrestrial intelligent species. Even more tantalizing would be if universal rules for communication among terrestrial species were to be identified. \n\nA key outcome of this workshop was that technosignature searches should be conducted in a manner consistent with Freeman Dyson's \"First Law of SETI Investigations,\" namely \"every search for alien civilizations should be planned to give interesting results even when no aliens are discovered.\" This approach to technosignature searches is commensurate with NASA's approach to biosignatures in that\nno single observation or measurement can be taken as providing full certainty for the detection of life. \n\nThere was broad agreement at the workshop that a variety of machine learning techniques could be of value in searching large data volumes. These techniques range from extensions to the classic matched filtering techniques to techniques in which the members of a data set can be organized into groups\nbased solely on the characteristics of the individual members. These machine learning techniques already are being applied, with increasing success, to a variety of problems in astronomy and other fields. Consequently, machine learning techniques present powerful tools for identifying anomalies in data. \n\nAreas of particular promise identified during the workshop were the following: \n\nData Mining of Large Sky Surveys Various large sky surveys are in the process of being conducted or will initiate in the next decade. Not only will these surveys be conducted at a variety of wavelengths, many of them are introducing a time domain aspect, enabling rich multi-parameter searches for anomalies to be conducted. \n\nAll-Sky Survey at Far-Infrared Wavelengths No technology can be perfectly efficient, because of the Second Law of Thermodynamics. Any technology using substantial amounts of energy therefore will radiate some fraction of that energy as \"waste heat,\" likely to be emitted at far-IR wavelengths. An all-sky survey at far-IR wavelengths could be profitable for both technosignature searches and the larger field of astronomy. \n\nSurveys with Radio Astronomical Interferometers Searches at radio wavelengths have a long history in the technosignature field. Traditionally, these surveys have been performed with a single large radio antenna. Many technosignatures have been found, but they have been interference from terrestrial transmitters. The emerging suite of radio astronomical interferometers offers new possibilities for a combination of interference rejection and opening additional parameter space for technosignature searches. \n\nArtifacts in the Solar System Even with the number of robotic spacecraft sent throughout the Solar System, there remains a great number of planetary bodies and vast reaches of interplanetary space that have been surveyed poorly, if at all. Further exploration of the Solar System is commensurate with larger planetary science objectives. Moreover, in the Solar System, there are terrestrial technosignatures on the Moon and Mars, the product of decades of international explorations of those bodies, that can be used as training grounds for searches for technosignatures elsewhere in the Solar System.", "doi": "10.26206/gvmj-sn65", "publisher": "Keck Institute for Space Studies", "publication_date": "2023" }, { "id": "authors:fc0wx-87p82", "collection": "authors", "collection_id": "fc0wx-87p82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221201-39196300.4", "type": "article", "title": "Multiwavelength Observations of the Obscuring Wind in the Radio-quiet Quasar MR 2251-178", "author": [ { "family_name": "Mao", "given_name": "Junjie", "orcid": "0000-0001-7557-9713", "clpid": "Mao-Junjie" }, { "family_name": "Kriss", "given_name": "G. A.", "orcid": "0000-0002-2180-8266", "clpid": "Kriss-Gerard-A" }, { "family_name": "Landt", "given_name": "H.", "clpid": "Landt-Hermine" }, { "family_name": "Mehdipour", "given_name": "M.", "orcid": "0000-0002-4992-4664", "clpid": "Mehdipour-Missagh" }, { "family_name": "Kaastra", "given_name": "J. S.", "orcid": "0000-0001-5540-2822", "clpid": "Kaastra-Jelle-S" }, { "family_name": "Miller", "given_name": "J. M.", "orcid": "0000-0003-2869-7682", "clpid": "Miller-Jon-M" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-Daniel" }, { "family_name": "Gallo", "given_name": "L. C.", "clpid": "Gallo-Luigi-C" }, { "family_name": "Gonzalez", "given_name": "A. G.", "orcid": "0000-0003-3678-5033", "clpid": "Gonzalez-Adam-G" }, { "family_name": "Simon", "given_name": "J. J.", "clpid": "Simon-Joseph-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Anand", "given_name": "S.", "orcid": "0000-0003-3768-7515", "clpid": "Anand-Shreya" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Karambelkar", "given_name": "V.", "orcid": "0000-0003-2758-159X", "clpid": "Karambelkar-Viraj-R" } ], "abstract": "Obscuring winds driven away from active supermassive black holes are rarely seen due to their transient nature. They have been observed with multiwavelength observations in a few Seyfert 1 galaxies and one broad absorption line radio-quiet quasar so far. An X-ray obscuration event in MR 2251-178 was caught in late-2020, which triggered multiwavelength (near-IR (NIR) to X-ray) observations targeting this radio-quiet quasar. In the X-ray band, the obscurer leads to a flux drop in the soft X-ray band from late-2020 to early-2021. X-ray obscuration events might have a quasi-period of two decades considering earlier events in 1980 and 1996. In the UV band, a forest of weak blueshifted absorption features emerged in the blue wing of Ly\u03b1 \u03bb1216 in late-2020. Our XMM-Newton, NuSTAR, and Hubble Space Telescope/COS observations are obtained simultaneously; hence, the transient X-ray obscuration event is expected to account for the UV outflow, although they are not necessarily caused by the same part of the wind. Both blueshifted and redshifted absorption features were found for He \u026a \u03bb10830, but no previous NIR spectra are available for comparison. The X-ray observational features of MR 2251-178 shared similarities with some other type 1 active galactic nuclei (AGNs) with obscuring wind. However, observational features in the UV to NIR bands are distinctly different from those seen in other AGN with obscuring winds. A general understanding of the observational variety and the nature of obscuring wind is still lacking.", "doi": "10.3847/1538-4357/ac99de", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2022-11-20", "series_number": "1", "volume": "940", "issue": "1", "pages": "Art. No. 41" }, { "id": "authors:17qpv-z8g38", "collection": "authors", "collection_id": "17qpv-z8g38", "cite_using_url": "https://authors.library.caltech.edu/records/17qpv-z8g38", "type": "article", "title": "A fast radio burst source at a complex magnetized site in a barred galaxy", "author": [ { "family_name": "Xu", "given_name": "H.", "clpid": "Xu-H" }, { "family_name": "Niu", "given_name": "J. R." }, { "family_name": "Chen", "given_name": "P." }, { "family_name": "Lee", "given_name": "K. J.", "orcid": "0000-0002-1435-0883" }, { "family_name": "Zhu", "given_name": "W. W.", "orcid": "0000-0001-5105-4058" }, { "family_name": "Dong", "given_name": "S.", "orcid": "0000-0002-1027-0990" }, { "family_name": "Zhang", "given_name": "B.", "orcid": "0000-0002-9725-2524" }, { "family_name": "Jiang", "given_name": "J. C." }, { "family_name": "Wang", "given_name": "B. J." }, { "family_name": "Xu", "given_name": "J. W." }, { "family_name": "Zhang", "given_name": "C. F." }, { "family_name": "Fu", "given_name": "H." }, { "family_name": "Filippenko", "given_name": "A. V." }, { "family_name": "Peng", "given_name": "E. W." }, { "family_name": "Zhou", "given_name": "D. J." }, { "family_name": "Zhang", "given_name": "Y. K." }, { "family_name": "Wang", "given_name": "P." }, { "family_name": "Feng", "given_name": "Y." }, { "family_name": "Li", "given_name": "Y." }, { "family_name": "Brink", "given_name": "T. G." }, { "family_name": "Li", "given_name": "D. Z.", "orcid": "0000-0001-7931-0607", "clpid": "Li-Dongzi" }, { "family_name": "Lu", "given_name": "W." }, { "family_name": "Yang", "given_name": "Y. P." }, { "family_name": "Caballero", "given_name": "R. N." }, { "family_name": "Cai", "given_name": "C." }, { "family_name": "Chen", "given_name": "M. Z." }, { "family_name": "Dai", "given_name": "Z. G." }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Esamdin", "given_name": "A." }, { "family_name": "Gan", "given_name": "H. Q." }, { "family_name": "Guhathakurta", "given_name": "P." }, { "family_name": "Han", "given_name": "J. L." }, { "family_name": "Hao", "given_name": "L. F." }, { "family_name": "Huang", "given_name": "Y. X." }, { "family_name": "Jiang", "given_name": "P." }, { "family_name": "Li", "given_name": "C. K." }, { "family_name": "Li", "given_name": "D." }, { "family_name": "Li", "given_name": "H." }, { "family_name": "Li", "given_name": "X. Q." }, { "family_name": "Li", "given_name": "Z. X." }, { "family_name": "Liu", "given_name": "Z. Y." }, { "family_name": "Luo", "given_name": "R." }, { "family_name": "Men", "given_name": "Y. P." }, { "family_name": "Niu", "given_name": "C. H." }, { "family_name": "Peng", "given_name": "W. X." }, { "family_name": "Qian", "given_name": "L." }, { "family_name": "Song", "given_name": "L. M." }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Stockton", "given_name": "A." }, { "family_name": "Sun", "given_name": "J. H." }, { "family_name": "Wang", "given_name": "F. Y." }, { "family_name": "Wang", "given_name": "M." }, { "family_name": "Wang", "given_name": "N." }, { "family_name": "Wang", "given_name": "W. Y." }, { "family_name": "Wu", "given_name": "X. F." }, { "family_name": "Xiao", "given_name": "S." }, { "family_name": "Xiong", "given_name": "S. L." }, { "family_name": "Xu", "given_name": "Y. H." }, { "family_name": "Xu", "given_name": "R. X." }, { "family_name": "Yang", "given_name": "J." }, { "family_name": "Yang", "given_name": "X." }, { "family_name": "Yao", "given_name": "R." }, { "family_name": "Yi", "given_name": "Q. B." }, { "family_name": "Yue", "given_name": "Y. L." }, { "family_name": "Yu", "given_name": "D. J." }, { "family_name": "Yu", "given_name": "W. F." }, { "family_name": "Yuan", "given_name": "J. P." }, { "family_name": "Zhang", "given_name": "B. B." }, { "family_name": "Zhang", "given_name": "S. B." }, { "family_name": "Zhang", "given_name": "S. N." }, { "family_name": "Zhao", "given_name": "Y." }, { "family_name": "Zheng", "given_name": "W. K." }, { "family_name": "Zhu", "given_name": "Y." }, { "family_name": "Zou", "given_name": "J. H." } ], "abstract": "Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts. Recent observations of a Galactic FRB suggest that at least some FRBs originate from magnetars, but the origin of cosmological FRBs is still not settled. Here we report the detection of 1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref. 9). These observations show irregular short-time variation of the Faraday rotation measure (RM), which scrutinizes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (au; Earth–Sun distance) of the source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.
", "doi": "10.1038/s41586-022-05071-8", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2022-09-22", "volume": "609", "pages": "685-688" }, { "id": "authors:k28t8-5m234", "collection": "authors", "collection_id": "k28t8-5m234", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220811-235078000", "type": "article", "title": "The WISE-2MASS Survey: Red Quasars Into the Radio Quiet Regime", "author": [ { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-Eilat" }, { "family_name": "Lacy", "given_name": "M.", "orcid": "0000-0002-3032-1783", "clpid": "Lacy-Mark" }, { "family_name": "LaMassa", "given_name": "S.", "orcid": "0000-0002-5907-3330", "clpid": "LaMassa-Stephanie-M" }, { "family_name": "Bradley", "given_name": "C.", "clpid": "Bradley-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Urrutia", "given_name": "T.", "orcid": "0000-0001-6746-9936", "clpid": "Urrutia-Tanya" }, { "family_name": "Gates", "given_name": "E. L.", "orcid": "0000-0002-3739-0423", "clpid": "Gates-Elinor-L" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Urry", "given_name": "M.", "orcid": "0000-0002-0745-9792", "clpid": "Urry-C-Megan" }, { "family_name": "Yoon", "given_name": "I.", "orcid": "0000-0001-9163-0064", "clpid": "Yoon-Ilsang" } ], "abstract": "We present a highly complete sample of broad-line (Type 1) QSOs out to z \u223c 3 selected by their mid-infrared colors, a method that is minimally affected by dust reddening. We remove host-galaxy emission from the spectra and fit for excess reddening in the residual QSOs, resulting in a Gaussian distribution of colors for unreddened (blue) QSOs, with a tail extending toward heavily reddened (red) QSOs, defined as having E(B \u2212 V) > 0.25. This radio-independent selection method enables us to compare red and blue QSO radio properties in both the FIRST (1.4 GHz) and VLASS (2\u20134 GHz) surveys. Consistent with recent results from optically selected QSOs from SDSS, we find that red QSOs have a significantly higher detection fraction and a higher fraction of compact radio morphologies at both frequencies. We employ radio stacking to investigate the median radio properties of the QSOs including those that are undetected in FIRST and VLASS, finding that red QSOs have significantly brighter radio emission and steeper radio spectral slopes compared with blue QSOs. Finally, we find that the incidence of red QSOs is strongly luminosity dependent, where red QSOs make up >40% of all QSOs at the highest luminosities. Overall, red QSOs comprise \u223c40% of higher luminosity QSOs, dropping to only a few percent at lower luminosities. Furthermore, red QSOs make up a larger percentage of the radio-detected QSO population. We argue that dusty AGN-driven winds are responsible for both the obscuration as well as excess radio emission seen in red QSOs.", "doi": "10.3847/1538-4357/ac6bee", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2022-08-01", "series_number": "2", "volume": "934", "issue": "2", "pages": "Art. No. 119" }, { "id": "authors:3116m-9rw43", "collection": "authors", "collection_id": "3116m-9rw43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220223-214606017", "type": "article", "title": "Gaia GraL: Gaia DR2 Gravitational Lens Systems. VII. XMM-Newton Observations of Lensed Quasars", "author": [ { "family_name": "Connor", "given_name": "Thomas", "orcid": "0000-0002-7898-7664", "clpid": "Connor-Thomas-P" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-Daniel" }, { "family_name": "Krone-Martins", "given_name": "Alberto", "orcid": "0000-0002-2308-6623", "clpid": "Krone-Martins-Alberto" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Walton", "given_name": "Dominic J.", "orcid": "0000-0001-5819-3552", "clpid": "Walton-Dominic-J" }, { "family_name": "Delchambre", "given_name": "Ludovic", "orcid": "0000-0003-2559-408X", "clpid": "Delchambre-Ludovic" }, { "family_name": "Ducourant", "given_name": "Christine", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-Christine" }, { "family_name": "Teixeira", "given_name": "Ramachrisna", "orcid": "0000-0002-6806-6626", "clpid": "Teixeira-Ramachrisna" }, { "family_name": "Le Campion", "given_name": "Jean-Fran\u00e7ois", "clpid": "Le-Campion-Jean-Fran\u00e7ois" }, { "family_name": "den Brok", "given_name": "Jakob Sebastian", "orcid": "0000-0002-8760-6157", "clpid": "den-Brok-Jakob-S" }, { "family_name": "Dobie", "given_name": "Dougal", "orcid": "0000-0003-0699-7019", "clpid": "Dobie-Dougal" }, { "family_name": "Galluccio", "given_name": "Laurent", "orcid": "0000-0002-8541-0476", "clpid": "Galluccio-Laurent" }, { "family_name": "Jalan", "given_name": "Priyanka", "orcid": "0000-0002-0524-5328", "clpid": "Jalan-Priyanka" }, { "family_name": "Klioner", "given_name": "Sergei A.", "orcid": "0000-0003-4682-7831", "clpid": "Kiloner-Sergei-A" }, { "family_name": "Kl\u00fcter", "given_name": "Jonas", "orcid": "0000-0002-3469-5133", "clpid": "Kl\u00fcter-Jonas" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-Ashish-A" }, { "family_name": "Negi", "given_name": "Vibhore", "orcid": "0000-0001-5824-1040", "clpid": "Negi-Vibhore" }, { "family_name": "Nierenberg", "given_name": "Anna", "orcid": "0000-0001-6809-2536", "clpid": "Nierenberg-Anna-M" }, { "family_name": "Petit", "given_name": "Quentin", "clpid": "Petit-Quentin" }, { "family_name": "Scarano", "given_name": "Sergio, Jr.", "orcid": "0000-0003-3739-4288", "clpid": "Scarano-Sergio-Jr" }, { "family_name": "Slezak", "given_name": "Eric", "clpid": "Slezak-Eric" }, { "family_name": "Sluse", "given_name": "Dominique", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-Dominique" }, { "family_name": "Sp\u00edndola-Duarte", "given_name": "Carolina", "orcid": "0000-0002-8052-7763", "clpid": "Sp\u00edndola-Duarte-Carolina" }, { "family_name": "Surdej", "given_name": "Jean", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-Jean" }, { "family_name": "Wambsganss", "given_name": "Joachim", "orcid": "0000-0002-8365-7619", "clpid": "Wambsganss-Joachim" }, { "literal": "Gaia GraL Team" } ], "abstract": "We present XMM-Newton X-ray observations of nine confirmed lensed quasars at 1 \u2272 z \u2272 3 identified by the Gaia Gravitational Lens program. Eight systems are strongly detected, with 0.3\u20138.0 keV fluxes F_(0.3\u22128.0) \u2273 5 \u00d710\u207b\u00b9\u2074 erg cm\u207b\u00b2 s\u207b\u00b9. Modeling the X-ray spectra with an absorbed power law, we derive power-law photon indices and 2\u201310 keV luminosities for the eight detected quasars. In addition to presenting sample properties for larger quasar population studies and for use in planning for future caustic-crossing events, we also identify three quasars of interest: a quasar that shows evidence of flux variability from previous ROSAT observations, the most closely separated individual lensed sources resolved by XMM-Newton, and one of the X-ray brightest quasars known at z > 3. These sources represent the tip of the discoveries that will be enabled by SRG/eROSITA.", "doi": "10.3847/1538-4357/ac4476", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2022-03-01", "series_number": "1", "volume": "927", "issue": "1", "pages": "Art. No. 45" }, { "id": "authors:p1epc-v0664", "collection": "authors", "collection_id": "p1epc-v0664", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210224-084056817", "type": "article", "title": "Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply Imaged Lensed Quasars", "author": [ { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-Daniel" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Krone-Martins", "given_name": "A.", "orcid": "0000-0002-2308-6623", "clpid": "Krone-Martins-Alberto" }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-Dominique" }, { "family_name": "Delchambre", "given_name": "L.", "orcid": "0000-0003-2559-408X", "clpid": "Delchambre-Ludovic" }, { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-Christine" }, { "family_name": "Teixeira", "given_name": "R.", "orcid": "0000-0002-6806-6626", "clpid": "Teixeira-Ramachrisna" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-Jean" }, { "family_name": "Boehm", "given_name": "C.", "clpid": "Boehm-C" }, { "family_name": "den Brok", "given_name": "J.", "orcid": "0000-0002-8760-6157", "clpid": "den-Brok-Jakob" }, { "family_name": "Dobie", "given_name": "D.", "orcid": "0000-0003-0699-7019", "clpid": "Dobie-Dougal" }, { "family_name": "Drake", "given_name": "A.", "clpid": "Drake-Andrew-J" }, { "family_name": "Galluccio", "given_name": "L.", "orcid": "0000-0002-8541-0476", "clpid": "Galluccio-Laurent" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Jalan", "given_name": "P.", "clpid": "Jalan-P" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "orcid": "0000-0002-3469-5133", "clpid": "Kl\u00fcter-Jonas" }, { "family_name": "LeCampion", "given_name": "J.-F.", "clpid": "LeCampion-J-F" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-Ashish-A" }, { "family_name": "Mignard", "given_name": "F.", "clpid": "Mignard-F" }, { "family_name": "Murphy", "given_name": "T.", "orcid": "0000-0002-2686-438X", "clpid": "Murphy-Tara" }, { "family_name": "Nierenberg", "given_name": "A.", "orcid": "0000-0001-6809-2536", "clpid": "Nierenberg-Anna-M" }, { "family_name": "Scarano", "given_name": "S., Jr.", "clpid": "Scarano-S-Jr" }, { "family_name": "Simon", "given_name": "J.", "orcid": "0000-0003-1407-6607", "clpid": "Simon-Joseph" }, { "family_name": "Slezak", "given_name": "E.", "clpid": "Slezak-E" }, { "family_name": "Spindola-Duarte", "given_name": "C.", "orcid": "0000-0002-8052-7763", "clpid": "Spindola-Duarte-Carolina" }, { "family_name": "Wambsganss", "given_name": "J.", "orcid": "0000-0002-8365-7619", "clpid": "Wambsganss-Joachim" } ], "abstract": "Combining the exquisite angular resolution of Gaia with optical light curves and WISE photometry, the Gaia Gravitational Lenses group (GraL) uses machine-learning techniques to identify candidate strongly lensed quasars, and has confirmed over two dozen new strongly lensed quasars from the Gaia Data Release 2. This paper reports on the 12 quadruply imaged quasars identified by this effort to date, which is a \u223c20% increase in the total number of confirmed quadruply imaged quasars. We discuss the candidate selection, spectroscopic follow-up, and lens modeling. We also report our spectroscopic failures as an aid for future investigations.", "doi": "10.3847/1538-4357/ac0f04", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2021-11-01", "series_number": "1", "volume": "921", "issue": "1", "pages": "Art. No. 42" }, { "id": "authors:c674f-hkg31", "collection": "authors", "collection_id": "c674f-hkg31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211027-160410998", "type": "article", "title": "Deep co-added sky from Catalina Sky Survey images", "author": [ { "family_name": "Singhal", "given_name": "Akshat", "orcid": "0000-0003-1275-1904", "clpid": "Singhal-Akshat" }, { "family_name": "Bhalerao", "given_name": "Varun", "orcid": "0000-0002-6112-7609", "clpid": "Bhalerao-Varun" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-Ashish-A" }, { "family_name": "Vaghmare", "given_name": "Kaustubh", "orcid": "0000-0003-4525-1172", "clpid": "Vaghmare-Kaustubh" }, { "family_name": "Jagade", "given_name": "Santosh", "clpid": "Jagade-Santosh" }, { "family_name": "Kulkarni", "given_name": "Sumeet", "clpid": "Kulkarni-Sumeet" }, { "family_name": "Vibhute", "given_name": "Ajay", "orcid": "0000-0003-1501-6972", "clpid": "Vibhute-Ajay" }, { "family_name": "Kembhavi", "given_name": "Ajit K.", "orcid": "0000-0003-0598-4152", "clpid": "Kembhavi-Ajit-K" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-Andrew-J" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-Ciro" }, { "family_name": "Christensen", "given_name": "Eric", "clpid": "Christensen-Eric" }, { "family_name": "Larson", "given_name": "Stephen", "orcid": "0000-0001-6643-6032", "clpid": "Larson-Stephen-M" }, { "family_name": "Beshore", "given_name": "Edward C.", "clpid": "Beshore-Edward-C" } ], "abstract": "A number of synoptic sky surveys are underway or being planned. Typically, they are done with small telescopes and relatively short exposure times. A search for transient or variable sources involves comparison with deeper baseline images, ideally obtained through the same telescope and camera. With that in mind, we have stacked images from the 0.68 m Schmidt telescope on Mt. Bigelow taken over 10 yr as part of the Catalina Sky Survey. In order to generate deep reference images for the Catalina Real-time Transient Survey (CRTS), close to 0.8 million images over 8000 fields and covering over 27 000 sq. deg have gone into the deep stack that goes up to 3 mag deeper than individual images. CRTS system does not use a filter in imaging; hence, there is no standard passband in which the optical magnitude is measured. We estimate depth by comparing these wide-band unfiltered co-added images with images in the g band and find that the image depth ranges from 22.0 to 24.2 across the sky, with a 200-image stack attaining an equivalent AB magnitude sensitivity of 22.8. We compared various state-of-the-art software packages for co-adding astronomical images and have used SWARP for the stacking. We describe here the details of the process adopted. This methodology may be useful in other panoramic imaging applications, and to other surveys as well. The stacked images are available through a server at Inter-University Centre for Astronomy and Astrophysics.", "doi": "10.1093/mnras/stab2246", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2021-11", "series_number": "4", "volume": "507", "issue": "4", "pages": "4983-4996" }, { "id": "authors:t325f-vze13", "collection": "authors", "collection_id": "t325f-vze13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210602-083054714", "type": "article", "title": "Detection of period variations of eclipsing binaries in the Catalina Sky Survey", "author": [ { "family_name": "Papageorgiou", "given_name": "Athanasios", "orcid": "0000-0002-3039-9257", "clpid": "Papageorgiou-Athanasios" }, { "family_name": "Catelan", "given_name": "M\u00e1rcio", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M\u00e1rcio" }, { "family_name": "Christopoulou", "given_name": "Panagiota-Eleftheria", "clpid": "Christopoulou-Panagiota-Eleftheria" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-Andrew-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present 126 eclipsing binary candidates among 4683 Catalina Sky Surveys (CSS) detached and semi-detached eclipsing binary systems (EBs) showing cyclic or quadratic period variations over a 12 yr time span. By using inverse Gaussian profiles of the eclipses coupled with a Markov chain Monte Carlo procedure, times of minima (ToM) were calculated and diagrams with eclipse timing variations (ETVs) were constructed. Numerical tests were performed, involving synthetic EBs with period variations generated by the PHOEBE 2.0 engine and actual data for EBs with well-known period variations from the literature, to verify that the calculation of ToM variations for our CSS systems is reliable. A total of 63 out of the 126 EBs show likely cyclic ETVs, while the remainder present quadratic behaviour instead. Periods, amplitudes, period change rates, and associated errors were determined by using sinusoidal and parabolic models. 12 out of the 63 EBs (19 per\u2009cent) that appear to exhibit periodic ETVs are low-mass candidates. Additionally, four out of 126 also have maximum quadrature light variations. The possibility that the cyclic variations are caused by the light traveltime effect due to the presence of a tertiary companion is investigated. The possible nature of the quadratic ETVs is also discussed.", "doi": "10.1093/mnras/stab646", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2021-05", "series_number": "2", "volume": "503", "issue": "2", "pages": "2979-2999" }, { "id": "authors:bvn29-cmw42", "collection": "authors", "collection_id": "bvn29-cmw42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201119-131350410", "type": "article", "title": "What we can learn from eclipsing binaries in large surveys: The case of EA Catalina systems", "author": [ { "family_name": "Papageorgiou", "given_name": "A.", "orcid": "0000-0002-3039-9257", "clpid": "Papageorgiou-Athanasios" }, { "family_name": "Christopoulou", "given_name": "P.-E.", "clpid": "Christopoulou-P-E" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M\u00e1rcio" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "With the recent availability of large-scale multi-epoch photometric datasets, we were able to study EBs en masse. Large samples are useful to determine not only statistical properties but for finding strange and curious systems that no one had ever studied before, binaries with peculiarities that may reveal physical significance. We present an updated and more detailed catalog of 4680 Northern EAs in the Catalina Sky Survey (CSS). This work includes, new systems, revised period determination and ephemerides, system morphology classification based on machine learning techniques, computation of principal physical parameters with the EBAI (Eclipsing Binary via Artificial Intelligence) and detection of eclipse timing variations. We identify several groups of interesting systems including those with low mass K and M dwarfs, systems with longterm modulation of the maximum brightness, systems with longterm period modulation, potential triple systems and systems with magnetic activity.", "doi": "10.31577/caosp.2020.50.4.774", "issn": "1335-1842", "publisher": "Central Library of the Slovak Academy of Sciences", "publication": "Contributions of the Astronomical Observatory Skalnat\u00e9 Pleso", "publication_date": "2020-11-02", "series_number": "4", "volume": "50", "issue": "4", "pages": "774-778" }, { "id": "authors:9gw3w-kwm43", "collection": "authors", "collection_id": "9gw3w-kwm43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200414-070718405", "type": "article", "title": "Deep Modeling of Quasar Variability", "author": [ { "family_name": "Tachibana", "given_name": "Yutaro", "orcid": "0000-0001-6584-6945", "clpid": "Tachibana-Yutaro" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Kawai", "given_name": "Nobuyuki", "orcid": "0000-0001-9656-0261", "clpid": "Kawai-Nobuyuki" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" } ], "abstract": "Quasars have long been known as intrinsically variable sources, but the physical mechanism underlying the temporal optical/UV variability is still not well understood. We propose a novel nonparametric method for modeling and forecasting the optical variability of quasars utilizing an AE neural network to gain insight into the underlying processes. The AE is trained with ~15,000 decade-long quasar light curves obtained by the Catalina Real-time Transient Survey selected with negligible flux contamination from the host galaxy. The AE's performance in forecasting the temporal flux variation of quasars is superior to that of the damped random walk process. We find a temporal asymmetry in the optical variability and a novel relation\u2014the amplitude of the variability asymmetry decreases as luminosity and/or black hole mass increases\u2014is suggested with the help of autoencoded features. The characteristics of the variability asymmetry are in agreement with those from the self-organized disk instability model, which predicts that the magnitude of the variability asymmetry decreases as the ratio of the diffusion mass to inflow mass in the accretion disk increases.", "doi": "10.3847/1538-4357/abb9a9", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2020-11-01", "series_number": "1", "volume": "903", "issue": "1", "pages": "Art. No. 54" }, { "id": "authors:rb9vc-rbe75", "collection": "authors", "collection_id": "rb9vc-rbe75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200413-151905111", "type": "article", "title": "Chandra Observations of Candidate Subparsec Binary Supermassive Black Holes", "author": [ { "family_name": "Saade", "given_name": "M. Lynne", "orcid": "0000-0001-7163-7015", "clpid": "Saade-M-L" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Brightman", "given_name": "Murray", "orcid": "0000-0002-8147-2602", "clpid": "Brightman-M" }, { "family_name": "Haiman", "given_name": "Zolt\u00e1n", "orcid": "0000-0003-3633-5403", "clpid": "Haiman-Z" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "D'Orazio", "given_name": "Daniel", "orcid": "0000-0002-1271-6247", "clpid": "D'Orazio-D-J" }, { "family_name": "Ford", "given_name": "K. E. S.", "clpid": "Ford-K-E-S" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Jun", "given_name": "Hyunsung D.", "orcid": "0000-0003-1470-5901", "clpid": "Jun-Hyunsung-David" }, { "family_name": "Kraft", "given_name": "Ralph P.", "orcid": "0000-0002-0765-0511", "clpid": "Kraft-R-P" }, { "family_name": "McKernan", "given_name": "Barry", "orcid": "0000-0002-9726-0508", "clpid": "McKernan-B" }, { "family_name": "Vikhlinin", "given_name": "Alexei", "orcid": "0000-0001-8121-0234", "clpid": "Vikhlinin-A" }, { "family_name": "Walton", "given_name": "Dominic J.", "orcid": "0000-0001-5819-3552", "clpid": "Walton-D-J" } ], "abstract": "We present analysis of Chandra X-ray observations of seven quasars that were identified as candidate subparsec binary supermassive black hole (SMBH) systems in the Catalina Real-Time Transient Survey based on the apparent periodicity in their optical light curves. Simulations predict that close-separation accreting SMBH binaries will have different X-ray spectra than single accreting SMBHs, including harder or softer X-ray spectra, ripple-like profiles in the Fe K-\u03b1 line, and distinct peaks in the spectrum due to the separation of the accretion disk into a circumbinary disk and mini disks around each SMBH. We obtained Chandra observations to test these models and assess whether these quasars could contain binary SMBHs. We instead find that the quasar spectra are all well fit by simple absorbed power-law models, with the rest-frame 2\u201310 keV photon indices, \u0393, and the X-ray-to-optical power slopes, \u03b1_(OX), indistinguishable from those of the larger quasar population. This may indicate that these seven quasars are not truly subparsec binary SMBH systems, or it may simply reflect that our sample size was too small to robustly detect any differences. Alternatively, the X-ray spectral changes might only be evident at energies higher than probed by Chandra. Given the available models and current data, no firm conclusions are drawn. These observations will help motivate and direct further work on theoretical models of binary SMBH systems, such as modeling systems with thinner accretion disks and larger binary separations.", "doi": "10.3847/1538-4357/abad31", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2020-09-10", "series_number": "2", "volume": "900", "issue": "2", "pages": "Art. No. 148" }, { "id": "authors:8nz1w-hvg98", "collection": "authors", "collection_id": "8nz1w-hvg98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200414-071817157", "type": "article", "title": "Multiple Chemodynamic Stellar Populations of the Ursa Minor Dwarf Spheroidal Galaxy", "author": [ { "family_name": "Pace", "given_name": "Andrew B.", "orcid": "0000-0002-6021-8760", "clpid": "Pace-A-B" }, { "family_name": "Kaplinghat", "given_name": "Manoj", "clpid": "Kaplinghat-M" }, { "family_name": "Kirby", "given_name": "Evan", "orcid": "0000-0001-6196-5162", "clpid": "Kirby-E-N" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Tollerud", "given_name": "Erik", "orcid": "0000-0002-9599-310X", "clpid": "Tollerud-E-J" }, { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" } ], "abstract": "We present a Bayesian method to identify multiple (chemodynamic) stellar populations in dwarf spheroidal galaxies (dSphs) using velocity, metallicity, and positional stellar data without the assumption of spherical symmetry. We apply this method to a new Keck/Deep Imaging Multi-Object Spectrograph (DEIMOS) spectroscopic survey of the Ursa Minor (UMi) dSph. We identify 892 likely members, making this the largest UMi sample with line-of-sight velocity and metallicity measurements. Our Bayesian method detects two distinct chemodynamic populations with high significance (in logarithmic Bayes factor, ln\u2009B \u223c 33). The metal-rich ([Fe/H] = \u22122.05 \u00b1 0.03) population is kinematically colder (radial velocity dispersion of \u03c3_v = 4.9^(+0.8)_(\u22121.0)kms\u207b\u00b9\u2060) and more centrally concentrated than the metal-poor (\u2060[Fe/H] = \u22122.29^(+0.05)_(\u22120.06)\u2060) and kinematically hotter population (\u2060\u03c3_v = 11.5^(+0.9)_(\u22120.8)kms\u207b\u00b9\u2060). Furthermore, we apply the same analysis to an independent Multiple Mirror Telescope (MMT)/Hectochelle data set and confirm the existence of two chemodynamic populations in UMi. In both data sets, the metal-rich population is significantly flattened (\u03f5 = 0.75 \u00b1 0.03) and the metal-poor population is closer to spherical (\u2060\u03f5 = 0.33^(+0.12)_(\u22120.09)\u2060). Despite the presence of two populations, we are able to robustly estimate the slope of the dynamical mass profile. We found hints for prolate rotation of order \u223c2kms\u207b\u00b9 in the MMT data set, but further observations are required to verify this. The flattened metal-rich population invalidates assumptions built into simple dynamical mass estimators, so we computed new astrophysical dark matter annihilation (J) and decay profiles based on the rounder, hotter metal-poor population and inferred log\u2081\u2080(J(0.\u22185)/GeV\u00b2cm\u207b\u2075) \u2248 19.1 for the Keck data set. Our results paint a more complex picture of the evolution of UMi than previously discussed.", "doi": "10.1093/mnras/staa1419", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2020-07", "series_number": "3", "volume": "495", "issue": "3", "pages": "3022-3040" }, { "id": "authors:1akcy-zcg63", "collection": "authors", "collection_id": "1akcy-zcg63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200624-144534783", "type": "article", "title": "Candidate Electromagnetic Counterpart to the Binary Black Hole Merger Gravitational-Wave Event S190521g", "author": [ { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Ford", "given_name": "K. E. S.", "clpid": "Ford-K-E-S" }, { "family_name": "McKernan", "given_name": "B.", "orcid": "0000-0002-9726-0508", "clpid": "McKernan-B" }, { "family_name": "Ross", "given_name": "N. P.", "orcid": "0000-0003-1830-6473", "clpid": "Ross-N-P" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Burdge", "given_name": "K.", "orcid": "0000-0002-7226-836X", "clpid": "Burdge-K-B" }, { "family_name": "Coughlin", "given_name": "M.", "orcid": "0000-0002-8262-2924", "clpid": "Coughlin-M-W" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Duev", "given_name": "D.", "orcid": "0000-0001-5060-8733", "clpid": "Duev-D-A" }, { "family_name": "Kasliwal", "given_name": "M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "van Velzen", "given_name": "S.", "orcid": "0000-0002-3859-8074", "clpid": "van-Velzen-S" }, { "family_name": "Belecki", "given_name": "J.", "clpid": "Belecki-J" }, { "family_name": "Bellm", "given_name": "E. C.", "orcid": "0000-0001-8018-5348", "clpid": "Bellm-E-C" }, { "family_name": "Burruss", "given_name": "R.", "clpid": "Burruss-R-S" }, { "family_name": "Cenko", "given_name": "S. B.", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Cunningham", "given_name": "V.", "orcid": "0000-0003-2292-0441", "clpid": "Cunningham-V" }, { "family_name": "Helou", "given_name": "G.", "orcid": "0000-0003-3367-3415", "clpid": "Helou-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Masci", "given_name": "F. J.", "orcid": "0000-0002-8532-9395", "clpid": "Masci-F-J" }, { "family_name": "Prince", "given_name": "T.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Reiley", "given_name": "D.", "clpid": "Reiley-D-J" }, { "family_name": "Rodriguez", "given_name": "H.", "clpid": "Rodriguez-Hector" }, { "family_name": "Rusholme", "given_name": "B.", "orcid": "0000-0001-7648-4142", "clpid": "Rusholme-B" }, { "family_name": "Smith", "given_name": "R. M.", "clpid": "Smith-R-M" }, { "family_name": "Soumagnac", "given_name": "M. T.", "orcid": "0000-0001-6753-1488", "clpid": "Soumagnac-M-T" } ], "abstract": "We report the first plausible optical electromagnetic counterpart to a (candidate) binary black hole merger. Detected by the Zwicky Transient Facility, the electromagnetic flare is consistent with expectations for a kicked binary black hole merger in the accretion disk of an active galactic nucleus [B. McKernan, K.\u2009E.\u2009S. Ford, I. Bartos et al., Astrophys. J. Lett. 884, L50 (2019)] and is unlikely [< O (0.01%))] due to intrinsic variability of this source. The lack of color evolution implies that it is not a supernova and instead is strongly suggestive of a constant temperature shock. Other false-positive events, such as microlensing or a tidal disruption event, are ruled out or constrained to be < O(0.1%). If the flare is associated with S190521g, we find plausible values of total mass M_(BBH) \u223c 100 M_\u2299, kick velocity v_k \u223c 200 km s\u207b\u00b9 at \u03b8 \u223c 60\u00b0 in a disk with aspect ratio H/a \u223c 0.01 (i.e., disk height H at radius a) and gas density \u03c1 \u223c 10\u207b\u00b9\u2070 g cm\u207b\u00b3. The merger could have occurred at a disk migration trap (a \u223c 700r_g; r_g \u2261 GM_(SMBH)/c\u00b2, where M_(SMBH) is the mass of the active galactic nucleus supermassive black hole). The combination of parameters implies a significant spin for at least one of the black holes in S190521g. The timing of our spectroscopy prevents useful constraints on broad-line asymmetry due to an off-center flare. We predict a repeat flare in this source due to a reencountering with the disk in \u223c1.6 yr(M_SMBH)/10\u2078 M_\u2299)(a/10\u00b3r_g)^(3/2).", "doi": "10.1103/PhysRevLett.124.251102", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2020-06-26", "series_number": "25", "volume": "124", "issue": "25", "pages": "Art. No. 251102" }, { "id": "authors:45chh-s8e21", "collection": "authors", "collection_id": "45chh-s8e21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-112841141", "type": "article", "title": "Understanding extreme quasar optical variability with CRTS: II. Changing-state quasars", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Ross", "given_name": "Nicholas P.", "orcid": "0000-0003-1830-6473", "clpid": "Ross-N-P" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "McKernan", "given_name": "Barry", "orcid": "0000-0002-9726-0508", "clpid": "McKernan-B" }, { "family_name": "Ford", "given_name": "K. E. Saavik", "clpid": "Ford-K-E-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Larson", "given_name": "Steve", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "Eric", "clpid": "Christensen-E" } ], "abstract": "We present the results of a systematic search for quasars in the Catalina Real-time Transient Survey exhibiting both strong photometric variability and spectroscopic variability over a decadal baseline. We identify 111 sources with specific patterns of optical and mid-infrared photometric behaviour and a defined spectroscopic change. These 'changing-state' quasars (CSQs) form a higher luminosity sample to complement existing sets of 'changing-look' AGNs and quasars in the literature. The CSQs (by selection) exhibit larger photometric variability than the changing-look quasars (CLQs). The spectroscopic variability is marginally stronger in the CSQs than CLQs as defined by the change in H\u2009\u03b2/[OIIIOIII] ratio. We find 48 sources with declining H\u2009\u03b2 flux and 63 sources with increasing H\u2009\u03b2 flux, and discover 8 sources with z > 0.8, further extending the redshift arm. Our CSQ sample compares to the literature CLQ objects in similar distributions of H\u2009\u03b2 flux ratios and differential Eddington ratios between high (bright) and low (dim) states. Taken as a whole, we find that this population of extreme varying quasars is associated with changes in the Eddington ratio and the time-scales imply cooling/heating fronts propagating through the disc.", "doi": "10.1093/mnras/stz3244", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2020-02", "series_number": "4", "volume": "491", "issue": "4", "pages": "4925-4948" }, { "id": "authors:q8869-pw738", "collection": "authors", "collection_id": "q8869-pw738", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200414-072917417", "type": "monograph", "title": "Gaia GraL: Gaia DR2 Gravitational Lens Systems. V. Doubly-imaged QSOs discovered from entropy and wavelets", "author": [ { "family_name": "Krone-Martins", "given_name": "A.", "clpid": "Krone-Martins-A" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Delchambre", "given_name": "L.", "clpid": "Delchambre-L" }, { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-C" }, { "family_name": "Teixeira", "given_name": "R.", "clpid": "Teixeira-R" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Scarano", "given_name": "S., Jr.", "clpid": "Scarano-S-Jr" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Galluccio", "given_name": "L.", "clpid": "Galluccio-L" }, { "family_name": "Jalan", "given_name": "P.", "clpid": "Jalan-P" }, { "family_name": "Wertz", "given_name": "O.", "orcid": "0000-0003-3849-2285", "clpid": "Wertz-O" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "clpid": "Kl\u00fcter-J" }, { "family_name": "Mignard", "given_name": "F.", "clpid": "Mignard-F" }, { "family_name": "Spindola-Duarte", "given_name": "C.", "clpid": "Spindola-Duarte-C" }, { "family_name": "Dobie", "given_name": "D.", "orcid": "0000-0003-0699-7019", "clpid": "Dobie-D" }, { "family_name": "Slezak", "given_name": "E.", "clpid": "Slezak-E" }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-D" }, { "family_name": "Murphy", "given_name": "T.", "orcid": "0000-0002-2686-438X", "clpid": "Murphy-T" }, { "family_name": "Boehm", "given_name": "C.", "clpid": "Boehm-C" }, { "family_name": "Nierenberg", "given_name": "A. M.", "clpid": "Nierenberg-A-M" }, { "family_name": "Bastian", "given_name": "U.", "clpid": "Bastian-U" }, { "family_name": "Wambsganss", "given_name": "J.", "clpid": "Wambsganss-J" }, { "family_name": "LeCampion", "given_name": "J.-F.", "clpid": "LeCampion-J-F" } ], "abstract": "The discovery of multiply-imaged gravitationally lensed QSOs is fundamental to many astronomical and cosmological studies. However, these objects are rare and challenging to discover due to requirements of high-angular resolution astrometric, multiwavelength photometric and spectroscopic data. This has limited the number of known systems to a few hundred objects. We aim to reduce the constraints on angular resolution and discover multiply-imaged QSO candidates by using new candidate selection principles based on unresolved photometric time-series and ground-based images from public surveys. We selected candidates for multiply-imaged QSOs based on low levels of entropy computed from Catalina unresolved photometric time-series or Euclidean similarity to known lenses in a space defined by the wavelet power spectra of Pan-STARSS DR2 or DECaLS DR7 images, combined with multiple {\\it Gaia} DR2 sources or large astrometric errors and supervised and unsupervised learning methods. We then confirmed spectroscopically some candidates with the Palomar Hale, Keck-I, and ESO/NTT telescopes. Here we report the discovery and confirmation of seven doubly-imaged QSOs and one likely double quasar. This demonstrates the potential of combining space-astrometry, even if unresolved, with low spatial-resolution photometric time-series and/or low-spatial resolution multi-band imaging to discover multiply-imaged lensed QSOs.", "doi": "10.48550/arXiv.1912.08977", "publisher": "arXiv", "publication_date": "2019-12-19" }, { "id": "authors:rasf5-gzm48", "collection": "authors", "collection_id": "rasf5-gzm48", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200302-105109375", "type": "book_section", "title": "Multi-View, Generative, Transfer Learning for Distributed Time Series Classification", "book_title": "2019 IEEE International Conference on Big Data (Big Data)", "author": [ { "family_name": "Das Bhattacharjee", "given_name": "Sreyasee", "clpid": "Das-Bhattacharjee-S" }, { "family_name": "Tolone", "given_name": "William J.", "clpid": "Tolone-W-J" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Elshambakey", "given_name": "Mohammed", "clpid": "Elshambakey-M" }, { "family_name": "Cho", "given_name": "Isaac", "clpid": "Cho-Isaac" }, { "family_name": "Nayeem", "given_name": "Abdullah al-Raihan", "clpid": "Nayeem-A-A-R" }, { "family_name": "Yuan", "given_name": "Junsong", "clpid": "Yuan-Junsong" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "In this paper, we propose an effective, multi-view,\ngenerative, transfer learning framework for multivariate timeseries\ndata. While generative models are demonstrated effective\nfor several machine learning tasks, their application to time-series\nclassification problems is underexplored. The need for additional\nexploration is motivated when data are large, annotations are\nunbalanced or scarce, or data are distributed and fragmented.\nRecent advances in computer vision attempt to use synthesized\nsamples with system generated annotations to overcome the lack\nor imbalance of annotated data. However, in multi-view problem\nsettings, view mismatches between the synthetic data and real\ndata pose additional challenges against harnessing new annotated\ndata collections. The proposed method offers important\ncontributions to facilitate knowledge sharing, while simultaneously\nensuring an effective solution for domain-specific, finelevel\ncategorizations. We propose a principled way to perform\nview adaptation in a cross-view learning environment, wherein\npairwise view similarity is identified by a smaller subset of source\nsamples that closely resemble the target data patterns. This\napproach integrates generative models within a deep classification\nframework to minimize the gap between source and target data.\nMore precisely, we design category specific conditional, generative\nmodels to update the source generator in order for transforming\nsource features so that they appear as target features and\nsimultaneously tune the associated discriminative model to distinguish\nthese features. During each learning iteration, the source\ngenerator is conditioned by a source training set represented as\nsome target-like features. This transformation in appearance was\nperformed via a target generator specifically learned for targetspecific\ncustomization per category. Afterward, a smaller source\ntraining set, indicating close target pattern resemblance in terms\nof the corresponding generative and discriminative loss, is used to\nfine-tune the source classification model parameters. Experiments\nshow that compared to existing approaches, our proposed multiview,\ngenerative, transfer learning framework improves timeseries\nclassification performance by around 4% in the UCI multiview\nactivity recognition dataset, while also showing a robust,\ngeneralized representation capacity in classifying several largescale\nmulti-view light curve collections.", "doi": "10.1109/bigdata47090.2019.9005452", "isbn": "9781728108582", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2019-12", "pages": "5585-5594" }, { "id": "authors:jdbjv-d4928", "collection": "authors", "collection_id": "jdbjv-d4928", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-085614019", "type": "article", "title": "Luminous Red Novae: Stellar Mergers or Giant Eruptions?", "author": [ { "family_name": "Pastorello", "given_name": "A.", "clpid": "Pastorello-A" }, { "family_name": "Mason", "given_name": "E." }, { "family_name": "Taubenberger", "given_name": "S." }, { "family_name": "Fraser", "given_name": "M." }, { "family_name": "Cortini", "given_name": "G." }, { "family_name": "Tomasella", "given_name": "L." }, { "family_name": "Botticella", "given_name": "M. T." }, { "family_name": "Elias-Rosa", "given_name": "N." }, { "family_name": "Kotak", "given_name": "R." }, { "family_name": "Smartt", "given_name": "S. J." }, { "family_name": "Benetti", "given_name": "S." }, { "family_name": "Cappellaro", "given_name": "E." }, { "family_name": "Turatto", "given_name": "M." }, { "family_name": "Tartaglia", "given_name": "L." }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Berton", "given_name": "M." }, { "family_name": "Briganti", "given_name": "F." }, { "family_name": "Brimacombe", "given_name": "J." }, { "family_name": "Bufano", "given_name": "F." }, { "family_name": "Cai", "given_name": "Y.-Z." }, { "family_name": "Chen", "given_name": "S." }, { "family_name": "Christensen", "given_name": "E. J." }, { "family_name": "Ciabattari", "given_name": "F." }, { "family_name": "Congiu", "given_name": "E." }, { "family_name": "Dimai", "given_name": "A." }, { "family_name": "Inserra", "given_name": "C." }, { "family_name": "Kankare", "given_name": "E." }, { "family_name": "Magill", "given_name": "L." }, { "family_name": "Maguire", "given_name": "K." }, { "family_name": "Martinelli", "given_name": "F." }, { "family_name": "Morales-Garoffolo", "given_name": "A." }, { "family_name": "Ochner", "given_name": "P." }, { "family_name": "Pignata", "given_name": "G." }, { "family_name": "Reguitti", "given_name": "A." }, { "family_name": "Sollerman", "given_name": "J." }, { "family_name": "Spiro", "given_name": "S." }, { "family_name": "Terreran", "given_name": "G." }, { "family_name": "Wright", "given_name": "D. E." } ], "abstract": "We present extensive datasets for a class of intermediate-luminosity optical transients known as luminous red novae. They show double-peaked light curves, with an initial rapid luminosity rise to a blue peak (at \u221213 to \u221215 mag), which is followed by a longer-duration red peak that sometimes is attenuated, resembling a plateau. The progenitors of three of them (NGC 4490\u22122011OT1, M 101\u22122015OT1, and SNhunt248), likely relatively massive blue to yellow stars, were also observed in a pre-eruptive stage when their luminosity was slowly increasing. Early spectra obtained during the first peak show a blue continuum with superposed prominent narrow Balmer lines, with P Cygni profiles. Lines of Fe II are also clearly observed, mostly in emission. During the second peak, the spectral continuum becomes much redder, H\u03b1 is barely detected, and a forest of narrow metal lines is observed in absorption. Very late-time spectra (\u223c6 months after blue peak) show an extremely red spectral continuum, peaking in the infrared (IR) domain. H\u03b1 is detected in pure emission at such late phases, along with broad absorption bands due to molecular overtones (such as TiO, VO). We discuss a few alternative scenarios for luminous red novae. Although major instabilities of single massive stars cannot be definitely ruled out, we favour a common envelope ejection in a close binary system, with possibly a final coalescence of the two stars. The similarity between luminous red novae and the outburst observed a few months before the explosion of the Type IIn SN 2011ht is also discussed.", "doi": "10.1051/0004-6361/201935999", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2019-10", "volume": "630", "pages": "Art. No. A75" }, { "id": "authors:fjxkr-y6v48", "collection": "authors", "collection_id": "fjxkr-y6v48", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191119-083003734", "type": "publication_whitepaper", "title": "Realizing the potential of astrostatistics and astroinformatics", "author": [ { "family_name": "Eadie", "given_name": "Gwendolyn", "clpid": "Eadie-G" }, { "family_name": "Loredo", "given_name": "Thomas J.", "orcid": "0000-0003-4692-4607", "clpid": "Loredo-T-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Siemiginowska", "given_name": "Aneta", "clpid": "Siemiginowska-A" }, { "family_name": "Feigelson", "given_name": "Eric", "orcid": "0000-0002-5077-6734", "clpid": "Feigelson-E-D" }, { "family_name": "Ford", "given_name": "Eric B.", "orcid": "0000-0001-6545-639X", "clpid": "Ford-E-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Ivezi\u0107", "given_name": "\u017deljko", "orcid": "0000-0001-5250-2633", "clpid": "Ivezi\u0107-\u017d" }, { "family_name": "Borne", "given_name": "Kirk", "orcid": "0000-0001-5608-255X", "clpid": "Borne-K-D" }, { "family_name": "Cisewski-Kehe", "given_name": "Jessi", "clpid": "Cisewski-Kehe-J" }, { "family_name": "Peek", "given_name": "J. E. G.", "orcid": "0000-0003-4797-7030", "clpid": "Peek-J-E-G" }, { "family_name": "Schafer", "given_name": "Chad", "clpid": "Schafer-C" }, { "family_name": "Yanamandra-Fisher", "given_name": "Padma A.", "clpid": "Yanamandra-Fisher-P-A" }, { "family_name": "Young", "given_name": "C. Alex", "clpid": "Young-C-A" } ], "abstract": "This Astro2020 State of the Profession Consideration White Paper highlights the growth of astrostatistics and astroinformatics in astronomy, identifies key issues hampering the maturation of these new subfields, and makes recommendations for structural improvements at different levels that, if acted upon, will make significant positive impacts across astronomy.", "doi": "10.48550/arXiv.1909.11714", "publisher": "arXiv", "publication_date": "2019-09-25" }, { "id": "authors:1nrp8-c4y82", "collection": "authors", "collection_id": "1nrp8-c4y82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-102430761", "type": "article", "title": "X-ray Properties of Radio-Selected Dual Active Galactic Nuclei", "author": [ { "family_name": "Gross", "given_name": "Arran C.", "orcid": "0000-0001-7681-9213", "clpid": "Gross-A-C" }, { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Myers", "given_name": "A. D.", "clpid": "Myers-A-D" }, { "family_name": "Wrobel", "given_name": "J. M.", "orcid": "0000-0001-9720-7398", "clpid": "Wrobel-J-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Merger simulations predict that tidally induced gas inflows can trigger kiloparsec-scale dual active galactic nuclei (dAGN) in heavily obscured environments. Previously, with the Very Large Array, we have confirmed four dAGN with redshifts between 0.04 < z < 0.22 and projected separations between 4.3 and 9.2 kpc in the Sloan Digital Sky Survey Stripe 82 field. Here, we present Chandra X-ray observations that spatially resolve these dAGN and compare their multiwavelength properties to those of single AGN from the literature. We detect X-ray emission from six of the individual merger components and obtain upper limits for the remaining two. Combined with previous radio and optical observations, we find that our dAGN have properties similar to nearby low-luminosity AGN, and they agree with the black hole fundamental plane relation well. There are three AGN-dominated X-ray sources, whose X-ray hardness-ratio derived column densities show that two are unobscured and one is obscured. The low obscured fraction suggests these dAGN are no more obscured than single AGN, in contrast to the predictions from simulations. These three sources show an apparent X-ray deficit compared to their mid-infrared continuum and optical [O iii] line luminosities, suggesting higher levels of obscuration, in tension with the hardness-ratio derived column densities. Enhanced mid-infrared and [O iii] luminosities from star formation may explain this deficit. There is ambiguity in the level of obscuration for the remaining five components because their hardness ratios may be affected by nonnuclear X-ray emissions, or are undetected altogether. They require further observations to be fully characterized.", "doi": "10.3847/1538-4357/ab3795", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2019-09-20", "series_number": "1", "volume": "883", "issue": "1", "pages": "Art. No. 50" }, { "id": "authors:mezfh-35s38", "collection": "authors", "collection_id": "mezfh-35s38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190620-143322841", "type": "article", "title": "A fast radio burst localized to a massive galaxy", "author": [ { "family_name": "Ravi", "given_name": "V.", "orcid": "0000-0002-7252-5485", "clpid": "Ravi-Vikram" }, { "family_name": "Catha", "given_name": "M.", "clpid": "Catha-Morgan" }, { "family_name": "D'Addario", "given_name": "L.", "clpid": "D'Addario-Larry-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Hallinan", "given_name": "G.", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Hobbs", "given_name": "R.", "clpid": "Hobbs-R" }, { "family_name": "Kocz", "given_name": "J.", "orcid": "0000-0003-0249-7586", "clpid": "Kocz-Jonathon" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Shih", "given_name": "J.", "clpid": "Shih-J" }, { "family_name": "Vedantham", "given_name": "H. K.", "orcid": "0000-0002-0872-181X", "clpid": "Vedantham-Harish-K" }, { "family_name": "Weinreb", "given_name": "S.", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Woody", "given_name": "D. P.", "clpid": "Woody-David-P" } ], "abstract": "Intense, millisecond-duration bursts of radio waves (named fast radio bursts) have been detected from beyond the Milky Way. Their dispersion measures\u2014which are greater than would be expected if they had propagated only through the interstellar medium of the Milky Way\u2014indicate extragalactic origins and imply contributions from the intergalactic medium and perhaps from other galaxies. Although several theories exist regarding the sources of these fast radio bursts, their intensities, durations and temporal structures suggest coherent emission from highly magnetized plasma. Two of these bursts have been observed to repeat, and one repeater (FRB 121102) has been localized to the largest star-forming region of a dwarf galaxy at a cosmological redshift of 0.19 (refs. 7,8,9). However, the host galaxies and distances of the hitherto non-repeating fast radio bursts are yet to be identified. Unlike repeating sources, these events must be observed with an interferometer that has sufficient spatial resolution for arcsecond localization at the time of discovery. Here we report the localization of a fast radio burst (FRB 190523) to a few-arcsecond region containing a single massive galaxy at a redshift of 0.66. This galaxy is different from the host of FRB 121102, as it is a thousand times more massive, with a specific star-formation rate (the star-formation rate divided by the mass) a hundred times smaller.", "doi": "10.1038/s41586-019-1389-7", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2019-08-15", "series_number": "7769", "volume": "572", "issue": "7769", "pages": "352-354" }, { "id": "authors:4jmw0-de434", "collection": "authors", "collection_id": "4jmw0-de434", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190809-104904061", "type": "article", "title": "Gaia GraL: Gaia DR2 gravitational lens systems. IV. Keck/LRIS spectroscopic confirmation of GRAL 113100\u2212441959 and model prediction of time delays", "author": [ { "family_name": "Wertz", "given_name": "O.", "orcid": "0000-0003-3849-2285", "clpid": "Wertz-O" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Krone-Martins", "given_name": "A.", "clpid": "Krone-Martins-A" }, { "family_name": "Delchambre", "given_name": "L.", "clpid": "Delchambre-L" }, { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-C" }, { "family_name": "J\u00f8rgensen", "given_name": "U. Gr\u00e5e", "clpid": "J\u00f8rgensen-U-G" }, { "family_name": "Dominik", "given_name": "M.", "orcid": "0000-0002-3202-0343", "clpid": "Dominik-M" }, { "family_name": "Burgdorf", "given_name": "M.", "clpid": "Burgdorf-M" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Mignard", "given_name": "F.", "clpid": "Mignard-F" }, { "family_name": "Teixeira", "given_name": "R.", "clpid": "Teixeira-R" }, { "family_name": "Galluccio", "given_name": "L.", "clpid": "Galluccio-L" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "clpid": "Kl\u00fcter-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Bastian", "given_name": "U.", "clpid": "Bastian-U" }, { "family_name": "Wambsganss", "given_name": "J.", "clpid": "Wambsganss-J" }, { "family_name": "Boehm", "given_name": "C.", "clpid": "Boehm-C" }, { "family_name": "LeCampion", "given_name": "J.-F.", "clpid": "LeCampion-J-F" }, { "family_name": "Slezak", "given_name": "E.", "clpid": "Slezak-E" } ], "abstract": "We report the spectroscopic confirmation and modeling of the quadruply imaged quasar GRAL 113100\u2013441959, the first gravitational lens (GL) to be discovered from a machine learning technique that only relies on the relative positions and fluxes of the observed images without considering colour informations. Follow-up spectra obtained with Keck/LRIS reveal the lensing nature of this quadruply imaged quasar with redshift z_s\u2004=\u20041.090 \u00b1 0.002, but show no evidence of the central lens galaxy. Using the image positions and G-band flux ratios provided by Gaia Data Release 2 as constraints, we modeled the system with a singular power-law elliptical mass distribution (SPEMD) plus external shear, to different levels of complexity. We show that relaxing the isothermal constraint of the SPEMD does not lead to statistically significant different results in terms of fitting the lensing data. We thus simplified the SPEMD to a singular isothermal ellipsoid to estimate the Einstein radius of the main lens galaxy \u03b8_E\u2004=\u20040.\u2033851, the intensity and position angle of the external shear (\u03b3,\u03b8_\u03b3)\u2004=\u2004(0.044,\u200611.\u00b05), and we predict the lensing galaxy position to be (\u03b8_(gal,1),\u2006\u03b8_(gal,2))\u2004=\u2004(\u22120.\u2033424,\u2006\u22120.\u2033744) with respect to image A. We provide time delay predictions for pairs of images, assuming a plausible range of lens redshift values z_l between 0.5 and 0.9. Finally, we examine the impact on time delays of the so-called source position transformation, a family of degeneracies existing between different mass density profiles that reproduce most of the lensing observables equally well. We show that this effect contributes significantly to the time delay error budget and cannot be ignored during the modeling. This has implications for robust cosmography applications of lensed systems. GRAL 113100\u2013441959 is the first in a series of seven new spectroscopically confirmed GLs discovered from Gaia Data Release 2.", "doi": "10.1051/0004-6361/201834573", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2019-08", "volume": "628", "pages": "Art. No. A17" }, { "id": "authors:7an0w-s2324", "collection": "authors", "collection_id": "7an0w-s2324", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191004-134753975", "type": "book_section", "title": "OVS+Tumor: a tool for enhanced lung tumor annotation in VR for machine learning training and analysis", "book_title": "ACM SIGGRAPH 2019 Virtual, Augmented, and Mixed Reality", "author": [ { "family_name": "Lombeyda", "given_name": "Santiago", "clpid": "Lombeyda-S-V" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Crichton", "given_name": "Daniel", "clpid": "Crichton-D-J" }, { "family_name": "Kincaid", "given_name": "Heather", "clpid": "Kincaid-H" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Patriotis", "given_name": "Christos", "clpid": "Patriotis-C" }, { "family_name": "Srivastava", "given_name": "Sudhir", "clpid": "Srivastava-S" } ], "abstract": "OVS+Tumor creates a seamless VR environment designed for intuitive interaction aiding in the complex task of parsing through 3D CT-scans and annotating candidate tumors. Through interactive subsetting and on-the-fly iso-cloud generation, a wider range of users beyond just domain experts (radiologists/surgeons) can generate a viable machine-learning training dataset.", "doi": "10.1145/3306449.3328825", "isbn": "9781450363204", "publisher": "ACM Press", "place_of_publication": "New York, NY", "publication_date": "2019-08", "pages": "Art. No. 26" }, { "id": "authors:wjxy4-9a843", "collection": "authors", "collection_id": "wjxy4-9a843", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191119-080709036", "type": "monograph", "title": "A fast radio burst localised to a massive galaxy", "author": [ { "family_name": "Ravi", "given_name": "V.", "orcid": "0000-0002-7252-5485", "clpid": "Ravi-Vikram" }, { "family_name": "Catha", "given_name": "M.", "clpid": "Catha-Morgan" }, { "family_name": "D'Addario", "given_name": "L.", "clpid": "D'Addario-Larry-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Hallinan", "given_name": "G.", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Hobbs", "given_name": "R.", "clpid": "Hobbs-R" }, { "family_name": "Kocz", "given_name": "J.", "orcid": "0000-0003-0249-7586", "clpid": "Kocz-Jonathon" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Shi", "given_name": "J.", "clpid": "Shi-J." }, { "family_name": "Vedantham", "given_name": "H. K.", "orcid": "0000-0002-0872-181X", "clpid": "Vedantham-Harish-K" }, { "family_name": "Weinreb", "given_name": "S.", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Woody", "given_name": "D. P.", "clpid": "Woody-David-P" } ], "abstract": "Intense, millisecond-duration bursts of radio waves have been detected from beyond the Milky Way [1]. Their extragalactic origins are evidenced by their large dispersion measures, which are greater than expected for propagation through the Milky Way interstellar medium alone, and imply contributions from the intergalactic medium and potentially host galaxies [2]. Although several theories exist for the sources of these fast radio bursts, their intensities, durations and temporal structures suggest coherent emission from highly magnetised plasma [3,4]. Two sources have been observed to repeat [5,6], and one repeater (FRB 121102) has been localised to the largest star-forming region of a dwarf galaxy at a cosmological redshift of 0.19 [7, 8]. However, the host galaxies and distances of the so far non-repeating fast radio bursts are yet to be identified. Unlike repeating sources, these events must be observed with an interferometer with sufficient spatial resolution for arcsecond localisation at the time of discovery. Here we report the localisation of a fast radio burst (FRB 190523) to a few-arcsecond region containing a single massive galaxy at a redshift of 0.66. This galaxy is in stark contrast to the host of FRB 121102, being a thousand times more massive, with a greater than hundred times lower specific star-formation rate. The properties of this galaxy highlight the possibility of a channel for FRB production associated with older stellar populations.", "doi": "10.48550/arXiv.1907.01542", "publisher": "arXiv", "publication_date": "2019-07-02" }, { "id": "authors:8wd6a-2rv47", "collection": "authors", "collection_id": "8wd6a-2rv47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190711-134821741", "type": "book_section", "title": "View-Adaptive Weighted Deep Transfer Learning for Distributed Time-Series Classification", "book_title": "2019 IEEE 43rd Annual Computer Software and Applications Conference (COMPSAC)", "author": [ { "family_name": "Das Bhattacharjee", "given_name": "Sreyasee", "clpid": "Das-Bhattacharjee-S" }, { "family_name": "Tolone", "given_name": "William J.", "clpid": "Tolone-W-J" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Elshambakey", "given_name": "Mohammed", "clpid": "Elshambakey-M" }, { "family_name": "Cho", "given_name": "Isaac", "clpid": "Cho-Isaac" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "In this paper, we propose an effective, multi-view, deep, transfer learning framework for multivariate time-series data. Though widely used for tasks such as computer vision, the application of transfer learning to time-series classification problems (e.g., classification of light curves) is underexplored. The proposed framework makes several important contributions to facilitate knowledge sharing, while simultaneously ensuring an effective solution for domain specific fine-level categorizations. First, in contrast to the traditional approaches, the proposed framework describes pairwise view similarity by identifying a smaller subset of source-view samples that closely resemble the target data patterns. Second, by means of two-phase learning, a generic baseline model is learned on a larger source data collection and later fine-tuned on a smaller target data collection, precisely approximating the target data patterns. Third, an effective view-adaptive timestamp weighting scheme evaluates the relative importance of each timestamp in a more data-driven manner, which enables a more flexible yet discriminative feature representation scheme in the presence of evolving data characteristics. As shown by experiments, compared to the existing approaches, our proposed deep transfer learning framework improves classification performance by around 2-3% in the UCI multi-view activity recognition dataset, while also showing a robust, generalized representation capacity in classifying several large-scale multi-view light curve collections.", "doi": "10.1109/compsac.2019.00061", "isbn": "9781728126074", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2019-07", "pages": "373-381" }, { "id": "authors:e243b-ehx43", "collection": "authors", "collection_id": "e243b-ehx43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190523-102755116", "type": "article", "title": "Physical Parameters of Northern Eclipsing Binaries in the Catalina Sky Survey", "author": [ { "family_name": "Papageorgiou", "given_name": "Athanasios", "orcid": "0000-0002-3039-9257", "clpid": "Papageorgiou-A" }, { "family_name": "Catelan", "given_name": "M\u00e1rcio", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Christopoulou", "given_name": "Panagiota-Eleftheria", "clpid": "Christopoulou-P-E" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present the physical properties for 2281 northern eclipsing binary (EB) stars with eclipsing Algol (EA)-type light-curve (LC) morphology, based on data extracted from the Catalina Sky Survey (CSS). Our study is based on the analysis of the Eclipsing Binary via Artificial Intelligence (EBAI) artificial neural network (ANN) tool. An intensive search for the optimal ANN topology was performed. In order to feed the ANN with LCs that are representative of the CSS observations, two independent methods, based on template fitting and on the Two-Gaussian Model, were applied. As a result, five principal physical parameters were determined using only the CSS LCs, namely the temperature ratio, T_2/T_1; the sum of relative radii, \u03c1_2 + \u03c1_1; \u03b5 sin \u03c9; \u03b5 cos \u03c9; and sin i, where e is the eccentricity, \u03c9 is the argument of periastron, and i is the orbital inclination. Parameter uncertainties were estimated based on a Monte Carlo approach. When the ANN predictions were out of its training limits (1540 EBs), the parameters of the systems are based on the matching templates technique only. The results are fully in agreement with the expected parameter values for detached EB systems and can be used as initial inputs for advanced and dedicated EB models and/or for statistical purposes.", "doi": "10.3847/1538-4365/ab13b8", "issn": "1538-4365", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Supplement Series", "publication_date": "2019-05", "series_number": "1", "volume": "242", "issue": "1", "pages": "Art. No. 6" }, { "id": "authors:p1zdw-6tk22", "collection": "authors", "collection_id": "p1zdw-6tk22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190320-074508464", "type": "article", "title": "A MegaCam Survey of Outer Halo Satellites. VII. A Single S\u00e9rsic Index versus Effective Radius Relation for Milky Way Outer Halo Satellites", "author": [ { "family_name": "Marchi-Lasch", "given_name": "Sebasti\u00e1n", "orcid": "0000-0002-4368-9835", "clpid": "Marchi-Lasch-S" }, { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "Santana", "given_name": "Felipe A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Carballo-Bello", "given_name": "Julio A.", "clpid": "Carballo-Bello-J-A" }, { "family_name": "Chanam\u00e9", "given_name": "Julio", "clpid": "Chanam\u00e9-J" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Stetson", "given_name": "Peter B.", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "In this work, we use structural properties of the Milky Way's outer halo (R_G > 25 kpc) satellites (dwarf spheroidal galaxies, ultra-faint dwarf (UFD) galaxies and globular clusters (GCs)) derived from deep, wide-field, and homogeneous data to present evidence of a correlation in the S\u00e9rsic index versus effective radius plane followed by a large fraction of outer halo GCs and satellite dwarf galaxies. We show that this correlation can be entirely reproduced by fitting empirical relations in the central surface brightness versus absolute magnitude and S\u00e9rsic index versus absolute magnitude parameter spaces, and by assuming the existence of two types of outer halo GCs: one of high surface brightness (HSB group), with properties similar to those of inner halo clusters; and another of low surface brightness (LSB group), which share characteristics with dwarf spheroidal and UFD galaxies. Given the similarities of LSB clusters with dwarf spheroidal and UFD galaxies, we discuss the possibility that outer halo clusters also originated inside dark matter halos and that tidal forces from different host galaxy potentials are responsible for the different properties between HSB and LSB clusters.", "doi": "10.3847/1538-4357/ab089c", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2019-03-20", "series_number": "1", "volume": "874", "issue": "1", "pages": "Art. No. 29" }, { "id": "authors:nf4dy-cd725", "collection": "authors", "collection_id": "nf4dy-cd725", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190228-141241567", "type": "article", "title": "Gaia GraL: Gaia DR2 Gravitational Lens Systems. III. A systematic blind search for new lensed systems", "author": [ { "family_name": "Delchambre", "given_name": "L.", "clpid": "Delchambre-L" }, { "family_name": "Krone-Martins", "given_name": "A.", "clpid": "Krone-Martins-A" }, { "family_name": "Wertz", "given_name": "O.", "orcid": "0000-0003-3849-2285", "clpid": "Wertz-O" }, { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-C" }, { "family_name": "Galluccio", "given_name": "L.", "clpid": "Galluccio-L" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "clpid": "Kl\u00fcter-J" }, { "family_name": "Mignard", "given_name": "F.", "clpid": "Mignard-F" }, { "family_name": "Teixeira", "given_name": "R.", "clpid": "Teixeira-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Bastian", "given_name": "U.", "clpid": "Bastian-U" }, { "family_name": "Wambsganss", "given_name": "J.", "clpid": "Wambsganss-J" }, { "family_name": "Le Campion", "given_name": "J.-F.", "clpid": "Le-Campion-J-F" }, { "family_name": "Slezak", "given_name": "E.", "clpid": "Slezak-E" } ], "abstract": "Aims. In this work, we aim to provide a reliable list of gravitational lens candidates based on a search performed over the entire Gaia Data Release 2 (Gaia DR2). We also aim to show that the astrometric and photometric information coming from the Gaia satellite yield sufficient insights for supervised learning methods to automatically identify strong gravitational lens candidates with an efficiency that is comparable to methods based on image processing. \n\nMethods. We simulated 106 623 188 lens systems composed of more than two images, based on a regular grid of parameters characterizing a non-singular isothermal ellipsoid lens model in the presence of an external shear. These simulations are used as an input for training and testing our supervised learning models consisting of extremely randomized trees (ERTs). These trees are finally used to assign to each of the 2 129 659 clusters of celestial objects extracted from the Gaia DR2 a discriminant value that reflects the ability of our simulations to match the observed relative positions and fluxes from each cluster. Once complemented with additional constraints, these discriminant values allow us to identify strong gravitational lens candidates out of the list of clusters. \n\nResults. We report the discovery of 15 new quadruply-imaged lens candidates with angular separations of less than 6\u2033 and assess the performance of our approach by recovering 12 of the 13 known quadruply-imaged systems with all their components detected in Gaia DR2 with a misclassification rate of fortuitous clusters of stars as lens systems that is below 1%. Similarly, the identification capability of our method regarding quadruply-imaged systems where three images are detected in Gaia DR2 is assessed by recovering 10 of the 13 known quadruply-imaged systems having one of their constituting images discarded. The associated misclassification rate varies between 5.83% and 20%, depending on the image we decided to remove.", "doi": "10.1051/0004-6361/201833802", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2019-02", "volume": "622", "pages": "Art. No. A165" }, { "id": "authors:3vymc-qfr29", "collection": "authors", "collection_id": "3vymc-qfr29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-081423822", "type": "article", "title": "Results of a systematic search for outburst events in 1.4 million galaxies", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" } ], "abstract": "We present an analysis of 9 yr of Catalina Surveys optical photometry for 1.4 million spectroscopically confirmed SDSS galaxies. We find 717 outburst events that were not reported by ongoing transient surveys. These events have time-scales ranging from weeks to years. More than two-thirds of these new events are found in star-forming galaxies, while such galaxies only constitute \u223c20 per cent of our sample. Based on the properties of the hosts and events, we find that almost all of the new events are likely to be associated with regular supernovae. However, a small number of long time-scale events are found among the galaxies containing AGNs. These events have similar properties to those recently found in the analyses of light curves of large samples of AGNs. Given the lack of such events among more than a million passive galaxies in the sample, we suggest that the long outbursts are associated with supermassive black holes or their environments.", "doi": "10.1093/mnras/sty2673", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2019-01", "series_number": "1", "volume": "482", "issue": "1", "pages": "98-117" }, { "id": "authors:00yf9-21365", "collection": "authors", "collection_id": "00yf9-21365", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190131-131445274", "type": "book_section", "title": "Context-Aware Deep Sequence Learning with Multi-View Factor Pooling for Time Series Classification", "book_title": "2018 IEEE International Conference on Big Data (Big Data)", "author": [ { "family_name": "Das Bhattacharjee", "given_name": "Sreyasee", "clpid": "Das-Bhattacharjee-S" }, { "family_name": "Tolone", "given_name": "William J.", "clpid": "Tolone-W-J" }, { "family_name": "Elshambakey", "given_name": "Mohammed", "clpid": "Elshambakey-M" }, { "family_name": "Cho", "given_name": "Isaac", "clpid": "Cho-Isaac" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "In this paper, we propose an effective, multi-view, multivariate deep classification model for time-series data. Multi-view methods show promise in their ability to learn correlation and exclusivity properties across different independent information resources. However, most current multi-view integration schemes employ only a linear model and, therefore, do not extensively utilize the relationships observed across different view-specific representations. Moreover, the majority of these methods rely exclusively on sophisticated, handcrafted features to capture local data patterns and, thus, depend heavily on large collections of labeled data. The multi-view, multivariate deep classification model for time-series data proposed in this paper makes important contributions to address these limitations. The proposed model derives a LSTM-based, deep feature descriptor to model both the view-specific data characteristics and cross-view interaction in an integrated deep architecture while driving the learning phase in a data-driven manner. The proposed model employs a compact context descriptor to exploit view-specific affinity information to design a more insightful context representation. Finally, the model uses a multi-view factor-pooling scheme for a context-driven attention learning strategy to weigh the most relevant feature dimensions while eliminating noise from the resulting fused descriptor. As shown by experiments, compared to the existing multi-view methods, the proposed multi-view deep sequential learning approach improves classification performance by roughly 4% in the UCI multi-view activity recognition dataset, while also showing significantly robust generalized representation capacity against its single-view counterparts, in classifying several large-scale multi-view light curve collections.", "doi": "10.1109/bigdata.2018.8622253", "isbn": "9781538650356", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2018-12", "pages": "959-966" }, { "id": "authors:rghrz-0z972", "collection": "authors", "collection_id": "rghrz-0z972", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181005-093940020", "type": "article", "title": "ALMA Resolves the Stellar Birth Explosion in Distant Quasar 3C298", "author": [ { "family_name": "Barthel", "given_name": "P. D.", "orcid": "0000-0002-0106-5776", "clpid": "Barthel-P-D" }, { "family_name": "Versteeg", "given_name": "M. J. F.", "clpid": "Versteeg-M-J-F" }, { "family_name": "Podigachoski", "given_name": "P.", "orcid": "0000-0003-3836-710X", "clpid": "Podigachoski-P" }, { "family_name": "Haas", "given_name": "M.", "clpid": "Haas-M" }, { "family_name": "Wilkes", "given_name": "B. J.", "orcid": "0000-0003-1809-2364", "clpid": "Wilkes-B-J" }, { "family_name": "de Breuck", "given_name": "C.", "orcid": "0000-0002-6637-3315", "clpid": "de-Breuck-Carlos" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Galaxies are believed to experience star formation and black-hole-driven nuclear activity symbiotically. The symbiosis may be more extreme in the distant universe, as far-infrared photometry with the Herschel Space Observatory has found many cases of ultraluminous cool dust emission in z > 1 radio galaxies and quasars, which could have its origin in the central black hole activity, or in extreme starbursts. We here present strong evidence for an extreme circumnuclear starburst in the z = 1.439 quasar 3C298. Our unparalleled 0.18 arcsec resolution Atacama Large Millimeter/submillimeter Array (ALMA) image at rest-frame 410 \u03bcm wavelength shows that the ~40 K dust in its host galaxy resides in an asymmetric circumnuclear structure. The morphology of this structure implies a starburst origin and a symbiotic physical relation with the active-galactic-nucleus-driven radio source. The symbiosis is likely to be a general property of distant massive galaxies.", "doi": "10.3847/2041-8213/aae3e2", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2018-10-10", "series_number": "1", "volume": "866", "issue": "1", "pages": "Art. No. L3" }, { "id": "authors:a3gbj-hcn39", "collection": "authors", "collection_id": "a3gbj-hcn39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181026-091414731", "type": "article", "title": "Gaia GraL: Gaia DR2 gravitational lens systems. II. The known multiply imaged quasars", "author": [ { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-C" }, { "family_name": "Wertz", "given_name": "O.", "orcid": "0000-0003-3849-2285", "clpid": "Wertz-O" }, { "family_name": "Krone-Martins", "given_name": "A.", "clpid": "Krone-Martins-A" }, { "family_name": "Teixeira", "given_name": "R.", "clpid": "Teixeira-R" }, { "family_name": "Le Campion", "given_name": "J.-F.", "clpid": "Le-Campion-J-F" }, { "family_name": "Galluccio", "given_name": "L.", "clpid": "Galluccio-L" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "clpid": "Kl\u00fcter-J" }, { "family_name": "Delchambre", "given_name": "L.", "clpid": "Delchambre-L" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Mignard", "given_name": "F.", "clpid": "Mignard-F" }, { "family_name": "Wambsganss", "given_name": "J.", "clpid": "Wambsganss-J" }, { "family_name": "Bastian", "given_name": "U.", "clpid": "Bastian-U" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Slezak", "given_name": "E.", "clpid": "Slezak-E" } ], "abstract": "Context. Thanks to its spatial resolution, the ESA/Gaia space mission offers a unique opportunity to discover new multiply imaged quasars and to study the already known lensed systems at sub-milliarcsecond astrometric precisions. \n\nAims. In this paper, we address the detection of the known multiply imaged quasars from the Gaia Data Release 2 (DR2) and determine the astrometric and photometric properties of the individually detected images found in the Gaia DR2 catalogue. \n\nMethods. We have compiled an exhaustive list of quasar gravitational lenses from the literature to search for counterparts in the Gaia DR2. We then analysed the astrometric and photometric properties of these Gaia's detections. To highlight the tremendous potential of Gaia at the sub-milliarcsecond level we finally performed a simple Bayesian modelling of the well-known gravitational lens system HE0435-1223, using Gaia DR2 and HST astrometry. \n\nResults. From 481 known multiply imaged quasars, 206 have at least one image found in the Gaia DR2. Among the 44 known quadruply imaged quasars of the list, 29 have at least one image in the Gaia DR2, 12 of which are fully detected (2MASX J01471020+4630433, HE 0435-1223, SDSS1004+4112, PG1115+080, RXJ1131-1231, 2MASS J11344050-2103230, 2MASS J13102005-1714579, B1422+231, J1606-2333, J1721+8842, WFI2033-4723, WGD2038-4008), eight have three counterparts, eight have two and one has only one. As expected, the modelling of HE0435-1223 shows that the model parameters are significantly better constrained when using Gaia astrometry compared to HST astrometry, in particular the relative positions of the background quasar source and the centroid of the deflector. The Gaia sub-milliarcsecond astrometry also significantly reduces the parameter correlations. \n\nConclusions. Besides providing an up-to-date list of multiply imaged quasars and their detection in the Gaia DR2, this paper shows that more complex modelling scenarios will certainly benefit from Gaia sub-milliarcsecond astrometry.", "doi": "10.1051/0004-6361/201833480", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2018-10", "volume": "618", "pages": "Art. No. A56" }, { "id": "authors:azy2b-r2w44", "collection": "authors", "collection_id": "azy2b-r2w44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180827-144724452", "type": "article", "title": "A Mid-IR Selected Changing-look Quasar and Physical Scenarios for Abrupt AGN Fading", "author": [ { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "McKernan", "given_name": "Barry", "orcid": "0000-0002-9726-0508", "clpid": "McKernan-B" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Ford", "given_name": "K. E. S.", "clpid": "Ford-K-E-S" }, { "family_name": "Ross", "given_name": "Nicholas P.", "orcid": "0000-0003-1830-6473", "clpid": "Ross-N-P" }, { "family_name": "Meisner", "given_name": "Aaron M.", "orcid": "0000-0002-1125-7384", "clpid": "Meisner-A-M" }, { "family_name": "Assef", "given_name": "Roberto J.", "orcid": "0000-0002-9508-3667", "clpid": "Assef-R-J" }, { "family_name": "Balokovi\u0107", "given_name": "Mislav", "orcid": "0000-0003-0476-6647", "clpid": "Balokovi\u0107-M" }, { "family_name": "Brightman", "given_name": "Murray", "orcid": "0000-0002-8147-2602", "clpid": "Brightman-M" }, { "family_name": "Dey", "given_name": "Arjun", "orcid": "0000-0002-4928-4003", "clpid": "Dey-A" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Eisenhardt", "given_name": "Peter", "clpid": "Eisenhardt-P-R-M" }, { "family_name": "Jun", "given_name": "Hyunsung D.", "orcid": "0000-0003-1470-5901", "clpid": "Jun-Hyunsung-David" } ], "abstract": "We report a new changing-look quasar, WISE J105203.55+151929.5 at z = 0.303, found by identifying highly mid-IR-variable quasars in the Wide-field Infrared Survey Explorer (WISE)/Near-Earth Object WISE Reactivation (NEOWISE) data stream. Compared to multiepoch mid-IR photometry of a large sample of SDSS-confirmed quasars, WISE J1052+1519 is an extreme photometric outlier, fading by more than a factor of two at 3.4 and 4.6 \u03bcm since 2009. Swift target-of-opportunity observations in 2017 show even stronger fading in the soft X-rays compared to the ROSAT detection of this source in 1995, with at least a factor of 15 decrease. We obtained second-epoch spectroscopy with the Palomar telescope in 2017 that, when compared with the 2006 archival SDSS spectrum, reveals that the broad H\u03b2 emission has vanished and that the quasar has become significantly redder. The two most likely interpretations for this dramatic change are source fading or obscuration, where the latter is strongly disfavored by the mid-IR data. We discuss various physical scenarios that could cause such changes in the quasar luminosity over this timescale, and favor changes in the innermost regions of the accretion disk that occur on the thermal and heating/cooling front timescales. We discuss possible physical triggers that could cause these changes, and predict the multiwavelength signatures that could distinguish these physical scenarios.", "doi": "10.3847/1538-4357/aac726", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2018-09-01", "series_number": "1", "volume": "864", "issue": "1", "pages": "Art. No. 27" }, { "id": "authors:t5ea3-myg82", "collection": "authors", "collection_id": "t5ea3-myg82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-164643913", "type": "article", "title": "An Updated Catalog of 4680 Northern Eclipsing Binaries with Algol-type Light-curve Morphology in the Catalina Sky Surveys", "author": [ { "family_name": "Papageorgiou", "given_name": "Athanasios", "orcid": "0000-0002-3039-9257", "clpid": "Papageorgiou-A" }, { "family_name": "Catelan", "given_name": "M\u00e1rcio", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Christopoulou", "given_name": "Panagiota-Eleftheria", "clpid": "Christopoulou-P-E" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present an updated catalog of 4680 northern eclipsing binaries (EBs) with Algol-type light-curve (LC) morphology (i.e., with well-defined beginnings and ends of primary and secondary eclipses), using data from the Catalina Sky Surveys. Our work includes revised period determinations, phenomenological parameters of the LCs, and system morphology classifications based on machine-learning techniques. While most of the new periods are in excellent agreement with those provided in the original Catalina catalogs, improved values are now available for ~10% of the stars. A total of 3456 EBs were classified as detached and 449 were classified as semi-detached, while 145 could not be classified unambiguously into either subtype. The majority of the SD systems seem to be comprised of short-period Algols. By applying color criteria, we searched for K- and M-type dwarfs in these data, and present a subsample of 609 EB candidates for further investigation. We report 119 EBs (2.5% of the total sample) that show maximum quadrature light variations over long timescales, with periods bracketing the range 4.5\u201318 years and a fractional luminosity variance range of 0.04\u20130.13. We discuss possible causes for this, making use of models of variable starspot activity in our interpretation of the results.", "doi": "10.3847/1538-4365/aad8a9", "issn": "0067-0049", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Supplement Series", "publication_date": "2018-09", "series_number": "1", "volume": "238", "issue": "1", "pages": "Art. No. 4" }, { "id": "authors:e5zwr-0s389", "collection": "authors", "collection_id": "e5zwr-0s389", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180822-091951596", "type": "article", "title": "From Space to Cyberspace", "author": [ { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "How 21st-century astronomy became a big data science: All sciences are based on empirical evidence. Data quantifies the observed or measured phenomena; they can stimulate new hypotheses, support or disprove existing theories, and ultimately lead us to a better understanding of the world. The information revolution has dramatically intensified this process by enabling vast growth in the volume, rate, and quality of data, and thus in the ways in which science is conducted. Astronomy has been on the front lines of these developments for the past three or four decades, and it is still pushing the boundary today.", "issn": "0003-0996", "publisher": "Sigma Xi", "publication": "American Scientist", "publication_date": "2018-09", "series_number": "5", "volume": "106", "issue": "5", "pages": "262-263" }, { "id": "authors:1kzsd-yhq81", "collection": "authors", "collection_id": "1kzsd-yhq81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180906-132818612", "type": "article", "title": "Gaia GraL: Gaia DR2 gravitational lens systems. I. New quadruply imaged quasar candidates around known quasars", "author": [ { "family_name": "Krone-Martins", "given_name": "A.", "clpid": "Krone-Martins-A" }, { "family_name": "Delchambre", "given_name": "L.", "clpid": "Delchambre-L" }, { "family_name": "Wertz", "given_name": "O.", "orcid": "0000-0003-3849-2285", "clpid": "Wertz-O" }, { "family_name": "Ducourant", "given_name": "C.", "orcid": "0000-0003-4843-8979", "clpid": "Ducourant-C" }, { "family_name": "Mignard", "given_name": "F.", "clpid": "Mignard-F" }, { "family_name": "Teixeira", "given_name": "R.", "clpid": "Teixeira-R" }, { "family_name": "Kl\u00fcter", "given_name": "J.", "clpid": "Kl\u00fcter-J" }, { "family_name": "Le Campion", "given_name": "J.-F.", "clpid": "Le-Campion-J-F" }, { "family_name": "Galluccio", "given_name": "L.", "clpid": "Galluccio-L" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Bastian", "given_name": "U.", "clpid": "Bastian-U" }, { "family_name": "Wambsganss", "given_name": "J.", "clpid": "Wambsganss-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Slezak", "given_name": "E.", "clpid": "Slezak-E" } ], "abstract": "Context. Multiply imaged gravitationally lensed quasars are among the most interesting and useful observable extragalactic phenomena. Because their study constitutes a unique tool in various fields of astronomy, they are highly sought, but difficult to find. Even in this era of all-sky surveys, discovering them remains a great challenge, with barely a few hundred systems currently known.\n\nAims. We aim to discover new multiply imaged quasar candidates in the recently published Gaia Data Release 2 (DR2), which is the astrometric and photometric all-sky survey with the highest spatial resolution that achieves effective resolutions from 0.4\u2033 to 2.2\u2033. \n\nMethods. We cross-matched a merged list of quasars and candidates with Gaia DR2 and found 1 839 143 counterparts within 0.5\u2033. We then searched matches with more than two Gaia DR2 counterparts within 6\u2033. We further narrowed the resulting list using astrometry and photometry compatibility criteria between the Gaia DR2 counterparts. A supervised machine-learning method, called extremely randomized trees, was finally adopted to assign a probability of being lensed to each remaining system. \n\nResults. We report the discovery of two quadruply imaged quasar candidates that are fully detected in Gaia DR2. These are the most promising new quasar lens candidates from Gaia DR2 and a simple singular isothermal ellipsoid lens model is able to reproduce their image positions to within ~1 mas. This Letter demonstrates the discovery potential of Gaia for gravitational lenses.", "doi": "10.1051/0004-6361/201833337", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2018-08", "volume": "616", "pages": "Art. No. L11" }, { "id": "authors:y2e9b-yqy68", "collection": "authors", "collection_id": "y2e9b-yqy68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180629-103946615", "type": "article", "title": "Luminous WISE-selected Obscured, Unobscured, and Red Quasars in Stripe 82", "author": [ { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Lacy", "given_name": "M.", "orcid": "0000-0002-3032-1783", "clpid": "Lacy-M" }, { "family_name": "LaMassa", "given_name": "S.", "orcid": "0000-0002-5907-3330", "clpid": "LaMassa-S-M" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Urrutia", "given_name": "T.", "orcid": "0000-0001-6746-9936", "clpid": "Urrutia-T" }, { "family_name": "Lovdal", "given_name": "Larson", "clpid": "Lovdal-L" }, { "family_name": "Crnogorcevic", "given_name": "M.", "clpid": "Crnogorcevic-M" }, { "family_name": "Daniels-Koch", "given_name": "H.", "clpid": "Daniels-Koch-H" }, { "family_name": "Hundal", "given_name": "Carol B.", "clpid": "Hundal-C-B" }, { "family_name": "Urry", "given_name": "M.", "orcid": "0000-0002-0745-9792", "clpid": "Urry-C-M" }, { "family_name": "Gates", "given_name": "E. L.", "orcid": "0000-0002-3739-0423", "clpid": "Gates-E-L" }, { "family_name": "Murray", "given_name": "S.", "clpid": "Murray-S-S" } ], "abstract": "We present a spectroscopically complete sample of 147 infrared-color-selected active galactic nuclei (AGNs) down to a 22 \u03bcm flux limit of 20 mJy over the ~270 deg^2 of the Sloan Digital Sky Survey Stripe 82 region. Most of these sources are in the QSO luminosity regime (L_(bol) \u2273 10^(12) L\u2299) and are found out to z \u2243 3. We classify the AGNs into three types, finding 57 blue, unobscured Type-1 (broad-lined) sources; 69 obscured, Type-2 (narrow-lined) sources; and 21 moderately reddened Type-1 sources (broad-lined and E(B \u2212 V) > 0.25). We study a subset of this sample in X-rays and analyze their obscuration to find that our spectroscopic classifications are in broad agreement with low, moderate, and large amounts of absorption for Type-1, red Type-1, and Type-2 AGNs, respectively. We also investigate how their X-ray luminosities correlate with other known bolometric luminosity indicators such as [O III] line luminosity (L_([O III])) and infrared luminosity (L_(6\u03bcm)). While the X-ray correlation with L_([O III]) is consistent with previous findings, the most infrared-luminous sources appear to deviate from established relations such that they are either underluminous in X-rays or overluminous in the infrared. Finally, we examine the luminosity function evolution of our sample, and by AGN type, in combination with the complementary, infrared-selected, AGN sample of Lacy et al. (2013), spanning over two orders of magnitude in luminosity. We find that the two obscured populations evolve differently, with reddened Type-1 AGNs dominating the obscured AGN fraction (~30%) for L_(5\u03bcm) > 10^(45) erg s^(\u22121), while the fraction of Type-2 AGNs with L_(5\u03bcm) < 10^(45) erg s^(\u22121) rises sharply from 40% to 80% of the overall AGN population.", "doi": "10.3847/1538-4357/aac5d8", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2018-07-01", "series_number": "1", "volume": "861", "issue": "1", "pages": "Art. No. 37" }, { "id": "authors:hz8c1-d9035", "collection": "authors", "collection_id": "hz8c1-d9035", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180612-092128138", "type": "article", "title": "A MegaCam Survey of Outer Halo Satellites. I. Description of the Survey", "author": [ { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Santana", "given_name": "Felipe A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Oyarz\u00fan", "given_name": "Grecco A.", "orcid": "0000-0003-0028-4130", "clpid": "Oyarz\u00fan-G-A" }, { "family_name": "Stetson", "given_name": "Peter B.", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We describe a deep, systematic imaging study of satellites in the outer halo of the Milky Way. Our sample consists of 58 stellar overdensities\u2014i.e., substructures classified as either globular clusters, classical dwarf galaxies, or ultra-faint dwarf galaxies\u2014that are located at Galactocentric distances of R_(GC) \u2265 25 kpc (outer halo) and out to ~400 kpc. This includes 44 objects for which we have acquired deep, wide-field, g- and r-band imaging with the MegaCam mosaic cameras on the 3.6 m Canada\u2013France\u2013Hawaii Telescope and the 6.5 m Magellan-Clay telescope. These data are supplemented by archival imaging, or published gr photometry, for an additional 14 objects, most of which were discovered recently in the Dark Energy Survey (DES). We describe the scientific motivation for our survey, including sample selection, observing strategy, data reduction pipeline, calibration procedures, and the depth and precision of the photometry. The typical 5\u03c3 point-source limiting magnitudes for our MegaCam imaging\u2014which collectively covers an area of \u224852 deg^2\u2014are g_(lim) \u2243 25.6 and r_(lim) \u2243 25.3 AB mag. These limits are comparable to those from the coadded DES images and are roughly a half-magnitude deeper than will be reached in a single visit with the Large Synoptic Survey Telescope. Our photometric catalog thus provides the deepest and most uniform photometric database of Milky Way satellites available for the foreseeable future. In other papers in this series, we have used these data to explore the blue straggler populations in these objects, their density distributions, star formation histories, scaling relations, and possible foreground structures.", "doi": "10.3847/1538-4357/aac168", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2018-06-10", "series_number": "1", "volume": "860", "issue": "1", "pages": "Art. No. 65" }, { "id": "authors:nphh3-8rx25", "collection": "authors", "collection_id": "nphh3-8rx25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180612-094525500", "type": "article", "title": "A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters", "author": [ { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Santana", "given_name": "Felipe A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Oyarz\u00fan", "given_name": "Grecco A.", "orcid": "0000-0003-0028-4130", "clpid": "Oyarz\u00fan-G-A" }, { "family_name": "Stetson", "given_name": "Peter B.", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present structural parameters from a wide-field homogeneous imaging survey of Milky Way satellites carried out with the MegaCam imagers on the 3.6 m Canada\u2013France\u2013Hawaii Telescope and 6.5 m Magellan-Clay telescope. Our survey targets an unbiased sample of \"outer halo\" satellites (i.e., substructures having galactocentric distances greater than 25 kpc) and includes classical dSph galaxies, ultra-faint dwarfs, and remote globular clusters. We combine deep, panoramic gr imaging for 44 satellites and archival gr imaging for 14 additional objects (primarily obtained with the DECam instrument as part of the Dark Energy Survey) to measure photometric and structural parameters for 58 outer halo satellites. This is the largest and most uniform analysis of Milky Way satellites undertaken to date and represents roughly three-quarters (58/81 \u2243 72%) of all known outer halo satellites. We use a maximum-likelihood method to fit four density laws to each object in our survey: exponential, Plummer, King, and S\u00e9rsic models. We systematically examine the isodensity contour maps and color\u2013magnitude diagrams for each of our program objects, present a comparison with previous results, and tabulate our best-fit photometric and structural parameters, including ellipticities, position angles, effective radii, S\u00e9rsic indices, absolute magnitudes, and surface brightness measurements. We investigate the distribution of outer halo satellites in the size\u2013magnitude diagram and show that the current sample of outer halo substructures spans a wide range in effective radius, luminosity, and surface brightness, with little evidence for a clean separation into star cluster and galaxy populations at the faintest luminosities and surface brightnesses.", "doi": "10.3847/1538-4357/aac16b", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2018-06-10", "series_number": "1", "volume": "860", "issue": "1", "pages": "Art. No. 66" }, { "id": "authors:459em-xqw29", "collection": "authors", "collection_id": "459em-xqw29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180613-105308891", "type": "article", "title": "A survey for dwarf galaxy remnants around 14 globular clusters in the outer halo", "author": [ { "family_name": "Sollima", "given_name": "A.", "clpid": "Sollima-A" }, { "family_name": "Mart\u00ednez Delgado", "given_name": "D.", "orcid": "0000-0003-3835-2231", "clpid": "Mart\u00ednez-Delgado-D" }, { "family_name": "Mu\u00f1oz", "given_name": "R. R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "Carballo-Bello", "given_name": "J. A.", "clpid": "Carballo-Bello-J-A" }, { "family_name": "Valls-Gabaud", "given_name": "D.", "clpid": "Valls-Gabaud-D" }, { "family_name": "Grebel", "given_name": "E. K.", "orcid": "0000-0002-1891-3794", "clpid": "Grebel-E-K" }, { "family_name": "Santana", "given_name": "F. A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report the results of a systematic photometric survey of the peripheral regions of a sample of 14 globular clusters in the outer halo of the Milky Way at distances d_(GC) > 25\u2009kpc from the Galactic Centre. The survey is aimed at searching for the remnants of the host satellite galaxies where these clusters could originally have been formed before being accreted on to the Galactic halo. The limiting surface brightness varies within our sample, but reaches \u03bc_(V, lim)\u2009=\u200930\u201332\u2009mag arcsec^(\u22122). For only two globular clusters (NGC 7492 and Whiting 1; already suggested to be associated with the Sagittarius galaxy), we detect extended stellar populations that cannot be associated with either the clusters themselves or with the surrounding Galactic field population. We show that the lack of substructures around globular clusters at these Galactocentric distances is still compatible with the predictions of cosmological simulations whereby in the outer halo the Galactic globular cluster system is built up through hierarchical accretion at early epochs.", "doi": "10.1093/mnras/sty539", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2018-06-01", "series_number": "4", "volume": "476", "issue": "4", "pages": "4814-4829" }, { "id": "authors:9ydkk-ae946", "collection": "authors", "collection_id": "9ydkk-ae946", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180329-152524491", "type": "article", "title": "SNhunt151: an explosive event inside a dense cocoon", "author": [ { "family_name": "Elias-Rosa", "given_name": "N.", "orcid": "0000-0002-1381-9125", "clpid": "Elias-Rosa-N" }, { "family_name": "Benetti", "given_name": "S", "orcid": "0000-0002-3256-0016", "clpid": "Benetti-S" }, { "family_name": "Cappellaro", "given_name": "E.", "orcid": "0000-0001-5008-8619", "clpid": "Cappellaro-E" }, { "family_name": "Pastorello", "given_name": "A.", "clpid": "Pastorello-A" }, { "family_name": "Terreran", "given_name": "G.", "clpid": "Terreran-G" }, { "family_name": "Morales-Garoffolo", "given_name": "A.", "clpid": "Morales-Garoffolo-A" }, { "family_name": "Howerton", "given_name": "S. C.", "clpid": "Howerton-S-C" }, { "family_name": "Valenti", "given_name": "S.", "orcid": "0000-0001-8818-0795", "clpid": "Valenti-S" }, { "family_name": "Kankare", "given_name": "E.", "orcid": "0000-0001-8257-3512", "clpid": "Kankare-E" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Tomasella", "given_name": "L.", "clpid": "Tomasella-L" }, { "family_name": "Tartaglia", "given_name": "L.", "orcid": "0000-0003-3433-1492", "clpid": "Tartaglia-L" }, { "family_name": "Kangas", "given_name": "T.", "clpid": "Kangas-T" }, { "family_name": "Ochner", "given_name": "P.", "clpid": "Ochner-P" }, { "family_name": "Filippenko", "given_name": "A. V.", "orcid": "0000-0003-3460-0103", "clpid": "Filippenko-A-V" }, { "family_name": "Ciabattari", "given_name": "F.", "clpid": "Ciabattari-F" }, { "family_name": "Geier", "given_name": "S.", "orcid": "0000-0002-3948-9339", "clpid": "Geier-S" }, { "family_name": "Howell", "given_name": "D. A.", "orcid": "0000-0003-4253-656X", "clpid": "Howell-D-A" }, { "family_name": "Isern", "given_name": "J.", "clpid": "Isern-J" }, { "family_name": "Leonini", "given_name": "S.", "clpid": "Leonini-S" }, { "family_name": "Pignata", "given_name": "G.", "orcid": "0000-0003-0006-0188", "clpid": "Pignata-G" }, { "family_name": "Turatto", "given_name": "M.", "clpid": "Turatto-M" } ], "abstract": "SNhunt151 was initially classified as a supernova (SN) impostor (nonterminal outburst of a massive star). It exhibited a slow increase in luminosity, lasting about 450\u2009d, followed by a major brightening that reaches M_V \u2248 \u221218\u2009mag. No source is detected to M_V \u2273 \u221213\u2009mag in archival images at the position of SNhunt151 before the slow rise. Low-to-mid-resolution optical spectra obtained during the pronounced brightening show very little evolution, being dominated at all times by multicomponent Balmer emission lines, a signature of interaction between the material ejected in the new outburst and the pre-existing circumstellar medium. We also analysed mid-infrared images from the Spitzer Space Telescope, detecting a source at the transient position in 2014 and 2015. Overall, SNhunt151 is spectroscopically a Type IIn SN, somewhat similar to SN 2009ip. However, there are also some differences, such as a slow pre-discovery rise, a relatively broad light-curve peak showing a longer rise time (\u223c50\u2009d), and a slower decline, along with a negligible change in the temperature around the peak (T \u2264 10^4\u2009K). We suggest that SNhunt151 is the result of an outburst, or an SN explosion, within a dense circumstellar nebula, similar to those embedding some luminous blue variables like \u03b7 Carinae and originating from past mass-loss events.", "doi": "10.1093/mnras/sty009", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2018-04-01", "series_number": "2", "volume": "475", "issue": "2", "pages": "2614-2631" }, { "id": "authors:pzpj1-pd468", "collection": "authors", "collection_id": "pzpj1-pd468", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180301-083148762", "type": "article", "title": "Supernovae 2016bdu and 2005gl, and their link with SN 2009ip-like transients: another piece of the puzzle", "author": [ { "family_name": "Pastorello", "given_name": "A.", "clpid": "Pastorello-A" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Supernova (SN) 2016bdu is an unusual transient resembling SN 2009ip. SN 2009ip-like events are characterized by a long-lasting phase of erratic variability that ends with two luminous outbursts a few weeks apart. The second outburst is significantly more luminous (about 3\u2009mag) than the first. In the case of SN 2016bdu, the first outburst (Event A) reached an absolute magnitude M_r \u2248 \u221215.3\u2009mag, while the second one (Event B) occurred over one month later and reached M_r \u2248 \u221218\u2009mag. By inspecting archival data, a faint source at the position of SN 2016bdu is several times in the past few years. We interpret these detections as signatures of a phase of erratic variability, similar to that experienced by SN 2009ip between 2008 and mid-2012, and resembling the currently observed variability of the luminous blue variable SN 2000ch in NGC 3432. Spectroscopic monitoring of SN 2016bdu during the second peak initially shows features typical of an SN IIn. One month after the Event B maximum, the spectra develop broad Balmer lines with P Cygni profiles and broad metal features. At these late phases, the spectra resemble those of a typical Type II SN. All members of this SN 2009ip-like group are remarkably similar to the Type IIn SN 2005gl. For this object, the claim of a terminal SN explosion is supported by the disappearance of the progenitor star. While the similarity with SN 2005gl supports a genuine SN explosion scenario for SN 2009ip-like events, the unequivocal detection of nucleosynthesized elements in their nebular spectra is still missing.", "doi": "10.1093/mnras/stx2668", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2018-02-11", "series_number": "1", "volume": "474", "issue": "1", "pages": "197-218" }, { "id": "authors:64c8s-edy94", "collection": "authors", "collection_id": "64c8s-edy94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180208-145104828", "type": "book_section", "title": "Deep-learnt classification of light curves", "book_title": "2017 IEEE Symposium Series on Computational Intelligence (SSCI)", "author": [ { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Sheth", "given_name": "K.", "orcid": "0000-0002-5496-4118", "clpid": "Sheth-K" }, { "family_name": "Gieseke", "given_name": "F.", "clpid": "Gieseke-F" }, { "family_name": "Pai", "given_name": "A.", "clpid": "Pai-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" } ], "abstract": "Astronomy light curves are sparse, gappy, and heteroscedastic. As a result standard time series methods regularly used for financial and similar datasets are of little help and astronomers are usually left to their own instruments and techniques to classify light curves. A common approach is to derive statistical features from the time series and to use machine learning methods, generally supervised, to separate objects into a few of the standard classes. In this work, we transform the time series to two-dimensional light curve representations in order to classify them using modern deep learning techniques. In particular, we show that convolutional neural networks based classifiers work well for broad characterization and classification. We use labeled datasets of periodic variables from CRTS survey and show how this opens doors for a quick classification of diverse classes with several possible exciting extensions.", "doi": "10.1109/SSCI.2017.8280984", "isbn": "978-1-5386-2727-3", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2017-12", "pages": "1-8" }, { "id": "authors:1x4tj-4mk13", "collection": "authors", "collection_id": "1x4tj-4mk13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181022-153934130", "type": "article", "title": "Understanding extreme quasar optical variability with CRTS: I. Major AGN flares", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Larson", "given_name": "Steve", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "Eric", "clpid": "Christensen-E" } ], "abstract": "There is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present the results of a systematic search for major flares in active galactic nucleus (AGN) in the Catalina Real-time Transient Survey as part of a broader study into extreme quasar variability. Such flares are defined in a quantitative manner as being atop of the normal, stochastic variability of quasars. We have identified 51 events from over 900 000 known quasars and high-probability quasar candidates, typically lasting 900 d and with a median peak amplitude of \u0394m = 1.25 mag. Characterizing the flare profile with a Weibull distribution, we find that nine of the sources are well described by a single-point single-lens model. This supports the proposal by Lawrence et al. that microlensing is a plausible physical mechanism for extreme variability. However, we attribute the majority of our events to explosive stellar-related activity in the accretion disc: superluminous supernovae, tidal disruption events and mergers of stellar mass black holes.", "doi": "10.1093/mnras/stx1456", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2017-10-01", "series_number": "4", "volume": "470", "issue": "4", "pages": "4112-4132" }, { "id": "authors:0fvm5-tby20", "collection": "authors", "collection_id": "0fvm5-tby20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180322-091256983", "type": "article", "title": "Challenges in the automated classification of variable stars in large databases", "author": [ { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" } ], "abstract": "With ever-increasing numbers of astrophysical transient surveys, new facilities and archives of astronomical time series, time domain astronomy is emerging as a mainstream discipline. However, the sheer volume of data alone - hundreds of observations for hundreds of millions of sources \u2013 necessitates advanced statistical and machine learning methodologies for scientific discovery: characterization, categorization, and classification. Whilst these techniques are slowly entering the astronomer's toolkit, their application to astronomical problems is not without its issues. In this paper, we will review some of the challenges posed by trying to identify variable stars in large data collections, including appropriate feature representations, dealing with uncertainties, establishing ground truths, and simple discrete classes.", "doi": "10.1051/epjconf/201715203001", "issn": "2100-014X", "publisher": "EDP Sciences", "publication": "EPJ Web of Conferences", "publication_date": "2017-09-08", "volume": "152", "pages": "Art. No. 03001" }, { "id": "authors:w7829-tba88", "collection": "authors", "collection_id": "w7829-tba88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170728-091458187", "type": "article", "title": "Long-term Periodicities of Cataclysmic Variables with Synoptic Surveys", "author": [ { "family_name": "Yang", "given_name": "Michael Ting-Chang", "clpid": "Yang-Michael-Ting-Chang" }, { "family_name": "Chou", "given_name": "Yi", "clpid": "Chou-Yi" }, { "family_name": "Ngeow", "given_name": "Chow-Choong", "orcid": "0000-0001-8771-7554", "clpid": "Ngeow-Chow-Choong" }, { "family_name": "Hu", "given_name": "Chin-Ping", "clpid": "Hu-Chin-Ping" }, { "family_name": "Su", "given_name": "Yi-Hao", "clpid": "Su-Yi-Hao" }, { "family_name": "Prince", "given_name": "Thomas A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Levitan", "given_name": "David", "clpid": "Levitan-D-B" }, { "family_name": "Laher", "given_name": "Russ", "orcid": "0000-0003-2451-5482", "clpid": "Laher-R-R" }, { "family_name": "Surace", "given_name": "Jason", "orcid": "0000-0001-7291-0087", "clpid": "Surace-J-A" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "Stanislav G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" } ], "abstract": "A systematic study on the long-term periodicities of known Galactic cataclysmic variables (CVs) was conducted. Among 1580 known CVs, 344 sources were matched and extracted from the Palomar Transient Factory (PTF) data repository. The PTF light curves were combined with the Catalina Real-Time Transient Survey (CRTS) light curves and analyzed. Ten targets were found to exhibit long-term periodic variability, which is not frequently observed in the CV systems. These long-term variations are possibly caused by various mechanisms, such as the precession of the accretion disk, hierarchical triple star system, magnetic field change of the companion star, and other possible mechanisms. We discuss the possible mechanisms in this study. If the long-term period is less than several tens of days, the disk precession period scenario is favored. However, the hierarchical triple star system or the variations in magnetic field strengths are most likely the predominant mechanisms for longer periods.", "doi": "10.1088/1538-3873/aa7a99", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2017-09", "series_number": "979", "volume": "129", "issue": "979", "pages": "Art. No. 094202" }, { "id": "authors:tj2s4-amz72", "collection": "authors", "collection_id": "tj2s4-amz72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170828-102107847", "type": "article", "title": "The Catalina Surveys Southern periodic variable star catalogue", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Torrealba", "given_name": "G.", "clpid": "Torrealba-G" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "McNaught", "given_name": "R. H.", "clpid": "McNaught-R-H" }, { "family_name": "Garradd", "given_name": "G.", "clpid": "Garradd-G" }, { "family_name": "Belokurov", "given_name": "V.", "orcid": "0000-0002-0038-9584", "clpid": "Belokurov-V" }, { "family_name": "Koposov", "given_name": "S. E.", "orcid": "0000-0003-2644-135X", "clpid": "Koposov-S-E" } ], "abstract": "Here, we present the results from our analysis of 6 yr of optical photometry taken by the Siding Spring Survey (SSS). This completes a search for periodic variable stars within the 30 000 deg^2 of the sky covered by the Catalina Surveys. The current analysis covers 81 million sources with declinations between \u221220\u00b0 and \u221275\u00b0 with median magnitudes in the range 11 < V < 19.5. We find approximately 34 000 new periodic variable stars in addition to the \u223c9000 RR Lyrae that we previously discovered in SSS data. This brings the total number of periodic variables identified in Catalina data to \u223c110 000. The new SSS periodic variable stars mainly consist of eclipsing binaries, RR Lyrae, LPVs, RS CVn stars, \u03b4 Scutis, and Anomalous Cepheids. By cross-matching these variable stars with those from prior surveys, we find that \u223c90\u2009per\u2009cent of the sources are new discoveries and recover \u223c95\u2009per\u2009cent of the known periodic variables in the survey region. For the known sources, we find excellent agreement between our catalogue and prior values of luminosity, period, and amplitude. However, we find many variable stars that had previously been misclassified. Examining the distribution of RR Lyrae, we find a population associated with the Large Magellanic Cloud (LMC) that extends more than 20\u00b0 from its centre confirming recent evidence for the existence of a very extended stellar halo in the LMC. By combining SSS photometry with Dark Energy Survey data, we identify additional LMC halo RR Lyrae, thus confirming the significance of the population.", "doi": "10.1093/mnras/stx1085", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2017-08", "series_number": "3", "volume": "469", "issue": "3", "pages": "3688-3712" }, { "id": "authors:fev5s-18z91", "collection": "authors", "collection_id": "fev5s-18z91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170908-091435782", "type": "article", "title": "'Zwicky's Nonet': a compact merging ensemble of nine galaxies and 4C 35.06, a peculiar radio galaxy with dancing radio jets", "author": [ { "family_name": "Biju", "given_name": "K. G.", "clpid": "Biju-K-G" }, { "family_name": "Bagchi", "given_name": "Joydeep", "clpid": "Bagchi-Joydeep" }, { "family_name": "Ishwara-Chandra", "given_name": "C. H.", "clpid": "Ishwara-Chandra-C-H" }, { "family_name": "Pandey-Pommier", "given_name": "M.", "clpid": "Pandey-Pommier-M" }, { "family_name": "Jacob", "given_name": "Joe", "clpid": "Jacob-J" }, { "family_name": "Patil", "given_name": "M. K.", "clpid": "Patil-M-K" }, { "family_name": "Kumar", "given_name": "P. Sunil", "clpid": "Kumar-P-Sunil" }, { "family_name": "Pandge", "given_name": "Mahadev", "clpid": "Pandge-M" }, { "family_name": "Dabhade", "given_name": "Pratik", "clpid": "Dabhade-P" }, { "family_name": "Gaikwad", "given_name": "Madhuri", "clpid": "Gaikwad-M" }, { "family_name": "Dhurde", "given_name": "Samir", "clpid": "Dhurde-S" }, { "family_name": "Abraham", "given_name": "Sheelu", "clpid": "Abraham-Sheelu" }, { "family_name": "Vivek", "given_name": "M.", "clpid": "Vivek-M" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report the results of our radio, optical and infrared studies of a peculiar radio source 4C 35.06, an extended radio-loud active galactic nucleus (AGN) at the centre of galaxy cluster Abell 407 (z = 0.047). The central region of this cluster hosts a remarkably tight ensemble of nine galaxies, the spectra of which resemble those of passive red ellipticals, embedded within a diffuse stellar halo of \u223c1 arcmin size. This system (named 'Zwicky's Nonet') provides unique and compelling evidence for a multiple-nucleus cD galaxy precursor. Multifrequency radio observations of 4C 35.06 with the Giant Meterwave Radio Telescope (GMRT) at 610, 235 and 150 MHz reveal a system of 400-kpc scale helically twisted and kinked radio jets and outer diffuse lobes. The outer extremities of jets contain extremely steep-spectrum (spectral index \u22121.7 to \u22122.5) relic/fossil radio plasma with a spectral age of a few\u2009\u00d7(10^7\u201310^8) yr. Such ultra-steep spectrum relic radio lobes without definitive hotspots are rare and they provide an opportunity to understand the life cycle of relativistic jets and physics of black hole mergers in dense environments. We interpret our observations of this radio source in the context of growth of its central black hole, triggering of its AGN activity and jet precession, all possibly caused by galaxy mergers in this dense galactic system. A slow conical precession of the jet axis due to gravitational perturbation between interacting black holes is invoked to explain the unusual jet morphology.", "doi": "10.1093/mnras/stx1476", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2017-07-29", "series_number": "1", "volume": "471", "issue": "1", "pages": "617-628" }, { "id": "authors:kdr17-qph67", "collection": "authors", "collection_id": "kdr17-qph67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-141822439", "type": "book_section", "title": "The EDRN knowledge environment: an open source, scalable informatics platform for biological sciences research", "book_title": "Micro- and Nanotechnology Sensors, Systems, and Applications IX", "author": [ { "family_name": "Crichton", "given_name": "Daniel", "clpid": "Crichton-D-J" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Anton", "given_name": "Kristen", "clpid": "Anton-K" }, { "family_name": "Cinquini", "given_name": "Luca", "clpid": "Cinquini-L" }, { "family_name": "Colbert", "given_name": "Maureen", "clpid": "Colbert-M" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kincaid", "given_name": "Heather", "clpid": "Kincaid-H" }, { "family_name": "Kelly", "given_name": "Sean", "clpid": "Kelly-S-C" }, { "family_name": "Liu", "given_name": "David", "clpid": "Liu-David" } ], "contributor": [ { "family_name": "George", "given_name": "Thomas", "clpid": "George-T" }, { "family_name": "Dutta", "given_name": "Achyut K.", "clpid": "Dutta-A-K" }, { "family_name": "Islam", "given_name": "M. Saif", "clpid": "Islam-M-S" } ], "abstract": "We describe here the Early Detection Research Network (EDRN) for Cancer's knowledge environment. It is an open source platform built by NASA's Jet Propulsion Laboratory with contributions from the California Institute of Technology, and Giesel School of Medicine at Dartmouth. It uses tools like Apache OODT, Plone, and Solr, and borrows heavily from JPL's Planetary Data System's ontological infrastructure. It has accumulated data on hundreds of thousands of biospecemens and serves over 1300 registered users across the National Cancer Institute (NCI). The scalable computing infrastructure is built such that we are being able to reach out to other agencies, provide homogeneous access, and provide seamless analytics support and bioinformatics tools through community engagement.", "doi": "10.1117/12.2263842", "isbn": "9781510608894", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2017-05-18", "pages": "Art. No. 101942A" }, { "id": "authors:1jyw6-vm494", "collection": "authors", "collection_id": "1jyw6-vm494", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170421-131659519", "type": "article", "title": "Extreme Variability in a Broad Absorption Line Quasar", "author": [ { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Arav", "given_name": "Nahum", "clpid": "Arav-N" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Chamberlain", "given_name": "Carter", "clpid": "Chamberlain-C" }, { "family_name": "Barth", "given_name": "Aaron J.", "orcid": "0000-0002-3026-0562", "clpid": "Barth-A-J" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Jun", "given_name": "Hyunsung D.", "orcid": "0000-0003-1470-5901", "clpid": "Jun-Hyunsung-David" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Steidel", "given_name": "Charles C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" } ], "abstract": "CRTS J084133.15+200525.8 is an optically bright quasar at z = 2.345 that has shown extreme spectral variability over the past decade. Photometrically, the source had a visual magnitude of V ~ 17.3 between 2002 and 2008. Then, over the following five years, the source slowly brightened by approximately one magnitude, to V ~ 16.2. Only ~1 in 10,000 quasars show such extreme variability, as quantified by the extreme parameters derived for this quasar assuming a damped random walk model. A combination of archival and newly acquired spectra reveal the source to be an iron low-ionization broad absorption line quasar with extreme changes in its absorption spectrum. Some absorption features completely disappear over the 9 years of optical spectra, while other features remain essentially unchanged. We report the first definitive redshift for this source, based on the detection of broad H\u03b1 in a Keck/MOSFIRE spectrum. Absorption systems separated by several 1000 km s^(\u22121) in velocity show coordinated weakening in the depths of their troughs as the continuum flux increases. We interpret the broad absorption line variability to be due to changes in photoionization, rather than due to motion of material along our line of sight. This source highlights one sort of rare transition object that astronomy will now be finding through dedicated time-domain surveys.", "doi": "10.3847/1538-4357/aa683c", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2017-04-20", "series_number": "2", "volume": "839", "issue": "2", "pages": "Art. No. 106" }, { "id": "authors:yn8a4-45584", "collection": "authors", "collection_id": "yn8a4-45584", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170331-095838217", "type": "article", "title": "Characterization of 9380 contact binaries from the CRTS Variable Sources Catalogue", "author": [ { "family_name": "Marsh", "given_name": "F. M.", "clpid": "Marsh-F-M" }, { "family_name": "Prince", "given_name": "T. A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Bellm", "given_name": "E. C.", "orcid": "0000-0001-8018-5348", "clpid": "Bellm-E-C" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We construct a sample of 9380 contact binaries (W UMa systems) by using the Catalina Real-Time Transient Survey Variables Sources Catalogue. By measuring brightness change rates, light-curve statistics, and temperatures for this sample, we improve the understanding of contact binary light-curve characteristics, and luminosity variability on decadal time-scales. We show that binaries with convective outer envelopes have a different distribution of light-curve amplitudes and magnitude differences between eclipse minima than binaries with radiative outer envelopes. We find that more than 2000 binaries exhibit a linear change in mean brightness over the 8-yr timespan of observations with at least 3\u03c3 significance. We note that 25.9 per cent of binaries with convective outer envelopes exhibit a significant change in brightness, while only 10.5 per cent of radiative binaries exhibit a significant change in brightness. In 205 binaries (2.2 per cent), we find that a sinusoid model better describes the luminosity trend within the 8-yr observation timespan. For these binaries, we report the amplitudes and periods (as estimated using observed half-periods) of this sinusoidal brightness variation and discuss possible mechanisms driving the variation.", "doi": "10.1093/mnras/stw2110", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2017-03", "series_number": "4", "volume": "465", "issue": "4", "pages": "4678-4689" }, { "id": "authors:qjse6-t2810", "collection": "authors", "collection_id": "qjse6-t2810", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180207-144554128", "type": "article", "title": "A Satellite Survey of Cloud Cover and Water Vapor in the Southwestern USA and Northern Mexico", "author": [ { "family_name": "Carrasco", "given_name": "E.", "clpid": "Carrasco-E" }, { "family_name": "Avila", "given_name": "R.", "clpid": "Avila-R" }, { "family_name": "Erasmus", "given_name": "A.", "clpid": "Erasmus-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Walker", "given_name": "A. R.", "clpid": "Walker-A-R" }, { "family_name": "Blum", "given_name": "R.", "clpid": "Blum-R-D" } ], "abstract": "Cloud cover and water vapor conditions in the southwestern USA and northern Mexico were surveyed as a preparatory work for the Thirty Meter Telescope (TMT) in situ site testing program. Although the telescope site is already selected, the TMT site testing team decided to make public these results for its usefulness for the community. Using 58 months of meteorological satellite observations between 1993 July and 1999 September, different atmospheric parameters were quantified from data of the 10.7 \u03bcm and of 6.7 \u03bcm windows. In particular, cloud cover and water vapor conditions were identified in preferred areas. As a result of the aerial analysis, 15 sites of existing and potential telescope were selected, compared, and ranked in terms of their observing quality. The clearest sites are located along the spine of the Baja peninsula and into southern California on mountain peaks above the temperature inversion layer. A steep gradient of cloudiness was observed along the coast where coastal cloud and fog are trapped below the inversion layer. Moving from west to east over the continent, a significant increase in cloudiness was observed. The analysis shows that San Pedro M\u00e1rtir, San Gorgonio Mountain and San Jacinto Peak have the largest fraction of clear sky conditions (~74%). The site with the optimal combination of clear skies and low precipitable water vapor is Boundary Peak, Nevada. An approach based in satellite data provided a reliable method for sites comparison.", "doi": "10.1088/1538-3873/129/973/035005", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2017-03", "series_number": "973", "volume": "129", "issue": "973", "pages": "Art. No. 035005" }, { "id": "authors:anjr4-qr165", "collection": "authors", "collection_id": "anjr4-qr165", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170428-114834477", "type": "article", "title": "Clustering on very small scales from a large sample of confirmed quasar pairs: does quasar clustering track from Mpc to kpc scales?", "author": [ { "family_name": "Eftekharzadeh", "given_name": "S.", "orcid": "0000-0002-8281-8388", "clpid": "Eftekharzadeh-Sarah" }, { "family_name": "Myers", "given_name": "A. D.", "clpid": "Myers-Adam-D" }, { "family_name": "Hennawi", "given_name": "J. F.", "orcid": "0000-0002-7054-4332", "clpid": "Hennawi-J-F" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Richards", "given_name": "G. T.", "clpid": "Richards-G-T" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-Ashish-A" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" } ], "abstract": "We present the most precise estimate to date of the clustering of quasars on very small scales, based on a sample of 47 binary quasars with magnitudes of g < 20.85 and proper transverse separations of \u223c25\u2009h^(\u22121) kpc. Our sample of binary quasars, which is about six times larger than any previous spectroscopically confirmed sample on these scales, is targeted using a kernel density estimation (KDE) technique applied to Sloan Digital Sky Survey (SDSS) imaging over most of the SDSS area. Our sample is 'complete' in that all of the KDE target pairs with 17.0 \u2272 R \u2272 36.2\u2009h^(\u22121) kpc in our area of interest have been spectroscopically confirmed from a combination of previous surveys and our own long-slit observational campaign. We catalogue 230 candidate quasar pairs with angular separations of <8 arcsec, from which our binary quasars were identified. We determine the projected correlation function of quasars (W-bar_p) in four bins of proper transverse scale over the range 17.0 \u2272 R \u2272 36.2\u2009h^(\u22121) kpc. The implied small-scale quasar clustering amplitude from the projected correlation function, integrated across our entire redshift range, is A = 24.1 \u00b1 3.6 at \u223c26.6\u2009h^(\u22121) kpc. Our sample is the first spectroscopically confirmed sample of quasar pairs that is sufficiently large to study how quasar clustering evolves with redshift at \u223c25\u2009h^(\u22121) kpc. We find that empirical descriptions of how quasar clustering evolves with redshift at \u223c25\u2009h^(\u22121) Mpc also adequately describe the evolution of quasar clustering at \u223c25\u2009h^(\u22121) kpc.", "doi": "10.1093/mnras/stx412", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2017-02-17", "series_number": "1", "volume": "468", "issue": "1", "pages": "77-90" }, { "id": "authors:xkjm1-hr417", "collection": "authors", "collection_id": "xkjm1-hr417", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160928-112139049", "type": "article", "title": "A MegaCam Survey of Outer Halo Satellites. VI: The Spatially Resolved Star Formation History of the Carina Dwarf Spheroidal Galaxy", "author": [ { "family_name": "Santana", "given_name": "Felipe A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "de Boer", "given_name": "T. J. L.", "clpid": "de-Boer-T-J-L" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Guzm\u00e1n", "given_name": "Andr\u00e9s E.", "clpid": "Guzm\u00e1n-A-E" }, { "family_name": "Stetson", "given_name": "Peter", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present the spatially resolved star-formation history (SFH) of the Carina dwarf spheroidal galaxy, obtained from deep, wide-field g and r imaging and a metallicity distribution from the literature. Our photometry covers ~2 deg^2, reaching up to ~10 times the half-light radius of Carina with a completeness higher than 50% at g ~ 24.5, more than one magnitude fainter than the oldest turnoff. This is the first time a combination of depth and coverage of this quality has been used to derive the SFH of Carina, enabling us to trace its different populations with unprecedented accuracy. We find that Carina's SFH consists of two episodes well separated by a star-formation temporal gap. These episodes occurred at old (> 10 Gyr) and intermediate (2\u20138 Gyr) ages. Our measurements show that the old episode comprises the majority of the population, accounting for 54 \u00b1 5% of the stellar mass within 1.3 times the King tidal radius, while the total stellar mass derived for Carina is 1.60 \u00b1 0.09 x 10^6 M_\u2609, and the stellar mass-to-light ratio is 1.8 \u00b1 0.2. The SFH derived is consistent with no recent star formation, which hints that the observed blue plume is due to blue stragglers. We conclude that the SFH of Carina evolved independently of the tidal field of the Milky Way, since the frequency and duration of its star-formation events do not correlate with its orbital parameters. This result is supported by the age\u2013metallicity relation observed in Carina and the gradients calculated indicating that outer regions are older and more metal-poor.", "doi": "10.3847/0004-637X/829/2/86", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2016-10-01", "series_number": "2", "volume": "829", "issue": "2", "pages": "Art. No. 86" }, { "id": "authors:ctdhr-aev17", "collection": "authors", "collection_id": "ctdhr-aev17", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170621-105114368", "type": "book_section", "title": "In Pursuit of High Redshift Galaxies", "book_title": "From the Realm of the Nebulae to Populations of Galaxies: Dialogues on a Century of Research", "author": [ { "family_name": "Rampazzo", "given_name": "Roberto", "orcid": "0000-0001-5318-9183", "clpid": "Rampazzo-R" }, { "family_name": "D'Onofrio", "given_name": "Mauro", "clpid": "D'Onofrio-M" }, { "family_name": "Zaggia", "given_name": "Simone", "orcid": "0000-0001-6081-379X", "clpid": "Zaggia-S" }, { "family_name": "Djorgovski", "given_name": "Stanislav George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Elmegreen", "given_name": "Debra M.", "orcid": "0000-0002-1392-3520", "clpid": "Elmegreen-D-M" }, { "family_name": "Poggianti", "given_name": "Bianca M.", "orcid": "0000-0001-8751-8360", "clpid": "Poggianti-B-M" }, { "family_name": "Calzetti", "given_name": "Daniela", "orcid": "0000-0002-5189-8004", "clpid": "Calzetti-D" }, { "family_name": "Combes", "given_name": "Francoise", "orcid": "0000-0003-2658-7893", "clpid": "Combes-F" }, { "family_name": "Longair", "given_name": "Malcolm S.", "clpid": "Longair-M-S" }, { "family_name": "Bromm", "given_name": "Volker", "clpid": "Bromm-V" } ], "contributor": [ { "family_name": "D'Onofrio", "given_name": "Mauro", "clpid": "D'Onofrio-M" }, { "family_name": "Rampazzo", "given_name": "Roberto", "clpid": "Rampazzo-R" }, { "family_name": "Zaggia", "given_name": "Simone", "clpid": "Zaggia-S" } ], "abstract": "Some contributions in Chap.\u20091 have highlighted the impact of the discovery in the 1960s of a handful of radio galaxies and Quasars in the redshift range z \u223c 0.2\u20130.4. About 40 years later, at the end of the twentieth Century, the systematic exploration of galaxies reached z \u223c 1\u20133. The combination of HST deep imaging and the coming into operation of the 8\u201310\u2009m class telescopes with their spectroscopic capabilities, move ahead the limits. At the same time, astronomers greatly improved their strategies to hunt high-redshift galaxies. Today, it is not infrequent the spectroscopic confirmation of galaxies at z \u223c 7\u20138, pushing the detection limits more or less to the end of the re-ionization era. The gauntlet to observe the so called \"first galaxies\", i.e. those assembling during the first billion years of the cosmic time, is throw down.", "doi": "10.1007/978-3-319-31006-0_6", "isbn": "978-3-319-31004-6", "publisher": "Springer", "place_of_publication": "Cham", "publication_date": "2016-07-27", "pages": "479-508" }, { "id": "authors:9hrp3-sdf69", "collection": "authors", "collection_id": "9hrp3-sdf69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170719-083244053", "type": "book_section", "title": "The Anatomy of Galaxies", "book_title": "From the Realm of the Nebulae to Populations of Galaxies: Dialogues on a Century of Research", "author": [ { "family_name": "D'Onofrio", "given_name": "Mauro", "clpid": "D'Onofrio-M" }, { "family_name": "Rampazzo", "given_name": "Roberto", "orcid": "0000-0001-5318-9183", "clpid": "Rampazzo-R" }, { "family_name": "Zaggia", "given_name": "Simone", "orcid": "0000-0001-6081-379X", "clpid": "Zaggia-S" }, { "family_name": "Longair", "given_name": "Malcolm S.", "clpid": "Longair-M-S" }, { "family_name": "Ferrarese", "given_name": "Laura", "clpid": "Ferrarese-L" }, { "family_name": "Marziani", "given_name": "Paola", "clpid": "Marziani-P" }, { "family_name": "Sulentic", "given_name": "Jack W.", "clpid": "Sulentic-J-W" }, { "family_name": "van der Kruit", "given_name": "Pieter C.", "clpid": "van-der-Kruit-P-C" }, { "family_name": "Laurikainen", "given_name": "Eija", "clpid": "Laurikainen-E" }, { "family_name": "Elmegreen", "given_name": "Debra M.", "orcid": "0000-0002-1392-3520", "clpid": "Elmegreen-D-M" }, { "family_name": "Combes", "given_name": "Francoise", "orcid": "0000-0003-2658-7893", "clpid": "Combes-F" }, { "family_name": "Bertin", "given_name": "Giuseppe", "clpid": "Bertin-G" }, { "family_name": "Fabbiano", "given_name": "Giuseppina", "orcid": "0000-0002-3554-3318", "clpid": "Fabbiano-G" }, { "family_name": "Giovanelli", "given_name": "Riccardo", "orcid": "0000-0001-8884-8492", "clpid": "Giovanelli-R" }, { "family_name": "Calzetti", "given_name": "Daniela", "orcid": "0000-0002-5189-8004", "clpid": "Calzetti-D" }, { "family_name": "Moss", "given_name": "David L.", "clpid": "Moss-D-L" }, { "family_name": "Matteucci", "given_name": "Francesca", "clpid": "Matteucci-F" }, { "family_name": "Djorgovski", "given_name": "Stanislav George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fraix-Burnet", "given_name": "Didier", "clpid": "Fraix-Burnet-D" }, { "family_name": "Graham", "given_name": "Alister W. McK.", "clpid": "Graham-A-W-M" }, { "family_name": "Tully", "given_name": "Brent R.", "clpid": "Tully-B-R" } ], "contributor": [ { "family_name": "D'Onofrio", "given_name": "Mauro", "clpid": "D'Onofrio-M" }, { "family_name": "Rampazzo", "given_name": "Roberto", "clpid": "Rampazzo-R" }, { "family_name": "Zaggia", "given_name": "Simone", "clpid": "Zaggia-S" } ], "abstract": "Just after WWII Astronomy started to live its \"Golden Age\", not differently to many other sciences and human activities, especially in the west side countries. The improved resolution of telescopes and the appearance of new efficient light detectors (e.g. CCDs in the middle eighty) greatly impacted the extragalactic researches. The first morphological analysis of galaxies were rapidly substituted by \"anatomic\" studies of their structural components, star and gas content, and in general by detailed investigations of their properties. As for the human anatomy, where the final goal was that of understanding the functionality of the organs that are essential for the life of the body, galaxies were dissected to discover their basic structural components and ultimately the mystery of their existence.", "doi": "10.1007/978-3-319-31006-0_4", "isbn": "978-3-319-31004-6", "publisher": "Springer", "place_of_publication": "Cham, Switzerland", "publication_date": "2016-07-27", "pages": "243-379" }, { "id": "authors:5gmhd-7th73", "collection": "authors", "collection_id": "5gmhd-7th73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170718-102535713", "type": "book_section", "title": "Extragalactic Astronomy: From Pioneers to Big Science", "book_title": "From the Realm of the Nebulae to Populations of Galaxies: Dialogues on a Century of Research", "author": [ { "family_name": "Rampazzo", "given_name": "Roberto", "orcid": "0000-0001-5318-9183", "clpid": "Rampazzo-R" }, { "family_name": "D'Onofrio", "given_name": "Mauro", "clpid": "D'Onofrio-M" }, { "family_name": "Zaggia", "given_name": "Simone", "orcid": "0000-0001-6081-379X", "clpid": "Zaggia-S" }, { "family_name": "Lattis", "given_name": "James M.", "clpid": "Lattis-J-M" }, { "family_name": "Haynes", "given_name": "Martha P.", "orcid": "0000-0001-5334-5166", "clpid": "Haynes-M-P" }, { "family_name": "Giovanelli", "given_name": "Riccardo", "orcid": "0000-0001-8884-8492", "clpid": "Giovanelli-R" }, { "family_name": "Karachentseva", "given_name": "Valentina", "clpid": "Karachentseva-V" }, { "family_name": "Longair", "given_name": "Malcolm S.", "clpid": "Longair-M-S" }, { "family_name": "Lindblad", "given_name": "Per-Olof", "clpid": "Lindblad-P-O" }, { "family_name": "Renzini", "given_name": "Alvio", "orcid": "0000-0002-7093-7355", "clpid": "Renzini-A" }, { "family_name": "de Carvalho", "given_name": "Reinaldo Ramos", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Kaifu", "given_name": "Norio", "clpid": "Kaifu-Norio" }, { "family_name": "Bland-Hawthorn", "given_name": "Jonathan", "clpid": "Bland-Hawthorn-Jonathan" }, { "family_name": "Djorgovski", "given_name": "Stanislav George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bianchi", "given_name": "Luciana", "orcid": "0000-0001-7746-5461", "clpid": "Bianchi-L-C" }, { "family_name": "Calzetti", "given_name": "Daniela", "orcid": "0000-0002-5189-8004", "clpid": "Calzetti-D" }, { "family_name": "Fabbiano", "given_name": "Giuseppina", "orcid": "0000-0002-3554-3318", "clpid": "Fabbiano-G" }, { "family_name": "Combes", "given_name": "Francoise", "orcid": "0000-0003-2658-7893", "clpid": "Combes-F" }, { "family_name": "Chiosi", "given_name": "Cesare", "orcid": "0000-0001-7107-8196", "clpid": "Chiosi-C" }, { "family_name": "Sulentic", "given_name": "Jack W.", "clpid": "Sulentic-J-W" } ], "contributor": [ { "family_name": "D'Onofrio", "given_name": "Mauro", "clpid": "D'Onofrio-M" }, { "family_name": "Rampazzo", "given_name": "Roberto", "clpid": "Rampazzo-R" }, { "family_name": "Zaggia", "given_name": "Simone", "clpid": "Zaggia-S" } ], "abstract": "At the beginning of the nineteenth century one of the scientific issues driving the research of astronomers, like the Herschels, was to test if all the nebul\u00e6 can be resolved into stars.", "doi": "10.1007/978-3-319-31006-0_1", "isbn": "978-3-319-31004-6", "publisher": "Springer", "place_of_publication": "Cham, Switzerland", "publication_date": "2016-07-27", "pages": "1-92" }, { "id": "authors:2efze-y6a02", "collection": "authors", "collection_id": "2efze-y6a02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160202-141416022", "type": "article", "title": "Real-time data mining of massive data streams from synoptic sky surveys", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" }, { "family_name": "Fuchs", "given_name": "T.", "clpid": "Fuchs-T-J" } ], "abstract": "The nature of scientific and technological data collection is evolving rapidly: data volumes and rates grow exponentially, with increasing complexity and information content, and there has been a transition from static data sets to data streams that must be analyzed in real time. Interesting or anomalous phenomena must be quickly characterized and followed up with additional measurements via optimal deployment of limited assets. Modern astronomy presents a variety of such phenomena in the form of transient events in digital synoptic sky surveys, including cosmic explosions (supernovae, gamma ray bursts), relativistic phenomena (black hole formation, jets), potentially hazardous asteroids, etc. We have been developing a set of machine learning tools to detect, classify and plan a response to transient events for astronomy applications, using the Catalina Real-time Transient Survey (CRTS) as a scientific and methodological testbed. The ability to respond rapidly to the potentially most interesting events is a key bottleneck that limits the scientific returns from the current and anticipated synoptic sky surveys. Similar challenge arises in other contexts, from environmental monitoring using sensor networks to autonomous spacecraft systems. Given the exponential growth of data rates, and the time-critical response, we need a fully automated and robust approach. We describe the results obtained to date, and the possible future developments.", "doi": "10.1016/j.future.2015.10.013", "issn": "0167739X", "publisher": "Elsevier", "publication": "Future Generation Computer Systems", "publication_date": "2016-06", "volume": "59", "pages": "95-104" }, { "id": "authors:g2675-a8a33", "collection": "authors", "collection_id": "g2675-a8a33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160509-092928454", "type": "article", "title": "An analysis of feature relevance in the classification of astronomical transients with machine learning methods", "author": [ { "family_name": "D'Isanto", "given_name": "A.", "clpid": "D'Isanto-A" }, { "family_name": "Cavuoti", "given_name": "S.", "orcid": "0000-0002-3787-4196", "clpid": "Cavuoti-S" }, { "family_name": "Brescia", "given_name": "M.", "orcid": "0000-0001-9506-5680", "clpid": "Brescia-M" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Longo", "given_name": "G.", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" }, { "family_name": "Riccio", "given_name": "G.", "orcid": "0000-0001-7020-1172", "clpid": "Riccio-G" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "The exploitation of present and future synoptic (multiband and multi-epoch) surveys requires an extensive use of automatic methods for data processing and data interpretation. In this work, using data extracted from the Catalina Real Time Transient Survey (CRTS), we investigate the classification performance of some well tested methods: Random Forest, MultiLayer Perceptron with Quasi Newton Algorithm and K-Nearest Neighbours, paying special attention to the feature selection phase. In order to do so, several classification experiments were performed. Namely: identification of cataclysmic variables, separation between galactic and extragalactic objects and identification of supernovae.", "doi": "10.1093/mnras/stw157", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2016-04-11", "series_number": "3", "volume": "457", "issue": "3", "pages": "3119-3132" }, { "id": "authors:v9r64-8s437", "collection": "authors", "collection_id": "v9r64-8s437", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160620-090009439", "type": "article", "title": "Interacting supernovae and supernova impostors. LSQ13zm: an outburst heralds the death of a massive star", "author": [ { "family_name": "Tartaglia", "given_name": "L.", "orcid": "0000-0003-3433-1492", "clpid": "Tartaglia-L" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report photometric and spectroscopic observations of the optical transient LSQ13zm. Historical data reveal the presence of an eruptive episode (that we label as '2013a') followed by a much brighter outburst ('2013b') three weeks later, that we argue to be the genuine supernova explosion. This sequence of events closely resemble those observed for SN 2010mc and (in 2012) SN 2009ip. The absolute magnitude reached by LSQ13zm during 2013a (M_R=\u221214.87\u00b10.25mag) is comparable with those of supernova impostors, while that of the 2013b event (M_R=\u221218.46\u00b10.21mag) is consistent with those of interacting supernovae. Our spectra reveal the presence of a dense and structured circumstellar medium, probably produced through numerous pre-supernova mass-loss events. In addition, we find evidence for high-velocity ejecta, with a fraction of gas expelled at more than 20000 km s^(\u22121). The spectra of LSQ13zm show remarkable similarity with those of well-studied core-collapse supernovae. From the analysis of the available photometric and spectroscopic data, we conclude that we first observed the last event of an eruptive sequence from a massive star, likely a Luminous Blue Variable, which a short time later exploded as a core-collapse supernova. The detailed analysis of archival images suggest that the host galaxy is a star-forming Blue Dwarf Compact Galaxy.", "doi": "10.1093/mnras/stw675", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2016-03-23", "series_number": "1", "volume": "459", "issue": "1", "pages": "1039-1059" }, { "id": "authors:73khy-22c35", "collection": "authors", "collection_id": "73khy-22c35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160208-074401021", "type": "article", "title": "Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429", "author": [ { "family_name": "Bellm", "given_name": "Eric C.", "orcid": "0000-0001-8018-5348", "clpid": "Bellm-E-C" }, { "family_name": "Kaplan", "given_name": "David L.", "orcid": "0000-0001-6295-2881", "clpid": "Kaplan-D-L" }, { "family_name": "Breton", "given_name": "Rene P.", "clpid": "Breton-R-P" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Bhalerao", "given_name": "Varun B.", "orcid": "0000-0002-6112-7609", "clpid": "Bhalerao-V-B" }, { "family_name": "Camilo", "given_name": "Fernando", "orcid": "0000-0002-1873-3718", "clpid": "Camilo-F" }, { "family_name": "Dahal", "given_name": "Sumit", "clpid": "Dahal-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Hessels", "given_name": "J. W. T.", "orcid": "0000-0003-2317-1446", "clpid": "Hessels-J-W-T" }, { "family_name": "Laher", "given_name": "Russ R.", "orcid": "0000-0003-2451-5482", "clpid": "Laher-R-R" }, { "family_name": "Levitan", "given_name": "David B.", "clpid": "Levitan-D-B" }, { "family_name": "Lewis", "given_name": "Fraser", "clpid": "Lewis-F" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Ofek", "given_name": "Eran O.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Prince", "given_name": "Thomas A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Ransom", "given_name": "Scott M.", "clpid": "Ransom-S-M" }, { "family_name": "Roberts", "given_name": "Mallory S. E.", "clpid": "Roberts-M-S-E" }, { "family_name": "Russell", "given_name": "David M.", "orcid": "0000-0002-3500-631X", "clpid": "Russell-D-M" }, { "family_name": "Sesar", "given_name": "Branimir", "orcid": "0000-0002-0834-3978", "clpid": "Sesar-B" }, { "family_name": "Surace", "given_name": "Jason A.", "orcid": "0000-0001-7291-0087", "clpid": "Surace-J-A" }, { "family_name": "Tang", "given_name": "Sumin", "orcid": "0000-0002-6225-8918", "clpid": "Tang-Sumin" } ], "abstract": "PSR J2129\u22120429 is a \"redback\" eclipsing millisecond pulsar binary with an unusually long 15.2 hr orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean m_R = 16.6 mag), allowing us to construct the longest baseline photometric data set available for such a system. We present 10 years of archival and new photometry of the companion from the Lincoln Near-Earth Asteroid Research Survey, the Catalina Real-time Transient Survey, the Palomar Transient Factory, the Palomar 60 inch, and the Las Cumbres Observatory Global Telescope. Radial velocity spectroscopy using the Double-Beam Spectrograph on the Palomar 200 inch indicates that the pulsar is massive: 1.74 \u00b1 0.18 M_\u2609. The G-type pulsar companion has mass 0.44 \u00b1 0.04 M_\u2609, one of the heaviest known redback companions. It is currently 95 \u00b1 1% Roche-lobe filling and only mildly irradiated by the pulsar. We identify a clear 13.1 mmag yr^(\u22121) secular decline in the mean magnitude of the companion as well as smaller-scale variations in the optical light curve shape. This behavior may indicate that the companion is cooling. Binary evolution calculations indicate that PSR J2129\u22120429 has an orbital period almost exactly at the bifurcation period between systems that converge into tighter orbits as black widows and redbacks and those that diverge into wider pulsar\u2013white dwarf binaries. Its eventual fate may depend on whether it undergoes future episodes of mass transfer and increased irradiation.", "doi": "10.3847/0004-637X/816/2/74", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2016-01-10", "series_number": "2", "volume": "816", "issue": "2", "pages": "Art. No. 74" }, { "id": "authors:q9enf-eh753", "collection": "authors", "collection_id": "q9enf-eh753", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160203-120802229", "type": "article", "title": "Gamma rays from the quasar PKS 1441+25: story of an escape", "author": [ { "family_name": "Abeysekara", "given_name": "A. U.", "clpid": "Abeysekara-A-U" }, { "family_name": "Archambault", "given_name": "S.", "clpid": "Archambault-S" }, { "family_name": "Archer", "given_name": "A.", "clpid": "Archer-A" }, { "family_name": "Aune", "given_name": "T.", "clpid": "Aune-T" }, { "family_name": "Barnacka", "given_name": "A.", "clpid": "Barnacka-A" }, { "family_name": "Benbow", "given_name": "W.", "clpid": "Benbow-W" }, { "family_name": "Bird", "given_name": "R.", "orcid": "0000-0002-4596-8563", "clpid": "Bird-Ralph" }, { "family_name": "Biteau", "given_name": "J.", "clpid": "Biteau-J" }, { "family_name": "Buckley", "given_name": "J. H.", "clpid": "Buckley-J-H" }, { "family_name": "Bugaev", "given_name": "V.", "clpid": "Bugaev-V" }, { "family_name": "Cardenzana", "given_name": "J. V.", "clpid": "Cardenzana-J-V" }, { "family_name": "Cerruti", "given_name": "M.", "orcid": "0000-0001-7891-699X", "clpid": "Cerruti-Matteo" }, { "family_name": "Chen", "given_name": "X.", "clpid": "Chen-X-Germany" }, { "family_name": "Christiansen", "given_name": "J. L.", "orcid": "0000-0002-8035-4778", "clpid": "Christiansen-J-L" }, { "family_name": "Ciupik", "given_name": "L.", "clpid": "Ciupik-L" }, { "family_name": "Connolly", "given_name": "M. P.", "clpid": "Connolly-M-P" }, { "family_name": "Coppi", "given_name": "P.", "clpid": "Coppi-P" }, { "family_name": "Cui", "given_name": "W.", "orcid": "0000-0002-6324-5772", "clpid": "Cui-Wei" }, { "family_name": "Dickinson", "given_name": "H. J.", "orcid": "0000-0003-0475-008X", "clpid": "Dickinson-H-J" }, { "family_name": "Dumm", "given_name": "J.", "clpid": "Dumm-J" }, { "family_name": "Eisch", "given_name": "J. D.", "clpid": "Eisch-J-D" }, { "family_name": "Errando", "given_name": "M.", "orcid": "0000-0002-1853-863X", "clpid": "Errando-Manel" }, { "family_name": "Falcone", "given_name": "A.", "clpid": "Falcone-A-D" }, { "family_name": "Feng", "given_name": "Q.", "clpid": "Feng-Q" }, { "family_name": "Finley", "given_name": "J. P.", "clpid": "Finley-J-P" }, { "family_name": "Fleischhack", "given_name": "H.", "clpid": "Fleischhack-H" }, { "family_name": "Flinders", "given_name": "A.", "clpid": "Flinders-A" }, { "family_name": "Fortin", "given_name": "P.", "clpid": "Fortin-P" }, { "family_name": "Fortson", "given_name": "L.", "orcid": "0000-0002-1067-8558", "clpid": "Fortson-L-F" }, { "family_name": "Furniss", "given_name": "A.", "clpid": "Furniss-A-K" }, { "family_name": "Gillanders", "given_name": "G. H.", "clpid": "Gillanders-G-H" }, { "family_name": "Griffin", "given_name": "S.", "clpid": "Griffin-S" }, { "family_name": "Grube", "given_name": "J.", "clpid": "Griffin-J" }, { "family_name": "Gyuk", "given_name": "G.", "clpid": "Gyuk-G" }, { "family_name": "H\u00fctten", "given_name": "M.", "orcid": "0000-0002-2133-5251", "clpid": "H\u00fctten-Moritz" }, { "family_name": "H\u00e5kansson", "given_name": "N.", "clpid": "Hakansson-N" }, { "family_name": "Hanna", "given_name": "D.", "clpid": "Hanna-D" }, { "family_name": "Holder", "given_name": "J.", "clpid": "Holder-J" }, { "family_name": "Humensky", "given_name": "T. B.", "clpid": "Humensky-T-B" }, { "family_name": "Johnson", "given_name": "C. A.", "clpid": "Johnson-C-A" }, { "family_name": "Kaaret", "given_name": "P.", "orcid": "0000-0002-3638-0637", "clpid": "Kaaret-P" }, { "family_name": "Kar", "given_name": "P.", "clpid": "Kar-P" }, { "family_name": "Kelley-Hoskins", "given_name": "N.", "clpid": "Kelley-Hoskins-N" }, { "family_name": "Khassen", "given_name": "Y.", "clpid": "Khassen-Y" }, { "family_name": "Kieda", "given_name": "D.", "clpid": "Kieda-D" }, { "family_name": "Krause", "given_name": "M.", "orcid": "0000-0001-7595-0914", "clpid": "Krause-Maria" }, { "family_name": "Krennrich", "given_name": "F.", "clpid": "Krennich-F" }, { "family_name": "Kumar", "given_name": "S.", "clpid": "Kumar-Sajan" }, { "family_name": "Lang", "given_name": "M. J.", "orcid": "0000-0003-4641-4201", "clpid": "Lang-Mark-J" }, { "family_name": "Maier", "given_name": "G.", "orcid": "0000-0001-9868-4700", "clpid": "Maier-Gernot" }, { "family_name": "McArthur", "given_name": "S.", "clpid": "McArthur-S" }, { "family_name": "McCann", "given_name": "A.", "orcid": "0000-0002-5221-6669", "clpid": "McCann-Andrew" }, { "family_name": "Meagher", "given_name": "K.", "orcid": "0000-0003-3967-1533", "clpid": "Meagher-Kevin" }, { "family_name": "Moriarty", "given_name": "P.", "clpid": "Moriarty-P" }, { "family_name": "Mukherjee", "given_name": "R.", "clpid": "Mukherjee-R" }, { "family_name": "Nieto", "given_name": "D.", "orcid": "0000-0003-3343-0755", "clpid": "Nieto-Daniel" }, { "family_name": "O'Faol\u00e1in de Bhr\u00f3ithe", "given_name": "A.", "clpid": "O'Faol\u00e1in-de-Bhr\u00f3ithe-A" }, { "family_name": "Ong", "given_name": "R. A.", "clpid": "Ong-R-A" }, { "family_name": "Otte", "given_name": "A. N.", "orcid": "0000-0002-5955-6383", "clpid": "Otte-Adam-Nepomuk" }, { "family_name": "Park", "given_name": "N.", "clpid": "Park-N" }, { "family_name": "Perkins", "given_name": "J. S.", "clpid": "Perkins-J-S" }, { "family_name": "Petrashyk", "given_name": "A.", "clpid": "Petrashyk-A" }, { "family_name": "Pohl", "given_name": "M.", "orcid": "0000-0001-7861-1707", "clpid": "Pohl-Martin" }, { "family_name": "Popkow", "given_name": "A.", "clpid": "Popkow-A" }, { "family_name": "Pueschel", "given_name": "E.", "orcid": "0000-0002-0529-1973", "clpid": "Pueschel-Elisa" }, { "family_name": "Quinn", "given_name": "J.", "orcid": "0000-0002-4855-2694", "clpid": "Quinn-John" }, { "family_name": "Ragan", "given_name": "K.", "clpid": "Ragan-K" }, { "family_name": "Ratliff", "given_name": "G.", "clpid": "Ratliff-G" }, { "family_name": "Reynolds", "given_name": "P. T.", "clpid": "Reynolds-P-T" }, { "family_name": "Richards", "given_name": "G. T.", "clpid": "Richards-G-T" }, { "family_name": "Roache", "given_name": "E.", "clpid": "Roache-E" }, { "family_name": "Rousselle", "given_name": "J.", "clpid": "Rousselle-J" }, { "family_name": "Santander", "given_name": "M.", "orcid": "0000-0001-7297-8217", "clpid": "Santander-Juan-Marcos" }, { "family_name": "Sembroski", "given_name": "G. H.", "clpid": "Sembroski-G-H" }, { "family_name": "Shahinyan", "given_name": "K.", "clpid": "Shahinyan-K" }, { "family_name": "Smith", "given_name": "A. W.", "clpid": "Smith-A-W" }, { "family_name": "Staszak", "given_name": "D.", "clpid": "Staszak-D" }, { "family_name": "Telezhinsky", "given_name": "I.", "clpid": "Telezhinsky-I" }, { "family_name": "Todd", "given_name": "N. W.", "clpid": "Todd-N-W" }, { "family_name": "Tucci", "given_name": "J. V.", "clpid": "Tucci-J-V" }, { "family_name": "Tyler", "given_name": "J.", "clpid": "Tyler-J-B" }, { "family_name": "Vassiliev", "given_name": "V. V.", "clpid": "Vassiliev-V-V" }, { "family_name": "Vincent", "given_name": "S.", "clpid": "Vincent-S" }, { "family_name": "Wakely", "given_name": "S. P.", "clpid": "Wakely-S-P" }, { "family_name": "Weiner", "given_name": "O. M.", "clpid": "Weiner-O-M" }, { "family_name": "Weinstein", "given_name": "A.", "orcid": "0000-0002-2126-2419", "clpid": "Weinstein-Amanda" }, { "family_name": "Wilhelm", "given_name": "A.", "clpid": "Wilhelm-A" }, { "family_name": "Williams", "given_name": "D. A.", "clpid": "Williams-D-A" }, { "family_name": "Zitzer", "given_name": "B.", "clpid": "Zitzer-B" }, { "family_name": "Smith", "given_name": "P. S.", "clpid": "Smith-P-S" }, { "family_name": "Holoien", "given_name": "T. W.-S.", "orcid": "0000-0001-9206-3460", "clpid": "Holoien-T-W-S" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-1072-2712", "clpid": "Prieto-J-L-ASTRO" }, { "family_name": "Kochanek", "given_name": "C. S.", "orcid": "0000-0001-6017-2961", "clpid": "Kochanek-C-S" }, { "family_name": "Stanek", "given_name": "K. Z.", "clpid": "Stanek-K-Z" }, { "family_name": "Shappee", "given_name": "B. J.", "orcid": "0000-0003-4631-1149", "clpid": "Shappee-B-J" }, { "family_name": "Hovatta", "given_name": "T.", "orcid": "0000-0002-2024-8199", "clpid": "Hovatta-T" }, { "family_name": "Max-Moerbeck", "given_name": "W.", "orcid": "0000-0002-5491-5244", "clpid": "Max-Moerbeck-W" }, { "family_name": "Pearson", "given_name": "T. J.", "orcid": "0000-0001-5213-6231", "clpid": "Pearson-T-J" }, { "family_name": "Reeves", "given_name": "R. A.", "orcid": "0000-0001-5704-271X", "clpid": "Reeves-R-A" }, { "family_name": "Richards", "given_name": "J. L.", "clpid": "Richards-J-L" }, { "family_name": "Readhead", "given_name": "A. C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Madejski", "given_name": "G. M.", "clpid": "Madejski-G-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the Universe. The detection of significant emission above 100 GeV from a distant quasar would show that some of the radiated gamma rays escape pair-production interactions with low-energy photons, be it the extragalactic background light (EBL), or the radiation near the supermassive black hole lying at the jet's base. VERITAS detected gamma-ray emission up to 200 GeV from PKS 1441+25 (z=0.939) during April 2015, a period of high activity across all wavelengths. This observation of PKS 1441+25 suggests that the emission region is located thousands of Schwarzschild radii away from the black hole. The gamma-ray detection also sets a stringent upper limit on the near-ultraviolet to near-infrared EBL intensity, suggesting that galaxy surveys have resolved most, if not all, of the sources of the EBL at these wavelengths.", "doi": "10.1088/2041-8205/815/2/L22", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2015-12-15", "series_number": "2", "volume": "815", "issue": "2", "pages": "Art. No. L22" }, { "id": "authors:9gj94-3y554", "collection": "authors", "collection_id": "9gj94-3y554", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160111-085514577", "type": "article", "title": "Binary Active Galactic Nuclei in Stripe 82: Constraints on Synchronized Black Hole Accretion in Major Mergers", "author": [ { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Wrobel", "given_name": "J. M.", "orcid": "0000-0001-9720-7398", "clpid": "Wrobel-J-M" }, { "family_name": "Myers", "given_name": "A. D.", "clpid": "Myers-A-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" } ], "abstract": "Representing simultaneous black hole accretion during a merger, binary active galactic nuclei (AGNs) could provide valuable observational constraints to models of galaxy mergers and AGN triggering. High-resolution radio interferometer imaging offers a promising method for identifying a large and uniform sample of binary AGNs because it probes a generic feature of nuclear activity and is free from dust obscuration. Our previous search yielded 52 strong candidates of kiloparsec-scale binaries over the 92 deg^2 of the Sloan Digital Sky Survey Stripe 82 area with 2\"-resolution Very Large Array (VLA) images. Here we present 0.\"3-resolution VLA 6 GHz observations for six candidates that have complete optical spectroscopy. The new data confirm the binary nature of four candidates and identify the other two as line of sight projections of radio structures from single AGNs. The four binary AGNs at z ~ 0.1 reside in major mergers with projected separations of 4.2\u201312 kpc. Optical spectral modeling shows that their hosts have stellar masses between 10.3", "doi": "10.1088/2041-8205/815/1/L6", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2015-12-10", "series_number": "1", "volume": "815", "issue": "1", "pages": "Art. No. L6" }, { "id": "authors:zdb7n-kb848", "collection": "authors", "collection_id": "zdb7n-kb848", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151222-095221596", "type": "article", "title": "Infrared Time Lags for the Periodic Quasar PG 1302-102", "author": [ { "family_name": "Jun", "given_name": "Hyunsung D.", "orcid": "0000-0003-1470-5901", "clpid": "Jun-Hyunsung-David" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mainzer", "given_name": "Amy", "clpid": "Mainzer-A-K" }, { "family_name": "Cutri", "given_name": "Roc M.", "orcid": "0000-0002-0077-2305", "clpid": "Cutri-R-M" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "The optical light curve of the quasar PG 1302-102 at z = 0.278 shows a strong, smooth 5.2 year periodic signal, detectable over a period of ~20 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. At this close separation, the nuclear black holes in PG 1302-102 will likely merge within ~ 10^5 years due to gravitational wave emission alone. Here, we report the rest-frame near-infrared time lags for PG 1302-102. Compiling data from WISE and Akari, we confirm that the periodic behavior reported in the optical light curve from Graham et al. is reproduced at infrared wavelengths, with best-fit observed-frame 3.4 and 4.6 \u00b5m time lags of (2219 \u00b1 153, 2408 \u00b1 148) days for a near face-on orientation of the torus, or (4103 \u00b1 153, 4292 \u00b1 148) days for an inclined system with relativistic Doppler boosting in effect. The periodicity in the infrared light curves and the light-travel time of the accretion disk photons to reach the dust glowing regions support that a source within the accretion disk is responsible for the optical variability of PG 1302-102, echoed at the farther out dusty regions. The implied distance of this dusty, assumed toroidal region is ~1.5 pc for a near face-on geometry or ~1.1 pc for the relativistic Doppler-boosted case.", "doi": "10.1088/2041-8205/814/1/L12", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2015-11-20", "series_number": "1", "volume": "814", "issue": "1", "pages": "Art. No. L12" }, { "id": "authors:b2hzs-yv010", "collection": "authors", "collection_id": "b2hzs-yv010", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151119-140541834", "type": "article", "title": "A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Larson", "given_name": "Steve", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "Eric", "clpid": "Christensen-E" } ], "abstract": "Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz frequency gravitational waves). Following our detection of a 5.2-year periodic signal in the quasar PG 1302\u2212102, we present a novel analysis of the optical variability of 243 500 known spectroscopically confirmed quasars using data from the Catalina Real-time Transient Survey (CRTS) to look for close (<0.1 pc) SMBH systems. Looking for a strong Keplerian periodic signal with at least 1.5 cycles over a baseline of nine years, we find a sample of 111 candidate objects. This is in conservative agreement with theoretical predictions from models of binary SMBH populations. Simulated data sets, assuming stochastic variability, also produce no equivalent candidates implying a low likelihood of spurious detections. The periodicity seen is likely attributable to either jet precession, warped accretion discs or periodic accretion associated with a close SMBH binary system. We also consider how other SMBH binary candidates in the literature appear in CRTS data and show that none of these are equivalent to the identified objects. Finally, the distribution of objects found is consistent with that expected from a gravitational-wave-driven population. This implies that circumbinary gas is present at small orbital radii and is being perturbed by the black holes. None of the sources is expected to merge within at least the next century. This study opens a new unique window to study a population of close SMBH binaries that must exist according to our current understanding of galaxy and SMBH evolution.", "doi": "10.1093/mnras/stv1726", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2015-10-21", "series_number": "2", "volume": "453", "issue": "2", "pages": "1562-1576" }, { "id": "authors:jegwy-f7v51", "collection": "authors", "collection_id": "jegwy-f7v51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160105-071616841", "type": "book_section", "title": "From stars to patients: Lessons from space science and astrophysics for health care informatics", "book_title": "2015 IEEE International Conference on Big Data (Big Data)", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Crichton", "given_name": "D. J.", "clpid": "Crichton-D-J" }, { "family_name": "Chaudhry", "given_name": "B.", "clpid": "Chaudhry-B" } ], "abstract": "Big Data are revolutionizing nearly every aspect of the modern society. One area where this can have a profound positive societal impact is the field of Health Care Informatics (HCI), which faces many challenges. The key idea behind this study is: can we use some of the experience and technical and methodological solutions from the fields that have successfully adapted to the Big Data era, namely astronomy and space science, to help accelerate the progress of HCI? We illustrate this with examples from the Virtual Observatory framework, and the NCI EDRN project. An effective sharing and reuse of tools, methods, and experiences from different fields can save a lot of effort, time, and expense. HCI can thus benefit from the proven solutions to big data challenges from other domains.", "doi": "10.1109/BigData.2015.7364135", "isbn": "978-1-4799-9925-5", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2015-10", "pages": "2957-2959" }, { "id": "authors:v2m9v-jee39", "collection": "authors", "collection_id": "v2m9v-jee39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150622-091514641", "type": "article", "title": "A Megacam Survey of Outer Halo Satellites. IV. Two Foreground Populations Possibly Associated with the Monoceros Substructure in the Direction of NGC 2419 and Koposov 2", "author": [ { "family_name": "Carballo-Bello", "given_name": "Julio A.", "clpid": "Carballo-Bello-J-A" }, { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "Carlin", "given_name": "Jeffrey L.", "orcid": "0000-0002-3936-9628", "clpid": "Carlin-J-L" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "The origin of the Galactic halo stellar structure known as the Monoceros Ring is still under debate. In this work, we study this halo substructure using deep Canada\u2013France\u2013Hawaii Telescope wide-field photometry obtained for the globular clusters NGC 2419 and Koposov 2, where the presence of Monoceros becomes significant because of their coincident projected position. Using Sloan Digital Sky Survey photometry and spectroscopy in the area surrounding these globulars and beyond, where the same Monoceros population is detected, we conclude that a second feature, which is not likely to be associated with Milky Way disk stars along the line of sight, is present as a foreground population. Our analysis suggests that the Monoceros Ring might be composed of an old stellar population of age Gyr and a new component ~4 Gyr younger at the same heliocentric distance. Alternatively, this detection might be associated with a second wrap of Monoceros in that direction of the sky and might also indicate a metallicity spread in the ring. The detection of such a low-density feature in other sections of this halo substructure will shed light on its nature.", "doi": "10.1088/0004-637X/805/1/51", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2015-05-20", "series_number": "1", "volume": "805", "issue": "1", "pages": "Art. No. 51" }, { "id": "authors:d0878-tj664", "collection": "authors", "collection_id": "d0878-tj664", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141121-123855990", "type": "article", "title": "A possible close supermassive black-hole binary in a quasar with optical periodicity", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Larson", "given_name": "Steve", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "Eric", "clpid": "Christensen-E" } ], "abstract": "Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302\u2212102 with a mean observed period of 1,884 \u00b1 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution.", "doi": "10.1038/nature14143", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2015-02-05", "series_number": "7537", "volume": "518", "issue": "7537", "pages": "74-76" }, { "id": "authors:gd846-wqj19", "collection": "authors", "collection_id": "gd846-wqj19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150309-102949260", "type": "article", "title": "A Serendipitous All Sky Survey for Bright Objects in the Outer Solar System", "author": [ { "family_name": "Brown", "given_name": "M. E.", "orcid": "0000-0002-8255-0545", "clpid": "Brown-M-E" }, { "family_name": "Bannister", "given_name": "M. T.", "clpid": "Bannister-M-T" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "McNaught", "given_name": "R.", "clpid": "McNaught-R" } ], "abstract": "We use seven year's worth of observations from the Catalina Sky Survey and the Siding Spring Survey covering most of the northern and southern hemisphere at galactic latitudes higher than 20\u00b0 to search for serendipitously imaged moving objects in the outer solar system. These slowly moving objects would appear as stationary transients in these fast cadence asteroids surveys, so we develop methods to discover objects in the outer solar system using individual observations spaced by months, rather than spaced by hours, as is typically done. While we independently discover eight known bright objects in the outer solar system, the faintest having V = 19.8 \u00b1 0.1, no new objects are discovered. We find that the survey is nearly 100% efficient at detecting objects beyond 25 AU for V \u227e 19.1 V \u227e 18.6 in the southern hemisphere) and that the probability that there is one or more remaining outer solar system object of this brightness left to be discovered in the unsurveyed regions of the galactic plane is approximately 32%.", "doi": "10.1088/0004-6256/149/2/69", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2015-02", "series_number": "2", "volume": "149", "issue": "2", "pages": "Art. No. 69" }, { "id": "authors:ed1yz-yer54", "collection": "authors", "collection_id": "ed1yz-yer54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150406-141838132", "type": "article", "title": "Discovery of \u223c9000 new RR Lyrae in the southern Catalina surveys", "author": [ { "family_name": "Torrealba", "given_name": "G.", "clpid": "Torrealba-G" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "McNaught", "given_name": "R. H.", "clpid": "McNaught-R-H" }, { "family_name": "Belokurov", "given_name": "V.", "orcid": "0000-0002-0038-9584", "clpid": "Belokurov-V" }, { "family_name": "Koposov", "given_name": "S. E.", "orcid": "0000-0003-2644-135X", "clpid": "Koposov-S-E" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" } ], "abstract": "We present the results of a deep, wide-area variability survey in the Southern hemisphere, the first of its kind. As part of the Catalina Sky Surveys, the Siding Spring Survey (SSS) has covered 14\u2009800 deg^2 in the declination range of \u221275\u00b0 \u2264 \u03b4 \u2264 \u221215\u00b0. To mine the enormous SSS data set efficiently, we have developed two algorithms: automatic period selection (APS) and automatic Fourier decomposition (AFD), which aim to sharpen the period estimation and produce robust light-curve models. Armed with the APS and AFD outputs, we classify 10\u2009540 ab-type RR Lyrae (RRab) stars (\u223c90 per cent of which are new) across the southern sky. As well as the positional information we supply photometric metallicities, and unreddened distances. For the RRab stars in the halo, a study of the photometric metallicity distribution reveals a nearly Gaussian shape with a mean metallicity of [Fe/H] = \u22121.4 dex and a dispersion of 0.3 dex. A spatial study of the RRab metallicities shows no significant radial gradient in the first \u223c7 kpc from the Galaxy centre. However, further out, a small negative gradient is clearly present. This is complemented by a very obvious correlation of the mean RR Lyrae metallicity with distance above the Galactic plane, z. We have also carried out an initial sub-structure search using the discovered RRab, and present the properties of the candidates with significance greater than 2\u03c3. Most prominent among these is a southern extension of the Sagittarius dwarf galaxy's stream system, reaching down to declinations \u223c-40 \u00b0.", "doi": "10.1093/mnras/stu2274", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2015-01-21", "series_number": "3", "volume": "446", "issue": "3", "pages": "2251-2266" }, { "id": "authors:rmz27-pbz60", "collection": "authors", "collection_id": "rmz27-pbz60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150227-092252129", "type": "article", "title": "Radio-selected Binary Active Galactic Nuclei from the Very Large Array Stripe 82 Survey", "author": [ { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Myers", "given_name": "A. D.", "clpid": "Myers-A-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" }, { "family_name": "Wrobel", "given_name": "J. M.", "orcid": "0000-0001-9720-7398", "clpid": "Wrobel-J-M" }, { "family_name": "Stockton", "given_name": "A.", "clpid": "Stockton-A" } ], "abstract": "Galaxy mergers play an important role in the growth of galaxies and their supermassive black holes. Simulations suggest that tidal interactions could enhance black hole accretion, which can be tested by the fraction of binary active galactic nuclei (AGNs) among galaxy mergers. However, determining the fraction requires a statistical sample of binaries. We have identified kiloparsec-scale binary AGNs directly from high-resolution radio imaging. Inside the 92\u2009deg^2 covered by the high-resolution Very Large Array survey of the Sloan Digital Sky Survey (SDSS) Stripe 82 field, we identified 22 grade A and 30 grade B candidates of binary radio AGNs with angular separations less than 5'' (10\u2009kpc at z = 0.1). Eight of the candidates have optical spectra for both components from the SDSS spectroscopic surveys and our Keck program. Two grade B candidates are projected pairs, but the remaining six candidates are all compelling cases of binary AGNs based on either emission line ratios or the excess in radio power compared to the H\u03b1-traced star formation rate. Only two of the six binaries were previously discovered by an optical spectroscopic search. Based on these results, we estimate that ~60% of our binary candidates would be confirmed once we obtain complete spectroscopic information. We conclude that wide-area high-resolution radio surveys offer an efficient method to identify large samples of binary AGNs. These radio-selected binary AGNs complement binaries identified at other wavelengths and are useful for understanding the triggering mechanisms of black hole accretion.", "doi": "10.1088/0004-637X/799/1/72", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2015-01-20", "series_number": "1", "volume": "799", "issue": "1", "pages": "Art. No. 72" }, { "id": "authors:4xhf5-t6f97", "collection": "authors", "collection_id": "4xhf5-t6f97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141106-093853314", "type": "article", "title": "1000 cataclysmic variables from the Catalina Real-time Transient Survey", "author": [ { "family_name": "Breedt", "given_name": "E.", "orcid": "0000-0001-6180-3438", "clpid": "Breedt-E" }, { "family_name": "G\u00e4nsicke", "given_name": "B. T.", "orcid": "0000-0002-2761-3005", "clpid": "G\u00e4nsicke-B-T" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Rodr\u00edguez-Gil", "given_name": "P.", "clpid": "Rodr\u00edguez-Gil-P" }, { "family_name": "Parsons", "given_name": "S. G.", "clpid": "Parsons-S-G" }, { "family_name": "Marsh", "given_name": "T. R.", "orcid": "0000-0002-2498-7589", "clpid": "Marsh-T-R" }, { "family_name": "Szkody", "given_name": "P.", "clpid": "Szkody-P" }, { "family_name": "Schreiber", "given_name": "M. R.", "clpid": "Schreiber-M-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Over six years of operation, the Catalina Real-time Transient Survey (CRTS) has identified 1043 cataclysmic variable (CV) candidates \u2013 the largest sample of CVs from a single survey to date. Here, we provide spectroscopic identification of 85 systems fainter than g \u2265 19, including three AM Canum Venaticorum binaries, one helium-enriched CV, one polar and one new eclipsing CV. We analyse the outburst properties of the full sample and show that it contains a large fraction of low-accretion-rate CVs with long outburst recurrence times. We argue that most of the high-accretion-rate dwarf novae in the survey footprint have already been found and that future CRTS discoveries will be mostly low-accretion-rate systems. We find that CVs with white-dwarf-dominated spectra have significantly fewer outbursts in their CRTS light curves compared to disc-dominated CVs, reflecting the difference in their accretion rates. Comparing the CRTS sample to other samples of CVs, we estimate the overall external completeness to be 23.6 per cent, but show that as much as 56 per cent of CVs have variability amplitudes that are too small to be selected using the transient selection criteria employed by current ground-based surveys. The full table of CRTS CVs, including their outburst and spectroscopic properties examined in this paper, is provided in the online materials.", "doi": "10.1093/mnras/stu1377", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2014-10-01", "series_number": "4", "volume": "443", "issue": "4", "pages": "3174-3207" }, { "id": "authors:vcn8b-z5k56", "collection": "authors", "collection_id": "vcn8b-z5k56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-112433536", "type": "book_section", "title": "Immersive and Collaborative Data Visualization Using Virtual Reality Platforms", "author": [ { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Cioc", "given_name": "Alex", "clpid": "Cioc-A" }, { "family_name": "Wang", "given_name": "Anwell", "clpid": "Wang-Anwell" }, { "family_name": "Zhang", "given_name": "Jerry", "clpid": "Zhang-Jerry" }, { "family_name": "Lawler", "given_name": "Elizabeth", "clpid": "Lawler-E" }, { "family_name": "Yeh", "given_name": "Stacy", "clpid": "Yeh-Stacy" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A" }, { "family_name": "Davidoff", "given_name": "Scott", "clpid": "Davidoff-S" }, { "family_name": "Norris", "given_name": "Jeffrey S.", "clpid": "Norris-J-S" }, { "family_name": "Longo", "given_name": "Giuseppe", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" } ], "abstract": "Effective data visualization is a key part of the discovery process in the era of \"big data\". It is the bridge between the quantitative content of the data and human intuition, and thus an essential component of the scientific path from data into knowledge and understanding. Visualization is also essential in the data mining process, directing the choice of the applicable algorithms, and in helping to identify and remove bad data from the analysis. However, a high complexity or a high dimensionality of modern data sets represents a critical obstacle. How do we visualize interesting structures and patterns that may exist in hyper-dimensional data spaces? A better understanding of how we can perceive and interact with multidimensional information poses some deep questions in the field of cognition technology and human-computer interaction. To this effect, we are exploring the use of immersive virtual reality platforms for scientific data visualization, both as software and inexpensive commodity hardware. These potentially powerful and innovative tools for multi-dimensional data visualization can also provide an easy and natural path to a collaborative data visualization and exploration, where scientists can interact with their data and their colleagues in the same visual space. Immersion provides benefits beyond the traditional \"desktop\" visualization tools: it leads to a demonstrably better perception of a datascape geometry, more intuitive data understanding, and a better retention of the perceived relationships in the data.", "doi": "10.1109/BigData.2014.7004282", "publisher": "IEEE", "publication_date": "2014-10" }, { "id": "authors:x9k8w-4vt74", "collection": "authors", "collection_id": "x9k8w-4vt74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141217-103710003", "type": "book_section", "title": "Automated Real-Time Classification and Decision Making in Massive Data Streams from Synoptic Sky Surveys", "book_title": "2014 IEEE 10th International Conference on e-Science", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" }, { "family_name": "Fuchs", "given_name": "T.", "clpid": "Fuchs-T-J" } ], "abstract": "The nature of scientific and technological data collection is evolving rapidly: data volumes and rates grow exponentially, with increasing complexity and information content, and there has been a transition from static data sets to data streams that must be analyzed in real time. Interesting or anomalous phenomena must be quickly characterized and followed up with additional measurements via optimal deployment of limited assets. Modern astronomy presents a variety of such phenomena in the form of transient events in digital synoptic sky surveys, including cosmic explosions (supernovae, gamma ray bursts), relativistic phenomena (black hole formation, jets), potentially hazardous asteroids, etc. We have been developing a set of machine learning tools to detect, classify and plan a response to transient events for astronomy applications, using the Catalina Real-time Transient Survey (CRTS) as a scientific and methodological testbed. The ability to respond rapidly to the potentially most interesting events is a key bottleneck that limits the scientific returns from the current and anticipated synoptic sky surveys. Similar challenge arise in other contexts, from environmental monitoring using sensor networks to autonomous spacecraft systems. Given the exponential growth of data rates, and the time-critical response, we need a fully automated and robust approach. We describe the results obtained to date, and the possible future developments.", "doi": "10.1109/eScience.2014.7", "isbn": "978-1-4799-4288-6", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2014-10", "pages": "204-211" }, { "id": "authors:xj13s-1hm79", "collection": "authors", "collection_id": "xj13s-1hm79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-140818440", "type": "article", "title": "Ultra-short Period Binaries from the Catalina Surveys", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Garc\u00eda-\u00c1lvarez", "given_name": "D.", "clpid": "Garc\u00eda-\u00c1lvarez-D" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Torrealba", "given_name": "G.", "clpid": "Torrealba-G" }, { "family_name": "Abraham", "given_name": "S.", "clpid": "Abraham-S" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" } ], "abstract": "We investigate the properties of 367 ultra-short period binary candidates selected from 31,000 sources recently identified from Catalina Surveys data. Based on light curve morphology, along with WISE, Sloan Digital Sky Survey, and GALEX multi-color photometry, we identify two distinct groups of binaries with periods below the 0.22 day contact binary minimum. In contrast to most recent work, we spectroscopically confirm the existence of M dwarf+M dwarf contact binary systems. By measuring the radial velocity variations for five of the shortest-period systems, we find examples of rare cool white dwarf (WD)+M dwarf binaries. Only a few such systems are currently known. Unlike warmer WD systems, their UV flux and optical colors and spectra are dominated by the M-dwarf companion. We contrast our discoveries with previous photometrically selected ultra-short period contact binary candidates and highlight the ongoing need for confirmation using spectra and associated radial velocity measurements. Overall, our analysis increases the number of ultra-short period contact binary candidates by more than an order of magnitude.", "doi": "10.1088/0004-637X/790/2/157", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2014-08-01", "series_number": "2", "volume": "790", "issue": "2", "pages": "Art. No. 157" }, { "id": "authors:xz016-fc530", "collection": "authors", "collection_id": "xz016-fc530", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-104855024", "type": "article", "title": "DAMEWARE: A Web Cyberinfrastructure for Astrophysical Data Mining", "author": [ { "family_name": "Brescia", "given_name": "Massimo", "orcid": "0000-0001-9506-5680", "clpid": "Brescia-M" }, { "family_name": "Cavuoti", "given_name": "Stefano", "orcid": "0000-0002-3787-4196", "clpid": "Cavuoti-S" }, { "family_name": "Longo", "given_name": "Giuseppe", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" }, { "family_name": "Nocella", "given_name": "Alfonso", "clpid": "Nocella-A" }, { "family_name": "Garofalo", "given_name": "Mauro", "clpid": "Garofalo-M" }, { "family_name": "Manna", "given_name": "Francesco", "clpid": "Manna-F" }, { "family_name": "Esposito", "given_name": "Francesco", "clpid": "Esposito-F" }, { "family_name": "Albano", "given_name": "Giovanni", "clpid": "Albano-G" }, { "family_name": "Guglielmo", "given_name": "Marisa", "clpid": "Guglielmo-M" }, { "family_name": "D'Angelo", "given_name": "Giovanni", "clpid": "D'Angelo-G" }, { "family_name": "Di Guido", "given_name": "Alessandro", "clpid": "Di-Guido-A" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Fiore", "given_name": "Michelangelo", "clpid": "Fiore-M" }, { "family_name": "D'Abrusco", "given_name": "Raffaele", "clpid": "D'Abrusco-R" } ], "abstract": "Astronomy is undergoing a methodological revolution triggered by an unprecedented wealth of complex and accurate data. The new panchromatic, synoptic sky surveys require advanced tools for discovering patterns and trends hidden behind data which are both complex and of high dimensionality. We present DAMEWARE (DAta Mining & Exploration Web Application REsource): a general purpose, web-based, distributed data mining environment developed for the exploration of large data sets, and finely tuned for astronomical applications. By means of graphical user interfaces, it allows the user to perform classification, regression, or clustering tasks with machine learning methods. Salient features of DAMEWARE include its ability to work on large datasets with minimal human intervention, and to deal with a wide variety of real problems such as the classification of globular clusters in the galaxy NGC1399; the evaluation of photometric redshifts; and, finally, the identification of candidate Active Galactic Nuclei in multiband photometric surveys. In all these applications, DAMEWARE allowed us to achieve better results than those attained with more traditional methods. With the aim of providing potential users with all needed information, in this paper we briefly describe the technological background of DAMEWARE, give a short introduction to some relevant aspects of data mining, followed by a summary of some science cases and, finally, provide a detailed description of a template use case.", "doi": "10.1086/677725", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2014-08", "series_number": "942", "volume": "126", "issue": "942", "pages": "783-797" }, { "id": "authors:gxacd-w3z77", "collection": "authors", "collection_id": "gxacd-w3z77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-141005358", "type": "article", "title": "The Catalina Surveys Periodic Variable Star Catalog", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Torrealba", "given_name": "G.", "clpid": "Torrealba-G" }, { "family_name": "Garc\u00eda-\u00c1lvarez", "given_name": "D.", "clpid": "Garc\u00eda-\u00c1lvarez-D" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Belokurov", "given_name": "V.", "orcid": "0000-0002-0038-9584", "clpid": "Belokurov-V" }, { "family_name": "Koposov", "given_name": "S. E.", "orcid": "0000-0003-2644-135X", "clpid": "Koposov-S-E" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "Boattini", "given_name": "A.", "clpid": "Boattini-A" }, { "family_name": "Gibbs", "given_name": "A.", "clpid": "Gibbs-A" }, { "family_name": "Hill", "given_name": "R.", "clpid": "Hill-R" }, { "family_name": "Kowalski", "given_name": "R.", "clpid": "Kowalski-R" }, { "family_name": "Johnson", "given_name": "J.", "clpid": "Johnson-J" }, { "family_name": "Shelly", "given_name": "F.", "clpid": "Shelly-F" } ], "abstract": "We present ~47,000 periodic variables found during the analysis of 5.4 million variable star candidates within a 20,000 deg^2 region covered by the Catalina Surveys Data Release-1 (CSDR1). Combining these variables with type ab RR Lyrae from our previous work, we produce an online catalog containing periods, amplitudes, and classifications for ~61,000 periodic variables. By cross-matching these variables with those from prior surveys, we find that >90% of the ~8000 known periodic variables in the survey region are recovered. For these sources, we find excellent agreement between our catalog and prior values of luminosity, period, and amplitude as well as classification. We investigate the rate of confusion between objects classified as contact binaries and type c RR Lyrae (RRc's) based on periods, colors, amplitudes, metallicities, radial velocities, and surface gravities. We find that no more than a few percent of the variables in these classes are misidentified. By deriving distances for this clean sample of ~5500 RRc's, we trace the path of the Sagittarius tidal streams within the Galactic halo. Selecting 146 outer-halo RRc's with SDSS radial velocities, we confirm the presence of a coherent halo structure that is inconsistent with current N-body simulations of the Sagittarius tidal stream. We also find numerous long-period variables that are very likely associated within the Sagittarius tidal stream system. Based on the examination of 31,000 contact binary light curves we find evidence for two subgroups exhibiting irregular light curves. One subgroup presents significant variations in mean brightness that are likely due to chromospheric activity. The other subgroup shows stable modulations over more than a thousand days and thereby provides evidence that the O'Connell effect is not due to stellar spots.", "doi": "10.1088/0067-0049/213/1/9", "issn": "0067-0049", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Supplement Series", "publication_date": "2014-07", "series_number": "1", "volume": "213", "issue": "1", "pages": "Art. No. 9" }, { "id": "authors:9ysqw-6pf06", "collection": "authors", "collection_id": "9ysqw-6pf06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140627-085416936", "type": "article", "title": "Cataclysmic variables from the Catalina Real-time Transient Survey", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "G\u00e4nsicke", "given_name": "B. T.", "orcid": "0000-0002-2761-3005", "clpid": "G\u00e4nsicke-B-T" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Wils", "given_name": "P.", "clpid": "Wils-P" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Yang", "given_name": "T. -C.", "clpid": "Yang-T-C" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" } ], "abstract": "We present 855 cataclysmic variable candidates detected by the Catalina Real-time Transient Survey (CRTS) of which at least 137 have been spectroscopically confirmed and 705 are new discoveries. The sources were identified from the analysis of five years of data, and come from an area covering three quarters of the sky. We study the amplitude distribution of the dwarf novae cataclysmic variables (CVs) discovered by CRTS during outburst, and find that in quiescence they are typically 2 mag fainter compared to the spectroscopic CV sample identified by the Sloan Digital Sky Survey. However, almost all CRTS CVs in the SDSS footprint have ugriz photometry. We analyse the spatial distribution of the CVs and find evidence that many of the systems lie at scale heights beyond those expected for a Galactic thin disc population. We compare the outburst rates of newly discovered CRTS CVs with the previously known CV population, and find no evidence for a difference between them. However, we find significant evidence for a systematic difference in orbital period distribution. We discuss the CVs found below the orbital period minimum and argue that many more are yet to be identified among the full CRTS CV sample. We cross-match the CVs with archival X-ray catalogues and find that most of the systems are dwarf novae rather than magnetic CVs.", "doi": "10.1093/mnras/stu639", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2014-06-21", "series_number": "2", "volume": "441", "issue": "2", "pages": "1186-1200" }, { "id": "authors:b23ef-q7y37", "collection": "authors", "collection_id": "b23ef-q7y37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140620-110505377", "type": "article", "title": "The supernova CSS121015:004244+132827: a clue for understanding superluminous supernovae", "author": [ { "family_name": "Benetti", "given_name": "S.", "orcid": "0000-0002-3256-0016", "clpid": "Benetti-S" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present optical photometry and spectra of the superluminous Type II/IIn supernova (SN) CSS121015:004244+132827 (z = 0.2868) spanning epochs from \u221230 d (rest frame) to more than 200 d after maximum. CSS121015 is one of the more luminous SNe ever found and one of the best observed. The photometric evolution is characterized by a relatively fast rise to maximum (\u223c40\u2009d in the SN rest frame), and by a linear post-maximum decline. The light curve shows no sign of a break to an exponential tail. A broad H\u03b1 is first detected at \u223c+40\u2009d (rest frame). Narrow, barely resolved Balmer and [O\u2009III] 5007 \u00c5 lines, with decreasing strength, are visible along the entire spectral evolution. The spectra are very similar to other superluminous supernovae (SLSNe) with hydrogen in their spectrum, and also to SN 2005gj, sometimes considered Type Ia interacting with H-rich circumstellar medium. The spectra are also similar to a subsample of H-deficient SLSNe. We propose that the properties of CSS121015 are consistent with the interaction of the ejecta with a massive, extended, opaque shell, lost by the progenitor decades before the final explosion, although a magnetar-powered model cannot be excluded. Based on the similarity of CSS121015 with other SLSNe (with and without H), we suggest that the shocked-shell scenario should be seriously considered as a plausible model for both types of SLSN.", "doi": "10.1093/mnras/stu538", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2014-06-11", "series_number": "1", "volume": "441", "issue": "1", "pages": "289-303" }, { "id": "authors:bxbt0-g2030", "collection": "authors", "collection_id": "bxbt0-g2030", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140618-082049787", "type": "article", "title": "Multifrequency Studies of the Peculiar Quasar 4C +21.35 during the 2010 Flaring Activity", "author": [ { "family_name": "Ackermann", "given_name": "M.", "clpid": "Ackermann-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "literal": "Fermi Large Area Telescope Collaboration" }, { "literal": "MAGIC Collaboration" } ], "abstract": "The discovery of rapidly variable Very High Energy (VHE; E > 100 GeV) \u03b3-ray emission from 4C +21.35 (PKS 1222+216) by MAGIC on 2010 June 17, triggered by the high activity detected by the Fermi Large Area Telescope (LAT) in high energy (HE; E > 100 MeV) \u03b3-rays, poses intriguing questions on the location of the \u03b3-ray emitting region in this flat spectrum radio quasar. We present multifrequency data of 4C +21.35 collected from centimeter to VHE during 2010 to investigate the properties of this source and discuss a possible emission model. The first hint of detection at VHE was observed by MAGIC on 2010 May 3, soon after a \u03b3-ray flare detected by Fermi-LAT that peaked on April 29. The same emission mechanism may therefore be responsible for both the HE and VHE emission during the 2010 flaring episodes. Two optical peaks were detected on 2010 April 20 and June 30, close in time but not simultaneous with the two \u03b3-ray peaks, while no clear connection was observed between the X-ray and \u03b3-ray emission. An increasing flux density was observed in radio and mm bands from the beginning of 2009, in accordance with the increasing \u03b3-ray activity observed by Fermi-LAT, and peaking on 2011 January 27 in the mm regime (230 GHz). We model the spectral energy distributions (SEDs) of 4C +21.35 for the two periods of the VHE detection and a quiescent state, using a one-zone model with the emission coming from a very compact region outside the broad line region. The three SEDs can be fit with a combination of synchrotron self-Compton and external Compton emission of seed photons from a dust torus, changing only the electron distribution parameters between the epochs. The fit of the optical/UV part of the spectrum for 2010 April 29 seems to favor an inner disk radius of", "doi": "10.1088/0004-637X/786/2/157", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2014-05-10", "series_number": "2", "volume": "786", "issue": "2", "pages": "Art. No. 157" }, { "id": "authors:t9e00-gkf53", "collection": "authors", "collection_id": "t9e00-gkf53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140429-133204484", "type": "article", "title": "Connection between optical and \u03b3-ray variability in blazars", "author": [ { "family_name": "Hovatta", "given_name": "T.", "orcid": "0000-0002-2024-8199", "clpid": "Hovatta-T" }, { "family_name": "Pavlidou", "given_name": "V.", "clpid": "Pavlidou-V" }, { "family_name": "King", "given_name": "O. G.", "clpid": "King-O-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Sesar", "given_name": "B.", "orcid": "0000-0002-0834-3978", "clpid": "Sesar-B" }, { "family_name": "Dancikova", "given_name": "R.", "clpid": "Dancikova-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A.", "clpid": "Drake-A" }, { "family_name": "Laher", "given_name": "R.", "orcid": "0000-0003-2451-5482", "clpid": "Laher-R-R" }, { "family_name": "Levitan", "given_name": "D.", "clpid": "Levitan-D" }, { "family_name": "Max-Moerbeck", "given_name": "W.", "orcid": "0000-0002-5491-5244", "clpid": "Max-Moerbeck-W" }, { "family_name": "Ofek", "given_name": "E. O.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Pearson", "given_name": "T. J.", "orcid": "0000-0001-5213-6231", "clpid": "Pearson-T-J" }, { "family_name": "Prince", "given_name": "T. A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Readhead", "given_name": "A. C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Richards", "given_name": "J. L.", "clpid": "Richards-J-L" }, { "family_name": "Surace", "given_name": "J.", "orcid": "0000-0001-7291-0087", "clpid": "Surace-J-A" } ], "abstract": "We use optical data from the Palomar Transient Factory (PTF) and the Catalina Real-Time Transient Survey (CRTS) to study the variability of \u03b3-ray-detected and non-detected objects in a large population of active galactic nuclei selected from the Candidate Gamma-Ray Blazar Survey and Fermi Gamma-Ray Space Telescope catalogues. Our samples include 714 sources with PTF data and 1244 sources with CRTS data. We calculate the intrinsic modulation index to quantify the optical variability amplitude in these samples. We find the \u03b3-ray-detected objects to be more variable than the non-detected ones. The flat spectrum radio quasars (FSRQs) are more variable than the BL Lac objects in our sample, but the significance of the difference depends on the sample used. When dividing the objects based on their synchrotron peak frequency, we find the low synchrotron peaked (LSP) objects to be significantly more variable than the high synchrotron peaked (HSP) ones, explaining the difference between the FSRQs and BL Lacs. This could be due to the LSPs being observed near their electron energy peak, while in the HSPs the emission is caused by lower energy electrons, which cool more slowly. We also find a significant correlation between the optical and \u03b3-ray fluxes that is stronger in the HSP BL Lacs than in the FSRQs. The FSRQs in our sample are also more Compton dominated than the HSP BL Lacs. These findings are consistent with models where the \u03b3-ray emission of HSP objects is produced by the synchrotron self-Compton mechanism, while the LSP objects need an additional external Compton component that increases the scatter in the flux\u2013flux correlation.", "doi": "10.1093/mnras/stt2494", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2014-03-21", "series_number": "1", "volume": "439", "issue": "1", "pages": "690-702" }, { "id": "authors:4jwpw-vrs60", "collection": "authors", "collection_id": "4jwpw-vrs60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140429-113118628", "type": "article", "title": "A novel variability-based method for quasar selection: evidence for a rest-frame \u223c54 d characteristic time-scale", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Chang", "given_name": "Melissa", "clpid": "Chang-Melissa" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" } ], "abstract": "We compare quasar-selection techniques based on their optical variability using data from the Catalina Real-time Transient Survey (CRTS). We introduce a new technique based on Slepian wavelet variance (SWV) that shows comparable or better performance to structure functions and damped random walk models but with fewer assumptions. Combining these methods with Wide-field Infrared Survey Explorer mid-IR colours produces a highly efficient quasar-selection technique which we have validated spectroscopically. The SWV technique also identifies characteristic time-scales in a time series, and we find a characteristic rest-frame time-scale of \u223c54\u2009d, confirmed in the light curves of \u223c18 000 quasars from CRTS, SDSS and MACHO data, and anticorrelated with absolute magnitude. This indicates a transition between a damped random walk and P(f) \u221d f^(\u22121/3) behaviours and is the first strong indication that a damped random walk model may be too simplistic to describe optical quasar variability.", "doi": "10.1093/mnras/stt2499", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2014-03", "series_number": "1", "volume": "439", "issue": "1", "pages": "703-718" }, { "id": "authors:z3atc-nyp51", "collection": "authors", "collection_id": "z3atc-nyp51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140106-103816959", "type": "article", "title": "Dust Reddened Quasars in FIRST and UKIDSS: Beyond the Tip of the Iceberg", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Urrutia", "given_name": "Tanya", "orcid": "0000-0001-6746-9936", "clpid": "Urrutia-T" }, { "family_name": "Lacy", "given_name": "Mark", "orcid": "0000-0002-3032-1783", "clpid": "Lacy-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Urry", "given_name": "Meg", "orcid": "0000-0002-0745-9792", "clpid": "Urry-C-M" }, { "family_name": "Croom", "given_name": "Scott", "orcid": "0000-0003-2880-9197", "clpid": "Croom-S-M" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Ge", "given_name": "Jian", "clpid": "Ge-Jian" } ], "abstract": "We present the results of a pilot survey to find dust-reddened quasars by matching the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio catalog to the UKIDSS near-infrared survey and using optical data from Sloan Digital Sky Survey to select objects with very red colors. The deep K-band limit provided by UKIDSS allows for finding more heavily reddened quasars at higher redshifts as compared with previous work using FIRST and Two Micron All Sky Survey (2MASS). We selected 87 candidates with K \u2264 17.0 from the UKIDSS Large Area Survey (LAS) First Data Release (DR1), which covers 190 deg^2. These candidates reach up to ~1.5 mag below the 2MASS limit and obey the color criteria developed to identify dust-reddened quasars. We have obtained 61 spectroscopic observations in the optical and/or near-infrared, as well as classifications in the literature, and have identified 14 reddened quasars with E(B \u2013 V) > 0.1, including 3 at z > 2. We study the infrared properties of the sample using photometry from the Wide-Field Infrared Survey Explorer and find that infrared colors improve the efficiency of red quasar selection, removing many contaminants in an infrared-to-optical color-selected sample alone. The highest-redshift quasars (z \u2273 2) are only moderately reddened, with E(B \u2013 V) ~ 0.2-0.3. We find that the surface density of red quasars rises sharply with faintness, comprising up to 17% of blue quasars at the same apparent K-band flux limit. We estimate that to reach more heavily reddened quasars (i.e., E(B \u2013 V) \u2273 0.5) at z > 2 and a depth of K = 17, we would need to survey at least ~2.5 times more area.", "doi": "10.1088/0004-637X/778/2/127", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2013-12-01", "series_number": "2", "volume": "778", "issue": "2", "pages": "Art. No. 127" }, { "id": "authors:1cxtk-phb72", "collection": "authors", "collection_id": "1cxtk-phb72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140107-071936778", "type": "article", "title": "A Plausible (Overlooked) Super-luminous Supernova in the Sloan Digital Sky Survey Stripe 82 Data", "author": [ { "family_name": "Kostrzewa-Rutkowska", "given_name": "Zuzanna", "clpid": "Kostrzewa-Rutkowska-Z" }, { "family_name": "Koz\u0142owski", "given_name": "Szymon", "clpid": "Koz\u0142owski-S" }, { "family_name": "Wyrzykowski", "given_name": "\u0141ukasz", "clpid": "Wyrzykowski-\u0141" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Koposov", "given_name": "Sergey", "clpid": "Koposov-S" } ], "abstract": "We present the discovery of a plausible super-luminous supernova (SLSN), found in the archival data of Sloan Digital Sky Survey (SDSS) Stripe 82, called PSN 000123+000504. The supernova (SN) peaked at m_g < 19.4 mag in the second half of 2005 September, but was missed by the real-time SN hunt. The observed part of the light curve (17 epochs) showed that the rise to the maximum took over 30 days, while the decline time lasted at least 70 days (observed frame), closely resembling other SLSNe of SN 2007bi type. The spectrum of the host galaxy reveals a redshift of z = 0.281 and the distance modulus of \u03bc = 40.77 mag. Combining this information with the SDSS photometry, we found the host galaxy to be an LMC-like irregular dwarf galaxy with an absolute magnitude of M_B = \u201318.2 \u00b1 0.2 mag and an oxygen abundance of 12+log[O/H]=8.3 \u00b1 0.2; hence, the SN peaked at M_g < \u201321.3 mag. Our SLSN follows the relation for the most energetic/super-luminous SNe exploding in low-metallicity environments, but we found no clear evidence for SLSNe to explode in low-luminosity (dwarf) galaxies only. The available information on the PSN 000123+000504 light curve suggests the magnetar-powered model as a likely scenario of this event. This SLSN is a new addition to a quickly growing family of super-luminous SNe.", "doi": "10.1088/0004-637X/778/2/168", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2013-12-01", "series_number": "2", "volume": "778", "issue": "2", "pages": "Art. No. 168" }, { "id": "authors:0vs2j-b0997", "collection": "authors", "collection_id": "0vs2j-b0997", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190507-083247188", "type": "book_section", "title": "Astrophysics in the Era of Massive Time-Domain Surveys", "author": [ { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Wo\u017aniak", "given_name": "P. R.", "clpid": "Wo\u017aniak-P-R" }, { "family_name": "Graham", "given_name": "M. J.", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A. A.", "clpid": "Mahabal-A-A" }, { "family_name": "Seaman", "given_name": "R.", "clpid": "Seaman-R" } ], "abstract": "Synoptic sky surveys are now the largest data producers in astronomy, entering the Petascale regime, opening the time domain for a systematic exploration. A great variety of interesting phenomena, spanning essentially all subfields of astronomy, can only be studied in the time domain, and these new surveys are producing large statistical samples of the known types of objects and events for further studies (e.g., SNe, AGN, variable stars of many kinds), and have already uncovered previously unknown\nsubtypes of these (e.g., rare or peculiar types of SNe). These surveys are generating a new science, and paving the way for even larger surveys to come, e.g., the LSST; our ability to fully exploit such forthcoming facilities depends critically on the science,\nmethodology, and experience that are being accumulated now. Among the outstanding challenges, the foremost is our ability to conduct an effective follow-up of the interesting events discovered by the surveys in any wavelength regime. The follow-up resources, especially spectroscopy, are already and, for the predictable future, will be severely limited, thus requiring an intelligent down-selection of the most astrophysically interesting events to follow. The first step in that process is an automated, real-time, iterative classification of events, that incorporates heterogeneous data from\nthe surveys themselves, archival and contextual information (spatial, temporal, and multiwavelength), and the incoming follow-up observations. The second step is an optimal automated event prioritization and allocation of the available follow-up resources that also change in time. Both of these challenges are highly non-trivial, and require a strong cyber-infrastructure based on the Virtual Observatory data grid, and the various astroinformatics efforts. Time domain astronomy is inherently an astronomy of telescope-computational systems, and will increasingly depend on novel\nmachine learning and artificial intelligence tools. Another arena with a strong potential for discovery is a purely archival, non-time-critical exploration of the time domain, with the time dimension adding the complexity to an already challenging problem of data mining of highly-dimensional parameter spaces produced by sky surveys.", "publisher": "Los Alamos National Laboratory", "publication_date": "2013-11" }, { "id": "authors:3n04p-mf956", "collection": "authors", "collection_id": "3n04p-mf956", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131223-130103790", "type": "article", "title": "Quasars Probing Quasars. VI. Excess H I Absorption within one Proper Mpc of z ~ 2 Quasars", "author": [ { "family_name": "Prochaska", "given_name": "J. Xavier", "orcid": "0000-0002-7738-6875", "clpid": "Prochaska-J-X" }, { "family_name": "Hennawi", "given_name": "Joseph F.", "orcid": "0000-0002-7054-4332", "clpid": "Hennawi-J-F" }, { "family_name": "Lee", "given_name": "Khee-Gan", "clpid": "Lee-Khee-Gan" }, { "family_name": "Cantalupo", "given_name": "Sebastiano", "orcid": "0000-0001-5804-1428", "clpid": "Cantalupo-S" }, { "family_name": "Bovy", "given_name": "Jo", "clpid": "Bovy-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ellison", "given_name": "Sara L.", "orcid": "0000-0002-1768-1899", "clpid": "Ellison-S-L" }, { "family_name": "Lau", "given_name": "Marie Wingyee", "clpid": "Lau-M-W" }, { "family_name": "Martin", "given_name": "Crystal L.", "clpid": "Martin-C-L" }, { "family_name": "Myers", "given_name": "Adam", "clpid": "Myers-A-D" }, { "family_name": "Rubin", "given_name": "Kate H. R.", "orcid": "0000-0001-6248-1864", "clpid": "Rubin-K-H-R" }, { "family_name": "Simcoe", "given_name": "Robert A.", "orcid": "0000-0003-3769-9559", "clpid": "Simcoe-R-A" } ], "abstract": "With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the H I Ly\u03b1 absorption transverse to luminous, z ~ 2 quasars at proper separations of 30 kpc < R_\u22a5 < 1 Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced H I Ly\u03b1 absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Ly\u03b1 equivalent width profile W = 2.3 \u00c5 (R_\u22a5/100 kpc)^(\u20130.46). We also observe a high (\u224360%) covering factor of strong, optically thick H I absorbers (H I column N_(HI)>10^(17.3) cm^(-2) at separations R_\u22a5 < 200 kpc, which decreases to ~20% at R_\u22a5 \u2243 1 Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function \u03be_(QA)(r) = (r/r_0)^\u03b3 with a large correlation length r_0=12.5^(+2.7)_(-1.4)h^(-1)Mpc(comoving) and y =1.68^(+0.14)_(-0.30). The H I absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M_(halo) \u2248 10^(12.5) M_\u2609 at z ~ 2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z ~ 2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.", "doi": "10.1088/0004-637X/776/2/136", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2013-10-20", "series_number": "2", "volume": "776", "issue": "2", "pages": "Art. No. 136" }, { "id": "authors:qnqav-z0d80", "collection": "authors", "collection_id": "qnqav-z0d80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131205-144250650", "type": "article", "title": "A comparison of period finding algorithms", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Duan", "given_name": "Victor", "clpid": "Duan-V" }, { "family_name": "Maker", "given_name": "Allison", "clpid": "Maker-A" } ], "abstract": "This paper presents a comparison of popular period finding algorithms applied to the light curves of variable stars from the Catalina Real-Time Transient Survey, MACHO and ASAS data sets. We analyse the accuracy of the methods against magnitude, sampling rates, quoted period, quality measures (signal-to-noise and number of observations), variability and object classes. We find that measure of dispersion-based techniques \u2013 analysis of variance with harmonics and conditional entropy \u2013 consistently give the best results but there are clear dependences on object class and light-curve quality. Period aliasing and identifying a period harmonic also remain significant issues. We consider the performance of the algorithms and show that a new conditional entropy-based algorithm is the most optimal in terms of completeness and speed. We also consider a simple ensemble approach and find that it performs no better than individual algorithms.", "doi": "10.1093/mnras/stt1264", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2013-10", "series_number": "4", "volume": "434", "issue": "4", "pages": "3423-3444" }, { "id": "authors:fzg75-k1604", "collection": "authors", "collection_id": "fzg75-k1604", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140324-134154762", "type": "book_section", "title": "Feature Selection Strategies for Classifying High Dimensional Astronomical Data Sets", "book_title": "Big Data, 2013 IEEE International Conference", "author": [ { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Fuchs", "given_name": "Thomas J.", "clpid": "Fuchs-T-J" }, { "family_name": "Turmon", "given_name": "Michael J.", "clpid": "Turmon-M-J" }, { "family_name": "Kumar", "given_name": "A. Arun", "clpid": "Kumar-A-A" }, { "family_name": "Philip", "given_name": "N. Sajeeth", "clpid": "Philip-N-S" }, { "family_name": "Yang", "given_name": "Michael Ting-Chang", "clpid": "Yang-Michael-Ting-Chang" }, { "family_name": "Longo", "given_name": "Giuseppe", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" } ], "contributor": [ { "family_name": "Hu", "given_name": "X.", "clpid": "Hu-X" }, { "family_name": "Lin", "given_name": "T. Y.", "clpid": "Lin-T-Y" }, { "family_name": "Raghavan", "given_name": "V.", "clpid": "Raghavan-V" }, { "family_name": "Wah", "given_name": "B.", "clpid": "Wah-B" }, { "family_name": "Baeza-Yates", "given_name": "R.", "clpid": "Baeza-Yates-R" }, { "family_name": "Fox", "given_name": "G.", "clpid": "Fox-G" }, { "family_name": "Shahabi", "given_name": "C.", "clpid": "Shahabi-C" }, { "family_name": "Smith", "given_name": "M.", "clpid": "Smith-M" }, { "family_name": "Yang", "given_name": "Q.", "clpid": "Yang-Q" }, { "family_name": "Ghani", "given_name": "R.", "clpid": "Ghani-R" }, { "family_name": "Fan", "given_name": "W.", "clpid": "Fan-W" }, { "family_name": "Lempel", "given_name": "R.", "clpid": "Lempel-R" }, { "family_name": "Nambiar", "given_name": "R.", "clpid": "Nambiar-R" } ], "abstract": "The amount of collected data in many scientific fields is increasing, all of them requiring a common task: extract knowledge from massive, multi parametric data sets, as rapidly and efficiently possible. This is especially true in astronomy where synoptic sky surveys are enabling new research frontiers in the time domain astronomy and posing several new object classification challenges in multi dimensional spaces; given the high number of parameters available for each object, feature selection is quickly becoming a crucial task in analyzing astronomical data sets. Using data sets extracted from the ongoing Catalina Real-Time Transient Surveys (CRTS) and the Kepler Mission we illustrate a variety of feature selection strategies used to identify the subsets that give the most information and the results achieved applying these techniques to three major astronomical problems.", "doi": "10.1109/BigData.2013.6691731", "isbn": "978-1-4799-1292-6", "publisher": "IEEE", "place_of_publication": "New York, NY", "publication_date": "2013-10", "pages": "35-45" }, { "id": "authors:4b88b-8x603", "collection": "authors", "collection_id": "4b88b-8x603", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131002-092100440", "type": "article", "title": "A MegaCam Survey of Outer Halo Satellites. II. Blue Stragglers in the Lowest Stellar Density Systems", "author": [ { "family_name": "Santana", "given_name": "Felipe A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Mu\u00f1oz", "given_name": "Ricardo R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "Geha", "given_name": "Marla", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Stetson", "given_name": "Peter", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Simon", "given_name": "Joshua D.", "clpid": "Simon-J-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present a homogeneous study of blue straggler stars across 10 outer halo globular clusters, 3 classical dwarf spheroidal galaxies, and 9 ultra-faint galaxies based on deep and wide-field photometric data taken with MegaCam on the Canada\u2013France\u2013Hawaii Telescope. We find blue straggler stars to be ubiquitous among these Milky Way satellites. Based on these data, we can test the importance of primordial binaries or multiple systems on blue straggler star formation in low-density environments. For the outer halo globular clusters, we find an anti-correlation between the specific frequency of blue stragglers and absolute magnitude, similar to that previously observed for inner halo clusters. When plotted against density and encounter rate, the frequency of blue stragglers is well fit by a single trend with a smooth transition between dwarf galaxies and globular clusters; this result points to a common origin for these satellites' blue stragglers. The fraction of blue stragglers stays constant and high in the low encounter rate regime spanned by our dwarf galaxies, and decreases with density and encounter rate in the range spanned by our globular clusters. We find that young stars can mimic blue stragglers in dwarf galaxies only if their ages are 2.5 \u00b1 0.5 Gyr and they represent ~1%\u20137% of the total number of stars, which we deem highly unlikely. These results point to mass-transfer or mergers of primordial binaries or multiple systems as the dominant blue straggler formation mechanism in low-density systems.", "doi": "10.1088/0004-637X/774/2/106", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2013-09-10", "series_number": "2", "volume": "774", "issue": "2", "pages": "Art. No. 106" }, { "id": "authors:znc8n-34k50", "collection": "authors", "collection_id": "znc8n-34k50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131002-125112999", "type": "article", "title": "Using conditional entropy to identify periodicity", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" } ], "abstract": "This paper presents a new period-finding method based on conditional entropy that is both efficient and accurate. We demonstrate its applicability on simulated and real data. We find that it has comparable performance to other information-based techniques with simulated data but is superior with real data, both for finding periods and for just identifying periodic behaviour. In particular, it is robust against common aliasing issues found with other period-finding algorithms.", "doi": "10.1093/mnras/stt1206", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2013-09", "series_number": "3", "volume": "434", "issue": "3", "pages": "2629-2635" }, { "id": "authors:sajf1-7cb28", "collection": "authors", "collection_id": "sajf1-7cb28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131107-153839658", "type": "article", "title": "Astrogenomics: big data, old problems, old solutions?", "author": [ { "family_name": "Golden", "given_name": "Aaron", "orcid": "0000-0002-8599-2031", "clpid": "Golden-A" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Greally", "given_name": "John M.", "clpid": "Greally-J-M" } ], "abstract": "The ominous warnings of a data deluge in the life sciences from high-throughput DNA sequencing data are being supplanted by a second deluge, of clich\u00e9s bemoaning our collective scientific fate unless we address the genomic data tsunami. It is imperative that we explore the many facets of the genome, not just sequence but also transcriptional and epigenetic variability, integrating these observations in order to attain a genuine understanding of how genes function, towards a goal of genomics-based personalized medicine. Determining any individual's genomic properties requires comparison to many others, sifting out the specific from the trends, requiring access to the many in order to yield information relevant to the few. This is the central big data challenge in genomics that still requires some sort of resolution. Is there a practical, feasible way of directly connecting the scientific community to this data universe?", "doi": "10.1186/gb-2013-14-8-129", "pmcid": "PMC4053852", "issn": "1465-6906", "publisher": "BioMed Central", "publication": "Genome Biology", "publication_date": "2013-08-13", "volume": "14", "pages": "Art. No. 129" }, { "id": "authors:y2sdd-zjr21", "collection": "authors", "collection_id": "y2sdd-zjr21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130613-102659523", "type": "article", "title": "Machine-assisted discovery of relationships in astronomy", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" } ], "abstract": "High-volume feature-rich data sets are becoming the bread-and-butter of 21st century astronomy but present significant challenges to scientific discovery. In particular, identifying scientifically significant relationships between sets of parameters is non-trivial. Similar problems in biological and geosciences have led to the development of systems which can explore large parameter spaces and identify potentially interesting sets of associations. In this paper, we describe the application of automated discovery systems of relationships to astronomical data sets, focusing on an evolutionary programming technique and an information-theory technique. We demonstrate their use with classical astronomical relationships \u2013 the Hertzsprung\u2013Russell diagram and the Fundamental Plane of elliptical galaxies. We also show how they work with the issue of binary classification which is relevant to the next generation of large synoptic sky surveys, such as the Large Synoptic Survey Telescope (LSST). We find that comparable results to more familiar techniques, such as decision trees, are achievable. Finally, we consider the reality of the relationships discovered and how this can be used for feature selection and extraction.", "doi": "10.1093/mnras/stt329", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2013-05", "series_number": "3", "volume": "431", "issue": "3", "pages": "2371-2384" }, { "id": "authors:a3smq-n5g46", "collection": "authors", "collection_id": "a3smq-n5g46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130408-082022888", "type": "article", "title": "Evidence for a Milky Way Tidal Stream Reaching Beyond 100 kpc", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Torrealba", "given_name": "G.", "clpid": "Torrealba-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" } ], "abstract": "We present the analysis of 1207 RR Lyrae found in photometry taken by the Catalina Survey's Mount Lemmon telescope. By combining accurate distances for these stars with measurements for ~14,000 type-ab RR Lyrae from the Catalina Schmidt telescope, we reveal an extended association that reaches Galactocentric distances beyond 100 kpc and overlaps the Sagittarius stream system. This result confirms earlier evidence for the existence of an outer halo tidal stream resulting from a disrupted stellar system. By comparing the RR Lyrae source density with that expected based on halo models, we find the detection has ~8\u03c3 significance. We investigate the distances, radial velocities, metallicities, and period-amplitude distribution of the RR Lyrae. We find that both radial velocities and distances are inconsistent with current models of the Sagittarius stream. We also find tentative evidence for a division in source metallicities for the most distant sources. Following prior analyses, we compare the locations and distances of the RR Lyrae with photometrically selected candidate horizontal branch stars and find supporting evidence that this structure spans at least 60\u00b0 of the sky. We investigate the prospects of an association between the stream and the unusual globular cluster NGC 2419.", "doi": "10.1088/0004-637X/765/2/154", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2013-03-10", "series_number": "2", "volume": "765", "issue": "2", "pages": "Art. No. 154" }, { "id": "authors:dpd20-1k188", "collection": "authors", "collection_id": "dpd20-1k188", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130808-104839527", "type": "article", "title": "VAST: An ASKAP Survey for Variables and Slow Transients", "author": [ { "family_name": "Murphy", "given_name": "Tara", "orcid": "0000-0002-2686-438X", "clpid": "Murphy-T" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, an ASKAP survey for Variables and Slow Transients. VAST will exploit the wide-field survey capabilities of ASKAP to enable the discovery and investigation of variable and transient phenomena from the local to the cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, interstellar scintillation, radio supernovae, and orphan afterglows of gamma-ray bursts. In addition, it will allow us to probe unexplored regions of parameter space where new classes of transient sources may be detected. In this paper we review the known radio transient and variable populations and the current results from blind radio surveys. We outline a comprehensive program based on a multi-tiered survey strategy to characterise the radio transient sky through detection and monitoring of transient and variable sources on the ASKAP imaging timescales of 5 s and greater. We also present an analysis of the expected source populations that we will be able to detect with VAST.", "doi": "10.1017/pasa.2012.006", "issn": "1323-3580", "publisher": "Cambridge University Press", "publication": "Publications of the Astonomical Society of Australia", "publication_date": "2013-02-15", "volume": "30", "pages": "Art. No. e006" }, { "id": "authors:nknvg-h3155", "collection": "authors", "collection_id": "nknvg-h3155", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130215-113118810", "type": "article", "title": "Probing the Outer Galactic Halo with RR Lyrae from the Catalina Surveys", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Torrealba", "given_name": "G.", "clpid": "Torrealba-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Belokurov", "given_name": "V.", "orcid": "0000-0002-0038-9584", "clpid": "Belokurov-V" }, { "family_name": "Koposov", "given_name": "S. E.", "orcid": "0000-0003-2644-135X", "clpid": "Koposov-S-E" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" } ], "abstract": "We present analysis of 12,227 type-ab RR Lyraes (RRLs) found among the 200 million public light curves in Catalina Surveys Data Release 1. These stars span the largest volume of the Milky Way ever surveyed with RRLs, covering ~20,000 deg2 of the sky (0\u00b0 < \u03b1 < 360\u00b0, \u201322\u00b0 < \u03b4 < 65\u00b0) to heliocentric distances of up to 60 kpc. Each of the RRLs is observed between 60 and 419 times over a six-year period. Using period finding and Fourier fitting techniques we determine periods and apparent magnitudes for each source. We find that the periods are generally accurate to \u03c3 = 0.002% in comparison to 2842 previously known RRLs and 100 RRLs observed in overlapping survey fields. We photometrically calibrate the light curves using 445 Landolt standard stars and show that the resulting magnitudes are accurate to ~0.05 mag using Sloan Digital Sky Survey (SDSS) data for ~1000 blue horizontal branch stars and 7788 RRLs. By combining Catalina photometry with SDSS spectroscopy, we analyze the radial velocity and metallicity distributions for >1500 of the RRLs. Using the accurate distances derived for the RRLs, we show the paths of the Sagittarius tidal streams crossing the sky at heliocentric distances from 20 to 60 kpc. By selecting samples of Galactic halo RRLs, we compare their velocity, metallicity, and distance with predictions from a recent detailed N-body model of the Sagittarius system. We find that there are some significant differences between the distances and structures predicted and our observations.", "doi": "10.1088/0004-637X/763/1/32", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2013-01-20", "series_number": "1", "volume": "763", "issue": "1", "pages": "Art. No. 32" }, { "id": "authors:qncny-bbw80", "collection": "authors", "collection_id": "qncny-bbw80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150713-125431089", "type": "book_section", "title": "Sky Surveys", "book_title": "Planets, Stars and Stellar Systems", "author": [ { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" } ], "contributor": [ { "family_name": "Oswalt", "given_name": "Terry D.", "clpid": "Oswalt-T-D" }, { "family_name": "Bond", "given_name": "Howard E.", "clpid": "Bond-H-E" } ], "abstract": "Sky surveys represent a fundamental data basis for astronomy. We use them to map in a systematic way the universe and its constituents and to discover new types of objects or phenomena. We review the subject, with an emphasis on the wide-field, imaging surveys, placing them in a broader scientific and historical context. Surveys are now the largest data generators in astronomy, propelled by the advances in information and computation technology, and have transformed the ways in which astronomy is done. This trend is bound to continue, especially with the new generation of synoptic sky surveys that cover wide areas of the sky repeatedly and open a new time domain of discovery. We describe the variety and the general properties of surveys, illustrated by a number of examples, the ways in which they may be quantified and compared, and offer some figures of merit that can be used to compare their scientific discovery potential. Surveys enable a very wide range of science, and that is perhaps their key unifying characteristic. As new domains of the observable parameter space open up thanks to the advances in technology, surveys are often the initial step in their exploration. Some science can be done with the survey data alone (or a combination of data from different surveys), and some require a targeted follow-up of potentially interesting sources selected from surveys. Surveys can be used to generate large, statistical samples of objects that can be studied as populations or as tracers of larger structures to which they belong. They can be also used to discover or generate samples of rare or unusual objects and may lead to discoveries of some previously unknown types. We discuss a general framework of parameter spaces that can be used for an assessment and comparison of different surveys and the strategies for their scientific exploration. As we are moving into the Petascale regime and beyond, an effective processing and scientific exploitation of such large data sets and data streams pose many challenges, some of which are specific to any given survey and some of which may be addressed in the framework of Virtual Observatory and Astroinformatics. The exponential growth of data volumes and complexity makes a broader application of data mining and knowledge discovery technologies critical in order to take a full advantage of this wealth of information. Finally, we discuss some outstanding challenges and prospects for the future.", "doi": "10.1007/978-94-007-5618-2_5", "isbn": "978-94-007-5617-5", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "2013", "pages": "223-281" }, { "id": "authors:h358s-cc927", "collection": "authors", "collection_id": "h358s-cc927", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160203-094000654", "type": "monograph", "title": "Digging Deeper: Algorithms for Computationally-Limited Searches in Astronomy", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Cutler", "given_name": "Curt", "clpid": "Cutler-C-J" }, { "family_name": "Elmegreen", "given_name": "Bruce G.", "orcid": "0000-0002-1723-6330", "clpid": "Elmegreen-B-G" }, { "family_name": "Vallisneri", "given_name": "M.", "orcid": "0000-0002-4162-0033", "clpid": "Vallisneri-M" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "Astronomy, like most other fields, is being deluged by exponentially growing streams of ever more complex data. While these massive data streams bring a great discovery potential, their full scientific exploitation poses many challenges, due to both data volumes and data complexity.\nMoreover, the need to discover and characterize interesting, faint signals in such data streams quickly and robustly, in order to deploy costly follow-up resources that are often necessary for\nthe full scientific returns, makes the challenges even sharper. Examples in astronomy include transient events and variable sources found in digital synoptic sky surveys, gravitational wave signals, faint radio transients, pulsars, and other types of variable sources in the next generation of panoramic radio surveys, etc. Similar situations arise in the context of space science and planetary exploration, environmental monitoring, security, etc. In most cases, rapid discovery\nand characterization of interesting signals is highly computationally limited. The goal of this study was to define a number of interesting, often mission-critical challenges of this nature in the\nbroader context of time-domain astronomy, but with an eye on their applicability elsewhere.", "doi": "10.26206/S5YB-TR47", "publisher": "Keck Institute for Space Studies", "publication_date": "2012-12" }, { "id": "authors:2ezgc-htq19", "collection": "authors", "collection_id": "2ezgc-htq19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130401-144342419", "type": "book_section", "title": "Flashes in a star stream: Automated classification of astronomical transient events", "book_title": "2012 IEEE 8th International Conference on E-Science", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Moghaddam", "given_name": "B.", "clpid": "Moghaddam-B" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" } ], "abstract": "An automated, rapid classification of transient events detected in the modern synoptic sky surveys is essential for their scientific utility and effective follow-up using scarce resources. This presents some unusual challenges: the data are sparse, heterogeneous and incomplete; evolving in time; and most of the relevant information comes not from the data stream itself, but from a variety of archival data and contextual information (spatial, temporal, and multi-wavelength). We are exploring a variety of novel techniques, mostly Bayesian, to respond to these challenges, using the ongoing CRTS sky survey as a testbed. The current surveys are already overwhelming our ability to effectively follow all of the potentially interesting events, and these challenges will grow by orders of magnitude over the next decade as the more ambitious sky surveys get under way. While we focus on an application in a specific domain (astrophysics), these challenges are more broadly relevant for event or anomaly detection and knowledge discovery in massive data streams.", "doi": "10.1109/eScience.2012.6404437", "isbn": "978-1-4673-4467-8", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2012-10", "pages": "1-8" }, { "id": "authors:3dyc7-3t150", "collection": "authors", "collection_id": "3dyc7-3t150", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121005-095516304", "type": "article", "title": "Data challenges of time domain astronomy", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A-J" }, { "family_name": "Longo", "given_name": "Giuseppe", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" } ], "abstract": "Astronomy has been at the forefront of the development of the techniques\nand methodologies of data intensive science for over a decade with large sky surveys\nand distributed efforts such as the Virtual Observatory. However, it faces a new data\ndeluge with the next generation of synoptic sky surveys which are opening up the time\ndomain for discovery and exploration. This brings both new scientific opportunities\nand fresh challenges, in terms of data rates from robotic telescopes and exponential\ncomplexity in linked data, but also for data mining algorithms used in classification\nand decision making. In this paper, we describe how an informatics-based approach\u2014\npart of the so-called \"fourth paradigm\" of scientific discovery\u2014is emerging to deal\nwith these. We review our experiences with the Palomar-Quest and Catalina Real-\nTime Transient Sky Surveys; in particular, addressing the issue of the heterogeneity\nof data associated with transient astronomical events (and other sensor networks) and\nhow to manage and analyze it.", "doi": "10.1007/s10619-012-7101-7", "issn": "0926-8782", "publisher": "Springer", "publication": "Distributed and Parallel Databases", "publication_date": "2012-10", "series_number": "5-6", "volume": "30", "issue": "5-6", "pages": "371-384" }, { "id": "authors:0q3fs-7ff83", "collection": "authors", "collection_id": "0q3fs-7ff83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121101-104020960", "type": "article", "title": "FIRST-2MASS Red Quasars: Transitional Objects Emerging from the Dust", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Urrutia", "given_name": "Tanya", "orcid": "0000-0001-6746-9936", "clpid": "Urrutia-T" }, { "family_name": "Lacy", "given_name": "Mark", "orcid": "0000-0002-3032-1783", "clpid": "Lacy-M" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Myers", "given_name": "Adam D.", "clpid": "Myers-A-D" }, { "family_name": "Ross", "given_name": "Nicholas P.", "orcid": "0000-0003-1830-6473", "clpid": "Ross-N-P" }, { "family_name": "Petitjean", "given_name": "Patrick", "clpid": "Petitjean-P" }, { "family_name": "Ge", "given_name": "Jian", "clpid": "Ge-Jian" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "York", "given_name": "Donald G.", "clpid": "York-D-G" } ], "abstract": "We present a sample of 120 dust-reddened quasars identified by matching radio sources detected at 1.4 GHz in the Faint Images of the Radio Sky at Twenty Centimeters survey with the near-infrared Two Micron All Sky Survey catalog and color-selecting red sources. Optical and/or near-infrared spectroscopy provide broad wavelength sampling of their spectral energy distributions that we use to determine their reddening, characterized by E(B \u2013 V). We demonstrate that the reddening in these quasars is best described by Small-Magellanic-Cloud-like dust. This sample spans a wide range in redshift and reddening (0.1 \u2272 z \u2272 3, 0.1 \u2272 E(B \u2013 V) \u2272 1.5), which we use to investigate the possible correlation of luminosity with reddening. At every redshift, dust-reddened quasars are intrinsically the most luminous quasars. We interpret this result in the context of merger-driven quasar/galaxy co-evolution where these reddened quasars are revealing an emergent phase during which the heavily obscured quasar is shedding its cocoon of dust prior to becoming a \"normal\" blue quasar. When correcting for extinction, we find that, depending on how the parent population is defined, these red quasars make up \u2272 15%-20% of the luminous quasar population. We estimate, based on the fraction of objects in this phase, that its duration is 15%-20% as long as the unobscured, blue quasar phase.", "doi": "10.1088/0004-637X/757/1/51", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2012-09-20", "series_number": "1", "volume": "757", "issue": "1", "pages": "Art. No. 51" }, { "id": "authors:ht0ff-31q11", "collection": "authors", "collection_id": "ht0ff-31q11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161019-145928167", "type": "book_section", "title": "Connecting the time domain community with the Virtual Astronomical Observatory", "book_title": "Observatory Operations: Strategies, Processes, and Systems IV", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Plante", "given_name": "Raymond L.", "clpid": "Plante-R-L" }, { "family_name": "Kantor", "given_name": "Jeffrey", "clpid": "Kantor-J" }, { "family_name": "Good", "given_name": "John C.", "clpid": "Good-J-C" } ], "contributor": [ { "family_name": "Peck", "given_name": "Alison B.", "clpid": "Peck-A-B" }, { "family_name": "Seaman", "given_name": "Robert L.", "clpid": "Seaman-R-L" }, { "family_name": "Comeron", "given_name": "Fernando", "clpid": "Comeron-F" } ], "abstract": "The time domain has been identified as one of the most important areas of astronomical research for the next decade. The Virtual Observatory is in the vanguard with dedicated tools and services that enable and facilitate the discovery, dissemination and analysis of time domain data. These range in scope from rapid notifications of time-critical astronomical transients to annotating long-term variables with the latest modelling results. In this paper, we will review the prior art in these areas and focus on the capabilities that the VAO is bringing to bear in support of time domain science. In particular, we will focus on the issues involved with the heterogeneous collections of (ancilllary) data associated with astronomical transients, and the time series characterization and classification tools required by the next generation of sky surveys, such as LSST and SKA.", "doi": "10.1117/12.926577", "isbn": "9780819491497", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-09-13", "pages": "Art. No. 84480P" }, { "id": "authors:082h7-smj59", "collection": "authors", "collection_id": "082h7-smj59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121031-100620006", "type": "article", "title": "CLaSPS: A New Methodology for Knowledge Extraction from Complex Astronomical Data Sets", "author": [ { "family_name": "D'Abrusco", "given_name": "R.", "clpid": "D'Abrusco-R" }, { "family_name": "Fabbiano", "given_name": "G.", "orcid": "0000-0002-3554-3318", "clpid": "Fabbiano-G" }, { "family_name": "Djorgovski", "given_name": "G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Laurino", "given_name": "O.", "clpid": "Laurino-O" }, { "family_name": "Longo", "given_name": "G.", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" } ], "abstract": "In this paper, we present the Clustering-Labels-Score Patterns Spotter (CLaSPS), a new methodology for the determination of correlations among astronomical observables in complex data sets, based on the application of distinct unsupervised clustering techniques. The novelty in CLaSPS is the criterion used for the selection of the optimal clusterings, based on a quantitative measure of the degree of correlation between the cluster memberships and the distribution of a set of observables, the labels, not employed for the clustering. CLaSPS has been primarily developed as a tool to tackle the challenging complexity of the multi-wavelength complex and massive astronomical data sets produced by the federation of the data from modern automated astronomical facilities. In this paper, we discuss the applications of CLaSPS to two simple astronomical data sets, both composed of extragalactic sources with photometric observations at different wavelengths from large area surveys. The first data set, CSC+, is composed of optical quasars spectroscopically selected in the Sloan Digital Sky Survey data, observed in the x-rays by Chandra and with multi-wavelength observations in the near-infrared, optical, and ultraviolet spectral intervals. One of the results of the application of CLaSPS to the CSC+ is the re-identification of a well-known correlation between the \u03b1_(OX) parameter and the near-ultraviolet color, in a subset of CSC+ sources with relatively small values of the near-ultraviolet colors. The other data set consists of a sample of blazars for which photometric observations in the optical, mid-, and near-infrared are available, complemented for a subset of the sources, by Fermi \u03b3-ray data. The main results of the application of CLaSPS to such data sets have been the discovery of a strong correlation between the multi-wavelength color distribution of blazars and their optical spectral classification in BL Lac objects and flat-spectrum radio quasars, and a peculiar pattern followed by blazars in the WISE mid-infrared colors space. This pattern and its physical interpretation have been discussed in detail in other papers by one of the authors.", "doi": "10.1088/0004-637X/755/2/92", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2012-08-20", "series_number": "2", "volume": "755", "issue": "2", "pages": "Art. No. 92" }, { "id": "authors:gpm71-4nh49", "collection": "authors", "collection_id": "gpm71-4nh49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120731-153352787", "type": "article", "title": "A Comprehensive View of a Strongly Lensed Planck-Associated Submillimeter Galaxy", "author": [ { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Scoville", "given_name": "N.", "orcid": "0000-0002-0438-3323", "clpid": "Scoville-N-Z" }, { "family_name": "Yan", "given_name": "L.", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" }, { "family_name": "Riechers", "given_name": "D. A.", "orcid": "0000-0001-9585-1462", "clpid": "Riechers-D-A" }, { "family_name": "Bradford", "given_name": "M.", "clpid": "Bradford-M" }, { "family_name": "Vieira", "given_name": "J.", "clpid": "Vieira-J" } ], "abstract": "We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9\u2013001132 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 \u03bcm flux density (~300 mJy). It is the only high-redshift Planck detection in the 130 deg^2 H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 \u03bcm and CO(1\u21920) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over ~1.6 kpc, the dust in a compact (~1 kpc) region ~3 kpc north of the stars, and the cold molecular gas in an extended (~7 kpc) disk ~5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by ~17, ~8, and ~7 times, respectively, by four lensing galaxies at z ~ 1. Intrinsically, the lensed galaxy is a warm (T_(dust) ~ 40-65 K), hyper-luminous (L_(IR) ~ 1.7 \u00d7 10^(13) L_\u2609; star formation rate (SFR) ~2000 M_\u2609 yr^(\u20131)), gas-rich (M_(gas)/M_(baryon) ~ 70%), young (M_(stellar)/SFR ~ 20 Myr), and short-lived (M_(gas)/SFR ~ 40 Myr) starburst. With physical properties similar to unlensed z > 2 SMGs, HATLAS J114637.9\u2013001132 offers a detailed view of a typical SMG through a powerful cosmic microscope.", "doi": "10.1088/0004-637X/753/2/134", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2012-07-10", "series_number": "2", "volume": "753", "issue": "2", "pages": "Art. No. 134" }, { "id": "authors:nzj84-mjn49", "collection": "authors", "collection_id": "nzj84-mjn49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120723-110203782", "type": "article", "title": "The Discovery of an Ultra-faint Star Cluster in the Constellation of Ursa Minor", "author": [ { "family_name": "Mu\u00f1oz", "given_name": "R. R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "Geha", "given_name": "M.", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Vargas", "given_name": "L. C.", "orcid": "0000-0001-7155-0040", "clpid": "Vargas-L-C" }, { "family_name": "Santana", "given_name": "F. A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Stetson", "given_name": "P.", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Simon", "given_name": "J. D.", "clpid": "Simon-J-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report the discovery of a new ultra-faint globular cluster in the constellation of Ursa Minor, based on stellar photometry from the MegaCam imager at the Canada-France-Hawaii Telescope. We find that this cluster, Mu\u00f1oz 1, is located at a distance of 45 \u00b1 5 kpc and at a projected distance of only 45' from the center of the Ursa Minor dwarf spheroidal galaxy. Using a maximum-likelihood technique we measure a half-light radius of 0farcm5, or equivalently 7 pc, and an ellipticity consistent with being zero. We estimate its absolute magnitude to be M_V = \u20130.4 \u00b1 0.9, which corresponds to L_V = 120^(+160)_\u2013(65) L_\u2609 and we measure a heliocentric radial velocity of \u2013137 \u00b1 4 km s^(\u20131) based on Keck/DEIMOS spectroscopy. This new satellite is separate from Ursa Minor by ~30 kpc and 110 km s^(\u20131) suggesting the cluster is not obviously associated with the dSph, despite the very close angular separation. Based on its photometric properties and structural parameters we conclude that Mu\u00f1oz 1 is a new ultra-faint stellar cluster. Along with Segue 3 this is one of the faintest stellar clusters known to date.", "doi": "10.1088/2041-8205/753/1/L15", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2012-07-01", "series_number": "1", "volume": "753", "issue": "1", "pages": "Art. No. L15" }, { "id": "authors:83xm0-3y005", "collection": "authors", "collection_id": "83xm0-3y005", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120724-165609500", "type": "article", "title": "The velocity dispersion and mass function of the outer halo globular cluster Palomar 4", "author": [ { "family_name": "Frank", "given_name": "Matthias J.", "clpid": "Frank-M-J" }, { "family_name": "Hilker", "given_name": "Michael", "clpid": "Hilker-M" }, { "family_name": "Baumgardt", "given_name": "Holger", "clpid": "Baumgardt-H" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Grebel", "given_name": "Eva K.", "orcid": "0000-0002-1891-3794", "clpid": "Grebel-E-K" }, { "family_name": "Haghi", "given_name": "Hosein", "clpid": "Haghi-H" }, { "family_name": "K\u00fcpper", "given_name": "Andreas H. W.", "clpid": "K\u00fcpper-A-H-W" }, { "family_name": "Djorgovski", "given_name": "Stanislav G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We obtained precise line-of-sight radial velocities of 23 member stars of the remote halo globular cluster Palomar 4 (Pal 4) using the High Resolution Echelle Spectrograph at the Keck I telescope.We also measured the mass function of the cluster down to a limiting magnitude of V \u223c 28 mag using archival Hubble Space Telescope/Wide Field Planetary Camera 2 (WFPC2) imaging. We derived the cluster's surface brightness profile based on the WFPC2 data and on broad-band imaging with the Low Resolution Imaging Spectrometer at the Keck II telescope.\nWe find a mean cluster velocity of 72.55 \u00b1 0.22 km s^(\u22121) and a velocity dispersion of 0.87 \u00b1 0.18 km s^(\u22121). The global mass function of the cluster, in the mass range 0.55 \u2264 M \u2264 0.85M_\u2299, is shallower than a Kroupa mass function and the cluster is significantly depleted in low-mass\nstars in its centre compared to its outskirts. Since the relaxation time of Pal 4 is of the order of a Hubble time, this points to primordial mass segregation in this cluster. Extrapolating the measured mass function towards lower mass stars and including the contribution of compact remnants, we derive a total cluster mass of 29 800M_\u2299. For this mass, the measured velocity dispersion is consistent with the expectations of Newtonian dynamics and below the prediction of modified Newtonian dynamics (MOND). Pal 4 adds to the growing body of evidence that the dynamics of star clusters in the outer Galactic halo can hardly be explained by MOND.", "doi": "10.1111/j.1365-2966.2012.21105.x", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2012-07", "series_number": "3", "volume": "423", "issue": "3", "pages": "2917-2932" }, { "id": "authors:0p9wj-3kd70", "collection": "authors", "collection_id": "0p9wj-3kd70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-141622366", "type": "book_section", "title": "Extracting Knowledge from Massive Astronomical Data Sets", "book_title": "Astrostatistics and Data Mining", "author": [ { "family_name": "Brescia", "given_name": "Massimo", "orcid": "0000-0001-9506-5680", "clpid": "Brescia-M" }, { "family_name": "Cavuoti", "given_name": "Stefano", "orcid": "0000-0002-3787-4196", "clpid": "Cavuoti-S" }, { "family_name": "Djorgovski", "given_name": "George S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Longo", "given_name": "Giuseppe", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" }, { "family_name": "Paolillo", "given_name": "Maurizio", "orcid": "0000-0003-4210-7693", "clpid": "Paolillo-M" } ], "contributor": [ { "family_name": "Sarro", "given_name": "Luis Manuel", "clpid": "Sarro-L-M" }, { "family_name": "Eyer", "given_name": "Laurent", "clpid": "Eyer-L" }, { "family_name": "O'Mullane", "given_name": "William", "clpid": "O'Mullane-W" }, { "family_name": "De Ridder", "given_name": "Joris", "clpid": "De-Ridder-J" } ], "abstract": "The exponential growth of astronomical data collected by both ground-based and spaceborne instruments has fostered the growth of astroinformatics: a new discipline lying at the intersection between astronomy, applied computer science, and information and computation technologies. At the very heart of astroinformatics is a complex set of methodologies usually called data mining (DM) or knowledge discovery in databases (KDD). In the astronomical domain, DM/KDD are still in a very early usage stage, even though new methods and tools are being continuously deployed to cope with the massive data sets (MDSs) that can only grow in the future. In this paper, we briefly outline some general problems encountered when applying DM/KDD methods to astrophysical problems and describe the DAME (Data Mining and Exploration) Web application. While specifically tailored to work on MDSs, DAME can be effectively applied also to smaller data sets. As an illustration, we describe two applications of DAME to two different problems: the identification of candidate GCs in external galaxies and the classification of active Galactic nuclei (AGN). We believe that tools and services of this nature will become increasingly necessary for data-intensive astronomy (and indeed all sciences) in the twenty-first century.", "doi": "10.1007/978-1-4614-3323-1_3", "isbn": "978-1-4614-3322-4", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2012-06-05", "pages": "31-45" }, { "id": "authors:b91qa-krv59", "collection": "authors", "collection_id": "b91qa-krv59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120529-152642299", "type": "article", "title": "Three quasi-stellar objects acting as strong gravitational lenses", "author": [ { "family_name": "Courbin", "given_name": "F.", "clpid": "Courbin-F" }, { "family_name": "Faure", "given_name": "C.", "clpid": "Faure-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "R\u00e9rat", "given_name": "F.", "clpid": "R\u00e9rat-F" }, { "family_name": "Tewes", "given_name": "M.", "clpid": "Tewes-M" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Boroson", "given_name": "T.", "orcid": "0000-0001-9481-1805", "clpid": "Boroson-T-A" }, { "family_name": "Dheeraj", "given_name": "R.", "clpid": "Dheeraj-R" }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-D" } ], "abstract": "We report the discovery of three new cases of quasi-stellar objects (QSOs) acting as strong gravitational lenses on background emission line galaxies: SDSS J0827+5224 (z_(QSO) = 0.293, z_s = 0.412), SDSS J0919+2720 (z_(QSO) = 0.209, z_s = 0.558), SDSS J1005+4016 (z_(QSO) = 0.230, z_s = 0.441). The selection was carried out using a sample of 22,298 SDSS spectra displaying at least four emission lines at a redshift beyond that of the foreground QSO. The lensing nature is confirmed from Keck imaging and spectroscopy, as well as from HST/WFC3 imaging in the F475W and F814W filters. Two of the QSOs have face-on spiral host galaxies and the third is a QSO+galaxy pair. The velocity dispersion of the host galaxies, inferred from simple lens modeling, is between \u03c3 = 210 and 285 km\u2009s^(-1), making these host galaxies comparable in mass with the SLACS sample of early-type strong lenses.", "doi": "10.1051/0004-6361/201118015", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2012-04", "volume": "540", "pages": "Art .No. A36" }, { "id": "authors:vnefv-2fn04", "collection": "authors", "collection_id": "vnefv-2fn04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120405-154548859", "type": "article", "title": "SN 2008jb: A \"Lost\" Core-collapse Supernova in a Star-forming Dwarf Galaxy at ~10 Mpc", "author": [ { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Lee", "given_name": "J. C.", "orcid": "0000-0002-2278-9407", "clpid": "Lee-Janice-C" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "McNaught", "given_name": "R.", "clpid": "McNaught-R" }, { "family_name": "Garradd", "given_name": "G.", "clpid": "Garradd-G" }, { "family_name": "Beacom", "given_name": "J. F.", "clpid": "Beacom-J-F" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Pojmanski", "given_name": "G.", "clpid": "Pojmanski-G" }, { "family_name": "Stanek", "given_name": "K. Z.", "clpid": "Stanek-K-Z" }, { "family_name": "Szczygie\u0142", "given_name": "D. M.", "clpid": "Szczygie\u0142-D-M" } ], "abstract": "We present the discovery and follow-up observations of SN 2008jb, a core-collapse supernova in the southern dwarf irregular galaxy ESO 302\u201314 (M_B = \u201315.3 mag) at 9.6 Mpc. This nearby transient was missed by galaxy-targeted surveys and was only found in archival optical images obtained by the Catalina Real-time Transient Survey and the All-Sky Automated Survey. The well-sampled archival photometry shows that SN 2008jb was detected shortly after explosion and reached a bright optical maximum, V_max \u2243 13.6 mag (M_(V, max) \u2243 \u201316.5). The shape of the light curve shows a plateau of ~100 days, followed by a drop of ~1.4 mag in the V band to a slow decline with an approximate ^(56)Co decay slope. The late-time light curve is consistent with 0.04 \u00b1 0.01 M_\u2609 of ^(56)Ni synthesized in the explosion. A spectrum of the supernova obtained two years after explosion shows a broad, boxy H\u03b1 emission line, which is unusual for normal Type II-Plateau supernovae at late times. We detect the supernova in archival Spitzer and WISE images obtained 8-14 months after explosion, which show clear signs of warm (600-700 K) dust emission. The dwarf irregular host galaxy, ESO 302\u201314, has a low gas-phase oxygen abundance, 12 + log(O/H) = 8.2 (~1/5 Z_\u2609), similar to those of the Small Magellanic Cloud and the hosts of long gamma-ray bursts and luminous core-collapse supernovae. This metallicity is one of the lowest among local (\u227210 Mpc) supernova hosts. We study the host environment using GALEX far-UV, R-band, and H\u03b1 images and find that the supernova occurred in a large star formation complex. The morphology of the H\u03b1 emission appears as a large shell (R \u2243 350 pc) surrounding the FUV and optical emission. Using the H\u03b1-to-FUV ratio and FUV and R-band luminosities, we estimate an age of ~9 Myr and a total mass of ~2 \u00d7 10^5 M_\u2609 for the star formation complex, assuming a single-age starburst. These properties are consistent with the expanding H\u03b1 supershells observed in many well-studied nearby dwarf galaxies, which are tell-tale signs of feedback from the cumulative effect of massive star winds and supernovae. The age estimated for the star-forming region where SN 2008jb exploded suggests a relatively high-mass progenitor star with an initial mass M ~ 20 M_\u2609 and warrants further study. We discuss the implications of these findings in the study of core-collapse supernova progenitors.", "doi": "10.1088/0004-637X/745/1/70", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2012-01-20", "series_number": "1", "volume": "145", "issue": "1", "pages": "70" }, { "id": "authors:5bp5g-smb91", "collection": "authors", "collection_id": "5bp5g-smb91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120403-070909699", "type": "article", "title": "The Nature of Double-Peaked [O III] Active Galactic Nuclei", "author": [ { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Myers", "given_name": "Adam D.", "clpid": "Myers-A-D" }, { "family_name": "Stockton", "given_name": "Alan", "clpid": "Stockton-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Aldering", "given_name": "G.", "clpid": "Aldering-G-S" }, { "family_name": "Rich", "given_name": "Jeffrey A.", "orcid": "0000-0002-5807-5078", "clpid": "Rich-J-A" } ], "abstract": "Active galactic nuclei (AGNs) with double-peaked [O III] lines are suspected to be sub-kpc or kpc-scale binary AGNs. However, pure gas kinematics can produce the same double-peaked line profile in spatially integrated spectra. Here we combine integral-field spectroscopy and high-resolution imaging of 42 double-peaked [O III] AGNs from the Sloan Digital Sky Survey to investigate the constituents of the population. We find two binary AGNs where the line splitting is driven by the orbital motion of the merging nuclei. Such objects account for only ~2% of the double-peaked AGNs. Almost all (~98%) of the double-peaked AGNs were selected because of gas kinematics; and half of those show spatially resolved narrow-line regions that extend 4-20 kpc from the nuclei. Serendipitously, we find two spectrally unresolved binary AGNs where gas kinematics produced the double-peaked [O III] lines. The relatively frequent serendipitous discoveries indicate that only ~1% of binary AGNs would appear double-peaked in Sloan spectra and 2.2^(+2.5)_(\u20130.8)% of all Sloan AGNs are binary AGNs. Therefore, the double-peaked sample does not offer much advantage over any other AGN samples in finding binary AGNs. The binary AGN fraction implies an elevated AGN duty cycle (8^(+8)_(\u20133)%), suggesting galaxy interactions enhance nuclear accretion. We illustrate that integral-field spectroscopy is crucial for identifying binary AGNs: several objects previously classified as \"binary AGNs\" with long-slit spectra are most likely single AGNs with extended narrow-line regions (ENLRs). The formation of ENLRs driven by radiation pressure is also discussed.", "doi": "10.1088/0004-637X/745/1/67", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2012-01-20", "series_number": "1", "volume": "745", "issue": "1", "pages": "Art. No. 67" }, { "id": "authors:gg9aa-y5t52", "collection": "authors", "collection_id": "gg9aa-y5t52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121105-131003860", "type": "book_section", "title": "The Catalina Real-time Transient Survey", "book_title": "New Horizons in Time-Domain Astronomy", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Catalan", "given_name": "M.", "clpid": "Catalan-M" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" } ], "contributor": [ { "family_name": "Griffin", "given_name": "R. E. M.", "clpid": "Griffin-R-E-M" }, { "family_name": "Hanisch", "given_name": "R. J.", "clpid": "Hanisch-R-J" }, { "family_name": "Seaman", "given_name": "Robert L.", "clpid": "Seaman-R-L" } ], "abstract": "The Catalina Real-time Transient Survey (CRTS) currently covers 33,000 deg^2 of the sky in search of transient astrophysical events, with time base-lines ranging from 10 minutes to ~7 years. Data provided by the Catalina Sky Survey provide an unequalled base-line against which > 4,000 unique optical transient events have been discovered and openly published in real-time. Here we highlight some of the discoveries of CRTS.", "doi": "10.1017/S1743921312000889", "isbn": "978-1-107-01985-0", "publisher": "Cambridge University Press", "place_of_publication": "New York", "publication_date": "2012", "pages": "306-308" }, { "id": "authors:1n7q2-2d193", "collection": "authors", "collection_id": "1n7q2-2d193", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121105-130132610", "type": "book_section", "title": "Exploring the Time Domain with Synoptic Sky Surveys", "book_title": "New Horizons in Time-Domain Astronomy", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" } ], "contributor": [ { "family_name": "Griffin", "given_name": "R. E. M.", "clpid": "Griffin-R-E-M" }, { "family_name": "Hanisch", "given_name": "R. J.", "clpid": "Hanisch-R-J" }, { "family_name": "Seaman", "given_name": "Robert L.", "clpid": "Seaman-R-L" } ], "abstract": "Synoptic sky surveys are becoming the largest data generators in astronomy, and they are opening a new research frontier that touches practically every field of astronomy. Opening the time domain to a systematic exploration will strengthen our understanding of a number of interesting known phenomena, and may lead to the discoveries of as yet unknown ones. We describe some lessons learned over the past decade, and offer some ideas that may guide strategic considerations in the planning and execution of future synoptic sky surveys.", "doi": "10.1017/S1743921312000488", "isbn": "978-1-107-01985-0", "publisher": "Cambridge University Press", "place_of_publication": "New York", "publication_date": "2012", "pages": "141-146" }, { "id": "authors:63ckw-b4a15", "collection": "authors", "collection_id": "63ckw-b4a15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121105-132022053", "type": "book_section", "title": "The VAO Transient Facility", "book_title": "New Horizons in Time-Domain Astronomy", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R" }, { "family_name": "Seaman", "given_name": "Rob", "clpid": "Seaman-R-L" } ], "contributor": [ { "family_name": "Griffin", "given_name": "R. E. M.", "clpid": "Griffin-R-E-M" }, { "family_name": "Hanisch", "given_name": "R. J.", "clpid": "Hanisch-R-J" }, { "family_name": "Seaman", "given_name": "Robert L.", "clpid": "Seaman-R-L" } ], "abstract": "The time-domain community wants robust and reliable tools to enable the production of, and subscription to, community-endorsed event notification packets (VOEvent). The Virtual Astronomical Observatory (VAO) Transient Facility (VTF) is being designed to be the premier brokering service for the community, both collecting and disseminating observations about time-critical astronomical transients but also supporting annotations and the application of intelligent machine-learning to those observations. Two types of activity associated with the facility can therefore be distinguished: core infrastructure, and user services. We review the prior art in both areas, and describe the planned capabilities of the VTF. In particular, we focus on scalability and quality-of-service issues required by the next generation of sky surveys such as LSST and SKA.", "doi": "10.1017/S1743921312000920", "isbn": "978-1-107-01985-0", "publisher": "Cambridge University Press", "place_of_publication": "New York", "publication_date": "2012", "pages": "318-320" }, { "id": "authors:2grgd-jy132", "collection": "authors", "collection_id": "2grgd-jy132", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120202-110752104", "type": "article", "title": "Structure and Dynamics of the Globular Cluster Palomar 13", "author": [ { "family_name": "Bradford", "given_name": "J. D.", "clpid": "Bradford-J-D" }, { "family_name": "Geha", "given_name": "M.", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "Mu\u00f1oz", "given_name": "R. R.", "clpid": "Mu\u00f1oz-R-R" }, { "family_name": "Santana", "given_name": "F. A.", "orcid": "0000-0002-4023-7649", "clpid": "Santana-F-A" }, { "family_name": "Simon", "given_name": "J. D.", "clpid": "Simon-J-D" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Stetson", "given_name": "P. B.", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Kirby", "given_name": "E.", "orcid": "0000-0001-6196-5162", "clpid": "Kirby-E-N" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present Keck/DEIMOS spectroscopy and Canada-France-Hawaii Telescope/MegaCam photometry for the Milky Way globular cluster Palomar 13. We triple the number of spectroscopically confirmed members, including many repeat velocity measurements. Palomar 13 is the only known globular cluster with possible evidence for dark matter, based on a Keck/High Resolution Echelle Spectrometer 21 star velocity dispersion of \u03c3 = 2.2 \u00b1 0.4 km s^(\u20131). We reproduce this measurement, but demonstrate that it is inflated by unresolved binary stars. For our sample of 61 stars, the velocity dispersion is \u03c3 = 0.7^(+0.6)_(\u20130.5) km s^(\u20131). Combining our DEIMOS data with literature values, our final velocity dispersion is \u03c3 = 0.4^(+0.4)_( \u20130.3) km s^(\u20131). We determine a spectroscopic metallicity of [Fe/H] = \u20131.6 \u00b1 0.1 dex, placing a 1\u03c3 upper limit of \u03c3_([Fe/H]) ~ 0.2 dex on any internal metallicity spread. We determine Palomar 13's total luminosity to be M_V = \u20132.8 \u00b1 0.4, making it among the least luminous known globular clusters. The photometric isophotes are regular out to the half-light radius and mildly irregular outside this radius. The outer surface brightness profile slope is shallower than typical globular clusters (\u03a3 \u03b1 r^\u03b7, \u03b7 = \u20132.8 \u00b1 0.3). Thus at large radius, tidal debris is likely affecting the appearance of Palomar 13. Combining our luminosity with the intrinsic velocity dispersion, we find a dynamical mass of M_(1/2) = 1.3^(+2:7)_(\u20131.3) \u00d7 10^3 M_\u2609 and a mass-to-light ratio of M/L_V = 2.4^(+5.0)_(\u20132.4) M_\u2609/L_\u2609. Within our measurement errors, the mass-to-light ratio agrees with the theoretical predictions for a single stellar population. We conclude that, while there is some evidence for tidal stripping at large radius, the dynamical mass of Palomar 13 is consistent with its stellar mass and neither significant dark matter, nor extreme tidal heating, is required to explain the cluster dynamics.", "doi": "10.1088/0004-637X/743/2/167", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2011-12-20", "series_number": "2", "volume": "743", "issue": "2", "pages": "Art. No. 167" }, { "id": "authors:kb9y1-0yf62", "collection": "authors", "collection_id": "kb9y1-0yf62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120103-120150934", "type": "article", "title": "New cataclysmic variable 1RXS J073346.0+261933 in Gemini", "author": [ { "family_name": "Denisenko", "given_name": "D. V.", "clpid": "Denisenko-D-V" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kryachko", "given_name": "T. V.", "clpid": "Kryachko-T-V" }, { "family_name": "Samokhvalov", "given_name": "A. V.", "clpid": "Samokhvalov-A-V" }, { "family_name": "Tkachenko", "given_name": "A. Yu.", "clpid": "Tkachenko-A-Y" } ], "abstract": "In the course of our search for the optical identifications of ROSAT X-ray sources, we have found a highly variable object with a very unusual behavior on long time scales, rare color indices, and a high X-ray-to-optical flux ratio. We present the archival light curve from the Catalina Sky Survey, optical spectroscopy from RTT150, and time-resolved photometry from the Astrotel-Caucasus telescope. The object appears to be a magnetic cataclysmic variable (a polar) with an orbital period P = 3.20 h.", "doi": "10.1134/S1063773711120036", "issn": "1063-7737", "publisher": "Springer", "publication": "Astronomy Letters", "publication_date": "2011-12", "series_number": "12", "volume": "37", "issue": "12", "pages": "858-863" }, { "id": "authors:hnseg-57c55", "collection": "authors", "collection_id": "hnseg-57c55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111205-113528709", "type": "article", "title": "A Kiloparsec-scale Binary Active Galactic Nucleus Confirmed by the Expanded Very Large Array", "author": [ { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Zhang", "given_name": "Zhi-Yu", "orcid": "0000-0002-7299-2876", "clpid": "Zhang-Zhi-Yu" }, { "family_name": "Assef", "given_name": "Roberto J.", "orcid": "0000-0002-9508-3667", "clpid": "Assef-R-J" }, { "family_name": "Stockton", "given_name": "Alan", "clpid": "Stockton-A" }, { "family_name": "Myers", "given_name": "Adam D.", "clpid": "Myers-A-D" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Wrobel", "given_name": "J. M.", "orcid": "0000-0001-9720-7398", "clpid": "Wrobel-J-M" }, { "family_name": "Riechers", "given_name": "Dominik A.", "orcid": "0000-0001-9585-1462", "clpid": "Riechers-D-A" } ], "abstract": "We report the confirmation of a kiloparsec-scale binary active galactic nucleus (AGN) with high-resolution radio images from the Expanded Very Large Array (EVLA). SDSS J150243.1+111557 is a double-peaked [O III] AGN at z = 0.39 selected from the Sloan Digital Sky Survey. Our previous near-infrared adaptive optics imaging reveals two nuclei separated by 1farcs4 (7.4 kpc), and our optical integral-field spectroscopy suggests that they are a type-1-type-2 AGN pair. However, these data alone cannot rule out the single AGN scenario where the narrow emission-line region associated with the secondary is photoionized by the broad-line AGN in the primary. Our new EVLA images at 1.4, 5.0, and 8.5 GHz show two steep-spectrum compact radio sources spatially coincident with the optical nuclei. The radio power of the type-2 AGN is an order-of-magnitude in excess of star-forming galaxies with similar extinction-corrected [O II] \u03bb3727 luminosities, indicating that the radio emission is powered by accretion. Therefore, SDSS J150243.1+111557 is one of the few confirmed kiloparsec-scale binary AGN systems. Spectral energy distribution modeling shows that SDSS J150243.1+111557 is a merger of two ~10^(11) M sun galaxies. With both black hole masses around 10^8 M_\u2609, the AGNs are accreting at ~10 times below the Eddington limit.", "doi": "10.1088/2041-8205/740/2/L44", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2011-10-20", "series_number": "2", "volume": "740", "issue": "2", "pages": "L44" }, { "id": "authors:b4b0d-akx18", "collection": "authors", "collection_id": "b4b0d-akx18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111004-113055775", "type": "article", "title": "Modeling of the HerMES Submillimeter Source Lensed by a Dark Matter Dominated Foreground Group of Galaxies", "author": [ { "family_name": "Gavazzi", "given_name": "R.", "clpid": "Gavazzo-R" }, { "family_name": "Cooray", "given_name": "A.", "orcid": "0000-0002-3892-0190", "clpid": "Cooray-A" }, { "family_name": "Blain", "given_name": "A.", "orcid": "0000-0001-7489-5167", "clpid": "Blain-A-W" }, { "family_name": "Bock", "given_name": "J. J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Bradford", "given_name": "C. M.", "orcid": "0000-0001-5261-7094", "clpid": "Bradford-C-M" }, { "family_name": "Bridge", "given_name": "C.", "clpid": "Bridge-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Dowell", "given_name": "C. D.", "clpid": "Dowell-C-D" }, { "family_name": "Fu", "given_name": "H.", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Levenson", "given_name": "L.", "clpid": "Levenson-L" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Murphy", "given_name": "E.", "orcid": "0000-0001-7089-7325", "clpid": "Murphy-E-J" }, { "family_name": "Nguyen", "given_name": "H. T.", "clpid": "Nguyen-Hien-Trong" }, { "family_name": "Riechers", "given_name": "D.", "orcid": "0000-0001-9585-1462", "clpid": "Riechers-D-A" }, { "family_name": "Schulz", "given_name": "B.", "clpid": "Schulz-B" }, { "family_name": "Shupe", "given_name": "D. L.", "orcid": "0000-0003-4401-0430", "clpid": "Shupe-David-L" }, { "family_name": "Vieira", "given_name": "J. D.", "clpid": "Vieira-J-D" }, { "family_name": "Xu", "given_name": "C. K.", "orcid": "0000-0002-1588-6700", "clpid": "Xu-C-Kevin" }, { "family_name": "Zemcov", "given_name": "M.", "orcid": "0000-0001-8253-1451", "clpid": "Zemcov-M" }, { "family_name": "Zmuidzinas", "given_name": "J.", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" } ], "abstract": "We present the results of a gravitational lensing analysis of the bright z_s = 2.957 submillimeter galaxy (SMG) HERMES found in the Herschel/SPIRE science demonstration phase data from the Herschel Multi-tiered Extragalactic Survey (HerMES) project. The high-resolution imaging available in optical and near-IR channels, along with CO emission obtained with the Plateau de Bure Interferometer, allows us to precisely estimate the intrinsic source extension and hence estimate the total lensing magnification to be \u03bc = 10.9 \u00b1 0.7. We measure the half-light radius R_(eff) of the source in the rest-frame near-UV and V bands that characterize the unobscured light coming from stars and find R_(eff),* = [2.0 \u00b1 0.1] kpc, in good agreement with recent studies on the SMG population. This lens model is also used to estimate the size of the gas distribution (R_(eff,gas) = [1.1 \u00b1 0.5] kpc) by mapping back in the source plane the CO (J = 5 \u2192 4) transition line emission. The lens modeling yields a relatively large Einstein radius R_(Ein) = 4\".10 \u00b1 0\".02, corresponding to a deflector velocity dispersion of [483 \u00b1 16] km s^(\u20131). This shows that HERMES is lensed by a galaxy group-size dark matter halo at redshift z_l ~ 0.6. The projected dark matter contribution largely dominates the mass budget within the Einstein radius with f_(dm)(< R_(Ein)) ~ 80%. This fraction reduces to f_(dm)(< R_(eff,G1) \u2243 4.5 kpc) ~ 47% within the effective radius of the main deflecting galaxy of stellar mass M_(*,G1) = [8.5 \u00b1 1.6] \u00d7 10^(11) M_\u2609. At this smaller scale the dark matter fraction is consistent with results already found for massive lensing ellipticals at z ~ 0.2 from the Sloan Lens ACS Survey.", "doi": "10.1088/0004-637X/738/2/125", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2011-09-10", "series_number": "2", "volume": "738", "issue": "2", "pages": "Art. No. 125" }, { "id": "authors:3h6ez-31845", "collection": "authors", "collection_id": "3h6ez-31845", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121105-133238798", "type": "book_section", "title": "Real-Time Classification of Transient Events in Synoptic Sky Surveys", "book_title": "New Horizons in Time-Domain Astronomy", "author": [ { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Chen", "given_name": "Y.", "orcid": "0000-0002-9730-9463", "clpid": "Chen-Yanbei" }, { "family_name": "Moghaddam", "given_name": "B.", "clpid": "Moghaddam-B" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" } ], "contributor": [ { "family_name": "Griffin", "given_name": "R. E. M.", "clpid": "Griffin-R-E-M" }, { "family_name": "Hanisch", "given_name": "R. J.", "clpid": "Hanisch-R-J" }, { "family_name": "Seaman", "given_name": "Robert L.", "clpid": "Seaman-R-L" } ], "abstract": "An automated rapid classification of the transient events detected in modern synoptic sky surveys is essential for their scientific utility and effective follow-up when resources are scarce. This problem will grow by orders of magnitude with the next generation of surveys. We are exploring a variety of novel automated classification techniques, mostly Bayesian, to respond to those challenges, using the ongoing CRTS sky survey as a testbed. We describe briefly some of the methods used.", "doi": "10.1017/S1743921312001056", "isbn": "978-1-107-01985-0", "publisher": "Cambridge University Press", "place_of_publication": "New York", "publication_date": "2011-09", "pages": "355-357" }, { "id": "authors:tmc0b-6q730", "collection": "authors", "collection_id": "tmc0b-6q730", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120215-070331816", "type": "article", "title": "Discovery, classification, and scientific exploration of transient events from the Catalina Real-time Transient Survey", "author": [ { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "R. D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Chen", "given_name": "Y.", "orcid": "0000-0002-9730-9463", "clpid": "Chen-Yanbei" }, { "family_name": "Moghaddam", "given_name": "B.", "clpid": "Moghaddam-B" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" } ], "abstract": "Exploration of the time domain - variable and transient objects and phenomena - is rapidly becoming a vibrant research frontier, touching on essentially every field of astronomy and astrophysics, from the Solar system to cosmology. Time domain astronomy is being enabled by the advent of the new generation of synoptic sky surveys that cover large areas on the sky repeatedly, and generating massive data streams. Their scientific exploration poses many challenges, driven mainly by the need for a real-time discovery, classification, and follow-up of the interesting events. Here we describe the Catalina Real-Time Transient Survey (CRTS), that discovers and publishes transient events at optical wavelengths in real time, thus benefiting the entire community. We describe some of the scientific results to date, and then focus on the challenges of the automated classification and prioritization of transient events. CRTS represents a scientific and a technological testbed and precursor for the larger surveys in the future, including the Large Synoptic Survey Telescope (LSST) and the Square Kilometer Array (SKA).", "doi": "10.48550/arXiv.1111.0313", "issn": "0304-9523", "publisher": "Indian Institute of Astrophysics", "publication": "Bulletin of the Astronomical Society of India", "publication_date": "2011-09", "series_number": "3", "volume": "39", "issue": "3", "pages": "387-408" }, { "id": "authors:3tcdr-58962", "collection": "authors", "collection_id": "3tcdr-58962", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110712-112722577", "type": "article", "title": "The Discovery and Nature of the Optical Transient CSS100217:102913+404220", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Neill", "given_name": "James D.", "orcid": "0000-0002-0466-1119", "clpid": "Neill-J-D" }, { "family_name": "Phinney", "given_name": "E. S.", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" } ], "abstract": "We report on the discovery and observations of the extremely luminous optical transient CSS100217:102913+404220 (CSS100217 hereafter). Spectroscopic observations showed that this transient was coincident with a galaxy at redshift z = 0.147 and reached an apparent magnitude of V ~ 16.3. After correcting for foreground Galactic extinction we determine the absolute magnitude to be M_V = \u201322.7 approximately 45 days after maximum light. Over a period of 287 rest-frame days, this event had an integrated bolometric luminosity of 1.3 \u00d7 10^(52) erg based on time-averaged bolometric corrections of ~15 from V- and R-band observations. Analysis of the pre-outburst Sloan Digital Sky Survey (SDSS) spectrum of the source shows features consistent with a narrow-line Seyfert 1 galaxy. High-resolution Hubble Space Telescope and Keck follow-up observations show that the event occurred within 150 pc of the nucleus of the galaxy, suggesting a possible link to the active nuclear region. However, the rapid outburst along with photometric and spectroscopic evolution are much more consistent with a luminous supernova. Line diagnostics suggest that the host galaxy is undergoing significant star formation. We use extensive follow-up of the event along with archival Catalina Sky Survey NEO search and SDSS data to investigate the three most likely sources of such an event: (1) an extremely luminous supernova, (2) the tidal disruption of a star by the massive nuclear black hole, and (3) variability of the central active galactic nucleus (AGN). We find that CSS100217 was likely an extremely luminous Type IIn supernova and occurred within the range of the narrow-line region of an AGN. We discuss how similar events may have been missed in past supernova surveys because of confusion with AGN activity.", "doi": "10.1088/0004-637X/735/2/106", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2011-07-10", "series_number": "2", "volume": "735", "issue": "2", "pages": "Art. No. 106" }, { "id": "authors:p79cc-hvc85", "collection": "authors", "collection_id": "p79cc-hvc85", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110607-080509623", "type": "article", "title": "Mergers in Double-peaked [O III] Active Galactic Nuclei", "author": [ { "family_name": "Fu", "given_name": "Hai", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Myers", "given_name": "Adam D.", "clpid": "Myers-A-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" } ], "abstract": "As a natural consequence of galaxy mergers, binary active galactic nuclei (AGNs) should be commonplace. Nevertheless, observational confirmations are rare, especially for binaries with separations less than 10 kpc. Such a system may show two sets of narrow emission lines in a single spectrum owing to the orbital motion of the binary. We have obtained high-resolution near-infrared images of 50 double-peaked [O III]\u03bb5007 AGNs with the Keck II laser guide star adaptive optics system. The Sloan Digital Sky Survey sample is compiled from the literature and consists of 17 type-1 AGNs between 0.18 < z < 0.56 and 33 type-2 AGNs between 0.03 < z < 0.24. The new images reveal eight type-1 and eight type-2 sources that are apparently undergoing mergers. These are strong candidates of kpc-scale binary AGNs because they show multiple components separated between 0.6 and 12 kpc and often disturbed morphologies. Because most of the type-1s are at higher redshifts than the type-2s, the higher merger fraction of type-1s (47% \u00b1 20%) compared to that of type-2s (24% \u00b1 10%) can be attributed to the general evolution of galaxy merger fraction with redshift. Furthermore, we show that AGN mergers are outliers of the M_(BH)^-\u03c3_\u2217 relation because of overestimated stellar velocity dispersions, illustrating the importance of removing mergers from the samples defining the M_(BH)^-\u03c3_\u2217 relations. Finally, we find that the emission-line properties are indistinguishable for spatially resolved and unresolved sources, emphasizing that scenarios involving a single AGN can produce the same double-peaked line profiles and they account for at least 70% of the double-peaked [O III] AGNs.", "doi": "10.1088/0004-637X/733/2/103", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2011-06-01", "series_number": "2", "volume": "733", "issue": "2", "pages": "Art. No. 103" }, { "id": "authors:2qa3f-jy958", "collection": "authors", "collection_id": "2qa3f-jy958", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110824-083050070", "type": "article", "title": "Discovery of a Multiply Lensed Submillimeter Galaxy in Early HerMES Herschel/SPIRE Data", "author": [ { "family_name": "Conley", "given_name": "A.", "clpid": "Conley-A" }, { "family_name": "Cooray", "given_name": "A.", "orcid": "0000-0002-3892-0190", "clpid": "Cooray-A" }, { "family_name": "Vieira", "given_name": "J. D.", "clpid": "Vieira-J-D" }, { "family_name": "Blain", "given_name": "A.", "orcid": "0000-0001-7489-5167", "clpid": "Blain-A-W" }, { "family_name": "Bock", "given_name": "J. J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Bradford", "given_name": "C. M.", "orcid": "0000-0001-5261-7094", "clpid": "Bradford-C-M" }, { "family_name": "Bridge", "given_name": "C.", "clpid": "Bridge-C" }, { "family_name": "Carpenter", "given_name": "J. M.", "orcid": "0000-0003-2251-0602", "clpid": "Carpenter-J-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Dowell", "given_name": "C. D.", "clpid": "Dowell-C-D" }, { "family_name": "Fu", "given_name": "H.", "orcid": "0000-0001-9608-6395", "clpid": "Fu-Hai" }, { "family_name": "Levenson", "given_name": "L.", "clpid": "Levenson-L" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Murphy", "given_name": "E.", "orcid": "0000-0001-7089-7325", "clpid": "Murphy-E-J" }, { "family_name": "Nguyen", "given_name": "H. T.", "clpid": "Nguyen-Hien-Trong" }, { "family_name": "Riechers", "given_name": "D.", "orcid": "0000-0001-9585-1462", "clpid": "Riechers-D-A" }, { "family_name": "Schulz", "given_name": "B.", "clpid": "Schulz-B" }, { "family_name": "Shupe", "given_name": "D. L.", "orcid": "0000-0003-4401-0430", "clpid": "Shupe-David-L" }, { "family_name": "Viero", "given_name": "M. P.", "clpid": "Viero-M-P" }, { "family_name": "Xu", "given_name": "C. K.", "orcid": "0000-0002-1588-6700", "clpid": "Xu-C-Kevin" }, { "family_name": "Zemcov", "given_name": "M.", "orcid": "0000-0001-8253-1451", "clpid": "Zemcov-M" }, { "family_name": "Zmuidzinas", "given_name": "J.", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" } ], "abstract": "We report the discovery of a bright (f(250 \u03bcm)>400 mJy), multiply lensed submillimeter galaxy HERMES J105751.1+573027 in Herschel/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880 \u03bcm Submillimeter Array observations resolve at least four images with a large separation of ~9\". A high-resolution adaptive optics K_p image with Keck/NIRC2 clearly shows strong lensing arcs. Follow-up spectroscopy gives a redshift of z = 2.9575, and the lensing model gives a total magnification of \u03bc ~ 11 \u00b1 1. The large image separation allows us to study the multi-wavelength spectral energy distribution (SED) of the lensed source unobscured by the central lensing mass. The far-IR/millimeter-wave SED is well described by a modified blackbody fit with an unusually warm dust temperature, 88 \u00b1 3 K. We derive a lensing-corrected total IR luminosity of (1.43 \u00b1 0.09) \u00d7 10^(13) L_\u2609, implying a star formation rate of ~2500 M_\u2609 yr^(\u20131). However, models primarily developed from brighter galaxies selected at longer wavelengths are a poor fit to the full optical-to-millimeter SED. A number of other strongly lensed systems have already been discovered in early Herschel data, and many more are expected as additional data are collected.", "doi": "10.1088/2041-8205/732/2/L35", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2011-05-10", "series_number": "2", "volume": "732", "issue": "2", "pages": "Art. No. L35" }, { "id": "authors:7q0dc-jnm70", "collection": "authors", "collection_id": "7q0dc-jnm70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110314-113209420", "type": "article", "title": "The Faint End of the Quasar Luminosity Function at z ~ 4: Implications for Ionization of the Intergalactic Medium and Cosmic Downsizing", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Dey", "given_name": "Arjun", "orcid": "0000-0002-4928-4003", "clpid": "Dey-A" }, { "family_name": "Jannuzi", "given_name": "Buell T.", "orcid": "0000-0002-1578-6582", "clpid": "Jannuzi-B-T" }, { "family_name": "Lee", "given_name": "Kyoung-Soo", "orcid": "0000-0003-3004-9596", "clpid": "Lee-Kyoung-Soo" } ], "abstract": "We present an updated determination of the z ~ 4 QSO luminosity function (QLF), improving the quality of the determination of the faint end of the QLF presented by Glikman et al. (2010). We have observed an additional 43 candidates from our survey sample, yielding one additional QSO at z = 4.23 and increasing the completeness of our spectroscopic follow-up to 48% for candidates brighter than R = 24 over our survey area of 3.76 deg^2. We study the effect of using K-corrections to compute the rest-frame absolute magnitude at 1450 \u00c5 compared with measuring M_(1450) directly from the object spectra. We find a luminosity-dependent bias: template-based K-corrections overestimate the luminosity of low-luminosity QSOs, likely due to their reliance on templates derived from higher luminosity QSOs. Combining our sample with bright quasars from the Sloan Digital Sky Survey and using spectrum-based M 1450 for all the quasars, we fit a double power law to the binned QLF. Our best fit has a bright-end slope, \u03b1 = 3.3 \u00b1 0.2, and faint-end slope, \u03b2 = 1.6^(+0.8)_(\u20130.6). Our new data revise the faint-end slope of the QLF down to flatter values similar to those measured at z ~ 3. The break luminosity, though poorly constrained, is at M* = \u201324.1^(+0.7)_(\u20131.9), approximately 1-1.5 mag fainter than at z ~ 3. This QLF implies that QSOs account for about half the radiation needed to ionize the intergalactic medium at these redshifts.", "doi": "10.1088/2041-8205/728/2/L26", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2011-02-20", "series_number": "2", "volume": "728", "issue": "2", "pages": "Art. No. L26" }, { "id": "authors:jwynb-sc777", "collection": "authors", "collection_id": "jwynb-sc777", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110510-135410406", "type": "book_section", "title": "Classification of Optical Transients: Experiences from PQ and CRTS Surveys", "book_title": "GAIA: At the Frontiers of Astrometry", "author": [ { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "R. D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Moghaddam", "given_name": "B.", "clpid": "Moghaddam-B" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" } ], "abstract": "Synoptic sky surveys are opening up exciting opportunities in time domain astronomy. Gaia will make a great contribution to this field. A crucial factor for good scientific returns is real-time classification of transients, in order to optimize their follow-up. We have been developing infrastructure towards this end starting from the completed Palomar-Quest (PQ) survey, and the ongoing Catalina Real-Time Transient Survey (CRTS). CRTS has been consistently producing transients for almost three years now. We describe here the efforts related to transient classification and event dissemination. Many of the technologies and methodologies we are developing may benefit Gaia.", "doi": "10.1051/eas/1045030", "isbn": "978-2-7598-0608-9", "publisher": "EDP Sciences", "place_of_publication": "Les Ulis, France", "publication_date": "2011", "pages": "173-178" }, { "id": "authors:gpwbk-cnv59", "collection": "authors", "collection_id": "gpwbk-cnv59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101029-100056391", "type": "article", "title": "First Earth-based Detection of a Superbolide on Jupiter", "author": [ { "family_name": "Hueso", "given_name": "R.", "orcid": "0000-0003-0169-123X", "clpid": "Hueso-R" }, { "family_name": "Wesley", "given_name": "A.", "clpid": "Wesley-A" }, { "family_name": "Go", "given_name": "C.", "clpid": "Go-C" }, { "family_name": "P\u00e9rez-Hoyos", "given_name": "S.", "orcid": "0000-0002-2587-4682", "clpid": "P\u00e9rez-Hoyos-S" }, { "family_name": "Wong", "given_name": "M. H.", "clpid": "Wong-M-H" }, { "family_name": "Fletcher", "given_name": "L. N.", "orcid": "0000-0001-5834-9588", "clpid": "Fletcher-L-N" }, { "family_name": "S\u00e1nchez-Lavega", "given_name": "A.", "orcid": "0000-0001-7355-1522", "clpid": "S\u00e1nchez-Lavega-A" }, { "family_name": "Boslough", "given_name": "M. B. E.", "clpid": "Boslough-M-B" }, { "family_name": "de Pater", "given_name": "I.", "orcid": "0000-0002-4278-3168", "clpid": "de-Pater-I" }, { "family_name": "Orton", "given_name": "G. S.", "orcid": "0000-0001-7871-2823", "clpid": "Orton-G-S" }, { "family_name": "Simon-Miller", "given_name": "A. A.", "clpid": "Simon-Miller-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Edwards", "given_name": "M. L.", "clpid": "Edwards-M-L" }, { "family_name": "Hammel", "given_name": "H. B.", "orcid": "0000-0001-8751-3463", "clpid": "Hammel-H-B" }, { "family_name": "Clarke", "given_name": "J. T.", "clpid": "Clarke-J-T" }, { "family_name": "Noll", "given_name": "K. S.", "clpid": "Noll-K-S" }, { "family_name": "Yanamandra-Fisher", "given_name": "P. A.", "clpid": "Yanamandra-Fisher-P-A" } ], "abstract": "Cosmic collisions on planets cause detectable optical flashes that range from terrestrial shooting stars to bright fireballs. On 2010 June 3 a bolide in Jupiter's atmosphere was simultaneously observed from the Earth by two amateur astronomers observing Jupiter in red and blue wavelengths. The bolide appeared as a flash of 2 s duration in video recording data of the planet. The analysis of the light curve of the observations results in an estimated energy of the impact of (0.9-4.0) \u00d7 10^(15) J which corresponds to a colliding body of 8-13 m diameter assuming a mean density of 2 g cm^(\u20133). Images acquired a few days later by the Hubble Space Telescope and other large ground-based facilities did not show any signature of aerosol debris, temperature, or chemical composition anomaly, confirming that the body was small and destroyed in Jupiter's upper atmosphere. Several collisions of this size may happen on Jupiter on a yearly basis. A systematic study of the impact rate and size of these bolides can enable an empirical determination of the flux of meteoroids in Jupiter with implications for the populations of small bodies in the outer solar system and may allow a better quantification of the threat of impacting bodies to Earth. The serendipitous recording of this optical flash opens a new window in the observation of Jupiter with small telescopes.", "doi": "10.1088/2041-8205/721/2/L129", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2010-10-01", "series_number": "2", "volume": "721", "issue": "2", "pages": "L129-L133" }, { "id": "authors:nzag4-6t256", "collection": "authors", "collection_id": "nzag4-6t256", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101027-091529164", "type": "article", "title": "The Size and Origin of Metal-enriched Regions in the Intergalactic Medium from Spectra of Binary Quasars", "author": [ { "family_name": "Martin", "given_name": "Crystal L.", "clpid": "Martin-C-L" }, { "family_name": "Scannapieco", "given_name": "Evan", "clpid": "Scannapieco-E" }, { "family_name": "Ellison", "given_name": "Sara L.", "orcid": "0000-0002-1768-1899", "clpid": "Ellison-S-L" }, { "family_name": "Hennawi", "given_name": "Joseph F.", "orcid": "0000-0002-7054-4332", "clpid": "Hennawi-J-F" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fournier", "given_name": "Amanda P.", "clpid": "Fournier-A-P" } ], "abstract": "We present tomography of the circum-galactic metal distribution at redshift 1.7-4.5 derived from echellete spectroscopy of binary quasars. We find C IV systems at similar redshifts in paired sightlines more often than expected for sightline-independent redshifts. As the separation of the sightlines increases from 36 kpc to 907 kpc, the amplitude of this clustering decreases. At the largest separations, the C IV systems cluster similar to the Lyman-break galaxies studied by Adelberger et al. in 2005. The C IV systems are significantly less correlated than these galaxies, however, at separations less than R_1 0.42 \u00b1 0.15 h^( \u20131) comoving Mpc. Measured in real space, i.e., transverse to the sightlines, this length scale is significantly smaller than the break scale estimated previously from the line-of-sight correlation function in redshift space by Scannapieco et al. in 2006. Using a simple model, we interpret the new real-space measurement as an indication of the typical physical size of enriched regions. We adopt this size for enriched regions and fit the redshift-space distortion in the line-of-sight correlation function. The fitted velocity kick is consistent with the peculiar velocity of galaxies as determined by the underlying mass distribution and places an upper limit on the average outflow (or inflow) speed of metals. The implied timescale for dispersing metals is larger than the typical stellar ages of Lyman-break galaxies, and we argue that enrichment by galaxies at z > 4.3 played a greater role in dispersing metals. To further constrain the growth of enriched regions, we discuss empirical constraints on the evolution of the C IV correlation function with cosmic time. This study demonstrates the potential of tomography for measuring the metal enrichment history of the circum-galactic medium.", "doi": "10.1088/0004-637X/721/1/174", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2010-09-20", "series_number": "1", "volume": "721", "issue": "1", "pages": "174-192" }, { "id": "authors:0j4c6-z6m65", "collection": "authors", "collection_id": "0j4c6-z6m65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100903-105120337", "type": "article", "title": "Binary Quasars at High Redshift. II. Sub-Mpc Clustering at z ~ 3-4", "author": [ { "family_name": "Shen", "given_name": "Yue", "orcid": "0000-0003-1659-7035", "clpid": "Shen-Yue" }, { "family_name": "Hennawi", "given_name": "Joseph F.", "orcid": "0000-0002-7054-4332", "clpid": "Hennawi-J-F" }, { "family_name": "Shankar", "given_name": "Francesco", "clpid": "Shankar-F" }, { "family_name": "Myers", "given_name": "Adam D.", "clpid": "Myers-A-D" }, { "family_name": "Strauss", "given_name": "Michael A.", "orcid": "0000-0002-0106-7755", "clpid": "Strauss-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fan", "given_name": "Xiaohui", "orcid": "0000-0003-3310-0131", "clpid": "Fan-Xiaohui" }, { "family_name": "Giocoli", "given_name": "Carlo", "clpid": "Giocoli-C" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Weinberg", "given_name": "David H.", "clpid": "Weinberg-D-H" } ], "abstract": "We present measurements of the small-scale (0.1 \u2272 r \u2272 1 h^(-1) Mpc) quasar two-point correlation function at z>2.9, for a flux-limited (i < 21) sample of 15 binary quasars compiled by Hennawi et al. The amplitude of the small-scale clustering increases from z ~ 3 to z ~ 4. The small-scale clustering amplitude is comparable to or lower than power-law extrapolations (assuming a fixed slope \u03b3 = 2) from the large-scale correlation function of the i < 20.2 quasar sample from the Sloan Digital Sky Survey. Using simple prescriptions relating quasars to dark matter halos, we model the observed small-scale clustering with halo occupation models. We found that the level of small-scale clustering favors an active fraction of black holes in (M \u2273 10^(13) h^(\u20131) M_\u2609) satellite halos f_s \u2273 0.1 at z \u2273 3.", "doi": "10.1088/0004-637X/719/2/1693", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2010-08-20", "series_number": "2", "volume": "719", "issue": "2", "pages": "1693-1698" }, { "id": "authors:0zcx2-jd089", "collection": "authors", "collection_id": "0zcx2-jd089", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100901-164255838", "type": "article", "title": "Binary Quasars at High Redshift. I. 24 New Quasar Pairs at z ~ 3-4", "author": [ { "family_name": "Hennawi", "given_name": "Joseph F.", "orcid": "0000-0002-7054-4332", "clpid": "Hennawi-J-F" }, { "family_name": "Myers", "given_name": "Adam D.", "clpid": "Myers-A-D" }, { "family_name": "Shen", "given_name": "Yue", "orcid": "0000-0003-1659-7035", "clpid": "Shen-Yue" }, { "family_name": "Strauss", "given_name": "Michael A.", "orcid": "0000-0002-0106-7755", "clpid": "Strauss-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fan", "given_name": "Xiaohui", "orcid": "0000-0003-3310-0131", "clpid": "Fan-Xiaohui" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Martin", "given_name": "Crystal L.", "clpid": "Martin-C-L" }, { "family_name": "Richards", "given_name": "Gordon T.", "clpid": "Richards-G-T" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Shankar", "given_name": "Francesco", "clpid": "Shankar-F" } ], "abstract": "The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high-redshift binary quasars. Using color-selection and photometric redshift techniques, we searched 8142 deg^2 of Sloan Digital Sky Survey imaging data for binary quasar candidates, and confirmed them with follow-up spectroscopy. Our sample of 27 high-redshift binaries (24 of them new discoveries) at redshifts 2.9 < z < 4.3 with proper transverse separations 10 kpc < R\u22a5 < 650 kpc increases the number of such objects known by an order of magnitude. Eight members of this sample are very close pairs with R < 100 kpc, and of these close systems four are at z>3.5. The completeness and efficiency of our well-defined selection algorithm are quantified using simulated photometry and we find that our sample is ~50% complete. Our companion paper uses this knowledge to make the first measurement of the small-scale clustering (R < 1 h^(\u20131) Mpc comoving) of high-redshift quasars. High-redshift binaries constitute exponentially rare coincidences of two extreme (M \u2273 10^9 M_\u2609) supermassive black holes. At z ~ 4, there is about one close binary per 10 Gpc^3, thus these could be the highest sigma peaks, the analogs of superclusters, in the early universe.", "doi": "10.1088/0004-637X/719/2/1672", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2010-08-20", "series_number": "2", "volume": "719", "issue": "2", "pages": "1672-1692" }, { "id": "authors:8cnae-69562", "collection": "authors", "collection_id": "8cnae-69562", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100831-085249278", "type": "article", "title": "Discovery of the Extremely Energetic Supernova 2008fz", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Prieto", "given_name": "J. L.", "orcid": "0000-0003-0943-0026", "clpid": "Prieto-J-L" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Balam", "given_name": "D.", "clpid": "Balam-D" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" } ], "abstract": "We report on the discovery and initial observations of the energetic type IIn supernova 2008fz. This object was discovered at redshift z = 0.133 and reached an apparent magnitude of V ~ 17. After correcting for Galactic extinction and redshift, we determine the peak absolute magnitude of the event to be M_V = \u201322.3, placing it among the most luminous supernovae discovered. The optical energy emitted by SN 2008fz (based on the light curve over an 88 day period) is possibly the most ever observed for a supernova (>1.4 \u00d7 10^(51) erg). The event was more luminous than the type IIn SN 2006gy, but exhibited the same smooth, slowly evolving light curve. As is characteristic of type IIn supernova, the early spectra of SN 2008fz initially exhibited narrow Balmer lines which were replaced by a broader component at later times. The spectra also show a blue continuum with no signs of Ca or Na absorption, suggesting that there is little extinction due to dust in the host or circumstellar material. No host galaxy is identified in prior co-added images reaching R ~ 22. From the supernova's redshift, we place an upper limit on the brightness of the host of M_R ~ \u201317 (similar to the brightness of the Small Magellanic Cloud). The presence of the supernova within such a faint galaxy follows the majority of recently discovered highly luminous supernovae. A possible reason for this is the combination of a high star formation rate in low-mass galaxies with a low-metallicity environment.", "doi": "10.1088/2041-8205/718/2/L127", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2010-08-01", "series_number": "2", "volume": "718", "issue": "2", "pages": "L127-L131" }, { "id": "authors:nj24h-p7k36", "collection": "authors", "collection_id": "nj24h-p7k36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100817-152822807", "type": "article", "title": "First case of strong gravitational lensing by a QSO: SDSS J0013+1523 at z = 0.120", "author": [ { "family_name": "Courbin", "given_name": "F.", "clpid": "Courbin-F" }, { "family_name": "Tewes", "given_name": "M.", "clpid": "Tewes-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-D" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "R\u00e9rat", "given_name": "F.", "clpid": "R\u00e9rat-F" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" } ], "abstract": "We present the first case of strong gravitational lensing by a QSO: SDSS J0013+1523 at z = 0.120. The discovery is the result of a systematic search for emission lines redshifted behind QSOs, among 22 298 spectra of the SDSS data release 7. Apart from the z = 0.120 spectral features of the foreground QSO, the spectrum of SDSS J0013+1523 also displays the [O II] and H\u03b2 emission lines and the [O III] doublet, all at the same redshift, z = 0.640. Using sharp Keck adaptive optics K-band images obtained using laser guide stars, we unveil two objects within a radius of 2\" from the QSO. Deep Keck optical spectroscopy clearly confirms one of these objects at z = 0.640 and shows traces of the [O III] emission line of the second object, also at z = 0.640. Lens modeling suggests that they represent two images of the same z = 0.640 emission-line galaxy. Our Keck spectra also allow us to measure the redshift of an intervening galaxy at z = 0.394, located 3.2\", away from the line of sight to the QSO. If the z = 0.120 QSO host galaxy is modeled as a singular isothermal sphere, its mass within the Einstein radius is M_E(r < 1\u2009h^(-1)\u2009kpc) = 2.16 \u00d7 10^(10) h^(-1) M_\u2299 and its velocity dispersion is \u03c3_(SIS) = 169 km s^(-1). This is about 1-\u03c3 away from the velocity dispersion estimated from the width of the QSO H\u03b2 emission line, \u03c3_*(M_(BH))= 124 \u00b1 47 km s^(-1). Deep optical HST imaging will be necessary to constrain the total radial mass profile of the QSO host galaxy using the detailed shape of the lensed source. This first case of a QSO acting as a strong lens on a more distant object opens new directions in the study of QSO host galaxies.", "doi": "10.1051/0004-6361/201014376", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2010-06", "volume": "516", "pages": "Art. No. L12" }, { "id": "authors:fnbxr-6sw69", "collection": "authors", "collection_id": "fnbxr-6sw69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100304-140339657", "type": "article", "title": "The Faint End of the Quasar Luminosity Function at z ~ 4", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Bogosavljevi\u0107", "given_name": "Milan", "clpid": "Bogosavljevi\u0107-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Dey", "given_name": "Arjun", "orcid": "0000-0002-4928-4003", "clpid": "Dey-A" }, { "family_name": "Jannuzi", "given_name": "Buell T.", "orcid": "0000-0002-1578-6582", "clpid": "Jannuzi-B-T" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "The evolution of the quasar luminosity function (QLF) is one of the basic cosmological measures providing insight into structure formation and mass assembly in the universe. We have conducted a spectroscopic survey to find faint quasars (\u201326.0 < M_(1450) < \u201322.0) at redshifts z = 3.8-5.2 in order to measure the faint end of the QLF at these early times. Using available optical imaging data from portions of the NOAO Deep Wide-Field Survey and the Deep Lens Survey, we have color-selected quasar candidates in a total area of 3.76 deg^2. Thirty candidates have R \u2264 23 mag. We conducted spectroscopic follow-up for 28 of our candidates and found 23 QSOs, 21 of which are reported here for the first time, in the 3.74 < z < 5.06 redshift range. We estimate our survey completeness through detailed Monte Carlo simulations and derive the first measurement of the density of quasars in this magnitude and redshift interval. We find that the binned luminosity function (LF) is somewhat affected by the K-correction used to compute the rest-frame absolute magnitude at 1450 \u00c5. Considering only our R \u2264 23 sample, the best-fit single power law (\u03a6 \u221d L^\u03b2) gives a faint-end slope \u03b2 = \u20131.6 \u00b1 0.2. If we consider our larger, but highly incomplete sample going 1 mag fainter, we measure a steeper faint-end slope \u20132 < \u03b2 < \u20132.5. In all cases, we consistently find faint-end slopes that are steeper than expected based on measurements at z ~ 3. We combine our sample with bright quasars from the Sloan Digital Sky Survey to derive parameters for a double-power-law LF. Our best fit finds a bright-end slope, \u03b1 = \u20132.4 \u00b1 0.2, and faint-end slope, \u03b2 = \u20132.3 \u00b1 0.2, without a well-constrained break luminosity. This is effectively a single power law, with \u03b2 = \u20132.7 \u00b1 0.1. We use these results to place limits on the amount of ultraviolet radiation produced by quasars and find that quasars are able to ionize the intergalactic medium at these redshifts.", "doi": "10.1088/0004-637X/710/2/1498", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2010-02-20", "series_number": "2", "volume": "710", "issue": "2", "pages": "1498-1514" }, { "id": "authors:ysj5e-s6969", "collection": "authors", "collection_id": "ysj5e-s6969", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-142758921", "type": "book_section", "title": "Exploring the Use of Virtual Worlds as a Scientific Research Platform: The Meta-Institute for Computational Astrophysics (MICA)", "book_title": "Facets of Virtual Environments", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Hut", "given_name": "P.", "clpid": "Hut-P" }, { "family_name": "McMillan", "given_name": "S.", "clpid": "McMillan-S" }, { "family_name": "Vesperini", "given_name": "E.", "clpid": "Vesperini-E" }, { "family_name": "Knop", "given_name": "R.", "clpid": "Knop-R-A" }, { "family_name": "Farr", "given_name": "W.", "clpid": "Farr-W" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" } ], "contributor": [ { "family_name": "Lehmann-Grube", "given_name": "Fritz", "clpid": "Lehmann-Grube-F" }, { "family_name": "Sablatnig", "given_name": "Jan", "clpid": "Sablatnig-J" } ], "abstract": "We describe the Meta-Institute for Computational Astrophysics (MICA), the first professional scientific organization based exclusively in virtual worlds (VWs). The goals of MICA are to explore the utility of the emerging VR and VWs technologies for scientific and scholarly work in general, and to facilitate and accelerate their adoption by the scientific research community. MICA itself is an experiment in academic and scientific practices enabled by the immersive VR technologies. We describe the current and planned activities and research directions of MICA, and offer some thoughts as to what the future developments in this arena may be.", "doi": "10.1007/978-3-642-11743-5_3", "isbn": "978-3-642-11742-8", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "2010-02-13", "pages": "29-43" }, { "id": "authors:1vxsc-8j432", "collection": "authors", "collection_id": "1vxsc-8j432", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110520-140854016", "type": "book_section", "title": "US VAO Facility for Rapid Transients", "book_title": "Astronomical data analysis software and systems XIX", "author": [ { "family_name": "Williams", "given_name": "R. D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Seaman", "given_name": "R.", "clpid": "Seaman-R" } ], "contributor": [ { "family_name": "Mizumoto", "given_name": "Yoshihiko", "clpid": "Mizumoto-Yoshihiko" }, { "family_name": "Morita", "given_name": "Koh-Ichiro", "clpid": "Morita-Koh-Ichiro" }, { "family_name": "Ohishi", "given_name": "Masatoshi", "clpid": "Ohishi-Masatoshi" } ], "abstract": "The US VAO Facility for Rapid Transients (if funded) will collect and disseminate observations about time-critical astronomical transients, and add annotations and intelligent machine-learning to those observations. The information can be \"pushed\" to subscribers, who may be either humans or machines that control telescopes. Subscribers can prepare precise \"triggers\" to decide which events should reach them and their machines, that may be based on the generic event, or on the specific vocabulary of parameters that define a particular type of observation. The system will not be centralized, but rather a set of interoperating nodes with caching. The twin thrusts are automation of process, and discrimination of interesting events.", "isbn": "978-1-58381-748-3", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2010", "pages": "123-126" }, { "id": "authors:vpn6f-v9g76", "collection": "authors", "collection_id": "vpn6f-v9g76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110520-131607293", "type": "book_section", "title": "Mixing Bayesian Techniques for Effective Real-time Classification of Astronomical Transients", "book_title": "Astronomical data analysis software and systems XIX", "author": [ { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R" }, { "family_name": "Moghaddam", "given_name": "Baback", "clpid": "Moghaddam-B" }, { "family_name": "Turmon", "given_name": "Michael", "clpid": "Turmon-M-J" } ], "contributor": [ { "family_name": "Mizumoto", "given_name": "Yoshihiko", "clpid": "Mizumoto-Y" }, { "family_name": "Morita", "given_name": "Koh-Ichiro", "clpid": "Morita-K-I" }, { "family_name": "Ohishi", "given_name": "Masatoshi", "clpid": "Ohishi-M" } ], "abstract": "With the recent advent of time domain astronomy through various surveys several approaches at classification of transient s are being tried. Choosing relatively interesting and rarer transients for follow-up is important since following all transients being detected per night is not possible given the limited resources available. In addition, the classification needs to be carried out using minimal number of observations available in order to catch some of the more interesting objects. We present details on two such classification methods: (1) using Bayesian networks with colors and contextual information, and (2) using Gaussian Process Regression and light-curves. Both can be carried out in real-time and from a very small number of epochs. In order to improve classification i.e. narrow down number of competing classes, it is important to combine as many different classifiers as possible. We mention how this can be accomplished using a higher order fusion network.", "isbn": "978-1-58381-748-3", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2010", "pages": "115-118" }, { "id": "authors:7m635-sdy03", "collection": "authors", "collection_id": "7m635-sdy03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-135127391", "type": "monograph", "title": "LSST Science Book, Version 2.0", "author": [ { "family_name": "Abell", "given_name": "Paul A.", "clpid": "Abell-P-A" }, { "family_name": "Bridge", "given_name": "Carrie R.", "clpid": "Bridge-C-R" }, { "family_name": "Brown", "given_name": "Michael E.", "orcid": "0000-0002-8255-0545", "clpid": "Brown-M-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Kulkarni", "given_name": "Shrinivas", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "literal": "LSST Science Collaborations" } ], "abstract": "A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.", "doi": "10.48550/arXiv.0912.0201", "publication_date": "2009-12-01" }, { "id": "authors:fwhqj-53584", "collection": "authors", "collection_id": "fwhqj-53584", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100106-135303416", "type": "article", "title": "Exploring the Optical Transient Sky with the Palomar Transient Factory", "author": [ { "family_name": "Rau", "given_name": "Arne", "orcid": "0000-0001-5990-6243", "clpid": "Rau-A" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Law", "given_name": "Nicholas M.", "orcid": "0000-0001-9380-6457", "clpid": "Law-N-M" }, { "family_name": "Bloom", "given_name": "Joshua S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Ciardi", "given_name": "David", "orcid": "0000-0002-5741-3047", "clpid": "Ciardi-D-R" }, { "family_name": "Djorgovski", "given_name": "George S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fox", "given_name": "Derek B.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Gal-Yam", "given_name": "Avishay", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Grillmair", "given_name": "Carl C.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Nugent", "given_name": "Peter E.", "orcid": "0000-0002-3389-0586", "clpid": "Nugent-P-E" }, { "family_name": "Ofek", "given_name": "Eran O.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Quimby", "given_name": "Robert M.", "orcid": "0000-0001-9171-5236", "clpid": "Quimby-R-M" }, { "family_name": "Reach", "given_name": "William T.", "orcid": "0000-0001-8362-4094", "clpid": "Reach-W-T" }, { "family_name": "Shara", "given_name": "Michael", "clpid": "Shara-M-M" }, { "family_name": "Bildsten", "given_name": "Lars", "clpid": "Bildsten-L" }, { "family_name": "Cenko", "given_name": "S. Bradley", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Drake", "given_name": "Andrew J.", "clpid": "Drake-A-J" }, { "family_name": "Filippenko", "given_name": "Alexei V.", "orcid": "0000-0003-3460-0103", "clpid": "Filippenko-A-V" }, { "family_name": "Helfand", "given_name": "David J.", "clpid": "Helfand-D-J" }, { "family_name": "Helou", "given_name": "George", "orcid": "0000-0003-3367-3415", "clpid": "Helou-G" }, { "family_name": "Howell", "given_name": "D. Andrew", "orcid": "0000-0003-4253-656X", "clpid": "Howell-D-A" }, { "family_name": "Poznanski", "given_name": "Dovi", "clpid": "Poznanski-D" }, { "family_name": "Sullivan", "given_name": "Mark", "orcid": "0000-0001-9053-4820", "clpid": "Sullivan-Mark" } ], "abstract": "The Palomar Transient Factory (PTF) is a wide-field experiment designed to investigate the optical transient and variable sky on time scales from minutes to years. PTF uses the CFH12k mosaic camera, with a field of view of 7.9 deg^2 and a plate scale of 1\u2033 pixel^(-1), mounted on the Palomar Observatory 48 inch Samuel Oschin Telescope. The PTF operation strategy is devised to probe the existing gaps in the transient phase space and to search for theoretically predicted, but not yet detected, phenomena, such as fallback supernovae, macronovae, .Ia supernovae, and the orphan afterglows of gamma-ray bursts. PTF will also discover many new members of known source classes, from cataclysmic variables in their various avatars to supernovae and active galactic nuclei, and will provide important insights into understanding galactic dynamics (through RR Lyrae stars) and the solar system (asteroids and near-Earth objects). The lessons that can be learned from PTF will be essential for the preparation of future large synoptic sky surveys like the Large Synoptic Survey Telescope. In this article we present the scientific motivation for PTF and describe in detail the goals and expectations for this experiment.", "doi": "10.1086/605911", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2009-12", "series_number": "886", "volume": "121", "issue": "886", "pages": "1334-1351" }, { "id": "authors:8xnwe-sk143", "collection": "authors", "collection_id": "8xnwe-sk143", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100108-092743274", "type": "article", "title": "The Palomar Transient Factory: System Overview, Performance, and First Results", "author": [ { "family_name": "Law", "given_name": "Nicholas M.", "orcid": "0000-0001-9380-6457", "clpid": "Law-N-M" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Dekany", "given_name": "Richard G.", "clpid": "Dekany-Richard" }, { "family_name": "Ofek", "given_name": "Eran O.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Quimby", "given_name": "Robert M.", "orcid": "0000-0001-9171-5236", "clpid": "Quimby-R-M" }, { "family_name": "Nugent", "given_name": "Peter E.", "orcid": "0000-0002-3389-0586", "clpid": "Nugent-P-E" }, { "family_name": "Surace", "given_name": "Jason", "orcid": "0000-0001-7291-0087", "clpid": "Surace-J-A" }, { "family_name": "Grillmair", "given_name": "Carl C.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Bloom", "given_name": "Joshua S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Bildsten", "given_name": "Lars", "clpid": "Bildsten-L" }, { "family_name": "Brown", "given_name": "Tim", "orcid": "0000-0002-1793-9968", "clpid": "Brown-T-M" }, { "family_name": "Cenko", "given_name": "Bradley", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Ciardi", "given_name": "David", "orcid": "0000-0002-5741-3047", "clpid": "Ciardi-D-R" }, { "family_name": "Croner", "given_name": "Ernest", "clpid": "Croner-E-E" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "van Eyken", "given_name": "Julian", "orcid": "0000-0003-2192-5371", "clpid": "van-Eyken-J-C" }, { "family_name": "Filippenko", "given_name": "Alexei V.", "orcid": "0000-0003-3460-0103", "clpid": "Filippenko-A-V" }, { "family_name": "Fox", "given_name": "Derek B.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Gal-Yam", "given_name": "Avishay", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Hale", "given_name": "David", "clpid": "Hale-D-D-S" }, { "family_name": "Haman", "given_name": "Nouhad", "clpid": "Haman-N" }, { "family_name": "Helou", "given_name": "George", "orcid": "0000-0003-3367-3415", "clpid": "Helou-G" }, { "family_name": "Henning", "given_name": "John", "clpid": "Henning-J-R" }, { "family_name": "Howell", "given_name": "D. Andrew", "orcid": "0000-0003-4253-656X", "clpid": "Howell-D-A" }, { "family_name": "Jacobsen", "given_name": "Janet", "clpid": "Jacobsen-J" }, { "family_name": "Laher", "given_name": "Russ", "orcid": "0000-0003-2451-5482", "clpid": "Laher-R-R" }, { "family_name": "Mattingly", "given_name": "Sean", "clpid": "Mattingly-S" }, { "family_name": "McKenna", "given_name": "Dan", "clpid": "McKenna-D-L" }, { "family_name": "Pickles", "given_name": "Andrew", "clpid": "Pickles-A" }, { "family_name": "Poznanski", "given_name": "Dovi", "clpid": "Poznanski-D" }, { "family_name": "Rahmer", "given_name": "Gustavo", "clpid": "Rahmer-G" }, { "family_name": "Rau", "given_name": "Arne", "orcid": "0000-0001-5990-6243", "clpid": "Rau-A" }, { "family_name": "Rosing", "given_name": "Wayne", "clpid": "Rosing-W" }, { "family_name": "Shara", "given_name": "Michael", "clpid": "Shara-M-M" }, { "family_name": "Smith", "given_name": "Roger", "clpid": "Smith-R-M" }, { "family_name": "Starr", "given_name": "Dan", "clpid": "Starr-D" }, { "family_name": "Sullivan", "given_name": "Mark", "orcid": "0000-0001-9053-4820", "clpid": "Sullivan-Mark" }, { "family_name": "Velur", "given_name": "Viswa", "clpid": "Velur-V" }, { "family_name": "Walters", "given_name": "Richard", "orcid": "0000-0002-1835-6078", "clpid": "Walters-R" }, { "family_name": "Zolkower", "given_name": "Jeff", "clpid": "Zolkower-J" } ], "abstract": "The Palomar Transient Factory (PTF) is a fully-automated, wide-field survey aimed at a systematic exploration of the optical transient sky. The transient survey is performed using a new 8.1 square degree camera installed on the 48 inch Samuel Oschin telescope at Palomar Observatory; colors and light curves for detected transients are obtained with the automated Palomar 60 inch telescope. PTF uses 80% of the 1.2 m and 50% of the 1.5 m telescope time. With an exposure of 60 s the survey reaches a depth of m_(g\u2032) \u2248 21.3 and m_R \u2248 20.6 (5\u03c3, median seeing). Four major experiments are planned for the five-year project: (1) a 5 day cadence supernova search; (2) a rapid transient search with cadences between 90 s and 1 day; (3) a search for eclipsing binaries and transiting planets in Orion; and (4) a 3\u03c0 sr deep H-alpha survey. PTF provides automatic, real-time transient classification and follow-up, as well as a database including every source detected in each frame. This paper summarizes the PTF project, including several months of on-sky performance tests of the new survey camera, the observing plans, and the data reduction strategy. We conclude by detailing the first 51 PTF optical transient detections, found in commissioning data.", "doi": "10.1086/648598", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2009-12", "series_number": "886", "volume": "121", "issue": "886", "pages": "1395-1408" }, { "id": "authors:n0gfz-zd677", "collection": "authors", "collection_id": "n0gfz-zd677", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100106-080049821", "type": "article", "title": "Damped and sub-damped Lyman-\u03b1 absorbers in z > 4 QSOs", "author": [ { "family_name": "Guimar\u00e3es", "given_name": "R.", "clpid": "Guimar\u00e3es-R" }, { "family_name": "Petitjean", "given_name": "P.", "clpid": "Petitjean-P" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Noterdaeme", "given_name": "P.", "clpid": "Noterdaeme-P" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" }, { "family_name": "da R. Poppe", "given_name": "P. C.", "clpid": "da-R-Poppe-P-C" }, { "family_name": "Aghaee", "given_name": "A.", "clpid": "Aghaee-A" } ], "abstract": "We present the results of a survey of damped (DLA, log N(H I) > 20.3) and sub-damped Lyman-\u03b1 systems (19.5 < log N(H I) < 20.3) at z > 2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4 < z_(em) < 6.3. Intermediate resolution (R ~ 4300) spectra were obtained with the Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total of 100 systems with log N(H I) > 19.5 were detected of which 40 systems are damped Lyman-\u03b1 systems for an absorption length of \u0394X = 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs. We study the evolution with redshift of the cosmological density of the neutral gas and find, consistent with previous studies at similar resolution, that \u03a9_(DLA,HI) decreases at z > 3.5. The overall cosmological evolution of \u03a9_(HI) shows a peak around this redshift. The H I column density distribution for log N(H I) \u2265 20.3 is fitted, consistent with previous surveys, with a single power-law of index \u03b1 ~ \u22121.8 \u00b1 0.25. This power-law overpredicts data at the high-end and a second, much steeper, power-law (or a gamma function) is needed. There is a flattening of the function at lower H I column densities with an index of \u03b1 ~ \u22121.4 for the column density range log N(H I) = 19.5\u221221. The fraction of H I mass in sub-DLAs is of the order of 30%. The H I column density distribution does not evolve strongly from z ~ 2.5 to z ~ 4.5.", "doi": "10.1051/0004-6361/200811541", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2009-12", "series_number": "1", "volume": "508", "issue": "1", "pages": "133-140" }, { "id": "authors:wbkp3-hek23", "collection": "authors", "collection_id": "wbkp3-hek23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091104-112101055", "type": "article", "title": "Highly Variable Objects in the Palomar-QUEST Survey: A Blazar Search Using Optical Variability", "author": [ { "family_name": "Bauer", "given_name": "Anne", "clpid": "Bauer-A" }, { "family_name": "Baltay", "given_name": "Charles", "clpid": "Baltay-C" }, { "family_name": "Coppi", "given_name": "Paolo", "clpid": "Coppi-P" }, { "family_name": "Donalek", "given_name": "Ciro", "clpid": "Donalek-C" }, { "family_name": "Drake", "given_name": "Andrew", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ellman", "given_name": "Nancy", "clpid": "Ellman-N" }, { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Jerke", "given_name": "Jonathan", "clpid": "Jerke-J" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Rabinowitz", "given_name": "David", "clpid": "Rabinowitz-D" }, { "family_name": "Scalzo", "given_name": "Richard", "clpid": "Scalzo-R" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R" } ], "abstract": "We identify 3113 highly variable objects in 7200 deg^2 of the Palomar-QUEST (PQ) Survey, which each varied by more than 0.4 mag simultaneously in two broadband optical filters on timescales from hours to roughly 3.5 years. The primary goal of the selection is to find blazars by their well-known violent optical variability. Because most known blazars have been found in radio and/or X-ray wavelengths, a sample discovered through optical variability may have very different selection effects, elucidating the range of behavior possible in these systems. A set of blazars selected in this unusual manner will improve our understanding of the physics behind this extremely variable and diverse class of active galactic nucleus (AGN). The object positions, variability statistics, and color information are available using the PQ CasJobs server. The time domain is just beginning to be explored over large sky areas; we do not know exactly what a violently variable sample will hold. About 20% of the sample has been classified in the literature; over 70% of those objects are known or likely AGNs. The remainder largely consists of a variety of variable stars, including a number of RR Lyrae and cataclysmic variables.", "doi": "10.1088/0004-637X/705/1/46", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2009-11-01", "series_number": "1", "volume": "705", "issue": "1", "pages": "46-53" }, { "id": "authors:8pz6k-02551", "collection": "authors", "collection_id": "8pz6k-02551", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090729-115119043", "type": "article", "title": "The velocity dispersion and mass-to-light ratio of the remote halo globular cluster NGC 2419", "author": [ { "family_name": "Baumgardt", "given_name": "H.", "clpid": "Baumgardt-H" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Hilker", "given_name": "M.", "clpid": "Hilker-M" }, { "family_name": "Rejkuba", "given_name": "M.", "clpid": "Rejkuba-M" }, { "family_name": "Mieske", "given_name": "S.", "clpid": "Mieske-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stetson", "given_name": "Peter", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" } ], "abstract": "Precise radial velocity measurements from high-resolution echelle spectrometer on the Keck I telescope are presented for 40 stars in the outer halo globular cluster NGC 2419. These data are used to probe the cluster's stellar mass function and search for the presence of dark matter in this cluster. NGC 2419 is one of the best Galactic globular clusters for such a study due to its long relaxation time (T_r0 \u2248 10^10 yr) and large Galactocentric distance (R_GC \u2248 90 kpc) \u2013 properties that make significant evolutionary changes in the low-mass end of the cluster mass function unlikely. We find a mean cluster velocity of\u3008v_r\u3009= \u221220.3 \u00b1 0.7 km s^\u22121 and an internal velocity dispersion of \u03c3 = 4.14 \u00b1 0.48 km s^\u22121, leading to a total mass of (9.0 \u00b1 2.2) \u00d7 10^5 M\u2299 and a global mass-to-light ratio of M/L_V = 2.05 \u00b1 0.50 in solar units. This mass-to-light ratio is in good agreement with what one would expect for a pure stellar system following a standard mass function at the metallicity of NGC 2419. In addition, the mass-to-light ratio does not appear to rise towards the outer parts of the cluster. Our measurements therefore rule out the presence of a dark matter halo with mass larger than ~10^7 M\u2299 inside the central 500 pc, which is lower than what is found for the central dark matter densities of dSph galaxies. We also discuss the relevance of our measurements for alternative gravitational theories such as Modified Newtonian Dynamics, and for possible formation scenarios of ultracompact dwarf galaxies.", "doi": "10.1111/j.1365-2966.2009.14932", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2009-07", "series_number": "4", "volume": "396", "issue": "4", "pages": "2051-2060" }, { "id": "authors:zt4cv-vt315", "collection": "authors", "collection_id": "zt4cv-vt315", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090828-094129210", "type": "article", "title": "Testing Fundamental Physics with Distant Star Clusters: Analysis of Observational Data on Palomar 14", "author": [ { "family_name": "Jordi", "given_name": "K.", "clpid": "Jordi-K" }, { "family_name": "Grebel", "given_name": "E. K.", "orcid": "0000-0002-1891-3794", "clpid": "Grebel-E-K" }, { "family_name": "Hilker", "given_name": "M.", "clpid": "Hilker-M" }, { "family_name": "Baumgardt", "given_name": "H.", "clpid": "Baumgardt-H" }, { "family_name": "Frank", "given_name": "M.", "clpid": "Frank-M" }, { "family_name": "Kroupa", "given_name": "P.", "clpid": "Kroupa-P" }, { "family_name": "Haghi", "given_name": "H.", "clpid": "Haghi-H" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Djorgovski", "given_name": "Stanislav G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We use the distant outer halo globular cluster Palomar 14 as a test case for classical versus modified Newtonian dynamics (MOND). Previous theoretical calculations have shown that the line-of-sight velocity dispersion predicted by these theories can differ by up to a factor of 3 for such sparse, remote clusters like Pal 14. We determine the line-of-sight velocity dispersion of Palomar 14 by measuring radial velocities of 17 red giant cluster members obtained using the Very Large Telescope and Keck telescope. The systemic velocity of Palomar 14 is (72.28 \u00b1 0.12) km s^(\u20131). The derived velocity dispersion of (0.38 \u00b1 0.12) km s^(\u20131) of the 16 definite member stars is in agreement with the theoretical prediction for the classical Newtonian case according to Baumgardt et al. In order to exclude the possibility that a peculiar mass function might have influenced our measurements, we derived the cluster's main-sequence mass function down to 0.53 M\u2299 using archival images obtained with the Hubble Space Telescope. We found a mass function slope of \u03b1 = 1.27 \u00b1 0.44, which is, compared to the canonical mass function, a significantly shallower slope. The derived lower limit on the cluster's mass is higher than the theoretically predicted mass in the case of MOND. Our data are consistent with a central density of \u03c1_0 = 0.1 M\u2299 pc^(\u20133). We need no dark matter in Palomar 14. If the cluster is on a circular orbit, our spectroscopic and photometric results argue against MOND, unless the cluster experienced significant mass loss.", "doi": "10.1088/0004-6256/137/6/4586", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2009-06", "series_number": "6", "volume": "137", "issue": "6", "pages": "4586-4596" }, { "id": "authors:39n6k-mvr72", "collection": "authors", "collection_id": "39n6k-mvr72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090821-113053346", "type": "article", "title": "First Results from the Catalina Real-Time Transient Survey", "author": [ { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Beshore", "given_name": "E.", "clpid": "Beshore-E" }, { "family_name": "Larson", "given_name": "S.", "orcid": "0000-0002-0057-8211", "clpid": "Larson-S" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Christensen", "given_name": "E.", "clpid": "Christensen-E" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Boattini", "given_name": "A.", "clpid": "Boattini-A" }, { "family_name": "Gibbs", "given_name": "A.", "clpid": "Gibbs-A" }, { "family_name": "Hill", "given_name": "R.", "clpid": "Hill-R" }, { "family_name": "Kowalski", "given_name": "R.", "clpid": "Kowalski-R" } ], "abstract": "We report on the results from the first six months of the Catalina Real-Time Transient Survey (CRTS). In order to search for optical transients (OTs) with timescales of minutes to years, the CRTS analyses data from the Catalina Sky Survey which repeatedly covers 26,000 of square degrees on the sky. The CRTS provides a public stream of transients that are bright enough to be followed up using small telescopes. Since the beginning of the survey, all CRTS transients have been made available to astronomers around the world in real time using HTML tables,RSS feeds, and VOEvents. As part of our public outreach program, the detections are now also available in Keyhole Markup Language through Google Sky. The initial discoveries include over 350 unique OTs rising more than 2 mag from past measurements. Sixty two of these are classified as supernovae (SNe), based on light curves, prior deep imaging and spectroscopic data. Seventy seven are due to cataclysmic variables (CVs; only 13 previously known), while an additional 100 transients were too infrequently sampled to distinguish between faint CVs and SNe. The remaining OTs include active galactic nucleus, blazars, high-proper-motions stars, highly variable stars (such as UV Ceti stars), and transients of an unknown nature. Our results suggest that there is a large population of SNe missed by many current SN surveys because of selection biases. These objects appear to be associated with faint host galaxies. We also discuss the unexpected discovery of white dwarf binary systems through dramatic eclipses.", "doi": "10.1088/0004-637X/696/1/870", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2009-05-01", "series_number": "1", "volume": "696", "issue": "1", "pages": "870-884" }, { "id": "authors:r9tvn-2r891", "collection": "authors", "collection_id": "r9tvn-2r891", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090824-150539016", "type": "article", "title": "The Environments of High-Redshift Quasi-Stellar Objects", "author": [ { "family_name": "Kim", "given_name": "Soyoung", "clpid": "Kim-Soyoung" }, { "family_name": "Stiavelli", "given_name": "Massimo", "clpid": "Stiavelli-M" }, { "family_name": "Trenti", "given_name": "M.", "clpid": "Trenti-M" }, { "family_name": "Pavlovsky", "given_name": "C. M.", "clpid": "Pavlovsky-C-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Scarlata", "given_name": "C.", "orcid": "0000-0002-9136-8876", "clpid": "Scarlata-C-M" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Dickinson", "given_name": "M.", "orcid": "0000-0001-5414-5131", "clpid": "Dickinson-Mark-E" }, { "family_name": "Panagia", "given_name": "N.", "clpid": "Panagia-N" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" } ], "abstract": "We present a sample of i_(775)-dropout candidates identified in five Hubble Advanced Camera for Surveys (ACS) fields centered on Sloan Digital Sky Survey quasi-stellar objects (QSOs) at redshift z ~ 6. Our fields are as deep as the GOODS ACS images, which are used as a reference field sample. We find them to be overdense in two fields, underdense in two fields, and as dense as the average density of GOODS in one field. The two excess fields show significantly different color distributions from that of GOODS at the 99% confidence level, strengthening the idea that the excess objects are indeed associated with the QSO. The distribution of i_(775)-dropout counts in the five fields is broader than that derived from GOODS at the 80%-96% confidence level, depending on which selection criteria were adopted to identify i_(775)-dropouts; its width cannot be explained by cosmic variance alone. Thus, QSOs seem to affect their environments in complex ways. We suggest the picture where the highest redshift QSOs are located in very massive overdensities and are therefore surrounded by an overdensity of lower mass halos. Radiative feedback by the QSO can in some cases prevent halos from becoming galaxies, thereby generating in extreme cases an underdensity of galaxies. The presence of both enhancement and suppression is compatible with the expected differences between lines of sight at the end of reionization as the presence of residual diffuse neutral hydrogen would provide young galaxies with shielding from the radiative effects of the QSO.", "doi": "10.1088/0004-637X/695/2/809", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2009-04-20", "series_number": "2", "volume": "695", "issue": "2", "pages": "809-817" }, { "id": "authors:ynpn9-n0j61", "collection": "authors", "collection_id": "ynpn9-n0j61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090904-104134607", "type": "article", "title": "Thirty Meter Telescope Site Testing I: Overview", "author": [ { "family_name": "Sch\u00f6ck", "given_name": "M.", "clpid": "Sch\u00f6ck-M" }, { "family_name": "Els", "given_name": "S.", "clpid": "Els-S" }, { "family_name": "Riddle", "given_name": "R.", "orcid": "0000-0002-0387-370X", "clpid": "Riddle-R-L" }, { "family_name": "Skidmore", "given_name": "W.", "clpid": "Skidmore-W" }, { "family_name": "Travouillon", "given_name": "T.", "clpid": "Travouillon-T" }, { "family_name": "Blum", "given_name": "R.", "clpid": "Blum-R" }, { "family_name": "Bustos", "given_name": "E.", "clpid": "Bustos-E" }, { "family_name": "Chanan", "given_name": "G.", "clpid": "Chanan-G" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gillett", "given_name": "P.", "clpid": "Gillett-P" }, { "family_name": "Gregory", "given_name": "B.", "clpid": "Gregory-B" }, { "family_name": "Nelson", "given_name": "J.", "clpid": "Nelson-J" }, { "family_name": "Ot\u00e1rola", "given_name": "A.", "clpid": "Ot\u00e1rola-A" }, { "family_name": "Seguel", "given_name": "J.", "clpid": "Seguel-J" }, { "family_name": "Vasquez", "given_name": "J.", "clpid": "Vasquez-J" }, { "family_name": "Walker", "given_name": "A.", "clpid": "Walker-A" }, { "family_name": "Walker", "given_name": "D.", "clpid": "Walker-D" }, { "family_name": "Wang", "given_name": "L.", "orcid": "0000-0002-9803-166X", "clpid": "Wang-L" } ], "abstract": "As part of the conceptual and preliminary design processes of the Thirty Meter Telescope (TMT), the TMT site-testing team has spent the last five years measuring the atmospheric properties of five candidate mountains in North and South America with an unprecedented array of instrumentation. The site-testing period was preceded by several years of analyses selecting the five candidates: Cerros Tolar, Armazones and Tolonchar in northern Chile; San Pedro M\u00e1rtir in Baja California, Mexico; and the 13 North (13N) site on Mauna Kea, Hawaii. Site testing was concluded by the selection of two remaining sites for further consideration, Armazones and Mauna Kea 13N. It showed that all five candidates are excellent sites for an extremely large astronomical observatory and that none of the sites stands out as the obvious and only logical choice based on its combined properties. This is the first article in a series discussing the TMT site-testing project.", "doi": "10.1086/599287", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2009-04", "series_number": "878", "volume": "121", "issue": "878", "pages": "384-395" }, { "id": "authors:njh6y-8ba84", "collection": "authors", "collection_id": "njh6y-8ba84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DALapj09", "type": "article", "title": "Cosmological Studies with Radio Galaxies and Supernovae", "author": [ { "family_name": "Daly", "given_name": "Ruth A.", "clpid": "Daly-R-A" }, { "family_name": "Mory", "given_name": "Matthew P.", "clpid": "Mory-M-P" }, { "family_name": "O'Dea", "given_name": "C. P.", "orcid": "0000-0001-6421-054X", "clpid": "O'Dea-C-P" }, { "family_name": "Kharb", "given_name": "P.", "orcid": "0000-0003-3203-1613", "clpid": "Kharb-P" }, { "family_name": "Baumont", "given_name": "S.", "clpid": "Baumont-S" }, { "family_name": "Guerra", "given_name": "E. J.", "clpid": "Guerra-E-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Physical sizes of extended radio galaxies can be employed as a cosmological \"standard ruler,\" using a previously developed method. Eleven new radio galaxies are added to our previous sample of 19 sources, forming a sample of 30 objects with redshifts between 0 and 1.8. This sample of radio galaxies are used to obtain the best-fit cosmological parameters in a quintessence model in a spatially flat universe, a cosmological constant model that allows for nonzero space curvature, and a rolling scalar field model in a spatially flat universe. Results obtained with radio galaxies are compared with those obtained with different supernova samples, and with combined radio galaxy and supernova samples. Results obtained with different samples are consistent, suggesting that neither method is seriously affected by systematic errors. Best-fit radio galaxy and supernovae model parameters determined in the different cosmological models are nearly identical, and are used to determine dimensionless coordinate distances to supernovae and radio galaxies, and distance moduli to the radio galaxies. The distance moduli to the radio galaxies can be combined with supernovae samples to increase the number of sources, particularly high-redshift sources, in the samples. The constraints obtained here with the combined radio galaxy plus supernovae dataset in the rolling scalar field model are quite strong. The best-fit parameter values suggest that \u03a9m is less than about 0.35, and the model parameter \u03b1 is close to zero; that is, a cosmological constant provides a good description of the data. We also obtain new constraints on the physics of engines that power the large-scale radio emission. The equation that describes the predicted size of each radio source is controlled by one model parameter, \u03b2, which parameterizes the extraction of energy from the black hole. Joint fits of radio galaxy and supernova samples indicate a best-fit value of \u03b2 that is very close to a special value for which the relationship between the braking magnetic field strength and the properties of the spinning black hole is greatly simplified, and the braking magnetic field strength depends only upon the spin angular momentum per unit mass and the gravitational radius of the black hole. The best-fit value of \u03b2 of 1.5 indicates that the beam power Lj and the initial spin energy of the black hole E are related by Lj \u221d E^2, and that the relationship that might naively be expected for an Eddington limited system, Lj \u221d E, is quite clearly ruled out for the jets in these systems.", "doi": "10.1088/0004-637X/691/2/1058", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2009-02-01", "series_number": "2", "volume": "691", "issue": "2", "pages": "1058-1067" }, { "id": "authors:9kvjr-fzy69", "collection": "authors", "collection_id": "9kvjr-fzy69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:GALaj09", "type": "article", "title": "The Northern Sky Optical Cluster Survey. III. A Cluster Catalog Covering PI Steradians", "author": [ { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Lopes", "given_name": "P. A. A.", "clpid": "Lopes-P-A-A" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Kohl-Moreira", "given_name": "J. L.", "clpid": "Kohl-Moreira-J-L" }, { "family_name": "Capelato", "given_name": "H. V.", "clpid": "Capelato-H-V" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z \u227e 0.25 drawn from the Digitized Second Palomar Observatory Sky Survey (DPOSS). The data presented here cover the Southern Galactic Cap, as well as the less well-calibrated regions of the Northern Galactic Cap. In addition, due to improvements in our cluster finder and measurement methods, we provide an updated catalog for the well-calibrated Northern Galactic Cap region previously published in Paper II. The complete survey covers 11,411 deg^2, with over 15,000 candidate clusters. We discuss improved photometric redshifts, richnesses, and optical luminosities which are provided for each cluster. A variety of substructure measures are computed for a subset of over 11,000 clusters. We also discuss the derivation of dynamical radii r 200 and its relation to cluster richness. A number of consistency checks between the three areas of the survey are also presented, demonstrating the homogeneity of the catalog over disjoint sky areas. We perform extensive comparisons to existing optically and X-ray-selected cluster catalogs, and derive new X-ray luminosities and temperatures for a subset of our clusters. We find that the optical and X-ray luminosities are well correlated, even using relatively shallow ROSAT All Sky Survey and DPOSS data. This survey provides a good comparison sample to the MaxBCG catalog based on Sloan Digital Sky Survey Data, and complements that survey at low redshifts 0.07 < z < 0.1.", "doi": "10.1088/0004-6256/137/2/2981", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2009-02", "series_number": "2", "volume": "137", "issue": "2", "pages": "2981-2999" }, { "id": "authors:3hq96-yrx02", "collection": "authors", "collection_id": "3hq96-yrx02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100913-153257900", "type": "book_section", "title": "Skyalert: Real-time Astronomy for You and Your Robots", "book_title": "Astronomical Data Analysis Software and Systems XVIII", "author": [ { "family_name": "Williams", "given_name": "R. D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "contributor": [ { "family_name": "Bohlender", "given_name": "David A.", "clpid": "Bohlender-D-A" }, { "family_name": "Durand", "given_name": "Daniel", "clpid": "Durand-D" }, { "family_name": "Dowler", "given_name": "Patrick", "clpid": "Dowler-P" } ], "abstract": "Skyalert.org is a web application to collect and disseminate observations about time-critical astronomical transients, and to add annotations and intelligent machine-learning to those observations. The information is \"pushed\" to subscribers, who may be either humans (email, text message etc.) or they may be machines that control telescopes. Subscribers can prepare precise \"trigger rules\" to decide which events should reach them and their robots, rules that may be based on sky position, or on the specific vocabulary of parameters that define a particular type of observation. Our twin thrusts are automation of process, and discrimination of interesting events.", "isbn": "978-1-58381-702-5", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2009", "pages": "115-119" }, { "id": "authors:zkjrj-14991", "collection": "authors", "collection_id": "zkjrj-14991", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:MAHaipcp08", "type": "book_section", "title": "Towards real-time classification of astronomical transients", "book_title": "International Conference on Classification and Discovery in Large Astronomical Surveys, Ringberg Castle, Germany, 14\u201317 October 2008", "author": [ { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Williams", "given_name": "R.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Drake", "given_name": "A.", "clpid": "Drake-A-J" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Graham", "given_name": "M.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Moghaddam", "given_name": "B.", "clpid": "Moghaddam-B" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" }, { "family_name": "Jewell", "given_name": "J.", "clpid": "Jewell-Jeffrey-B" }, { "family_name": "Khosla", "given_name": "A.", "clpid": "Khosla-A" }, { "family_name": "Hensleya", "given_name": "B.", "clpid": "Hensleya-B" } ], "contributor": [ { "family_name": "Bailer-Jones", "given_name": "Coryn A. L.", "clpid": "Bailer-Jones-C-A-L" } ], "abstract": "Exploration of time domain is now a vibrant area of research in astronomy, driven by the advent of digital synoptic sky surveys. While panoramic surveys can detect variable or transient events, typically some follow-up observations are needed; for short-lived phenomena, a rapid response is essential. Ability to automatically classify and prioritize transient events for follow-up studies becomes critical as the data rates increase. We have been developing such methods using the data streams from the Palomar-Quest survey, the Catalina Sky Survey and others, using the VOEventNet framework. The goal is to automatically classify transient events, using the new measurements, combined with archival data (previous and multi-wavelength measurements), and contextual information (e.g., Galactic or ecliptic latitude, presence of a possible host galaxy nearby, etc.); and to iterate them dynamically as the follow-up data come in (e.g., light curves or colors). We have been investigating Bayesian methodologies for classification, as well as discriminated follow-up to optimize the use of available resources, including Naive Bayesian approach, and the non-parametric Gaussian process regression. We will also be deploying variants of the traditional machine learning techniques such as Neural Nets and Support Vector Machines on datasets of reliably classified transients as they build up.", "doi": "10.1063/1.3059064", "isbn": "9780735406131", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2008-12-05", "pages": "287-293" }, { "id": "authors:9m4q7-e2t36", "collection": "authors", "collection_id": "9m4q7-e2t36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DONaipcp08", "type": "book_section", "title": "New approaches to object classification in synoptic sky surveys", "book_title": "Classification and discovery in large astronomical surveys : proceedings of the International Conference \"Classification and Discovery in Large Astronomical Surveys\", Ringberg Castle, Germany, 14\u201317 October 2008", "author": [ { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Marney", "given_name": "S.", "clpid": "Marney-S" }, { "family_name": "Drake", "given_name": "A.", "clpid": "Drake-A" }, { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" } ], "abstract": "Digital synoptic sky surveys pose several new object classification challenges. In surveys where real-time detection and classification of transient events is a science driver, there is a need for an effective elimination of instrument-related artifacts which can masquerade as transient sources in the detection pipeline, e.g., unremoved large cosmic rays, saturation trails, reflections, crosstalk artifacts, etc. We have implemented such an Artifact Filter, using a supervised neural network, \nfor the real-time processing pipeline in the Palomar-Quest (PQ) survey. After the training phase, for each object it takes as input a set of measured morphological parameters and returns the probability of it being a real object. Despite the relatively low number of training cases for many kinds of artifacts, the overall artifact classification rate is around 90%, with no genuine transients misclassified during our real-time scans. Another question is how to assign an optimal star-galaxy \nclassification in a multi-pass survey, where seeing and other conditions change between different epochs, potentially producing inconsistent classifications for the same object. We have implemented a star/galaxy multipass classifier that makes use of external and a priori knowledge to find the optimal classification from the individually derived ones. Both these techniques can be applied to other, similar surveys and data sets.", "doi": "10.1063/1.3059057", "isbn": "9780735406131", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2008-12-05", "pages": "252-256" }, { "id": "authors:9x9hf-hs688", "collection": "authors", "collection_id": "9x9hf-hs688", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090512-082134987", "type": "article", "title": "An exploratory search for z \u2273 6 quasars in the UKIDSS early data release", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Eigenbrod", "given_name": "Alexander", "clpid": "Eigenbrod-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Meylan", "given_name": "Georges", "clpid": "Meylan-G" }, { "family_name": "Thompson", "given_name": "David", "clpid": "Thompson-D" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Courbin", "given_name": "Fr\u00e9d\u00e9ric", "clpid": "Courbin-F" } ], "abstract": "We conducted an exploratory search for quasars at z ~ 6-8, using the Early Data Release (EDR) from the United Kingdom Infrared Deep Sky Survey (UKIDSS) cross-matched to panoramic optical imagery. High-redshift quasar candidates are chosen using multi-color selection in i, z, Y, J, H, and K bands. After removal of apparent instrumental artifacts, our candidate list consisted of 34 objects. We further refined this list with deeper imaging in the optical for ten of our candidates. Twenty-five candidates were followed up spectroscopically in the near-infrared and in the optical. We confirmed 25 of our spectra as very low-mass main-sequence stars or brown dwarfs, which were indeed expected as the main contaminants of this exploratory search. The lack of quasar detection is not surprising: the estimated probability of finding a single z > 6 quasar down to the limit of UKIDSS in 27.3 deg^2 of the EDR is <5%. We find that the most important limiting factor in this work is the depth of the available optical data. Experience gained in this pilot project can help refine high-redshift quasar selection criteria for subsequent UKIDSS data releases.", "doi": "10.1088/0004-6256/136/3/954", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2008-09", "series_number": "3", "volume": "136", "issue": "3", "pages": "954-962" }, { "id": "authors:p2sej-9cz54", "collection": "authors", "collection_id": "p2sej-9cz54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:FUEaanda08", "type": "article", "title": "Evidence for metallicity spreads in three massive M 31 globular clusters", "author": [ { "family_name": "Fuentes-Carrera", "given_name": "I.", "clpid": "Fuentes-Carrera-I" }, { "family_name": "Jablonka", "given_name": "P.", "clpid": "Jablonka-P" }, { "family_name": "Sarajedini", "given_name": "A.", "clpid": "Sarajedini-A" }, { "family_name": "Bridges", "given_name": "T.", "clpid": "Bridges-T" }, { "family_name": "Djorgovski", "given_name": "G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" } ], "abstract": "Aims. We quantify the intrinsic width of the red giant branches of three massive globular clusters in M 31 in a search for metallicity spreads within these objects. \n\nMethods. We present HST/ACS observations of three massive clusters in M 31, G78, G213, and G280. A thorough description of the photometry extraction and calibration is presented. After derivation of the color-magnitude diagrams, we quantify the intrinsic width of the red giant branch of each cluster. \n\nResults. This width translates into a metallicity dispersion that indicates a complex star formation history for this type of system. For G78, \u03c3[Fe/H] = 0.86 \u00b1 0.37; for G213, 0.89 \u00b1 0.20; and for G280, 1.03 \u00b1 0.26. We find that the metallicity dispersion of the clusters does not scale with mean metallicity. We also find no trend with the cluster mass. We discuss some possible formation scenarios that would explain our results.", "doi": "10.1051/0004-6361:20078899", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2008-06", "series_number": "3", "volume": "483", "issue": "3", "pages": "769-781" }, { "id": "authors:1fb1h-2vr19", "collection": "authors", "collection_id": "1fb1h-2vr19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DALapj08", "type": "article", "title": "Improved constraints on the acceleration history of the Universe and the properties of the dark energy", "author": [ { "family_name": "Daly", "given_name": "Ruth A.", "clpid": "Daly-R-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Freeman", "given_name": "Kenneth A.", "clpid": "Freeman-K-A" }, { "family_name": "Mory", "given_name": "Matthew P.", "clpid": "Mory-M-P" }, { "family_name": "O'Dea", "given_name": "C. P.", "orcid": "0000-0001-6421-054X", "clpid": "O'Dea-C-P" }, { "family_name": "Kharb", "given_name": "P.", "orcid": "0000-0003-3203-1613", "clpid": "Kharb-P" }, { "family_name": "Baum", "given_name": "S.", "clpid": "Baum-S" } ], "abstract": "We extend and apply a model-independent analysis method developed earlier by Daly & Djorgovski to new supernova, radio galaxy, and galaxy cluster samples to study the acceleration history of the universe and the properties of the dark energy. There is good agreement between results obtained with radio galaxies and supernovae, suggesting that both distance indicators are reliable. The deceleration parameter q(z) is obtained assuming only the validity of the FRW metric, allowing for a range of values of space curvature, and independent of a gravity theory and the physical nature of the contents of the universe. We show that q_0 is independent of space curvature, and obtain q_0 = \u2212 0.48 \u00b1 0.11. The transition redshift when q0 = 0 is z_T = 0.78(^+0.08)_(\u22120.27) for zero space curvature, and has a weak dependence on space curvature. We find good agreement between model-independent quantities and those predicted by general relativity, indicating that GR provides a good description of the data over look-back times of ten billion years.", "doi": "10.1086/528837", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2008-04-10", "series_number": "1", "volume": "677", "issue": "1", "pages": "1-11" }, { "id": "authors:wh4kr-w6d16", "collection": "authors", "collection_id": "wh4kr-w6d16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100721-115108366", "type": "article", "title": "The Palomar-Quest digital synoptic sky survey", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Baltay", "given_name": "C.", "clpid": "Baltay-C" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Rabinowitz", "given_name": "D.", "clpid": "Rabinowitz-D" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Bauer", "given_name": "A.", "clpid": "Bauer-A" }, { "family_name": "Scalzo", "given_name": "R.", "clpid": "Scalzo-R" }, { "family_name": "Ellman", "given_name": "N.", "clpid": "Ellman-N" }, { "family_name": "Jerke", "given_name": "J.", "clpid": "Jerke-J" } ], "abstract": "We describe briefly the Palomar-Quest (PQ) digital synoptic sky survey, including its parameters, data processing, status, and plans. Exploration of the time domain is now the central scientific and technological focus of the survey. To this end, we have developed a real-time pipeline for detection of transient sources.We describe some of the early results, and lessons learned which may be useful for other, similar projects, and time-domain astronomy in general. Finally, we discuss some issues and challenges posed by the real-time analysis and scientific exploitation of massive data streams from modern synoptic sky surveys.", "doi": "10.1002/asna.200710948", "issn": "0004-6337", "publisher": "Wiley", "publication": "Astronomische Nachrichten", "publication_date": "2008-03", "series_number": "3", "volume": "329", "issue": "3", "pages": "263-265" }, { "id": "authors:w69n0-04f63", "collection": "authors", "collection_id": "w69n0-04f63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100722-100956038", "type": "article", "title": "Automated probabilistic classification of transients and variables", "author": [ { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Turmon", "given_name": "M.", "orcid": "0000-0002-6463-063X", "clpid": "Turmon-M" }, { "family_name": "Jewell", "given_name": "J.", "clpid": "Jewell-Jeffrey-B" }, { "family_name": "Williams", "given_name": "R. R.", "clpid": "Williams-R-R" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. G.", "clpid": "Graham-M-G" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "literal": "Palomar-QUEST team" } ], "abstract": "There is an increasing number of large, digital, synoptic sky surveys, in which repeated observations are obtained over large areas of the sky in multiple epochs. Likewise, there is a growth in the number of (often automated or robotic) follow-up facilities with varied capabilities in terms of instruments, depth, cadence, wavelengths, etc., most of which are geared toward some specific astrophysical phenomenon. As the number of detected transient events grows, an automated, probabilistic classification of the detected variables and transients becomes increasingly important, so that an optimal use can be made of follow-up facilities, without unnecessary duplication of effort. We describe a methodology now under development for a prototype event classification system; it involves Bayesian and Machine Learning classifiers, automated incorporation of feedback from follow-up observations, and discriminated or directed follow-up requests. This type of methodology may be essential for the massive synoptic sky surveys in the future.", "doi": "10.1002/asna.200710943", "issn": "0004-6337", "publisher": "Wiley", "publication": "Astronomische Nachrichten", "publication_date": "2008-03", "series_number": "3", "volume": "329", "issue": "3", "pages": "288-291" }, { "id": "authors:vdbb6-pvf95", "collection": "authors", "collection_id": "vdbb6-pvf95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100909-134647174", "type": "article", "title": "A nearly model-independent characterization of dark energy properties as a function of redshift", "author": [ { "family_name": "Daly", "given_name": "Ruth A.", "clpid": "Daly-R-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Understanding the acceleration of the universe and its cause is one of the key problems in physics and cosmology\ntoday, and is best studied using a variety of mutually complementary approaches. Daly and Djorgovski (2003,\n2004) proposed a model independent approach to determine the expansion and acceleration history of the universe\nand a number of important physical parameters of the dark energy as functions of redshift directly from the data.\nHere, we apply the method to explicitly determine the first and second derivatives of the coordinate distance with\nrespect to redshift, y' and y\", and combine them to solve for the kinetic and potential energy density of the dark\nenergy as functions of redshift, K(z) and V(z).\nA data set of 228 supernova and 20 radio galaxy measurements with redshifts from zero to 1.79 is used for this\nstudy. Values of y' and y\" are combined to study the dimensionless acceleration rate of the universe as a function\nof redshift, q(z). The only assumptions underlying our determination of q(z) are that the universe is described\nby a Robertson-Walker (RW) metric and is spatially flat. We find that the universe is accelerating today, and\nwas decelerating in the recent past. The transition from acceleration to deceleration occurs at a redshift of about\nZ_T = 0.42 \u00b1 ^(0.08)_(0.06). Values of y' and y\" are combined to determine K(z) and V(z). These are shown to be consistent\nwith the values expected in a standard Lambda Cold Dark Matter (LCDM) model.", "doi": "10.1016/j.nuclphysbps.2007.08.024", "issn": "0920-5632", "publisher": "Elsevier", "publication": "Nuclear Physics B - Proceedings Supplements", "publication_date": "2007-11", "volume": "173", "pages": "19-23" }, { "id": "authors:72kc9-kwa54", "collection": "authors", "collection_id": "72kc9-kwa54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100909-150310515", "type": "article", "title": "Dark Energy From Vacuum Fluctuations", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gurzadyan", "given_name": "V. G.", "clpid": "Gurzadyan-V-G" } ], "abstract": "We describe briefly a novel interpretation of the physical nature of dark energy (DE), based on the vacuum fluctuations\nmodel by Gurzadyan & Xue, and describe an internally consistent solution for the behavor of DE as a function of redshift. A\nkey choice is the nature of the upper bound used for the computation of energy density contributions by vacuum modes. We\nshow that use of the comoving horizon radius produces a viable model, whereas use of the proper horizon radius is\ninconsistent with the observations. After introduction of a single phenomenological parameter, the model is consistent with\nall of the curently available data, and fits them as well as the standard cosmological constant model, while making testable\npredictions. While some substantial interpretative uncertainties remain, future developments of this model may lead to\nsignificant new insights into the physical nature of DE.", "doi": "10.1016/j.nuclphysbps.2007.08.056", "issn": "0920-5632", "publisher": "Elsevier", "publication": "Nuclear Physics B - Proceedings Supplements", "publication_date": "2007-11", "volume": "173", "pages": "6-10" }, { "id": "authors:y4h2e-6kb43", "collection": "authors", "collection_id": "y4h2e-6kb43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DALaipcp07", "type": "book_section", "title": "The Acceleration History of the Universe and the Properties of the Dark Energy", "book_title": "Supernova 1987A: 20 Years after Supernovae and Gamma-Ray Bursters, Aspen, CO, 19-23 February 2007", "author": [ { "family_name": "Daly", "given_name": "Ruth A.", "clpid": "Daly-R-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Immler", "given_name": "Stefan" }, { "family_name": "Weiler", "given_name": "Kurt" }, { "family_name": "McCray", "given_name": "Richard" } ], "abstract": "The model-independent method of using type Ia supernovae proposed and developed by Daly & Djorgovski (2003, 2004) has been applied to the Riess et al. (2007) supernovae sample. Assuming only a Robertson-Walker metric, we find q0 = \u22120.5\u00b10.13, indicating that the universe is accelerating today. This result is purely kinematic, is independent of the contents of the universe, and does not require that a theory of gravity be specified. Our model-independent method allows a determination of q(z) for a particular value of space curvature. When q(z) transitions from negative to positive values, the universe transitions from an accelerating to a decelerating state. For zero space curvature, we find that the universe transitions from acceleration to deceleration at a zedshift of about zT = 0.35-0.7+0.15 for the Riess et al. (2007) sample.If a theory of gravity is specified, the supernovae data can be used to determine the pressure, energy density, and equation of state of the dark energy, and the potential and kinetic energy density of a dark energy scalar field as functions of redshift. The relevant equations from General Relativity are applied, and these functions are obtained. The results are consistent with predictions in the standard Lambda Cold Dark Matter model at about the two sigma level.", "doi": "10.1063/1.2803581", "isbn": "978-0-7354-0448-9", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2007-10-02", "pages": "298-302" }, { "id": "authors:4y0k2-3pw67", "collection": "authors", "collection_id": "4y0k2-3pw67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091020-090102382", "type": "article", "title": "The peculiar horizontal branch morphology of the Galactic globular clusters NGC 6388 and NGC 6441: new insights from UV observations", "author": [ { "family_name": "Busso", "given_name": "G.", "clpid": "Busso-G" }, { "family_name": "Cassisi", "given_name": "S.", "clpid": "Cassisi-S" }, { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" }, { "family_name": "Castellani", "given_name": "M.", "clpid": "Castellani-M" }, { "family_name": "Romaniello", "given_name": "M.", "clpid": "Romaniello-M" }, { "family_name": "Catelan", "given_name": "M.", "orcid": "0000-0001-6003-8877", "clpid": "Catelan-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Recio Blanco", "given_name": "A.", "clpid": "Recio-Blanco-A" }, { "family_name": "Renzini", "given_name": "A.", "orcid": "0000-0002-7093-7355", "clpid": "Renzini-A" } ], "abstract": "Context. In this paper we present multiband optical and UV Hubble Space Telescope photometry of the two Galactic globular clusters NGC 6388 and NGC 6441.\n\nAims. We investigate the properties of their anomalous horizontal branches in different photometric planes in order to shed light on the nature of the physical mechanism(s) responsible for the existence of an extended blue tail and of a slope in the horizontal branch, visible in all the color-magnitude diagrams.\n\nMethods. New photometric data have been collected and carefully reduced. Empirical data have been compared with updated stellar models of low-mass, metal-rich, He-burning structures, transformed to the observational plane with appropriate model atmospheres.\n\nResults. We have obtained the first UV color-magnitude diagrams for NGC 6388 and NGC 6441. These diagrams confirm previous results, obtained in optical bands, about the presence of a sizeable stellar population of extremely hot horizontal branch stars. At least in NGC 6388, we find a clear indication that at the hot end of the horizontal branch the distribution of stars forms a hook-like feature, closely resembling those observed in NGC 2808 and Omega Cen. We briefly review the theoretical scenarios that have been suggested for interpreting this observational feature. We also investigate the tilted horizontal branch morphology and provide further evidence that supports early suggestions that this feature cannot be interpreted as an effect of differential reddening. We show that a possible solution of the puzzle is to assume that a small fraction - ranging between 10-20% - of the stellar population in the two clusters is strongly helium-enriched (Y ~ 0.40 in NGC 6388 and Y ~ 0.35 in NGC 6441). The occurrence of a spread in the He abundance between the canonical value (Y ~ 0.26) and the quoted upper limits can significantly help in explaining the \"whole\" morphology of the horizontal branch and the pulsational properties of the variable stars in the target clusters.", "doi": "10.1051/0004-6361:20077806", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2007-10", "series_number": "1", "volume": "474", "issue": "1", "pages": "105-119" }, { "id": "authors:wz2bk-6a741", "collection": "authors", "collection_id": "wz2bk-6a741", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091016-151324786", "type": "article", "title": "Hubble Space Telescope and Spitzer Observations of the Afterglow and Host Galaxy of GRB 050904 at z = 6.295", "author": [ { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Chary", "given_name": "R.", "orcid": "0000-0001-7583-0621", "clpid": "Chary-R-R" }, { "family_name": "Cowie", "given_name": "L. L.", "orcid": "0000-0002-6319-1575", "clpid": "Cowie-L-L" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Fox", "given_name": "D. B.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Cenko", "given_name": "S. B.", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Soderberg", "given_name": "A. M.", "clpid": "Soderberg-A-M" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "McCarthy", "given_name": "P. J.", "clpid": "McCarthy-P-J" }, { "family_name": "Gladders", "given_name": "M. D.", "clpid": "Gladders-M-D" }, { "family_name": "Peterson", "given_name": "B. A.", "clpid": "Peterson-B-A" }, { "family_name": "Barger", "given_name": "A. J.", "orcid": "0000-0002-3306-1606", "clpid": "Barger-A-J" } ], "abstract": "We present deep Hubble Space Telescope (HST ) and Spitzer Space Telescope observations of GRB 050904 at z = 6:295. We detect the afterglow in the H band more than 3 weeks after the burst and confirm the presence of a jet break at t \u2248 2:1 days. This leads to an estimated opening angle of about 4\u00b0 and a beaming-corrected energy of about 10^(51) ergs, similar to those of lower redshift gamma-ray bursts (GRBs). We do not detect an underlying host galaxy with either HST or Spitzer. From the upper limits we infer an extinction-corrected absolute magnitude M_(UV) \u2273 -20:3 mag, or L \u227e L^*, a star formation rate of \u227e 5.7M_\u2299 yr^(-1), and a stellar mass of \u227e few x 10^9 M_\u2299. A comparison to spectroscopically confirmed galaxies at z > 5:5 reveals that the host of GRB 050904 is fainter and has a lower star formation rate than at least 80% of these objects. Finally, using our luminosity limits, and the metallicity of about 0.05 Z_\u2299 inferred from the afterglow absorption spectrum, we place the first limit on the luminosity-metallicity relation at z > 6. Future afterglow and host galaxy observations of z \u2273 4 GRBs should elucidate whether the mass- and luminosity-metallicity relations continue to evolve beyond the present limits of z \u227e 2.", "doi": "10.1086/519511", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2007-08-10", "series_number": "1", "volume": "665", "issue": "1", "pages": "102-106" }, { "id": "authors:1nr2k-8ys76", "collection": "authors", "collection_id": "1nr2k-8ys76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090409-153118437", "type": "article", "title": "Discovery of two spectroscopically peculiar, low-luminosity quasars at z ~ 4", "author": [ { "family_name": "Glikman", "given_name": "Eilat", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "Daniel", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Bogosavljevi\u0107", "given_name": "Milan", "clpid": "Bogosavljevi\u0107-M" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "We report the discovery of two low-luminosity quasars at z ~ 4, both of which show prominent N iv] \u03bb1486 emission. This line is extremely rare in quasar spectra at any redshift; detecting it in two of a sample of 23 objects\n(i.e., ~9% of the sample) is intriguing and is likely due to the low-luminosity, high-redshift quasar sample we are\nstudying. This is still a poorly explored regime, where contributions from associated, early starbursts may be significant. One interpretation of this line posits photoionization by very massive young stars. Seeing N iv] \u03bb1486 emission in a high-redshift quasar may thus be understood in the context of coformation and early coevolution of galaxies and their supermassive black holes. Alternatively, we may be seeing a phenomenon related to the early evolution of quasar broad emission line regions. The nondetection (and possibly even broad absorption) of N v \u03bb1240 line in the spectrum of one of these quasars may support that interpretation. These two objects may signal a new faint quasar population or an early AGN evolutionary stage at high redshifts.", "doi": "10.1086/520085", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2007-07-10", "series_number": "2", "volume": "663", "issue": "2", "pages": "L73-L76" }, { "id": "authors:7xryf-zrr77", "collection": "authors", "collection_id": "7xryf-zrr77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091113-105347141", "type": "article", "title": "Discovery of a Probable Physical Triple Quasar", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Courbin", "given_name": "F.", "clpid": "Courbin-F" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Sluse", "given_name": "D.", "orcid": "0000-0001-6116-2095", "clpid": "Sluse-D" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" } ], "abstract": "We report the discovery of the first known probable case of a physical triple quasar. A previously known double system, QQ 1429-008 at z = 2.076, is shown to contain a third, fainter QSO component at the same redshift. Deep optical and IR imaging has failed to reveal a plausible lensing galaxy group or a cluster, and we are unable to construct any viable lensing model that could lead to the observed distribution of source positions and relative intensities of the three QSO image components. There are also hints of differences in the broadband spectral energy distributions of the different components, which are more naturally understood if they are physically distinct active galactic nuclei (AGNs). Therefore, we conclude that this system is most likely a physical triple quasar, the first such close QSO grouping known at any redshift. The projected component separations are ~30-50 kpc, typical of interacting galaxy systems. The existence of this highly unusual system supports the standard picture in which galaxy interactions lead to the onset of QSO activity.", "doi": "10.1086/519162", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2007-06-10", "series_number": "1", "volume": "662", "issue": "1", "pages": "L1-L5" }, { "id": "authors:x1fzm-30t34", "collection": "authors", "collection_id": "x1fzm-30t34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:GUImnras07", "type": "article", "title": "Evidence for overdensity around z_(em) > 4 quasars from the proximity effect", "author": [ { "family_name": "Guimar\u00e3es", "given_name": "R.", "clpid": "Guimar\u00e3es-R" }, { "family_name": "Petitjean", "given_name": "P.", "clpid": "Petitjean-P" }, { "family_name": "Rollinde", "given_name": "E.", "clpid": "Rollinde-E" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Srianand", "given_name": "R.", "clpid": "Srianand-R" }, { "family_name": "Aghaee", "given_name": "A.", "clpid": "Aghaee-A" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" } ], "abstract": "We study the density field around z_(em) > 4 quasars using high-quality medium spectral resolution Echelle Spectrograph and Imager\u2013Keck spectra ( R\u223c 4300 , signal-to-noise ratio (S/N) > 25) of 45 high-redshift quasars selected from a total of 95 spectra. This large sample considerably increases the statistics compared to previous studies. The redshift evolution of the mean photoionization rate and the median optical depth of the intergalactic medium (IGM) are derived statistically from the observed transmitted flux and the pixel optical depth probability distribution function, respectively. This is used to study the so-called proximity effect, that is, the observed decrease of the median optical depth of the IGM in the vicinity of the quasar caused by enhanced photoionization rate due to photons emitted by the quasar. We show that the proximity effect is correlated with the luminosity of the quasars, as expected. By comparing the observed decrease of the median optical depth with the theoretical expectation, we find that the optical depth does not decrease as rapidly as expected when approaching the quasar if the gas in its vicinity is part of the standard IGM. We interpret this effect as revealing gaseous overdensities on scales as large as \u223c15 h^(\u22121) Mpc. The mean overdensity is of the order of 2 and 5 within, respectively, 10 and 3 h^(\u22121) Mpc. If true, this would indicate that high-redshift quasars are located in the centre of overdense regions that could evolve with time into massive clusters of galaxies. The overdensity is correlated with luminosity: brighter quasars show higher overdensities.", "doi": "10.1111/j.1365-2966.2007.11624.x", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2007-05-11", "series_number": "2", "volume": "377", "issue": "2", "pages": "657-666" }, { "id": "authors:rfpy0-4cz14", "collection": "authors", "collection_id": "rfpy0-4cz14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091019-104150426", "type": "article", "title": "The ERO Host Galaxy of GRB 020127: Implications for the Metallicity of GRB Progenitors", "author": [ { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Fox", "given_name": "D. B.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present optical and near-IR observations of the host galaxy of GRB 020127, for which we measure R - K_s = 6.2 mag. This is only the second GRB host to date classified as an ERO. The spectral energy distribution (SED) is typical of a dusty starburst galaxy, with a redshift z \u2248 1.9, a luminosity L \u2248 5L^*, and an inferred stellar mass of M_* ~ 10^(11)-10^(12) M_\u2299, two orders of magnitude more massive than typical GRB hosts. A comparison to the z ~ 2 mass-metallicity (M-Z) relation suggests that the host metallicity is about 0.5-1Z_\u2299. This result shows that at least some GRBs occur in massive, metal-enriched galaxies, and that the proposed low-metallicity bias of GRB progenitors is not as severe as previously claimed. Instead, we propose that the blue colors and sub-L^* luminosities of most GRB hosts reflect their young starburst populations. This explanation also accounts for the prevalence of low-redshift GRBs in low-mass galaxies, since star formation activity shifts from high- to low-mass galaxies as a function of decreasing redshift (\"downsizing\"). Thus, the low-metallicity bias claimed for z \u227e 0.2 GRB hosts is likely a secondary effect, which reflects the M-Z relation, and consequently GRBs and their hosts may serve as a reliable tracer of cosmic star formation activity.", "doi": "10.1086/513007", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2007-05-01", "series_number": "1", "volume": "660", "issue": "1", "pages": "504-508" }, { "id": "authors:y34ss-sdh52", "collection": "authors", "collection_id": "y34ss-sdh52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:COHaj07", "type": "article", "title": "Integrated-light Two Micron All Sky Survey infrared photometry of Galactic globular clusters", "author": [ { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "Hsieh", "given_name": "Scott", "clpid": "Hsieh-Scott" }, { "family_name": "Metchev", "given_name": "Stanimir", "orcid": "0000-0003-3050-8203", "clpid": "Metchev-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Malkan", "given_name": "M.", "orcid": "0000-0001-6919-1237", "clpid": "Malkan-M" } ], "abstract": "We have mosaicked Two Micron All Sky Survey (2MASS) images to derive surface brightness profiles in J, H, and K_s for 104 Galactic globular clusters. We fit these with King profiles and show that the core radii are identical to within the errors for each of these IR colors and are identical to the core radii at V in essentially all cases. We derive integrated-light colors V-J, V-H, V-K_s, J-H, and J-Ks for these globular clusters. Each color shows a reasonably tight relation between the dereddened colors and metallicity. Fits to these are given for each color. The IR-IR colors have very small errors, due largely to the all-sky photometric calibration of the 2MASS survey, while the V-IR colors have substantially larger uncertainties. We find fairly good agreement with measurements of integrated-light colors for a smaller sample of Galactic globular clusters by M. Aaronson, M. Malkan, and D. Kleinmann from 1977. Our results provide a calibration for the integrated light of distant single-burst old stellar populations from very low to solar metallicities. A comparison of our dereddened measured colors with predictions from several models of the integrated light of single-burst old populations shows good agreement in the low-metallicity domain for V-K_s colors but also shows an offset at a fixed [Fe/H] of ~0.1 mag in J-K_s, which we ascribe to photometric system transformation issues. Some of the models fail to reproduce the behavior of the integrated-light colors of the Galactic globular clusters near solar metallicity.", "doi": "10.1086/509127", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2007-01", "series_number": "1", "volume": "133", "issue": "1", "pages": "99-121" }, { "id": "authors:4e9kp-14y78", "collection": "authors", "collection_id": "4e9kp-14y78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110210-090345699", "type": "book_section", "title": "Some Pattern Recognition Challenges in Data-Intensive Astronomy", "book_title": "The18th International Conference on Pattern Recognition", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Donalek", "given_name": "C.", "clpid": "Donalek-C" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Drake", "given_name": "A. J.", "clpid": "Drake-A-J" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Glikman", "given_name": "E.", "orcid": "0000-0003-0489-3750", "clpid": "Glikman-E" } ], "abstract": "We review some of the recent developments and\nchallenges posed by the data analysis in modern\ndigital sky surveys, which are representative of the\ninformation-rich astronomy in the context of Virtual\nObservatory. Illustrative examples include the\nproblems of an automated star-galaxy classification\nin complex and heterogeneous panoramic imaging\ndata sets, and an automated, iterative, dynamical\nclassification of transient events detected in synoptic\nsky surveys. These problems offer good opportunities\nfor productive collaborations between astronomers\nand applied computer scientists and statisticians, and\nare representative of the kind of challenges now\npresent in all data-intensive fields. We discuss briefly\nsome emergent types of scalable scientific data\nanalysis systems with a broad applicability.", "doi": "10.1109/ICPR.2006.1064", "isbn": "0-7695-2521-0", "publisher": "IEEE", "place_of_publication": "Los Alamitos, CA", "publication_date": "2006-09-18", "pages": "856-863" }, { "id": "authors:szbzg-s2w11", "collection": "authors", "collection_id": "szbzg-s2w11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110721-100440243", "type": "article", "title": "X-Ray Galaxy Clusters in NoSOCS: Substructure and the Correlation of Optical and X-Ray Properties", "author": [ { "family_name": "Lopes", "given_name": "P. A. A.", "clpid": "Lopes-P-A-A" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Capelato", "given_name": "H. V.", "clpid": "Capelato-H-V" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Brunner", "given_name": "R. J.", "clpid": "Brunner-R-J" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "We present a comparison of optical and X-ray properties of galaxy clusters in the northern sky, using literature data from BAX and optically selected clusters in DPOSS. We determine the recovery rate of X-ray-detected clusters in the optical as a function of richness, redshift, and X-ray luminosity, showing that the missed clusters are typically low-contrast systems when observed optically (either poor or at high redshifts). We employ four different statistical tests to test for the presence of substructure using optical two-dimensional data. We find that approximately 35% of the clusters show strong signs of substructure in the optical. However, the results are test-dependent, with variations also due to the magnitude range and radius utilized. We have also performed a comparison of X-ray luminosity and temperature with optical galaxy counts (richness). We find that the slope and scatter of the relations between richness and the X-ray properties are heavily dependent on the density contrast of the clusters. The selection of substructure-free systems does not improve the correlation between X-ray luminosity and richness, but this comparison also shows much larger scatter than one obtained using the X-ray temperature. In the latter case, the sample is significantly reduced because temperature measurements are available only for the most massive (and thus high-contrast) systems. However, the comparison between temperature and richness is very sensitive to the exclusion of clusters showing signs of substructure. The correlation of X-ray luminosity and richness is based on the largest sample to date (~750 clusters), while tests involving temperature use a similar number of objects as previous works (\u227e100). The results presented here are in good agreement with existing literature.", "doi": "10.1086/505630", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2006-09-01", "series_number": "1", "volume": "648", "issue": "1", "pages": "209-229" }, { "id": "authors:5f9ea-ak914", "collection": "authors", "collection_id": "5f9ea-ak914", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100319-102726492", "type": "article", "title": "Multivariate analysis of globular cluster horizontal branch morphology: searching for the second parameter", "author": [ { "family_name": "Recio-Blanco", "given_name": "A.", "clpid": "Recio-Blanco-A" }, { "family_name": "Aparicio", "given_name": "A.", "clpid": "Aparicio-A" }, { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" }, { "family_name": "De Angeli", "given_name": "F.", "clpid": "De-Angeli-F" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Aims. The interpretation of globular cluster horizontal branch (HB) morphology is a classical problem that can significantly blur our understanding of stellar populations.\nMethods. We present a new multivariate analysis connecting the effective temperature extent of the HB with other cluster parameters. The work is based on Hubble Space Telescope photometry of 54 Galactic globular clusters.\nResults. The present study reveals the important role of the total mass of the globular cluster on its HB morphology. More massive clusters tend to have HBs more extended to higher temperatures. For a set of three input variables including the temperature extension of the HB, [Fe/H] and M_V, the first two eigenvectors account for 90% of the total sample variance.\nConclusions. Possible effects of cluster self-pollution on HB morphology, stronger in more massive clusters, could explain the results derived here.", "doi": "10.1051/0004-6361:20053006", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2006-06-04", "series_number": "3", "volume": "452", "issue": "3", "pages": "875-884" }, { "id": "authors:jgqe4-zxe92", "collection": "authors", "collection_id": "jgqe4-zxe92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110228-090446023", "type": "article", "title": "Quasars as probes of late reionization and early structure formation", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bogosavljevic", "given_name": "M.", "clpid": "Bogosavljevic-M" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "Observations of QSOs at z ~ 5.7\u20136.4 show the appearance of Gunn\u2013Peterson troughs around z ~ 6, and a change in the slope of the IGM optical depth \u03c4(z) near z ~ 5.5. These results are interpreted as a signature of the end of the reionization era, which probably started at considerably higher redshifts. However, there also appears to be a substantial cosmic variance in the transmission of the IGM, both along some lines of sight, and among different lines of sight, in this intriguing redshift regime. We suggest that this is indicative of a spatially uneven reionization, possibly caused by the bias-driven primordial clustering of the reionization sources. There is also some independent evidence for a strong clustering of QSOs at z ~ 4\u20135 and galaxies around them, supporting the idea of the strong biasing of the first luminous sources at these redshifts. Larger samples of high-z QSOs are needed in order to provide improved, statistically significant constraints for the models of these phenomena. We expect that the Palomar-Quest (PQ) survey will soon provide a new set of QSOs to be used as cosmological probes in this redshift regime.", "doi": "10.1016/j.newar.2005.11.015", "issn": "1387-6473", "publisher": "Elsevier", "publication": "New Astronomy Reviews", "publication_date": "2006-03", "series_number": "1-3", "volume": "50", "issue": "1-3", "pages": "140-145" }, { "id": "authors:kbzb2-wpc32", "collection": "authors", "collection_id": "kbzb2-wpc32", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2005.115", "type": "book_section", "title": "Virtual Astronomy, Information Technology, and the New Scientific Methodology", "book_title": "Seventh International Workshop on Computer Architecture for Machine Perception (CAMP'05)", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Di Gesu", "given_name": "V.", "clpid": "Di-Gesu-V" }, { "family_name": "Tegolo", "given_name": "D.", "clpid": "Tegolo-D" } ], "abstract": "All sciences, including astronomy, are now entering the era of information abundance. The exponentially increasing volume and complexity of modern data sets promises to transform the scientific practice, but also poses a number of common technological challenges. The Virtual Observatory concept is the astronomical community's response to these challenges: it aims to harness the progress in information technology in the service of astronomy, and at the same time provide a valuable testbed for information technology and applied computer science. Challenges broadly fall into two categories: data handling (or \"data farming\"), including issues such as archives, intelligent storage, databases, interoperability, fast networks, etc., and data mining, data understanding, and knowledge discovery, which include issues such as automated clustering and classification, multivariate correlation searches, pattern recognition, visualization in highly hyperdimensional parameter spaces, etc., as well as various applications of machine learning in these contexts. Such techniques are forming a methodological foundation for science with massive and complex data sets in general, and are likely to have a much broather impact on the modern society, commerce, information economy, security, etc. There is a powerful emerging synergy between the\ncomputationally enabled science and the science-driven computing, which will drive the progress in science, scholarship, and many other venues in the 21st century.", "doi": "10.1109/CAMP.2005.53", "isbn": "0-7695-2255-6", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2005-07", "pages": "125-132" }, { "id": "authors:wfh33-w9f25", "collection": "authors", "collection_id": "wfh33-w9f25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-133357882", "type": "article", "title": "Morphology of low-redshift compact galaxy clusters -- I. Shapes and radial profiles", "author": [ { "family_name": "Strazzullo", "given_name": "V.", "clpid": "Strazzullo-V" }, { "family_name": "Paolillo", "given_name": "M.", "orcid": "0000-0003-4210-7693", "clpid": "Paolillo-M" }, { "family_name": "Longo", "given_name": "G.", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" }, { "family_name": "Puddu", "given_name": "E.", "clpid": "Puddu-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" } ], "abstract": "The morphology of clusters of galaxies may be described with a set of parameters which contain information concerning the formation and evolutionary history of these systems. In this paper we present a preliminary study of the morphological parameters of a sample of 28 compact Abell clusters extracted from Digitized Palomar Sky Survey data, measured with a procedure based on the use of the CIAO-SHERPA software, developed at the Centre for Astrophysics for X-ray data analysis. The morphology of galaxy clusters is parametrized by their apparent ellipticity, position angle of the major axis, centre coordinates, core radius and \u03b2-model power-law index. Our procedure provides estimates of these parameters (and of the related uncertainties) by simultaneously fitting them all, overcoming some of the difficulties induced by sparse data and low-number statistics typical of this kind of analysis. The cluster parameters were fitted in a 6 \u00d7 6 Mpc^2 region, measuring the background in a 4 < R < 5 Mpc annulus. We also explore the correlations between shape and profile parameters and other cluster properties. Our results can be summarized as follows: one-third of this compact cluster sample has core radii smaller than 100 kpc, i.e. near the limit that our data allow us to resolve, possibly consistent with cusped models. The remaining clusters span a broad range of core radii up to \u223c1500 kpc, including some apparently regular clusters with well-resolved core radii. More than 80 per cent of this sample has ellipticity higher than 0.2. The alignment between the cluster and the major axis of the dominant galaxy is confirmed at a high significance level, while no correlation is observed with other bright cluster members. No significant correlation is found between cluster richness and ellipticity. Instead, cluster richness is found to correlate, albeit with large scatter, with the cluster core radius. Finally, in contrast to claims in previous works, a flat universe seems to be favoured, and in any case is not excluded, by the power-law index \u03b2 of our number density profiles.", "doi": "10.1111/j.1365-2966.2005.08880.x", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2005-05-01", "series_number": "1", "volume": "359", "issue": "1", "pages": "191-210" }, { "id": "authors:aev5t-bar32", "collection": "authors", "collection_id": "aev5t-bar32", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2005.114", "type": "monograph", "title": "Virtual Observatory: From Concept to Implementation", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" } ], "abstract": "We review the origins of the Virtual Observatory (VO) concept, and the current status of the efforts in this field. VO is the response of the astronomical community to the challenges posed by the modern massive and complex data sets. It is a framework in which information technology is harnessed to organize, maintain, and explore the rich information content of the exponentially growing data sets, and to enable a qualitatively new science to be done with them. VO will become a complete, open, distributed, web-based framework for astronomy of the early 21st century. A number of significant efforts worldwide are now striving to convert this vision into reality. The technological and methodological challenges posed by the information-rich astronomy are also common to many other fields. We see a fundamental change in the way all science is done, driven by the information technology revolution.", "doi": "10.48550/arXiv.0504006", "publication_date": "2005-04-01" }, { "id": "authors:19j6v-4my77", "collection": "authors", "collection_id": "19j6v-4my77", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2005.118", "type": "book_section", "title": "Grist: Grid-based Data Mining for Astronomy", "author": [ { "family_name": "Jacob", "given_name": "Joseph C.", "clpid": "Jacob-J-C" }, { "family_name": "Katz", "given_name": "Daniel S.", "clpid": "Katz-D-S" }, { "family_name": "Miller", "given_name": "Craig D.", "clpid": "Miller-C-D" }, { "family_name": "Walia", "given_name": "Harshpreet", "clpid": "Walia-H" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Babu", "given_name": "Jogesh", "clpid": "Babu-J" }, { "family_name": "Vanden Berk", "given_name": "Daniel E.", "clpid": "Vanden-Berk-D-E" }, { "family_name": "Nichol", "given_name": "Robert", "clpid": "Nichol-R" } ], "contributor": [ { "family_name": "Shopbell", "given_name": "P. L.", "clpid": "Shopbell-P-L" }, { "family_name": "Britton", "given_name": "M. C.", "clpid": "Britton-M-C" }, { "family_name": "Ebert", "given_name": "R.", "clpid": "Ebert-R-J" } ], "abstract": "The Grist project is developing a grid-technology based system as a research environment for astronomy with massive and complex datasets. This knowledge extraction system will consist of a library of distributed grid services controlled by a work ow system, compliant with standards emerging from the grid computing, web services, and virtual observatory communities. This new technology is being used to find high redshift quasars, study peculiar variable objects, search for transients in real time, and fit SDSS QSO spectra to measure black hole masses. Grist services are also a component of the \"hyperatlas\" project to serve high-resolution multi-wavelength imagery over the Internet. In support of these science and outreach objectives, the Grist framework will provide the enabling fabric to tie together distributed grid services in the areas of data access, federation, mining, subsetting, source extraction, image mosaicking, statistics, and visualization.", "publisher": "Astronomical Society of the Pacific", "publication_date": "2005" }, { "id": "authors:xvytb-mm997", "collection": "authors", "collection_id": "xvytb-mm997", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160818-142549441", "type": "book_section", "title": "Virtual Observatory: From Concept to Implementation", "book_title": "From Clark Lake to the Long Wavelength Array: Bill Erickson's Radio Science", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" } ], "contributor": [ { "family_name": "Kassim", "given_name": "Namir E.", "clpid": "Kassim-Namir-E" }, { "family_name": "Perez", "given_name": "Mario R.", "clpid": "Perez-Mario-R" }, { "family_name": "Junor", "given_name": "William", "clpid": "Junor-William" }, { "family_name": "Henning", "given_name": "Patricia A.", "clpid": "Henning-Patricia-A" } ], "abstract": "We review the origins of the Virtual Observatory (VO) concept, and the current status of the efforts in this field. VO is the response of the astronomical community to the challenges posed by the modern massive and complex data sets. It is a framework in which information technology is harnessed to organize, maintain, and explore the rich information content of the exponentially growing data sets, and to enable a qualitatively new science to be done with them. VO will become a complete, open, distributed, web-based framework for astronomy of the early 21st century. A number of significant efforts worldwide are now striving to convert this vision into reality. The technological and methodological challenges posed by the information-rich astronomy are also common to many other fields. We see a fundamental change in the way all science is done, driven by the information technology revolution.", "isbn": "1-58381-213-X", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2005", "pages": "517-530" }, { "id": "authors:eqggf-nrn19", "collection": "authors", "collection_id": "eqggf-nrn19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110811-102455986", "type": "book_section", "title": "Time Domain Explorations with Digital Sky Surveys", "book_title": "Astronomical Data Analysis Software and Systems XIV", "author": [ { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Kollipara", "given_name": "Priya", "clpid": "Kollipara-P" }, { "family_name": "Granett", "given_name": "Benjamin", "clpid": "Granett-B" }, { "family_name": "Krause", "given_name": "Elisabeth", "clpid": "Krause-E" }, { "family_name": "Williams", "given_name": "Roy D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Bogosavljevic", "given_name": "M.", "clpid": "Bogosavljevic-M" }, { "family_name": "Baltay", "given_name": "C.", "clpid": "Baltay-C" }, { "family_name": "Rabinowitz", "given_name": "D.", "clpid": "Rabinowitz-D" }, { "family_name": "Bauer", "given_name": "A.", "clpid": "Bauer-A" }, { "family_name": "Andrews", "given_name": "P.", "clpid": "Andrews-P" }, { "family_name": "Ellman", "given_name": "N.", "clpid": "Ellman-N" }, { "family_name": "Duffau", "given_name": "S.", "clpid": "Duffau-S" }, { "family_name": "Jerke", "given_name": "J.", "clpid": "Jerke-J" }, { "family_name": "Rengstorf", "given_name": "A.", "clpid": "Rengstorf-A" }, { "family_name": "Brunner", "given_name": "R. J.", "clpid": "Brunner-R-J" }, { "family_name": "Musser", "given_name": "J.", "clpid": "Musser-J" }, { "family_name": "Mufson", "given_name": "S.", "clpid": "Mufson-S" }, { "family_name": "Gebhard", "given_name": "M.", "clpid": "Gebhard-M" } ], "contributor": [ { "family_name": "Shopbell", "given_name": "Patrick L.", "clpid": "Shopbell-P-L" }, { "family_name": "Britton", "given_name": "Matthew C.", "clpid": "Britton-M-C" }, { "family_name": "Ebert", "given_name": "Rick", "clpid": "Ebert-R-J" } ], "abstract": "One of the new frontiers of astronomical research is the exploration of time variability on the sky at different wavelengths and flux levels. We have carried out a pilot project using DPOSS data to study strong variables and transients, and are now extending it to the new Palomar-QUEST synoptic sky survey. We report on our early findings and outline the methodology to be implemented in preparation for a real-time transient detection pipeline. In addition to large numbers of known types of highly variable sources (e.g., SNe, CVs, OVV QSOs, etc.), we expect to find numerous transients whose nature may be established by a rapid follow-up. Whereas we will make all detected variables publicly available through the web, we anticipate that email alerts would be issued in the real time for a subset of events deemed to be the most interesting. This real-time process entails many challenges, in an effort to maintain a high completeness while keeping the contamination low. We will utilize distributed Grid services developed by the GRIST project, and implement a variety of advanced statistical and machine learning techniques.", "isbn": "1-58381-215-6", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2005", "pages": "604-608" }, { "id": "authors:ewy8z-hjt79", "collection": "authors", "collection_id": "ewy8z-hjt79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110810-140105650", "type": "book_section", "title": "VOStat: A Distributed Statistical Toolkit for the Virtual Observatory", "book_title": "Astronomical Data Analysis Software and Systems XIV", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Williams", "given_name": "Roy D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Babu", "given_name": "G. Jogesh", "clpid": "Babu-G-J" }, { "family_name": "Feigelson", "given_name": "Eric D.", "orcid": "0000-0002-5077-6734", "clpid": "Feigelson-E-D" }, { "family_name": "Vanden Berk", "given_name": "Daniel E.", "clpid": "Vanden-Berk-D-E" }, { "family_name": "Nichol", "given_name": "Robert", "clpid": "Nichol-R-C" }, { "family_name": "Wasserman", "given_name": "Larry", "clpid": "Wasserman-L" } ], "contributor": [ { "family_name": "Shopbell", "given_name": "Patrick L.", "clpid": "Shopbell-P-L" }, { "family_name": "Britton", "given_name": "Matthew C.", "clpid": "Britton-M-C" }, { "family_name": "Ebert", "given_name": "Rick", "clpid": "Ebert-R" } ], "abstract": "The nature of astronomical data is changing: data volumes are following Moore's law with a doubling every 18 months and data sets consisting of a billion data vectors in a 100-dimensional parameter space are becoming commonplace. Sophisticated statistical techniques are crucial to fully and efficiently exploit these and maximize the scientific return. A long-standing limitation, however, on the range and capability of such analyses has been the paucity of non-proprietary software.\n\nVOStat is the result of a cross-disciplinary collaboration between astronomers and statisticians to meet these challenges; it is a prototype knowledge-based statistical toolkit implemented within the VO paradigm for the entire astronomical community. VOStat consists of an easily extensible distributed web-based framework transparently accessed via a single science endpoint.\n\nAn exploratory science application is presented to demonstrate some of the functionality currently offered by VOStat.", "isbn": "1-58381-215-6", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2005", "pages": "394-398" }, { "id": "authors:tpzkk-gyg45", "collection": "authors", "collection_id": "tpzkk-gyg45", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2005.117", "type": "book_section", "title": "Time Domain Explorations With Digital Sky Surveys", "author": [ { "family_name": "Mahabal", "given_name": "Ashish A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Kollipara", "given_name": "Priya", "clpid": "Kollipara-P" }, { "family_name": "Granett", "given_name": "Benjamin", "clpid": "Granett-B" }, { "family_name": "Krause", "given_name": "Elisabeth", "clpid": "Krause-E" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R" }, { "family_name": "Bogosavljevic", "given_name": "M.", "clpid": "Bogosavljevic-M" }, { "family_name": "Baltay", "given_name": "C.", "clpid": "Baltay-C" }, { "family_name": "Rabinowitz", "given_name": "D.", "clpid": "Rabinowitz-D" }, { "family_name": "Bauer", "given_name": "A.", "clpid": "Bauer-A" }, { "family_name": "Andrews", "given_name": "P.", "clpid": "Andrews-P" }, { "family_name": "Ellman", "given_name": "N.", "clpid": "Ellman-N" }, { "family_name": "Duffau", "given_name": "S.", "clpid": "Duffau-S" }, { "family_name": "Jerke", "given_name": "J.", "clpid": "Jerke-J" }, { "family_name": "Rengstorf", "given_name": "A.", "clpid": "Rengstorf-A" }, { "family_name": "Brunner", "given_name": "R.", "clpid": "Brunner-R" }, { "family_name": "Musser", "given_name": "J.", "clpid": "Musser-J" }, { "family_name": "Mufson", "given_name": "S.", "clpid": "Mufson-S" }, { "family_name": "Gebhard", "given_name": "M.", "clpid": "Gebhard-M" } ], "contributor": [ { "family_name": "Shopbell", "given_name": "P. L." }, { "family_name": "Britton", "given_name": "M. C." }, { "family_name": "Ebert", "given_name": "R." } ], "abstract": "One of the new frontiers of astronomical research is the exploration of time variability on the sky at different wavelengths and flux levels. We have carried out a pilot project using DPOSS data to study strong variables and transients, and are now extending it to the new Palomar-QUEST synoptic sky survey. We report on our early findings and outline the methodology to be implemented in preparation for a real-time transient detection pipeline. In addition to large numbers of known types of highly variable sources (e.g., SNe, CVs, OVV QSOs, etc.), we expect to find numerous transients whose nature may be established by a rapid follow-up. Whereas we will make all detected variables publicly available through the web, we anticipate that email alerts would be issued in the real time for a subset of events deemed to be the most interesting. This real-time process entails many challenges, in an effort to maintain a high completeness while keeping the contamination low. We will utilize distributed Grid services developed by the GRIST project, and implement a variety of advanced statistical and machine learning techniques.", "publisher": "Astronomical Society of the Pacific", "publication_date": "2005" }, { "id": "authors:thwec-a0060", "collection": "authors", "collection_id": "thwec-a0060", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2004.219", "type": "conference_item", "title": "Exploring the Time Domain with the Palomar-QUEST Sky Survey", "author": [ { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Graham", "given_name": "M.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Granett", "given_name": "B.", "clpid": "Granett-B" }, { "family_name": "Bogosavljevic", "given_name": "M.", "clpid": "Bogosavljevic-M" }, { "family_name": "Baltay", "given_name": "C.", "clpid": "Baltay-C" }, { "family_name": "Rabinowitz", "given_name": "D.", "clpid": "Rabinowitz-D" }, { "family_name": "Bauer", "given_name": "A.", "clpid": "Bauer-A" }, { "family_name": "Andrews", "given_name": "P.", "clpid": "Andrews-P" }, { "family_name": "Morgan", "given_name": "N.", "clpid": "Morgan-N" }, { "family_name": "Snyder", "given_name": "J.", "clpid": "Snyder-J" }, { "family_name": "Ellman", "given_name": "N.", "clpid": "Ellman-N" }, { "family_name": "Duffau", "given_name": "S.", "clpid": "Duffau-S" }, { "family_name": "Musser", "given_name": "J.", "clpid": "Musser-J" }, { "family_name": "Mufson", "given_name": "S.", "clpid": "Mufson-S" }, { "family_name": "Gebhard", "given_name": "M.", "clpid": "Gebhard-M" }, { "family_name": "Brunner", "given_name": "R.", "clpid": "Brunner-R" }, { "family_name": "Rengstorf", "given_name": "A.", "clpid": "Rengstorf-A" } ], "abstract": "Discoveries in astronomy are often made through a systematic exploration of\npreviously poorly covered regions of the observable parameter space [1,2]. In\nparticular, exploration of the time variability on the sky over a broad range of\nux levels and wavelengths is rapidly becoming a new frontier of astronomical\nresearch [3,4]. Many exciting astrophysical phenomena are known in the time\ndomain: all manner of variable stars, stellar explosions such as SNe and GRBs,\nvariable AGN, pulsars, microlensing events, etc. Yet undoubtedly many more\nremain to be discovered.\nA number of surveys and experiments exploring the time domain are already\nin progress (see, e.g., [5,6] for listings), and even more ambitious synoptic sky\nsurveys are being planned, e.g., [7,8]. The important factors in such programs\nare (1) the area covered, (2) the depth of coverage, (3) number of wavelengths\nused, and (4) the baseline(s) in time.", "publisher": "Caltech Library", "publication_date": "2004-10" }, { "id": "authors:p828p-sky71", "collection": "authors", "collection_id": "p828p-sky71", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2004.218", "type": "conference_item", "title": "Palomar-QUEST: A case study in designing sky surveys in the VO era", "author": [ { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Baltay", "given_name": "Charles", "clpid": "Baltay-C" }, { "family_name": "Rabinowitz", "given_name": "Dave", "clpid": "Rabinowitz-D" }, { "family_name": "Bauer", "given_name": "Anne", "clpid": "Bauer-A" }, { "family_name": "Snyder", "given_name": "Jeff", "clpid": "Snyder-J" }, { "family_name": "Morgan", "given_name": "Nick", "clpid": "Morgan-N" }, { "family_name": "Andrews", "given_name": "Peter", "clpid": "Andrews-P" }, { "family_name": "Szalay", "given_name": "Alexander S.", "clpid": "Szalay-A-S" }, { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "Musser", "given_name": "Jim", "clpid": "Musser-J" } ], "abstract": "The advent of wide-area multicolour synoptic sky surveys is\nleading to data sets unprecedented in size, complexity and data through-\nput. VO technology offers a way to exploit these to the full but re-\nquires changes in design philosophy. The Palomar-QUEST survey is a\nmajor new survey being undertaken by Caltech, Yale, JPL and Indi-\nana University to repeatedly observe\n1/3 of the sky (\u223c 15000 sq. deg. between \u201327\u00b0 \u2264\n \u03b4 \u2264 27\u00b0) in seven passbands. Utilising the 48-inch\nOschin Schmidt Telescope at the Palomar Observatory with the 112-CCD\nQUEST camera covering the full 4\u00b0 x 4\u00b0 field of view, it will generate\n\u223c 1TB of data per month. In this paper, we review the design of QUEST\nas a VO resource, a federated data set and an exemplar of VO standards.", "publisher": "Caltech Library", "publication_date": "2004-10" }, { "id": "authors:200nk-xdt26", "collection": "authors", "collection_id": "200nk-xdt26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181219-142606813", "type": "book_section", "title": "Thirty Meter Telescope site testing system", "book_title": "Ground-based Telescopes", "author": [ { "family_name": "Skidmore", "given_name": "Warren", "clpid": "Skidmore-W" }, { "family_name": "Sch\u00f6ck", "given_name": "Matthias", "clpid": "Sch\u00f6ck-M" }, { "family_name": "Tokovinin", "given_name": "Andrei", "clpid": "Tokovinin-A-A" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Walker", "given_name": "Alistair", "clpid": "Walker-A-R" }, { "family_name": "Blum", "given_name": "Robert", "clpid": "Blum-R-D" }, { "family_name": "Travouillon", "given_name": "Tony", "clpid": "Travouillon-T" }, { "family_name": "Seguel", "given_name": "Juan", "clpid": "Seguel-J" }, { "family_name": "Bustos", "given_name": "Edison", "clpid": "Bustos-E-E" }, { "family_name": "Walker", "given_name": "David", "clpid": "Walker-D" }, { "family_name": "Vasquez", "given_name": "Joselina", "clpid": "Vasquez-J" }, { "family_name": "Gillett", "given_name": "Paul", "clpid": "Gillett-P-E" } ], "contributor": [ { "family_name": "Oschmann", "given_name": "Jacobus M.", "clpid": "Oschmann-J-M" } ], "abstract": "The Thirty Meter Telescope (TMT) site testing team are developing a suite of instruments to measure the atmospheric and optical characteristics of candidate TMT sites. Identical sets of robotically operating instruments will be placed at each candidate site. The fully developed system will comprise of a combined MASS/DIMM. a SODAR, tower mounted thermal probes and a portable DIMM. These instruments have overlapping altitude coverage and provide a measure of the C^2_n profile from the ground up with sufficient resolution to make conclusions about the ground layer and high altitude turbulence characteristics. The overlapping altitude coverage is essential to ensure consistency between these very different instruments. In addition to checking for consistency in the overlap regions, procedures are being used to cross check between instruments, i.e. the calculation of the isoplanatic angle from both the MASS and DIMM and that the integrals of the C^2_n profiles from the MASS, SODAR and 30m tower gives the same r_0 value as measured by the DIMM. We discuss a variation of the traditional DIMM system in which we employ a continuous drift mode readout technique giving a maximum of nearly 300 samples per second. Findings of our major equipment testing campaigns and first field deployment are presented that demonstrate our progress in developing a rigorous approach to site testing.", "doi": "10.1117/12.549384", "isbn": "9780819454218", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-09-28", "pages": "154-164" }, { "id": "authors:ehyn8-2y078", "collection": "authors", "collection_id": "ehyn8-2y078", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-105225741", "type": "book_section", "title": "The Thirty Meter Telescope site testing system", "book_title": "Ground-based Telescopes", "author": [ { "family_name": "Skidmore", "given_name": "Warren", "clpid": "Skidmore-W" }, { "family_name": "Sch\u00f6ck", "given_name": "Matthias", "clpid": "Sch\u00f6ck-M" }, { "family_name": "Tokovinin", "given_name": "Andrei", "clpid": "Tokovinin-A" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Walker", "given_name": "Alistair", "clpid": "Walker-A" }, { "family_name": "Blum", "given_name": "Robert", "clpid": "Blum-R-D" }, { "family_name": "Travouillon", "given_name": "Tony", "clpid": "Travouillon-T" }, { "family_name": "Seguel", "given_name": "Juan", "clpid": "Seguel-J" }, { "family_name": "Bustos", "given_name": "Edison", "clpid": "Bustos-E" }, { "family_name": "Walker", "given_name": "David", "clpid": "Walker-D" }, { "family_name": "Vasquez", "given_name": "Joselino", "clpid": "Vasquez-J" }, { "family_name": "Gillett", "given_name": "Paul", "clpid": "Gillett-P" } ], "contributor": [ { "family_name": "Oschmann", "given_name": "Jacobus M., Jr.", "clpid": "Oschmann-J-M-Jr" } ], "abstract": "The Thirty Meter Telescope (TMT) site testing team are developing a suite of instruments to measure the atmospheric and optical characteristics of candidate TMT sites. Identical sets of robotically operating instruments will be placed at each candidate site. The fully developed system will comprise of a combined MASS/DIMM. a SODAR, tower mounted thermal probes and a portable DIMM. These instruments have overlapping altitude coverage and provide a measure of the C^2_n profile from the ground up with sufficient resolution to make conclusions about the ground layer and high altitude turbulence characteristics. The overlapping altitude coverage is essential to ensure consistency between these very different instruments. In addition to checking for consistency in the overlap regions, procedures are being used to cross check between instruments, i.e. the calculation of the isoplanatic angle from both the MASS and DIMM and that the integrals of the C^2_n profiles from the MASS, SODAR and 30m tower gives the same r0 value as measured by the DIMM. We discuss a variation of the traditional DIMM system in which we employ a continuous drift mode readout technique giving a maximum of nearly 300 samples per second. Findings of our major equipment testing campaigns and first field deployment are presented that demonstrate our progress in developing a rigorous approach to site testing.", "doi": "10.1117/12.549384", "isbn": "0819454397", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-09-28", "pages": "154-164" }, { "id": "authors:nf6dc-jdh03", "collection": "authors", "collection_id": "nf6dc-jdh03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170408-154737429", "type": "article", "title": "Direct Determination of the Kinematics of the Universe and Properties of the Dark Energy as Functions of Redshift", "author": [ { "family_name": "Daly", "given_name": "Ruth A.", "clpid": "Daly-R-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Understanding the nature of dark energy, which appears to drive the expansion of the universe, is one of the central problems of physical cosmology today. In an earlier paper we proposed a novel method to determine the expansion rate E(z) and the deceleration parameter q(z) in a largely model-independent way, directly from the data on coordinate distances y(z). Here we expand this methodology to include measurements of the pressure of dark energy p(z), its normalized energy density fraction f(z), and the equation-of-state parameter w(z). We then apply this methodology to a new, combined data set of distances to supernovae and radio galaxies. In evaluating E(z) and q(z), we make only the assumptions that the FRW metric applies and that the universe is spatially flat (an assumption strongly supported by modern cosmic microwave background radiation measurements). The determinations of E(z) and q(z) are independent of any theory of gravity. For evaluations of p(z), f(z), and w(z), a theory of gravity must be adopted, and general relativity is assumed here. No a priori assumptions regarding the properties or redshift evolution of the dark energy are needed. We obtain trends for y(z) and E(z) that are fully consistent with the standard Friedmann-Lema\u00eetre concordance cosmology with \u03a9_0 = 0.3 and \u039b_0 = 0.7. The measured trend for q(z) deviates systematically from the predictions of this model on a ~1-2 \u03c3 level but may be consistent for smaller values of \u039b_0. We confirm our previous result that the universe transitions from acceleration to deceleration at a redshift zT \u2248 0.4. The trends for p(z), f(z), and w(z) are consistent with being constant at least out to z ~ 0.3-0.5 and broadly consistent with being constant out to higher redshifts, but with large uncertainties. For the present values of these parameters we obtain E_0 = 0.97 \u00b1 0.03, q_0 = -0.35 \u00b1 0.15, p_0 = -0.6 \u00b1 0.15, f_0 = -0.62 - (\u03a9_0 - 0.3) \u00b1 0.05, and w_0 = -0.9 - \u03b5(\u03a9_0 - 0.3) \u00b1 0.1, where \u03a9_0 is the density parameter for nonrelativistic matter and \u03b5 \u2248 1.5 \u00b1 0.1. We note that in the standard Friedmann-Lema\u00eetre models p_0 = -\u039b_0, and thus we can measure the value of the cosmological constant directly and obtain results in agreement with other contemporary results.", "doi": "10.1086/422673", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2004-09-10", "series_number": "2", "volume": "612", "issue": "2", "pages": "652-659" }, { "id": "authors:zmv2x-xpx47", "collection": "authors", "collection_id": "zmv2x-xpx47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BABss04", "type": "article", "title": "Some statistical and computational challenges, and opportunities in astronomy", "author": [ { "family_name": "Babu", "given_name": "G. Jogesh", "clpid": "Babu-G-J" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "The data complexity and volume of astronomical findings have increased in recent decades due to major technological improvements in instrumentation and data collection methods. The contemporary astronomer is flooded with terabytes of raw data that produce enormous multidimensional catalogs of objects (stars, galaxies, quasars, etc.) numbering in the billions, with hundreds of measured numbers for each object. The astronomical community thus faces a key task: to enable efficient and objective scientific exploitation of enormous multifaceted data sets and the complex links between data and astrophysical theory. In recognition of this task, the National Virtual Observatory (NVO) initiative recently emerged to federate numerous large digital sky archives, and to develop tools to explore and understand these vast volumes of data. The effective use of such integrated massive data sets presents a variety of new challenging statistical and algorithmic problems that require methodological advances. An interdisciplinary team of statisticians, astronomers and computer scientists from The Pennsylvania State University, California Institute of Technology and Carnegie Mellon University is developing statistical methodology for the NVO. A brief glimpse into the Virtual Observatory and the work of the Penn State-led team is provided here.", "doi": "10.1214/088342304000000774", "issn": "0883-4237", "publisher": "Statistical Science", "publication": "Statistical Science", "publication_date": "2004-05-01", "series_number": "2", "volume": "19", "issue": "2", "pages": "322-332" }, { "id": "authors:7qmph-qr812", "collection": "authors", "collection_id": "7qmph-qr812", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-155149117", "type": "article", "title": "Relative Frequencies of Blue Stragglers in Galactic Globular Clusters: Constraints for the Formation Mechanisms", "author": [ { "family_name": "Piotto", "given_name": "Giampaolo", "clpid": "Piotto-G" }, { "family_name": "de Angeli", "given_name": "Francesca", "clpid": "de-Angeli-Fr" }, { "family_name": "King", "given_name": "Ivan R.", "clpid": "King-I-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bono", "given_name": "Giuseppe", "clpid": "Bono-G" }, { "family_name": "Cassisi", "given_name": "Santi", "clpid": "Cassisi-S" }, { "family_name": "Meylan", "given_name": "Georges", "clpid": "Meylan-G" }, { "family_name": "Recio-Blanco", "given_name": "Alejandra", "clpid": "Recio-Blanco-A" }, { "family_name": "Rich", "given_name": "R. M.", "orcid": "0000-0003-0427-8387", "clpid": "Rich-R-M" }, { "family_name": "Davies", "given_name": "Melvyn B.", "clpid": "Davies-M-B" } ], "abstract": "We discuss the main properties of the Galactic globular cluster (GC) blue straggler stars (BSSs), as inferred from our new catalog containing nearly 3000 BSSs. The catalog has been extracted from the photometrically homogeneous V versus (B-V) color-magnitude diagrams (CMDs) of 56 GCs, based on Wide Field Planetary Camera 2 images of their central cores. In our analysis, we used consistent relative distances based on the same photometry and calibration. The number of BSSs has been normalized to obtain relative frequencies (F_(BSS)) and specific densities (N_S) using different stellar populations extracted from the CMD. The cluster F_(BSS) is significantly smaller than the relative frequency of field BSSs. We find a significant anticorrelation between the BSS relative frequency in a cluster and its total absolute luminosity (mass). There is no statistically significant trend between the BSS frequency and the expected collision rate. The value of F_(BSS) does not depend on other cluster parameters, apart from a mild dependence on the central density. Post-core-collapse clusters act like normal clusters as far as the BSS frequency is concerned. We also show that the BSS luminosity function for the most luminous clusters is significantly different, with a brighter peak and extending to brighter luminosities than in the less luminous clusters. These results imply that the efficiency of BSS production mechanisms and their relative importance vary with the cluster mass.", "doi": "10.1086/383617", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2004-04-01", "series_number": "2", "volume": "604", "issue": "2", "pages": "L109-L112" }, { "id": "authors:t0t5n-ged24", "collection": "authors", "collection_id": "t0t5n-ged24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150327-075339070", "type": "article", "title": "Astronomy: Out of the Dark Ages", "author": [ { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Light from the most distant sources known, emitted when the Universe\nwas only a billion years old, hints at a complex history of star and\ngalaxy formation, and at their effect on the primordial gas around them.", "doi": "10.1038/427790a", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2004-02-26", "series_number": "6977", "volume": "427", "issue": "6977", "pages": "790-791" }, { "id": "authors:7sc89-yat33", "collection": "authors", "collection_id": "7sc89-yat33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-145414550", "type": "article", "title": "First Two Host Galaxies of X\u2010Ray Flashes: XRF 011030 and XRF 020427", "author": [ { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Fox", "given_name": "D.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "van Dokkum", "given_name": "P. G.", "orcid": "0000-0002-8282-9888", "clpid": "van-Dokkum-P-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" } ], "abstract": "Given the paucity of empirical constraints, the nature of the newly recognized phenomena called X-ray flashes (XRFs) has been an open question. However, with the recent detections of radio and X-ray afterglow it is finally possible to study the large- and small-scale environments of XRFs. We present Chandra, Hubble Space Telescope (HST), and Keck observations of the fields of XRFs 011030 and 020427. Astrometric comparisons of the X-ray transient positions and the HST images reveal the XRFs to be associated with faint blue galaxies. Photometric evidence of these putative hosts suggests that these two XRFs originated from redshifts less than z ~ 3.5, and thus cannot be due to GRBs at very high redshifts. In both host-burst offsets and host properties, these XRFs could have been drawn from distributions similar to those measured of gamma-ray bursts (GRBs). We conclude with a discussion of the implications of this XRF-GRB host connection for the possible progenitors of XRFs.", "doi": "10.1086/379310", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-12-20", "series_number": "2", "volume": "599", "issue": "2", "pages": "957-963" }, { "id": "authors:25yqj-qd768", "collection": "authors", "collection_id": "25yqj-qd768", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-151012873", "type": "article", "title": "A Model\u2010Independent Determination of the Expansion and Acceleration Rates of the Universe as a Function of Redshift and Constraints on Dark Energy", "author": [ { "family_name": "Daly", "given_name": "Ruth A.", "clpid": "Daly-R-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Determination of the expansion and acceleration history of the universe is one of the fundamental goals of cosmology. Detailed measurements of these rates as a function of redshift can provide new physical insights into the nature and evolution of the dark energy, which apparently dominates the global dynamics of the universe at the present epoch. We present here dimensionless coordinate distances y(z) to 20 radio galaxies reaching out to z \u2248 1.8, the redshift range currently not covered by supernova standard-candle observations. There is very good agreement between coordinate distances to radio galaxies and supernovae for the redshift range in which these measurements overlap, suggesting that neither is plagued at this level by unknown systematic errors. We develop a simple numerical method for a direct determination of the expansion and acceleration rates, E(z) and q(z), from the data, which makes no assumptions about the underlying cosmological model or the equation of state parameter w. This differential method is in contrast to the traditional cosmological tests, in which particular model equations are integrated and then compared with the observations. The new approach is model independent, but at a cost of being noisier and highly sensitive to the amount and quality of the available data. We illustrate the method by applying it to the currently available supernova data and the data on radio galaxies presented here. We derive the expansion rate of the universe as a function of redshift, E(z), and for the first time we obtain a direct estimate of the acceleration rate of the universe as a function of redshift, q(z), in a way that is independent of assumptions regarding the dark energy and its redshift evolution. The current observations indicate that the universe makes a transition from acceleration to deceleration at a redshift greater than 0.3, with a best-fit estimate of about 0.45; this transition redshift and our determinations of E(z) are broadly in agreement with the currently popular Friedmann-Lemaitre cosmology with \u03a9_m = 0.3 and \u03a9_\u039b = 0.7, even though no model assumptions are made in deriving the fits for E(z) and q(z). With the advent of much better and richer data sets in the future, our direct method can provide a useful complementarity and an independent check on the traditional cosmological tests.", "doi": "10.1086/378230", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-11-01", "series_number": "1", "volume": "597", "issue": "1", "pages": "9-20" }, { "id": "authors:cw4hw-kgp92", "collection": "authors", "collection_id": "cw4hw-kgp92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-154025946", "type": "article", "title": "Discovery of a Clustered Quasar Pair at z\u2009\u2248\u20095: Biased Peaks in Early Structure Formation", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Brunner", "given_name": "R.", "clpid": "Brunner-R-J" } ], "abstract": "We report the discovery of a quasar at z = 4.96 \u00b1 0.03 within a few Mpc of the quasar SDSS 0338+0021 at z = 5.02 \u00b1 0.02. The newly found quasar has SDSS i and z magnitudes of \u224821.2, and an estimated absolute magnitude M_B \u2248 -25.2. The projected separation on the sky is 196'', and the redshift difference \u0394z = 0.063 \u00b1 0.008. The probability of finding this quasar pair by chance in the absence of clustering in this particular volume is ~10^(-4) to 10^(-3). We conclude that the two objects probably mark a large-scale structure, possibly a protocluster, at z \u2248 5. This is the most distant such structure currently known. Our search in the field of 13 other QSOs at z \u2273 4.8 so far has not resulted in any detections of comparable luminous QSO pairs, and it is thus not yet clear how representative is this structure at z \u2248 5. However, along with the other evidence for clustering of quasars and young galaxies at somewhat lower redshifts, the observations are at least qualitatively consistent with a strong biasing of the first luminous and massive objects, in agreement with general predictions of theoretical models. More extensive searches for clustered quasars and luminous galaxies at these redshifts will provide valuable empirical constraints for our understanding of early galaxy and structure formation.", "doi": "10.1086/377524", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-10-10", "series_number": "1", "volume": "596", "issue": "1", "pages": "67-71" }, { "id": "authors:ydfrn-76435", "collection": "authors", "collection_id": "ydfrn-76435", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-145719740", "type": "article", "title": "New Damped Ly\u03b1 Metallicities from Echellette Spectrograph and Imager Spectroscopy of Five Palomar Sky Survey Quasars", "author": [ { "family_name": "Prochaska", "given_name": "Jason X.", "orcid": "0000-0002-7738-6875", "clpid": "Prochaska-J-X" }, { "family_name": "Castro", "given_name": "Sandra", "clpid": "Castro-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "This paper presents chemical abundance measurements for 12 new z > 3 damped Ly\u03b1 systems discovered toward five quasars from the Palomar Sky Survey. We determine H I column densities from profile fits to the observed damped Ly\u03b1 profiles and measure ionic column densities and limits for all observed metal line transitions. This data set, acquired with the Echellette Spectrograph and Imager on the Keck II telescope, adds to the rapidly growing database of damped Ly\u03b1 abundances. It will impact studies of chemical evolution in the early universe and help identify candidates for detailed follow-up observations with echelle spectrographs. We report the discovery of the first quasar sight line with four cosmologically distinct damped Ly\u03b1 systems.", "doi": "10.1086/376793", "issn": "0067-0049", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Supplement Series", "publication_date": "2003-10", "series_number": "2", "volume": "148", "issue": "2", "pages": "317-326" }, { "id": "authors:3y3xm-axm32", "collection": "authors", "collection_id": "3y3xm-axm32", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-144036689", "type": "article", "title": "Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Ly\u03b1 Systems", "author": [ { "family_name": "Prochaska", "given_name": "Jason X.", "orcid": "0000-0002-7738-6875", "clpid": "Prochaska-J-X" }, { "family_name": "Gawiser", "given_name": "Eric", "clpid": "Gawiser-E" }, { "family_name": "Wolfe", "given_name": "Arthur M.", "clpid": "Wolfe-A-M" }, { "family_name": "Castro", "given_name": "Sandra", "clpid": "Castro-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We discuss accurate metallicity measurements for 125 damped Ly\u03b1 (DLA) systems at 0.5 < z < 5, including \u224850 new measurements from our recently published Echellette Spectrograph and Imager surveys. This data set is analyzed to determine the age-metallicity relation of neutral gas in the universe. Contrary to previous analyses, this sample shows statistically significant evolution in the cosmic mean metallicity. The best linear fit for metallicity evolution is -0.26 \u00b1 0.07 dex per unit redshift. The DLA systems continue to maintain a floor in metallicity of \u22481/700 solar, independent of observational effects. This metallicity threshold limits the prevalence of primordial gas in high-redshift galaxies and stresses the correspondence between damped systems and star formation. Finally, we comment on an apparent \"missing metals problem:\" the mean metallicity of the damped systems is \u224810 times lower than the value expected from their inferred star formation history. This problem is evident in current theoretical treatments of galaxy formation and may indicate a serious flaw in our understanding of the interplay between star formation and metal enrichment.", "doi": "10.1086/378945", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-09-20", "series_number": "1", "volume": "595", "issue": "1", "pages": "L9-L12" }, { "id": "authors:f4n80-adt46", "collection": "authors", "collection_id": "f4n80-adt46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-142815408", "type": "article", "title": "Peculiar Broad Absorption Line Quasars Found in The Digitized Palomar Observatory Sky Survey", "author": [ { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "Hall", "given_name": "Patrick B.", "clpid": "Hall-P-B" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Lopes", "given_name": "P. A. A.", "clpid": "Lopes-P-A-A" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F-H" }, { "family_name": "Darling", "given_name": "J.", "orcid": "0000-0003-2511-2060", "clpid": "Darling-J" }, { "family_name": "Desai", "given_name": "V.", "orcid": "0000-0002-1340-0543", "clpid": "Desai-V" } ], "abstract": "With the recent release of large (i.e., \u2273100 million objects), well-calibrated photometric surveys, such as Digitized Palomar Observatory Sky Survey (DPOSS), Two Micron All Sky Survey, and Sloan Digital Sky Survey, spectroscopic identification of important targets is no longer a simple issue. In order to enhance the returns from a spectroscopic survey, candidate sources are often preferentially selected to be of interest, such as brown dwarfs or high-redshift quasars. This approach, while useful for targeted projects, risks missing new or unusual species. We have, as a result, taken the alternative path of spectroscopically identifying interesting sources with the sole criterion being that they are in low-density areas of the g-r and r-i color space defined by DPOSS. In this paper, we present three peculiar broad absorption line quasars that were discovered during this spectroscopic survey, demonstrating the efficacy of this approach. PSS J0052+2405 is an iron low-ionization broad absorption line (LoBAL) quasar at a redshift z = 2.4512 \u00b1 0.0001 with very broad absorption from many species. PSS J0141+3334 is a reddened LoBAL quasar at z = 3.005 \u00b1 0.005 with no obvious emission lines. PSS J1537+1227 is an iron LoBAL at a redshift of z = 1.212 \u00b1 0.007 with strong narrow Mg II and Fe II emission. Follow-up high-resolution spectroscopy of these three quasars promises to improve our understanding of BAL quasars. The sensitivity of particular parameter spaces, in this case a two-color space, to the redshift of these three sources is dramatic, raising questions about traditional techniques of defining quasar populations for statistical analysis.", "doi": "10.1086/375763", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2003-07", "series_number": "1", "volume": "126", "issue": "1", "pages": "53-62" }, { "id": "authors:dwqe7-qcg77", "collection": "authors", "collection_id": "dwqe7-qcg77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150401-140640866", "type": "article", "title": "The bright optical afterglow of the nearby \u03b3-ray burst of 29 March 2003", "author": [ { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Peterson", "given_name": "B. A.", "clpid": "Peterson-B-A" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Soderberg", "given_name": "A. M.", "clpid": "Soderberg-A-M" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Blain", "given_name": "A. W.", "orcid": "0000-0001-7489-5167", "clpid": "Blain-A-W" }, { "family_name": "Chapman", "given_name": "S. C.", "clpid": "Chapman-S-C" } ], "abstract": "Past studies of cosmological y-ray bursts (GRBs) have been hampered by their extreme distances, resulting in faint afterglows. A nearby GRB could potentially shed much light on the origin of these events, but GRBs with a redshift z \u2264 0.2 have been estimated to occur only rarely, about once per decade. Here we report the discovery of the bright optical afterglow emission from the burst of 29 March 2003 (GRB030329; ref. 2). The brightness of the afterglow and the prompt report of its position resulted in extensive follow-up observations at many wavelengths, along with the measurement of the redshift, z = 0.169 (ref. 4). The y-ray and afterglow properties of GRB030329 are similar to those of GRBs at cosmological redshifts. Observations have already identified the progenitor as a massive star that exploded as a supernova.", "doi": "10.1038/nature01734", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2003-06-19", "series_number": "6942", "volume": "423", "issue": "6942", "pages": "844-847" }, { "id": "authors:g7rf2-21b44", "collection": "authors", "collection_id": "g7rf2-21b44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190924-080104925", "type": "article", "title": "Discovery of GRB 020405 and Its Late Red Bump", "author": [ { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "McCarthy", "given_name": "P.", "clpid": "McCarthy-P-J" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Jerjen", "given_name": "H.", "clpid": "Jerjen-H" }, { "family_name": "Flint", "given_name": "K.", "clpid": "Flint-K" }, { "family_name": "Phillips", "given_name": "A.", "clpid": "Phillips-A" }, { "family_name": "Warren", "given_name": "B. E.", "clpid": "Warren-B-E" }, { "family_name": "Axelrod", "given_name": "T. S.", "clpid": "Axelrod-T-S" }, { "family_name": "Chevalier", "given_name": "R. A.", "clpid": "Chevalier-R-A" }, { "family_name": "Holtzman", "given_name": "J.", "clpid": "Holtzman-J-A" }, { "family_name": "Kimble", "given_name": "R. A.", "clpid": "Kimble-R-A" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Wheeler", "given_name": "J. C.", "clpid": "Wheeler-J-C" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" }, { "family_name": "Piro", "given_name": "L.", "clpid": "Piro-L" }, { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Cline", "given_name": "T.", "clpid": "Cline-T" }, { "family_name": "Guidorzi", "given_name": "C.", "orcid": "0000-0001-6869-0835", "clpid": "Guidorzi-C" }, { "family_name": "Montanari", "given_name": "E.", "clpid": "Montanari-E" }, { "family_name": "Mazets", "given_name": "E.", "clpid": "Mazets-E-P" }, { "family_name": "Golenetskii", "given_name": "S.", "clpid": "Golenetskii-S-V" }, { "family_name": "Mitrofanov", "given_name": "I.", "clpid": "Mitrofanov-I-G" }, { "family_name": "Anfimov", "given_name": "D.", "clpid": "Anfimov-D" }, { "family_name": "Kozyrev", "given_name": "A.", "clpid": "Kozyrev-A-S" }, { "family_name": "Litvak", "given_name": "M.", "clpid": "Litvak-M-L" }, { "family_name": "Sanin", "given_name": "A.", "clpid": "Sanin-A-B" }, { "family_name": "Boynton", "given_name": "W.", "clpid": "Boynton-W-V" }, { "family_name": "Fellows", "given_name": "C.", "clpid": "Fellows-C" }, { "family_name": "Harshman", "given_name": "K.", "clpid": "Harshman-K" }, { "family_name": "Shinohara", "given_name": "C.", "clpid": "Shinohara-C" }, { "family_name": "Gal-Yam", "given_name": "A.", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Ofek", "given_name": "E.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Lipkin", "given_name": "Y.", "clpid": "Lipkin-Y-M" } ], "abstract": "We present the discovery of GRB 020405 made with the Interplanetary Network (IPN). With a duration of 60 s, the burst appears to be a typical long-duration event. We observed the 75 arcmin2 IPN error region with the Mount Stromlo Observatory's 50 inch robotic telescope and discovered a transient source that subsequently decayed and was also associated with a variable radio source. We identify this source as the afterglow of GRB 020405. Subsequent observations by other groups found varying polarized flux and established a redshift of 0.690 to the host galaxy. Motivated by the low redshift, we triggered observations with WFPC2 on board the Hubble Space Telescope (HST). Modeling the early ground-based data with a jet model, we find a clear red excess over the decaying optical light curves that is present between day 10 and day 141 (the last HST epoch). This bump has the spectral and temporal features expected of an underlying supernova (SN). In particular, the red color of the putative SN is similar to that of the SN associated with GRB 011121 at late time. Restricting the sample of GRBs to those with z < 0.7, a total of five bursts, red bumps at late times are found in GRB 970228, GRB 011121, and GRB 020405. It is possible that the simplest idea, namely, that all long-duration \u03b3-ray bursts have underlying SNe with a modest dispersion in their properties (especially peak luminosity), is sufficient to explain the nondetections.", "doi": "10.1086/374730", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-06-01", "series_number": "2", "volume": "589", "issue": "2", "pages": "838-843" }, { "id": "authors:v0d4q-6tv46", "collection": "authors", "collection_id": "v0d4q-6tv46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190924-102314226", "type": "article", "title": "Hubble Space Telescope and Ground-based Optical and Ultraviolet Observations of GRB 010222", "author": [ { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Reichart", "given_name": "D.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Brown", "given_name": "T. M.", "orcid": "0000-0002-1793-9968", "clpid": "Brown-T-M" }, { "family_name": "Kimble", "given_name": "R. A.", "clpid": "Kimble-R-A" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Gal-Yam", "given_name": "A.", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Fox", "given_name": "D.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 optical and Space Telescope Imaging Spectrograph (STIS) near-ultraviolet MAMA observations and ground-based optical observations of GRB 010222, spanning 15 hr to 71 days. The observations are well described by a relativistic blast wave model with a hard electron energy distribution, p = 1.57^(+0.04)_(-0.03), and a jet transition at t* = 0.93^(+0.15)_(-0.06) days. These values are slightly larger than previously found as a result of a correction for the contribution from the host galaxy to the late-time ground-based observations and the larger temporal baseline provided by the HST observations. The host galaxy is found to contain a very compact core (size <0 25), which coincides with the position of the optical transient. The STIS near-ultraviolet MAMA observations allow for an investigation of the extinction properties along the line of sight to GRB 010222. We find that the far-ultraviolet curvature component c4 is rather large. In combination with the low optical extinction, AV = 0.110^(+0.010)_(-0.021) mag, when compared with the hydrogen column inferred from X-ray observations, we suggest that this is evidence for dust destruction.", "doi": "10.1086/368123", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-04-10", "series_number": "1", "volume": "587", "issue": "1", "pages": "135-142" }, { "id": "authors:m94ck-9sx54", "collection": "authors", "collection_id": "m94ck-9sx54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141117-141533147", "type": "article", "title": "A Molecular Einstein Ring: Imaging a Starburst Disk Surrounding a Quasi-Stellar Object", "author": [ { "family_name": "Carilli", "given_name": "C. L.", "orcid": "0000-0001-6647-3861", "clpid": "Carilli-C-L" }, { "family_name": "Lewis", "given_name": "G. F.", "clpid": "Lewis-G-F" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Cox", "given_name": "P.", "orcid": "0000-0003-2027-8221", "clpid": "Cox-Pierre" }, { "family_name": "Bertoldi", "given_name": "F.", "orcid": "0000-0002-1707-1775", "clpid": "Bertoldi-F" }, { "family_name": "Omont", "given_name": "A.", "orcid": "0000-0002-4721-3922", "clpid": "Omont-A" } ], "abstract": "Images of the molecular CO 2-1 line emission and the radio continuum emission from the redshift 4.12 gravitationally lensed quasi-stellar object (QSO) PSS J2322+1944 reveal an Einstein ring with a diameter of 1.5\u2033. These observations are modeled as a star-forming disk surrounding the QSO nucleus with a radius of 2 kiloparsecs. The implied massive star formation rate is 900 solar masses per year. At this rate, a substantial fraction of the stars in a large elliptical galaxy could form on a dynamical time scale of 108 years. The observation of active star formation in the host galaxy of a high-redshift QSO supports the hypothesis of coeval formation of supermassive black holes and stars in spheroidal galaxies.", "doi": "10.1126/science.1082600", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2003-04-03", "series_number": "5620", "volume": "300", "issue": "5620", "pages": "773-775" }, { "id": "authors:ffye2-yck59", "collection": "authors", "collection_id": "ffye2-yck59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190924-112423363", "type": "article", "title": "The Northern Sky Optical Cluster Survey. II. An Objective Cluster Catalog for 5800 Square Degrees", "author": [ { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Lopes", "given_name": "P. A. A.", "clpid": "Lopes-P-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Brunner", "given_name": "R. J.", "clpid": "Brunner-R-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" } ], "abstract": "We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the digitized Second Palomar Observatory Sky Survey. This cluster catalog, derived from the best calibrated plates in the high-latitude (|b| > 30\u00b0) northern Galactic cap region, covers 5800 deg^2 and contains 8155 candidate clusters. A simple adaptive kernel density mapping technique, combined with the SExtractor object detection algorithm, is used to detect galaxy overdensities, which we identify as clusters. Simulations of the background galaxy distribution and clusters of varying richnesses and redshifts allow us to optimize detection parameters and measure the completeness and contamination rates for our catalog. Cluster richnesses and photometric redshifts are measured, using integrated colors and magnitudes for each cluster. An extensive spectroscopic survey is used to confirm the photometric results. This catalog, with well-characterized sample properties, provides a sound basis for future studies of cluster physics and large-scale structure.", "doi": "10.1086/368240", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2003-04", "series_number": "4", "volume": "125", "issue": "4", "pages": "2064-2084" }, { "id": "authors:ygabm-ryd41", "collection": "authors", "collection_id": "ygabm-ryd41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150401-121318655", "type": "article", "title": "Early optical emission from the \u03b3-ray burst of 4 October 2002", "author": [ { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Yost", "given_name": "S.", "clpid": "Yost-S-A" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Torii", "given_name": "K.", "clpid": "Torii-K" }, { "family_name": "Kato", "given_name": "T", "clpid": "Kato-Tosio" }, { "family_name": "Yamaoka", "given_name": "H.", "clpid": "Yamaoka-H" }, { "family_name": "Sako", "given_name": "M.", "clpid": "Sako-Masao" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Soderberg", "given_name": "A. M.", "clpid": "Soderberg-A-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Barth", "given_name": "A. J.", "orcid": "0000-0002-3026-0562", "clpid": "Barth-A-J" }, { "family_name": "Pravdo", "given_name": "S. H.", "clpid": "Pravdo-S-H" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Gal-Yam", "given_name": "A.", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Lipkin", "given_name": "Y.", "clpid": "Lipkin-Y" }, { "family_name": "Mauch", "given_name": "T.", "clpid": "Mauch-T" }, { "family_name": "Harrison", "given_name": "C.", "clpid": "Harrison-C" }, { "family_name": "Buttery", "given_name": "H.", "clpid": "Buttery-H" } ], "abstract": "Observations of the long-lived emission\u2014or 'afterglow'\u2014of long-duration gamma-ray bursts place them at cosmological distances, but the origin of these energetic explosions remains a mystery. Observations of optical emission contemporaneous with the burst of gamma-rays should provide insight into the details of the explosion, as well as into the structure of the surrounding environment. One bright optical flash was detected during a burst, but other efforts have produced negative results. Here we report the discovery of the optical counterpart of GRB021004 only 193 seconds after the event. The initial decline is unexpectedly slow and requires varying energy content in the y-ray burst blastwave over the course of the first hour. Further analysis of the X-ray and optical afterglow suggests additional energy variations over the first few days.", "doi": "10.1038/nature01504", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2003-03-20", "series_number": "6929", "volume": "422", "issue": "6929", "pages": "284-286" }, { "id": "authors:pg0ha-f0051", "collection": "authors", "collection_id": "pg0ha-f0051", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-091002940", "type": "article", "title": "Keck Spectroscopy and Hubble Space Telescope Imaging of GRB 000926: Probing a Host Galaxy at z = 2.038", "author": [ { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Holtzman", "given_name": "J. A.", "clpid": "Holtzman-J-A" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" } ], "abstract": "We present early-time Keck spectroscopic observations and late-time Hubble Space Telescope (HST) imaging of GRB 000926. The HST images show a small offset between the optical transient and a bright, compact knot in the host galaxy. Combined with the large equivalent widths measured for metallic absorption lines by the Keck Echellette Spectrograph and Imager (ESI) and the Low Resolution Imaging Spectrometer, this indicates that the GRB exploded inside a region of high stellar density. The ESI spectroscopy reveals two absorption systems centered at z = 2.0379 \u00b1 0.0008 with a velocity separation of 168 km s^(-1), which we interpret as being due to individual features in the host galaxy. The ratios of chromium to zinc equivalent widths indicate that the host is depleted in dust relative to local values to a similar degree as damped Ly\u03b1 systems at the same redshift.", "doi": "10.1086/367603", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-03-20", "series_number": "1", "volume": "586", "issue": "1", "pages": "128-134" }, { "id": "authors:38ehr-fse69", "collection": "authors", "collection_id": "38ehr-fse69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190924-105340235", "type": "article", "title": "Redshift Determination of GRB 990506 and GRB 000418 with the Echellete Spectrograph Imager on Keck", "author": [ { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" } ], "abstract": "Using the Echellete Spectrograph Imager (ESI) on the Keck II 10 m telescope we have measured the redshifts of the host galaxies of gamma-ray bursts GRB 990506 and GRB 000418, z = 1.30658 \u00b1 0.00004 and 1.1181 \u00b1 0.0001, respectively. Thanks to the excellent spectral resolution of ESI (\u03bb/\u0394\u03bb = 13000), we resolved the [O II] \u03bb3727 doublet in both cases. The measured redshift of GRB 990506 is the highest known for a dark-burst GRB, though entirely consistent with the notion that dark and non\u2013dark bursts have a common progenitor origin. The relative strengths of the [O II], He I, [Ne III], and H\u03b3 emission lines suggest that the host of GRB 000418 is a starburst galaxy, rather than a LINER or Seyfert 2. Since the host of GRB 000418 has been detected at submillimeter wavelengths, these spectroscopic observations suggest that the submillimeter emission is due to star formation (as opposed to AGN) activity. The [O II]-derived unobscured star formation rates are 13 and 55 M_\u2299 yr^(-1) for the hosts of GRB 990506 and GRB 000418, respectively. In contrast, the star formation rate of the host of GRB 000418 derived from submillimeter observations is 20 times larger.", "doi": "10.1086/367805", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2003-03", "series_number": "3", "volume": "125", "issue": "3", "pages": "999-1005" }, { "id": "authors:0mvf3-ds747", "collection": "authors", "collection_id": "0mvf3-ds747", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190918-104431296", "type": "article", "title": "GRB 010921: Strong Limits on an Underlying Supernova from the Hubble Space Telescope", "author": [ { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Henden", "given_name": "A. A.", "clpid": "Henden-A-A" }, { "family_name": "Klose", "given_name": "S.", "clpid": "Klose-S" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Axelrod", "given_name": "T. S.", "clpid": "Axelrod-T-S" }, { "family_name": "McCarthy", "given_name": "P.", "clpid": "McCarthy-P-J" }, { "family_name": "Holtzman", "given_name": "J.", "clpid": "Holtzman-J" }, { "family_name": "Halpern", "given_name": "J. P.", "clpid": "Halpern-J-P" }, { "family_name": "Kimble", "given_name": "R. A.", "clpid": "Kimble-R-A" }, { "family_name": "Wheeler", "given_name": "J. C.", "clpid": "Wheeler-J-C" }, { "family_name": "Chevalier", "given_name": "R. A.", "clpid": "Chevalier-R-A" }, { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Ricker", "given_name": "G. R.", "clpid": "Ricker-G-R" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Piro", "given_name": "L.", "clpid": "Piro-L" } ], "abstract": "GRB 010921 was the first HETE-2 gamma-ray burst (GRB) to be localized via its afterglow emission. The low redshift of the host galaxy, z = 0.451, prompted us to undertake intensive multicolor observations with the Hubble Space Telescope with the goal of searching for an underlying supernova (SN) component. We do not detect any coincident SN to a limit 1.33 mag fainter than SN 1998bw at 99.7% confidence, making this one of the most sensitive searches for an underlying SN. Analysis of the afterglow data allows us to infer that the GRB was situated behind a net extinction (Milky Way and the host galaxy) of A_V ~ 1.8 mag in the observer frame. Thus, had it not been for such heavy extinction, our data would have allowed us to probe for an underlying SN with brightness approaching those of more typical Type Ib/c SNe.", "doi": "10.1086/345734", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2003-02-20", "series_number": "2", "volume": "584", "issue": "2", "pages": "931-936" }, { "id": "authors:qahq6-mdw60", "collection": "authors", "collection_id": "qahq6-mdw60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180111-100855939", "type": "book_section", "title": "The cosmic gamma-ray bursts and their host galaxies in a cosmological context", "book_title": "Discoveries and Research Prospects from 6- to 10-Meter-Class Telescopes II", "author": [ { "family_name": "Djorgovski", "given_name": "Stan G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Frail", "given_name": "Dale A.", "clpid": "Frail-D-A" }, { "family_name": "Harrison", "given_name": "Fiona A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Bloom", "given_name": "Joshua S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Berger", "given_name": "Edo", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Fox", "given_name": "D.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Soderberg", "given_name": "A. M.", "clpid": "Soderberg-A-M" }, { "family_name": "Galama", "given_name": "Titus J.", "clpid": "Galama-T-J" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Sari", "given_name": "Re'em", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S.", "clpid": "Yost-S-A" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Castro", "given_name": "S. M.", "clpid": "Castro-S-M" }, { "family_name": "Goodrich", "given_name": "Robert", "clpid": "Goodrich-R-W" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F" } ], "contributor": [ { "family_name": "Guhathakurta", "given_name": "Puragra", "clpid": "Guhathakurta-P" } ], "abstract": "Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are now starting to provide interesting or even unique new insights in observational cosmology. Observed GRB host galaxies have a median magnitude R~25 mag, and show a range of luminosities, morphologies, and star formation rates, with a median redshift z~1. They represent a new way of identifying a population of star-forming galaxies at cosmological redshifts, which is mostly independent of the traditional selection methods. They seem to be broadly similar to the normal field galaxy populations at comparable redshifts and magnitudes, and indicate at most a mild luminosity evolution over the redshift range they probe. Studies of GRB optical afterglows seen in absorption provide a powerful new probe of the ISM in dense, central regions of their host galaxies, which is complementary to the traditional studies using QSO absorption line systems. Some GRB hosts are heavily obscured, and provide a new way to select a population of cosmological sub-mm sources. A census of detected optical tranistents may provide an important new way to constrain the total obscured fraction of star formation over the history of the universe. Finally, detection of GRB afterglows at high redshifts (z>6) may provide a unique way to probe the primordial star formation, massive IMF, early IGM, and chemical enrichment at the end of the cosmic reionization era.", "doi": "10.1117/12.457700", "isbn": "0-8194-4613-0", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2003-02-13", "pages": "238-247" }, { "id": "authors:h3sqq-a9m57", "collection": "authors", "collection_id": "h3sqq-a9m57", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191002-141041671", "type": "monograph", "title": "Correlations of Globular Cluster Properties: Their Interpretations and Uses", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S-M" }, { "family_name": "Federici", "given_name": "L.", "clpid": "Federici-L" }, { "family_name": "Parmeggiani", "given_name": "G.", "clpid": "Parmeggiani-G" }, { "family_name": "Cacciari", "given_name": "C.", "clpid": "Cacciari-C" }, { "family_name": "Fusi Pecci", "given_name": "F.", "clpid": "Fusi-Pecci-F" }, { "family_name": "Rich", "given_name": "R. M.", "orcid": "0000-0003-0427-8387", "clpid": "Rich-R-M" }, { "family_name": "Jou", "given_name": "T.", "clpid": "Jou-T" } ], "abstract": "Correlations among the independently measured physical properties of globular clusters (GCs) can provide powerful tests for theoretical models and new insights into their dynamics, formation, and evolution. We review briefly some of the previous work, and present preliminary results from a comparative study of GC correlations in the Local Group galaxies. The results so far indicate that these diverse GC systems follow the same fundamental correlations, suggesting a commonality of formative and evolutionary processes which produce them.", "doi": "10.48550/arXiv.0302129", "publication_date": "2003-02-06" }, { "id": "authors:yz4my-dpj75", "collection": "authors", "collection_id": "yz4my-dpj75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-095417789", "type": "monograph", "title": "Cosmological Uses of Gamma-Ray Bursts", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Fox", "given_name": "D.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Soderberg", "given_name": "A. M.", "clpid": "Soderberg-A-M" }, { "family_name": "Sari", "given_name": "Re'em", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S.", "clpid": "Yost-S-A" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Castro", "given_name": "S. M.", "clpid": "Castro-S-M" }, { "family_name": "Goodrich", "given_name": "R.", "clpid": "Goodrich-R-W" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F-H" } ], "abstract": "Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are starting to provide interesting or even unique new insights in observational cosmology. GRBs represent a new way of identifying a population of star-forming galaxies at cosmological redshifts. GRB hosts are broadly similar to the normal field galaxy populations at comparable redshifts and magnitudes, and indicate at most a mild luminosity evolution out to z ~ 1.5 - 2. GRB optical afterglows seen in absorption provide a powerful new probe of the ISM in dense, central regions of their host galaxies, complementary to the traditional studies using QSO absorbers. Some GRB hosts are heavily obscured, and provide a new way to select a population of cosmological sub-mm sources, and a novel constraint on the total obscured fraction of star formation over the history of the universe. Finally, detection of GRB afterglows at z > 6 may provide a unique way to probe the primordial star formation, massive IMF, early IGM, and chemical enrichment at the end of the cosmic reionization era.", "doi": "10.48550/arXiv.0302004", "publication_date": "2003-01-31" }, { "id": "authors:cpxt9-v7j04", "collection": "authors", "collection_id": "cpxt9-v7j04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180710-091738917", "type": "book_section", "title": "CELT site testing program", "book_title": "Future Giant Telescopes", "author": [ { "family_name": "Sch\u00f6ck", "given_name": "Matthias", "clpid": "Sch\u00f6ck-M" }, { "family_name": "Erasmus", "given_name": "D. Andr\u00e9", "clpid": "Erasmus-D-A" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Chanan", "given_name": "Gary A.", "clpid": "Chanan-G" }, { "family_name": "Nelson", "given_name": "Jerry E.", "clpid": "Nelson-J-E" } ], "contributor": [ { "family_name": "Roger", "given_name": "J.", "clpid": "Roger-J" }, { "family_name": "Angel", "given_name": "P.", "clpid": "Angel-P" }, { "family_name": "Gilmozzi", "given_name": "Roberto", "clpid": "Gilmozzi-R" } ], "abstract": "The California Extremely Large Telescope, CELT, is a proposed 30-m telescope. Choosing the best possible site for CELT is essential in order to extract the best science from the observations and to reduce the complexity of the telescope. Site selection is therefore currently one of the most critical pacing items of the CELT project. In this paper, we first present selected results from a survey of the atmospheric transparency at optical and infrared wavelengths over the southwestern USA and northern Mexico using satellite data. Results of a similar study of South America have been reported elsewhere. These studies will serve as the pre-selection criterion of the sites at which we will perform on-site testing. We then describe the current status of on-site turbulence evaluation efforts and the future plans of the CELT site testing program.", "doi": "10.1117/12.459124", "isbn": "081944619X", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2003-01-30", "pages": "541-552" }, { "id": "authors:10mfc-rds74", "collection": "authors", "collection_id": "10mfc-rds74", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2003.202", "type": "conference_item", "title": "Hyperatlas: A New Framework for Image Federation", "author": [ { "family_name": "Williams", "given_name": "R. D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Feldmann", "given_name": "M. T.", "clpid": "Feldmann-M-T" }, { "family_name": "Jacob", "given_name": "J. C.", "clpid": "Jacob-J-C" } ], "abstract": "Hyperatlas is an open standard intended to facilitate the large-scale federation of image-based data. The subject of hyperatlas is the space of sphere-to-plane projection mappings (the FITS-WCS information), and the standard consists of coherent collections of these on which data can be resampled and thereby federated with other image data. We hope for a distributed effort that will produce a multi-faceted image atlas of the sky, made by federating many different surveys at different wavelengths and different times. We expect that hyperatlas-compliant imagery will be published and discovered through an International Virtual Observatory Alliance (IVOA) registry, and that grid-based services will emerge for the required resampling and mosaicking.", "doi": "10.48550/arXiv.0312195", "publication_date": "2003" }, { "id": "authors:yvamh-r5t19", "collection": "authors", "collection_id": "yvamh-r5t19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-143613576", "type": "book_section", "title": "The Roles of Small Telescopes in a Virtual Observatory Environment", "book_title": "The Future of Small Telescopes in the New Millennium", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Oswalt", "given_name": "Terry D.", "clpid": "Oswalt-T-D" } ], "abstract": "The advent of the Virtual Observatory (VO) concept signals a paradigm shift in the way astronomy will be done in the era of information abundance and ubiquitous networking. Small telescopes will be playing a number of essential roles in this new research environment, probably contributing a major portion of all data taken in astronomy, both as surveying instruments, and as follow-up facilities. In this review we describe the VO concept and its background, and how small telescopes will fit in this emergent way of doing astronomy in the 21st century.", "doi": "10.1007/978-94-010-0253-0_9", "isbn": "978-1-4020-0951-8", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "2003", "pages": "85-95" }, { "id": "authors:rj4nc-94470", "collection": "authors", "collection_id": "rj4nc-94470", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-144623682", "type": "book_section", "title": "Challenges for Cluster Analysis in a Virtual Observatory", "book_title": "Statistical Challenges in Astronomy", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Brunner", "given_name": "R.", "clpid": "Brunner-R-J" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R" }, { "family_name": "Granat", "given_name": "R.", "clpid": "Granat-R" }, { "family_name": "Stolorz", "given_name": "P.", "clpid": "Stolorz-P" } ], "contributor": [ { "family_name": "Feigelson", "given_name": "Eric D.", "clpid": "Feigelson-E-D" }, { "family_name": "Babu", "given_name": "G. Jogesh", "clpid": "Babu-G-J" } ], "abstract": "There has been an unprecedented and continuing growth in the volume, quality, and complexity of astronomical data sets over the past few years, mainly through large digital sky surveys. Virtual Observatory (VO) concept represents a scientific and technological framework needed to cope with this data flood. We review some of the applied statistics and computing challenges posed by the analysis of large and complex data sets expected in the VO-based research. The challenges are driven both by the size and the complexity of the data sets (billions of data vectors in parameter spaces of tens or hundreds of dimensions), by the heterogeneity of the data and measurement errors, the selection effects and censored data, and by the intrinsic clustering properties (functional form, topology) of the data distribution in the parameter space of observed attributes. Examples of scientific questions one may wish to address include: objective determination of the numbers of object classes present in the data, and the membership probabilities for each source; searches for unusual, rare, or even new types of objects and phenomena; discovery of physically interesting multivariate correlations which may be present in some of the clusters; etc.", "doi": "10.1007/0-387-21529-8_9", "isbn": "978-0-387-95546-9", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2003", "pages": "127-141" }, { "id": "authors:3kk1s-qjy38", "collection": "authors", "collection_id": "3kk1s-qjy38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190923-103407493", "type": "article", "title": "The Faint Optical Afterglow and Host Galaxy of GRB 020124: Implications for the Nature of Dark Gamma\u2010Ray Bursts", "author": [ { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Axelrod", "given_name": "T. S.", "clpid": "Axelrod-T-S" }, { "family_name": "Chevalier", "given_name": "R. A.", "clpid": "Chevalier-R-A" }, { "family_name": "Colbert", "given_name": "E.", "clpid": "Colbert-E" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Halpern", "given_name": "J. P.", "clpid": "Halpern-J-P" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Holtzman", "given_name": "J.", "clpid": "Holtzman-J" }, { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Kimble", "given_name": "R. A.", "clpid": "Kimble-R-A" }, { "family_name": "McCarthy", "given_name": "P. J.", "clpid": "McCarthy-P-J" }, { "family_name": "Piro", "given_name": "L.", "clpid": "Piro-L" }, { "family_name": "Reichart", "given_name": "D.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Ricker", "given_name": "G. R.", "clpid": "Ricker-G-R" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Wheeler", "given_name": "J. C.", "clpid": "Wheeler-J-C" }, { "family_name": "Vanderppek", "given_name": "R.", "clpid": "Vanderppek-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" } ], "abstract": "We present ground-based optical observations of GRB 020124 starting 1.6 hr after the burst, as well as subsequent Very Large Array and Hubble Space Telescope (HST) observations. The optical afterglow of GRB 020124 is one of the faintest afterglows detected to date, and it exhibits a relatively rapid decay, F_\u03bd \u221d t^(-1.60\u00b10.04), followed by further steepening. In addition, a weak radio source was found coincident with the optical afterglow. The HST observations reveal that a positionally coincident host galaxy must be the faintest host to date, R \u2273 29.5 mag. The afterglow observations can be explained by several models requiring little or no extinction within the host galaxy, A_V^(host) \u2248 0-0.9 mag. These observations have significant implications for the interpretation of the so-called dark bursts (bursts for which no optical afterglow is detected), which are usually attributed to dust extinction within the host galaxy. The faintness and relatively rapid decay of the afterglow of GRB 020124, combined with the low inferred extinction, indicate that some dark bursts are intrinsically dim and not dust obscured. Thus, the diversity in the underlying properties of optical afterglows must be observationally determined before substantive inferences can be drawn from the statistics of dark bursts.", "doi": "10.1086/344262", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-12-20", "series_number": "2", "volume": "581", "issue": "2", "pages": "981-987" }, { "id": "authors:dgpaj-jqb45", "collection": "authors", "collection_id": "dgpaj-jqb45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-093541133", "type": "book_section", "title": "yourSky: rapid desktop access to custom astronomical image mosaics", "book_title": "Virtual Observatories", "author": [ { "family_name": "Jacob", "given_name": "Joseph C.", "clpid": "Jacob-J-C" }, { "family_name": "Brunner", "given_name": "Robert", "clpid": "Brunner-R-J" }, { "family_name": "Curkendall", "given_name": "David W.", "clpid": "Curkendall-D-W" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Good", "given_name": "John C.", "clpid": "Good-J-C" }, { "family_name": "Husman", "given_name": "Laura", "clpid": "Husman-L" }, { "family_name": "Kremenek", "given_name": "George", "clpid": "Kremenek-G" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "contributor": [ { "family_name": "Szalay", "given_name": "Alexander S.", "clpid": "Szalay-A-S" } ], "abstract": "The yourSky custom astronomical image mosaicking software has a Web portal architecture that allows access via ordinary desktop computers with low bandwidth network connections to high performance and highly customizable mosaicking software deployed in a high performance computing and communications environment. The emphasis is on custom access to image mosaics constructed from terabytes of raw image data stored in remote archives. In this context, custom access refers to new technology that enables on the fly mosaicking to meet user-specified criteria for region of the sky to be mosaicked, datasets to be used, resolution, coordinate system, projection, data type and image format. The yourSky server is a fully automated end-to-end system that handles all aspects of the mosaic construction. This includes management of mosaic requests, determining which input images are required to fulfill each request, management of a data cache for both input image plates and output mosaics, retrieval of input image plates from massive remote archives, image mosaic construction on a multiprocessor system, and making the result accessible to the user on the desktop. The URL for yourSky is http://yourSky.jpl.nasa.gov.", "doi": "10.1117/12.461514", "isbn": "0819446254", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2002-12-16", "pages": "53-64" }, { "id": "authors:fxv00-gr748", "collection": "authors", "collection_id": "fxv00-gr748", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-100710320", "type": "book_section", "title": "Topic maps for custom viewing of data", "book_title": "Virtual Observatories", "author": [ { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R-E" }, { "family_name": "Brunner", "given_name": "Robert", "clpid": "Brunner-R-J" } ], "contributor": [ { "family_name": "Szalay", "given_name": "Alexander S.", "clpid": "Szalay-A-S" } ], "abstract": "A Topic Map is a structured network of hyperlinks that points into an information pool. Topic Maps have an existence independent of the information pool and hence different Topic Maps can form different layers above the same information pool and provide us with different views of it. We explore the use of Topic Maps with the Unified Column Descriptor (UCD) scheme developed in the frame of the ESO-CDS data mining project. UCD, with its multi-tier hierarchical structure, categorizes parameters reported in tables and catalogs. By using Topic Maps we show how columns from different catalogs with similar but not identical descriptions could be combined. A direct application for the Virtual Observatory community is that of merging catalogs in order to generate customized views of data.", "doi": "10.1117/12.461516", "isbn": "0819446254", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2002-12-16", "pages": "65-76" }, { "id": "authors:y6asc-tvr84", "collection": "authors", "collection_id": "y6asc-tvr84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-145648191", "type": "monograph", "title": "Cosmic Gamma-Ray Bursts, Their Afterglows, and Their Host Galaxies", "author": [ { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "This is a review article for the book \"Compact Stellar X-Ray Sources\", Editors W. Lewin and M. van der Klis, to be published by Cambridge University Press in 2003. It covers the phenomenology of cosmic gamma-ray bursts, the theory of their afterglows, and the observations and interpretation of their host galaxies.", "doi": "10.48550/arXiv.0211620", "publication_date": "2002-11-28" }, { "id": "authors:g4j47-k7192", "collection": "authors", "collection_id": "g4j47-k7192", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190924-090846820", "type": "article", "title": "Infrared Counterpart of the Microquasar GRS 1758\u2212258", "author": [ { "family_name": "Rothstein", "given_name": "D. M.", "clpid": "Rothstein-D-M" }, { "family_name": "Eikenberry", "given_name": "S. S.", "clpid": "Eikenberry-S-S" }, { "family_name": "Chatterjee", "given_name": "S.", "orcid": "0000-0002-2878-1502", "clpid": "Chatterjee-S" }, { "family_name": "Egami", "given_name": "E.", "clpid": "Egami-Eichi" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Heindl", "given_name": "W. A.", "clpid": "Heindl-W-A" } ], "abstract": "We present revised infrared (2.2 \u03bcm) astrometry of the field containing the Galactic microquasar GRS 1758-258, using observations at the Keck I 10 m telescope. We find three candidates for the microquasar within a 3 \u03c3 error circle but none within 2 \u03c3. We show that if the 18.4 day X-ray period of GRS 1758-258 is due to a binary orbit, then only one of the three candidates, an early K-type giant, is large enough to power the microquasar via Roche lobe overflow. We therefore identify this star as the infrared counterpart of GRS 1758-258, which we classify as a low-mass X-ray binary. Long-term infrared monitoring of this source should provide further information about the microquasar system, including a confirmation of the X-ray period and an estimate of the compact object's mass.", "doi": "10.1086/345546", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-11-20", "series_number": "1", "volume": "580", "issue": "1", "pages": "L61-L63" }, { "id": "authors:9nrcm-s8326", "collection": "authors", "collection_id": "9nrcm-s8326", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190918-092056565", "type": "article", "title": "Time\u2010dependent Optical Spectroscopy of GRB 010222: Clues to the Gamma\u2010Ray Burst Environment", "author": [ { "family_name": "Mirabal", "given_name": "N.", "clpid": "Mirabal-N" }, { "family_name": "Halpern", "given_name": "J. P.", "clpid": "Halpern-J-P" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Ebeling", "given_name": "H.", "clpid": "Ebeling-H" }, { "family_name": "Bunker", "given_name": "A.", "clpid": "Bunker-A-J" }, { "family_name": "Dawson", "given_name": "S.", "clpid": "Dawson-S" }, { "family_name": "Dey", "given_name": "A.", "orcid": "0000-0002-4928-4003", "clpid": "Dey-A" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" } ], "abstract": "We present sequential optical spectra of the afterglow of GRB 010222 obtained 1 day apart using the Low-Resolution Imaging Spectrometer (LRIS) and the Echellette Spectrograph and Imager (ESI) on the Keck Telescopes. Three low-ionization absorption systems are spectroscopically identified at z_1 = 1.47688, z_2 = 1.15628, and z_3 = 0.92747. The higher resolution ESI spectrum reveals two distinct components in the highest redshift system at z_1a = 1.47590 and z_1b = 1.47688. We interpret the z_1b = 1.47688 system as an absorption feature of the disk of the host galaxy of GRB 010222. The best-fitted power-law optical continuum and [Zn/Cr] ratio imply low dust content or a local gray dust component near the burst site. In addition, we do not detect strong signatures of vibrationally excited states of H2. If the gamma-ray burst took place in a superbubble or young stellar cluster, there are no outstanding signatures of an ionized absorber either. Analysis of the spectral time dependence at low resolution shows no significant evidence for absorption-line variability. This lack of variability is confronted with time-dependent photoionization simulations designed to apply the observed flux from GRB 010222 to a variety of assumed atomic gas densities and cloud radii. The absence of time dependence in the absorption lines implies that high-density environments are disfavored. In particular, if the GRB environment was dust free, its density was unlikely to exceed n_(H I) = 10^2 cm^(-3). If depletion of metals onto dust is similar to Galactic values or less than solar abundances are present, then n_(H I) \u2265 2 \u00d7 10^4 cm^(-3) is probably ruled out in the immediate vicinity of the burst.", "doi": "10.1086/342619", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-10-20", "series_number": "2", "volume": "578", "issue": "2", "pages": "818-832" }, { "id": "authors:hy0h0-4pp86", "collection": "authors", "collection_id": "hy0h0-4pp86", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-150227509", "type": "monograph", "title": "The Digitized Second Palomar Observatory Sky Survey (DPOSS) II: Photometric Calibration", "author": [ { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Brunner", "given_name": "R. J.", "clpid": "Brunner-R-J" }, { "family_name": "Lopes", "given_name": "P. A. A.", "clpid": "Lopes-P-A-A" } ], "abstract": "We present the photometric calibration technique for the Digitized Second Palomar Observatory Sky Survey (DPOSS), used to create seamless catalogs of calibrated objects over large sky areas. After applying a correction for telescope vignetting, the extensive plate overlap regions are used to transform sets of plates onto a common instrumental photometric system. Photometric transformations to the Gunn gri system for each plate, for stars and galaxies, are derived using these contiguous stitched areas and an extensive CCD imaging library obtained for this purpose. We discuss the resulting photometric accuracy, survey depth, and possible systematic errors.", "doi": "10.48550/arXiv.0210298", "publication_date": "2002-10-14" }, { "id": "authors:7pd8y-b1c22", "collection": "authors", "collection_id": "7pd8y-b1c22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170408-172051331", "type": "article", "title": "The Broadband Afterglow of GRB 980329", "author": [ { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Reichart", "given_name": "D.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Moriarty-Schieven", "given_name": "G. H.", "clpid": "Moriarty-Schieven-G-H" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Goodrich", "given_name": "R. W.", "clpid": "Goodrich-R-W" }, { "family_name": "Larkin", "given_name": "J. E.", "orcid": "0000-0001-7687-3965", "clpid": "Larkin-J-E" }, { "family_name": "Walter", "given_name": "F.", "orcid": "0000-0003-4793-7880", "clpid": "Walter-F" }, { "family_name": "Shepherd", "given_name": "D. S.", "clpid": "Shepherd-D-S" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Taylor", "given_name": "G. B.", "orcid": "0000-0001-6495-7731", "clpid": "Taylor-G-B" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" } ], "abstract": "We present radio observations of the afterglow of the bright \u03b3-ray burst GRB 980329 made between 1 month and several years after the burst, a reanalysis of previously published submillimeter data, and late-time optical and near-infrared (NIR) observations of the host galaxy. From the absence of a spectral break in the optical/NIR colors of the host galaxy, we exclude the earlier suggestion that GRB 980329 lies at a redshift of z \u2273 5. We combine our data with the numerous multiwavelength observations of the early afterglow, fit a comprehensive afterglow model to the entire broadband data set, and derive fundamental physical parameters of the blast wave and its host environment. Models for which the ejecta expand isotropically require both a high circumburst density and extreme radiative losses from the shock. No low-density model (n \u00ab 10 cm^(-3)) fits the data. A burst with a total energy of ~10^(51) ergs, with the ejecta narrowly collimated to an opening angle of a few degrees, driven into a surrounding medium with density of ~20 cm^(-3), provides a satisfactory fit to the light curves over a range of redshifts.", "doi": "10.1086/342175", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-09-20", "series_number": "1", "volume": "577", "issue": "1", "pages": "155-163" }, { "id": "authors:g5wj2-s0x20", "collection": "authors", "collection_id": "g5wj2-s0x20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180208-074341308", "type": "article", "title": "HST color-magnitude diagrams of 74 galactic globular clusters in the HST F439W and F555W bands", "author": [ { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" }, { "family_name": "King", "given_name": "I. R.", "clpid": "King-I-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Sosin", "given_name": "C.", "clpid": "Sosin-C" }, { "family_name": "Zoccali", "given_name": "M.", "clpid": "Zoccali-M" }, { "family_name": "Saviane", "given_name": "I.", "clpid": "Saviane-I" }, { "family_name": "De Angeli", "given_name": "F.", "clpid": "De-Angeli-F" }, { "family_name": "Riello", "given_name": "M.", "clpid": "Riello-M" }, { "family_name": "Recio Blanco", "given_name": "A.", "clpid": "Recio-Blanco-A" }, { "family_name": "Rich", "given_name": "R. M.", "orcid": "0000-0003-0427-8387", "clpid": "Rich-R-M" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Renzini", "given_name": "A.", "orcid": "0000-0002-7093-7355", "clpid": "Renzini-A" } ], "abstract": "We present the complete photometric database and the color-magnitude diagrams for 74 Galactic globular clusters observed with the HST/WFPC2 camera in the F439W and F555W bands. A detailed discussion of the various reduction steps is also presented, and of the procedures to transform instrumental magnitudes into both the HST F439W and F555W flight system and the standard Johnson B and V systems. We also describe the artificial star experiments which have been performed to derive the star count completeness in all the relevant branches of the color magnitude diagram. The entire photometric database and the completeness function will be made available on the Web immediately after the publication of the present paper.", "doi": "10.1051/0004-6361:20020820", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy & Astrophysics", "publication_date": "2002-08-09", "series_number": "3", "volume": "391", "issue": "3", "pages": "945-965" }, { "id": "authors:fk0k8-j9v82", "collection": "authors", "collection_id": "fk0k8-j9v82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-103451435", "type": "article", "title": "Palomar 13: An Unusual Stellar System in the Galactic Halo", "author": [ { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Castro", "given_name": "Sandra", "clpid": "Castro-S-M" }, { "family_name": "McCarthy", "given_name": "J. K.", "clpid": "McCarthy-J-K" } ], "abstract": "We report the first results of a program to study the internal kinematics of globular clusters in the outer halo of the Milky Way. Using the Keck telescope and High Resolution Echelle Spectrometer, we have measured precise radial velocities for 30 candidate red giants in the direction of Palomar 13, an object traditionally cataloged as a compact, low-luminosity globular cluster. We have combined these radial velocities with published proper motion membership probabilities and new CCD photometry from the Keck and Canada-France-Hawaii telescopes to isolate a sample of 21 probable members. We find a systemic velocity of \u3008v_r\u3009s = 24.1 \u00b1 0.5 km s^(-1) and a projected, intrinsic velocity dispersion of \u03c3_p= 2.2 \u00b1 0.4 km s^(-1). Although modest, this dispersion is nevertheless several times larger than that expected for a globular cluster of this luminosity and central concentration. Taken at face value, it implies a mass-to-light ratio of \u03d2_V = 40^(+24)_(-17) based on the best-fit King-Michie model. The surface density profile of Palomar 13 also appears unusual compared to most Galactic globular clusters; depending upon the details of background subtraction and model-fitting, Palomar 13 either contains a substantial population of \"extratidal\" stars, or is considerably more spatially extended than previously suspected. The full surface density profile is equally well fitted by a King-Michie model having a high concentration and large tidal radius, or by a Navarro-Frenk-White model. We examine\u2014and tentatively reject\u2014a number of possible origins for the observed characteristics of Palomar 13 (e.g., velocity \"jitter\" among the red giant branch stars, spectroscopic binary stars, nonstandard mass functions, modified Newtonian dynamics) and conclude that the two leading explanations are either catastrophic heating during a recent perigalacticon passage or the presence of a dark matter halo. The available evidence therefore suggests that Palomar 13 is either a globular cluster that is now in the process of dissolving into the Galactic halo or a faint, dark matter-dominated stellar system.", "doi": "10.1086/340978", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-08-01", "series_number": "2", "volume": "574", "issue": "2", "pages": "783-804" }, { "id": "authors:aprqc-a6w34", "collection": "authors", "collection_id": "aprqc-a6w34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-083753488", "type": "article", "title": "Unusually Long Duration Gamma\u2010Ray Burst GRB 000911: Discovery of the Afterglow and Host Galaxy", "author": [ { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Morrison", "given_name": "G.", "clpid": "Morrison-G" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Axelrod", "given_name": "T. S.", "clpid": "Axelrod-T-S" }, { "family_name": "Cline", "given_name": "T.", "clpid": "Cline-T" }, { "family_name": "Golenetskii", "given_name": "S.", "clpid": "Golenetskii-S" }, { "family_name": "Mazets", "given_name": "E.", "clpid": "Mazets-E" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Trombka", "given_name": "J.", "clpid": "Trombka-J" } ], "abstract": "Of all the well-localized gamma-ray bursts, GRB 000911 has the longest duration (T_(90) = 500 s) and ranks in the top 1% of BATSE bursts for fluence. Here we report the discovery of the afterglow of this unique burst. In order to simultaneously fit our radio and optical observations, we are required to invoke a model involving a hard electron distribution, p ~ 1.5, and a jet-break time less than 1.5 days. A spectrum of the host galaxy taken 111 days after the burst reveals a single emission line, interpreted as [O II] at a redshift z = 1.0585, and a continuum break that we interpret as the Balmer limit at this redshift. Despite the long T_(90), the afterglow of GRB 000911 is not unusual in any other way when compared to the set of afterglows studied to date. We conclude that the duration of the GRB plays little part in determining the physics of the afterglow.", "doi": "10.1086/340585", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-07-01", "series_number": "1", "volume": "573", "issue": "1", "pages": "85-91" }, { "id": "authors:0fws9-0ne57", "collection": "authors", "collection_id": "0fws9-0ne57", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-101423701", "type": "article", "title": "Detection of a Supernova Signature Associated with GRB 011121", "author": [ { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Reichart", "given_name": "D.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "McCarthy", "given_name": "P. J.", "clpid": "McCarthy-P-J" }, { "family_name": "Chevalier", "given_name": "R. A.", "clpid": "Chevalier-R-A" }, { "family_name": "Wheeler", "given_name": "J. C.", "clpid": "Wheeler-J-C" }, { "family_name": "Halpern", "given_name": "J. P.", "clpid": "Halpern-J-P" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Axelrod", "given_name": "T. S.", "clpid": "Axelrod-T-S" }, { "family_name": "Kimble", "given_name": "R. A.", "clpid": "Kimble-R-A" }, { "family_name": "Holtzman", "given_name": "J.", "clpid": "Holtzman-J" }, { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Piro", "given_name": "L.", "clpid": "Piro-L" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" } ], "abstract": "Using observations from an extensive monitoring campaign with the Hubble Space Telescope, we present the detection of an intermediate-time flux excess that is redder in color relative to the afterglow of GRB 011121, currently distinguished as the gamma-ray burst with the lowest known redshift. The red \"bump,\" which exhibits a spectral rollover at ~7200 \u00c5, is well described by a redshifted Type Ic supernova that occurred approximately at the same time as the gamma-ray burst event. The inferred luminosity is about half that of the bright supernova SN 1998bw. These results serve as compelling evidence for a massive star origin of long-duration gamma-ray bursts. Models that posit a supernova explosion weeks to months preceding the gamma-ray burst event are excluded by these observations. Finally, we discuss the relationship between spherical core-collapse supernovae and gamma-ray bursts.", "doi": "10.1086/341551", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-06-10", "series_number": "1", "volume": "572", "issue": "1", "pages": "L45-L49" }, { "id": "authors:fs0e7-r6279", "collection": "authors", "collection_id": "fs0e7-r6279", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190918-083156797", "type": "article", "title": "GRB 011121: A Massive Star Progenitor", "author": [ { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" } ], "abstract": "Of the cosmological gamma-ray bursts, GRB 011121 has the lowest redshift, z = 0.36. More importantly, the multicolor excess in the afterglow detected in the Hubble Space Telescope (HST) light curves is compelling observational evidence of an underlying supernova. Here we present near-infrared and radio observations of the afterglow, and from our comprehensive afterglow modeling, we find evidence favoring a wind-fed circumburst medium. Lacking X-ray data, we are unable to conclusively measure the mass-loss rate, M, but obtain an estimate, M ~ 2 \u00d7 10^(-7)/vw_3 M\u2609 yr^(-1), where vw_3 is the speed of the wind from the progenitor in units of 10^3 km s^(-1). This M is similar to that inferred for the progenitor of the Type Ibc supernova SN 1998bw that has been associated with the peculiar burst GRB 980425. Our data, taken in conjunction with the HST results of Bloom et al., provide a consistent picture: the long-duration GRB 011121 had a massive star progenitor that exploded as a supernova at about the same time as the gamma-ray burst event. Finally, we note that the gamma-ray profile of GRB 011121 is similar to that of GRB 980425.", "doi": "10.1086/341552", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2002-06-10", "series_number": "1", "volume": "572", "issue": "1", "pages": "L51-L55" }, { "id": "authors:p4zqn-knd81", "collection": "authors", "collection_id": "p4zqn-knd81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140703-135258516", "type": "publication_deliverable", "title": "California Extremely Large Telescope: Conceptual Design for a Thirty-Meter Telescope", "author": [ { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "Dekany", "given_name": "Richard", "clpid": "Dekany-Richard" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ellis", "given_name": "Richard S.", "orcid": "0000-0001-7782-7071", "clpid": "Ellis-R-S" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "MacMartin", "given_name": "Douglas G.", "orcid": "0000-0003-1987-9417", "clpid": "MacMartin-D-G" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-K" }, { "family_name": "Murray", "given_name": "Richard M.", "orcid": "0000-0002-5785-7481", "clpid": "Murray-R-M" }, { "family_name": "Padin", "given_name": "S.", "clpid": "Padin-S" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Steidel", "given_name": "Charles C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" }, { "family_name": "Taylor", "given_name": "Keith", "clpid": "Taylor-K" }, { "family_name": "Tombrello", "given_name": "T. A.", "clpid": "Tombrello-T-A" }, { "literal": "California Institute of Technology" }, { "literal": "University of California" } ], "abstract": "Following great success in the creation of the Keck Observatory, scientists at the California Institute of\nTechnology and the University of California have begun to explore the scientific and technical prospects\nfor a much larger telescope. The Keck telescopes will remain the largest telescopes in the world for a\nnumber of years, with many decades of forefront research ahead after that. Though these telescopes\nhave produced dramatic discoveries, it is already clear that even larger telescopes must be built if we\nare to address some of the most profound questions about our universe. The time required to build a\nlarger telescope is approximately ten years, and the California community is presently well-positioned\nto begin its design and construction. The same scientists who conceived, led the design, and guided\nthe construction of the Keck Observatory have been intensely engaged in a study of the prospects for\nan extremely large telescope. Building on our experience with the Keck Observatory, we have concluded\nthat the large telescope is feasible and is within the bounds set by present-day technology. Our reference\ntelescope has a diameter of 30 meters, the largest size we believe can be built with acceptable risk. The\nproject is currently designated the California Extremely Large Telescope (CELT).", "publisher": "California Institute of Technology", "publication_date": "2002-06" }, { "id": "authors:kdxa7-zx055", "collection": "authors", "collection_id": "kdxa7-zx055", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170328-125204254", "type": "article", "title": "CO and Dust in PSS 2322+1944 at a redshift of 4.12", "author": [ { "family_name": "Cox", "given_name": "P.", "orcid": "0000-0003-2027-8221", "clpid": "Cox-Pierre" }, { "family_name": "Omont", "given_name": "A.", "orcid": "0000-0002-4721-3922", "clpid": "Omont-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bertoldi", "given_name": "F.", "orcid": "0000-0002-1707-1775", "clpid": "Bertoldi-F" }, { "family_name": "Pety", "given_name": "J.", "clpid": "Pety-J" }, { "family_name": "Carilli", "given_name": "C. L.", "orcid": "0000-0001-6647-3861", "clpid": "Carilli-C-L" }, { "family_name": "Isaak", "given_name": "K. G.", "clpid": "Isaak-K-G" }, { "family_name": "Beelen", "given_name": "A.", "clpid": "Beelen-A" }, { "family_name": "McMahon", "given_name": "R. G.", "clpid": "McMahon-R-G" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" } ], "abstract": "Using the IRAM interferometer we have detected J = 4 \u2192 3 and 5 \u2192 4 CO line emission toward the radio quiet quasar PSS 2322+1944. At a redshift of z_(CO) = 4.1199 this is the fourth and strongest detection of CO at z > 4. The velocity-integrated CO J = 4 \u2192 3 and J = 5 \u2192 4 line fluxes are 4.21 \u00b1 0.40 and 3.74 \u00b1 0.56 Jy km s^(-1), and the linewidth is \u2248 300 km s^(-1). The CO J = 10 \u2192 9 was searched for but not detected with an upper intensity limit of 30 mJy. The 1.35 mm (250 \u00b5m rest wavelength) continuum flux density is 7.5 \u00b1 1.3 mJy, in agreement with previous bolometer measurements at 1.2 mm with the 30-m IRAM telescope. The 3 mm (580 \u00b5m rest wavelength) continuum is not detected with a 3 \u03c3 upper limit of 0.7 mJy. We also report observations of the 450 \u00b5m continuum in PSS 2322+1944 using the SCUBA array at the JCMT. The quasar was detected with a 450 \u00b5m flux density of 79 \u00b1 19 mJy. At the angular resolution of 4.\"8 x 2.\" at 1.3 mm and 6.\"2 x 4.\"9 at 3.2 mm, the interferometer observations do not show evidence of spatial extension in the continuum or CO line emission. Assuming no gravitational magnification, we estimate a molecular gas mass of \u2248 2.5 x 10^(11) M_\u2609. The molecular gas is warm (40-100K) and dense (10^(3.5) 10^(4.1) cm^(-3). The infrared-to-CO luminosity ratio is \u2248185 L_\u2609 (K km-s^(-1) pc^2)^(-1), comparable to the values found for ultraluminous infrared galaxies. The detection of CO emission in this high redshift QSO provides further evidence that the radio emission and the millimeter to submillimeter continuum emission are predominantly powered by a starburst which is coeval with the AGN activity.", "doi": "10.1051/0004-6361:20020382", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "2002-05", "series_number": "2", "volume": "387", "issue": "2", "pages": "406-411" }, { "id": "authors:03wrh-fkf36", "collection": "authors", "collection_id": "03wrh-fkf36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-144059466", "type": "article", "title": "GRB 010222: A Burst within a Starburst", "author": [ { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Bertoldi", "given_name": "F.", "orcid": "0000-0002-1707-1775", "clpid": "Bertoldi-F" }, { "family_name": "Moriarty\u2010Schieven", "given_name": "G. H.", "clpid": "Moriarty\u2010Schieven-G-H" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Gerardy", "given_name": "C. L.", "clpid": "Gerardy-C-L" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Walter", "given_name": "F.", "orcid": "0000-0003-4793-7880", "clpid": "Walter-F" }, { "family_name": "Shepherd", "given_name": "D. S.", "clpid": "Shepherd-D-S" }, { "family_name": "Halpern", "given_name": "J.", "clpid": "Halpern-J-P" }, { "family_name": "Peck", "given_name": "A. B.", "clpid": "Peck-A-B" }, { "family_name": "Menten", "given_name": "K. M.", "orcid": "0000-0001-6459-0669", "clpid": "Menten-K-M" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Fox", "given_name": "D. W.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" } ], "abstract": "We present millimeter- and submillimeter-wavelength observations and near-infrared K-band imaging toward the bright gamma-ray burst GRB 010222. Over seven different epochs, a constant source was detected with an average flux density of 3.74 \u00b1 0.53 mJy at 350 GHz and 1.05 \u00b1 0.22 mJy at 250 GHz, giving a spectral index \u03b1 = 3.78 \u00b1 0.25 (where F \u221d \u03bd^\u03b1). We rule out the possibility that this emission originated from the burst or its afterglow, and we conclude that it is due to a dusty, high-redshift starburst galaxy (SMM J14522+4301). We argue that the host galaxy of GRB 010222 is the most plausible counterpart of SMM J14522+4301, based in part on the centimeter detection of the host at the expected level. The optical/near-IR properties of the host galaxy of GRB 010222 suggest that it is a blue sub-L* galaxy, similar to other GRB host galaxies. This contrasts with the enormous far-infrared luminosity of this galaxy based on our submillimeter detection (L_(Bol) \u2248 4 \u00d710^(12) L\u2609). We suggest that this GRB host galaxy has a very high star formation rate, SFR \u2248 600 M\u2609 yr^(-1), most of which is unseen at optical wavelengths.", "doi": "10.1086/324718", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2002-02-01", "series_number": "2", "volume": "565", "issue": "2", "pages": "829-835" }, { "id": "authors:jye65-rg886", "collection": "authors", "collection_id": "jye65-rg886", "cite_using_url": "https://resolver.caltech.edu/CaltechCACR:2002.003", "type": "conference_item", "title": "Atlasmaker: A Grid-based Implementation of the Hyperatlas", "author": [ { "family_name": "Williams", "given_name": "R. D.", "orcid": "0000-0002-9145-8580", "clpid": "Williams-R-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Feldmann", "given_name": "M. T.", "clpid": "Feldmann-M-T" }, { "family_name": "Jacob", "given_name": "J. C.", "clpid": "Jacob-J-C" } ], "abstract": "The Atlasmaker project is using Grid technology, in combination with NVO interoperability, to create new knowledge resources in astronomy. The product is a multi-faceted, multi-dimensional, scientifically trusted image atlas of the sky, made by federating many different surveys at different wavelengths, times, resolutions, polarizations, etc. The Atlasmaker software does resampling and mosaicking of image collections, and is well-suited to operate with the Hyperatlas standard. Requests can be satisfied via on-demand computations or by accessing a data cache. Computed data is stored in a distributed virtual file system, such as the Storage Resource Broker (SRB). We expect these atlases to be a new and powerful paradigm for knowledge extraction in astronomy, as well as a magnificent way to build educational resources. The system is being incorporated into the data analysis pipeline of the Palomar-Quest synoptic survey, and is being used to generate all-sky atlases from the 2MASS, SDSS, and DPOSS surveys for joint object detection.", "doi": "10.48550/arXiv.0312196", "publication_date": "2002" }, { "id": "authors:e5m7p-pvw51", "collection": "authors", "collection_id": "e5m7p-pvw51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-145447977", "type": "book_section", "title": "Massive Datasets in Astronomy", "book_title": "Handbook of Massive Data Sets", "author": [ { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Prince", "given_name": "Thomas A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Szalay", "given_name": "Alex S.", "clpid": "Szalay-A-S" } ], "contributor": [ { "family_name": "Abello", "given_name": "James", "clpid": "Abello-J" }, { "family_name": "Pardalos", "given_name": "Panos M.", "clpid": "Pardalos-P-M" }, { "family_name": "Resende", "given_name": "Mauricio G. C.", "clpid": "Resende-M-G-C" } ], "abstract": "Astronomy has a long history of acquiring, systematizing, and interpreting large quantities of data. Starting from the earliest sky atlases through the first major photographic sky surveys of the 20th century, this tradition is continuing today, and at an ever increasing rate.\n\nLike many other fields, astronomy has become a very data-rich science, driven by the advances in telescope, detector, and computer technology. Numerous large digital sky surveys and archives already exist, with information content measured in multiple Terabytes, and even larger, multi-Petabyte data sets are on the horizon. Systematic observations of the sky, over a range of wavelengths, are becoming the primary source of astronomical data. Numerical simulations are also producing comparable volumes of information. Data mining promises to both make the scientific utilization of these data sets more effective and more complete, and to open completely new avenues of astronomical research.\n\nTechnological problems range from the issues of database design and federation, to data mining and advanced visualization, leading to a new toolkit for astronomical research. This is similar to challenges encountered in other data-intensive fields today.\n\nThese advances are now being organized through a concept of the Virtual Observatories, federations of data archives and services representing a new information infrastructure for astronomy of the 21 st century. In this article, we provide an overview of some of the major datasets in astronomy, discuss different techniques used for archiving data, and conclude with a discussion of the future of massive datasets in astronomy.", "doi": "10.1007/978-1-4615-0005-6_27", "isbn": "978-1-4613-4882-5", "publisher": "Springer", "place_of_publication": "Boston, MA", "publication_date": "2002", "pages": "931-979" }, { "id": "authors:9a4e6-cmj45", "collection": "authors", "collection_id": "9a4e6-cmj45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130429-112326246", "type": "article", "title": "Beaming in gamma-ray bursts: evidence for a standard energy reservoir", "author": [ { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" }, { "family_name": "Diercks", "given_name": "A.", "clpid": "Diercks-A" }, { "family_name": "Goodrich", "given_name": "R. W.", "clpid": "Goodrich-R-W" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F" } ], "abstract": "We present a comprehensive sample of all gamma-ray burst (GRB) afterglows with known distances, and we derive their conical opening angles based on observed broadband breaks in their light curves. Within the framework of this conical jet model, we correct for the geometry and we find that the gamma-ray energy release is narrowly clustered around 5 \u00d7 10^(50) ergs. We draw three conclusions. First, the central engines of GRBs release energies that are comparable to ordinary supernovae. Second, the broad distribution in fluence and luminosity for GRBs is largely the result of a wide variation of opening angles. Third, only a small fraction of GRBs are visible to a given observer, and the true GRB rate is several hundred times larger than the observed rate.", "doi": "10.1086/338119", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2001-11-20", "series_number": "1", "volume": "562", "issue": "1", "pages": "L55-L58" }, { "id": "authors:gp1vj-z7521", "collection": "authors", "collection_id": "gp1vj-z7521", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-092405965", "type": "book_section", "title": "Exploration of parameter spaces in a virtual observatory", "book_title": "Astronomical Data Analysis", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Mahabal", "given_name": "A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Brunner", "given_name": "R.", "clpid": "Brunner-R-J" }, { "family_name": "Williams", "given_name": "R.", "clpid": "Williams-R-E" }, { "family_name": "Granat", "given_name": "R.", "clpid": "Granat-R" }, { "family_name": "Curkendall", "given_name": "D.", "clpid": "Curkendall-D-W" }, { "family_name": "Jacob", "given_name": "J.", "clpid": "Jacob-J-C" }, { "family_name": "Stolorz", "given_name": "P.", "clpid": "Stolorz-P" } ], "contributor": [ { "family_name": "Starck", "given_name": "J.-L.", "clpid": "Starck-J-L" }, { "family_name": "Murtagh", "given_name": "Fionn", "clpid": "Murtagh-F" } ], "abstract": "Like every other field of intellectual endeavor, astronomy is being revolutionized by the advances in information technology. There is an ongoing exponential growth in the volume, quality, and complexity of astronomical data sets, mainly through large digital sky surveys and archives. The Virtual Observatory (VO) concept represents a scientific and technological framework needed to cope with this data flood. Systematic exploration of the observable parameter spaces, covered by large digital sky surveys spanning a range of wavelengths, will be one of the primary modes of research with a VO. This is where the truly new discoveries will be made, and new insights be gained about the already known astronomical objects and phenomena. We review some of the methodological challenges posed by the analysis of large and complex data sets expected in the VO-based research. The challenges are driven both by the size and the complexity of the data sets (billions of data vectors in parameter spaces of tens or hundreds of dimensions), by the heterogeneity of the data and measurement errors, including differences in basic survey parameters for the federated data sets (e.g., in the positional accuracy and resolution, wavelength coverage, time baseline, etc), various selection effects, as well as the intrinsic clustering properties (functional form, topology) of the data distributions in the parameter spaces of observed attributes. Answering these challenges will require substantial collaborative efforts and partnerships between astronomers, computer scientists, and statisticians.", "doi": "10.1117/12.447189", "isbn": "9780819441911", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2001-11-01", "pages": "43-52" }, { "id": "authors:7j1wj-hap91", "collection": "authors", "collection_id": "7j1wj-hap91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-110835813", "type": "book_section", "title": "Topic maps as a virtual observatory tool", "book_title": "Astronomical Data Analysis", "author": [ { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Brunner", "given_name": "Robert", "clpid": "Brunner-R-J" }, { "family_name": "Williams", "given_name": "Roy", "clpid": "Williams-R-E" } ], "contributor": [ { "family_name": "Starck", "given_name": "Jean-Luc", "clpid": "Starck-J-L" }, { "family_name": "Murtagh", "given_name": "Fionn D.", "clpid": "Murtagh-F-D" } ], "abstract": "One major component of the VO will be catalogs measuring gigabytes and terrabytes if not more. Some mechanism like XML will be used for structuring the information. However, such mechanisms are not good for information retrieval on their own. For retrieval we use queries. Topic Maps that have started becoming popular recently are excellent for segregating information that results from a query. A Topic Map is a structured network of hyperlinks above an information pool. Different Topic Maps can form different layers above the same information pool and provide us with different views of it. This facilitates in being able to ask exact questions, aiding us in looking for gold needles in the proverbial haystack. Here we will discuss the specifics of what Topic Maps are and how they can be implemented within the VO framework.", "doi": "10.1117/12.447170", "isbn": "9780819441911", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2001-11-01", "pages": "161-172" }, { "id": "authors:bhd3v-rxw03", "collection": "authors", "collection_id": "bhd3v-rxw03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-124023773", "type": "article", "title": "On the Threshold of the Reionization Epoch", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" } ], "abstract": "Discovery of the cosmic reionization epoch would represent a significant milestone in cosmology. We present Keck spectroscopy of the quasar SDSS 1044-0125, at z = 5.73. The spectrum shows a dramatic increase in the optical depth at observed wavelengths \u03bb \u2273 7550 \u00c5, corresponding to z_(abs) \u2273 5.2. Only a few small, narrow transmission regions are present in the spectrum beyond that point and out to the redshifts where the quasar signal begins. We interpret this result as a signature of the trailing edge of the cosmic reionization epoch, which we estimate to occur around \u3008z\u3009~ 6 (as indeed confirmed by subsequent observations by Becker et al.) and extending down to z ~ 5.2. This behavior is expected in the modern theoretical models of the reionization era, which predict a patchy and gradual onset of reionization. The remaining transmission windows we see may correspond to the individual reionization bubbles (Str\u00f6mgren spheres) embedded in a still largely neutral intergalactic medium, intersected by the line of sight to the quasar. Future spectroscopic observations of quasars at comparable or larger redshifts will provide a more detailed insight into the structure and extent of the reionization era.", "doi": "10.1086/324175", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2001-10-10", "series_number": "1", "volume": "560", "issue": "1", "pages": "L5-L8" }, { "id": "authors:zqdjm-ha232", "collection": "authors", "collection_id": "zqdjm-ha232", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-144922867", "type": "monograph", "title": "The National Virtual Observatory", "author": [ { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Prince", "given_name": "Thomas A.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Szalay", "given_name": "Alex S.", "clpid": "Szalay-A-S" } ], "abstract": "As a scientific discipline, Astronomy is rather unique. We only have one laboratory, the Universe, and we cannot, of course, change the initial conditions and study the resulting effects. On top of this, acquiring Astronomical data has historically been a very labor-intensive effort. As a result, data has traditionally been preserved for posterity. With recent technological advances, however, the rate at which we acquire new data has grown exponentially, which has generated a Data Tsunami, whose wave train threatens to overwhelm the field. In this conference proceedings, we present and define the concept of virtual observatories, which we feel is the only logical answer to this dilemma.", "doi": "10.48550/arXiv.0108381", "publication_date": "2001-08-23" }, { "id": "authors:af0wg-mxe27", "collection": "authors", "collection_id": "af0wg-mxe27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KULaipcp01a", "type": "book_section", "title": "The afterglows of gamma-ray bursts", "book_title": "Explosive Phenomena in Astrophysical Objects: First KIAS Astrophysics Workshop, Seoul, Korea, 24-27 May 2000", "author": [ { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F" }, { "family_name": "Diercks", "given_name": "A.", "clpid": "Diercks-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Goodrich", "given_name": "R. W.", "clpid": "Goodrich-R-W" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" } ], "contributor": [ { "family_name": "Chang", "given_name": "Heon-Young" }, { "family_name": "Yi", "given_name": "Insu" }, { "family_name": "Rho", "given_name": "Mannque" }, { "family_name": "Lee", "given_name": "Chang-Hwan" } ], "abstract": "Gamma-ray burst astronomy has undergone a revolution in the last three years, spurred by the discovery of fading long-wavelength counterparts. We now know that at least the long duration GRBs lie at cosmological distances with estimated electromagnetic energy release of 10^51\u201310^53 erg, making these the brightest explosions in the Universe. In this article we review the current observational state, beginning with the statistics of X-ray, optical, and radio afterglow detections. We then discuss the insights these observations have given to the progenitor population, the energetics of the GRB events, and the physics of the afterglow emission. We focus particular attention on the evidence linking GRBs to the explosion of massive stars. Throughout, we identify remaining puzzles and uncertainties, and emphasize promising observational tools for addressing them. The imminent launch of HETE-2 and the increasingly sophisticated and coordinated ground-based and space-based observations have primed this field for fantastic growth. This overview is a combined write-up of talks given at this conference and in NASA's Goddard Space Flight Center.", "doi": "10.1063/1.1368281", "isbn": "1563969874", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2001-03-23", "pages": "240-260" }, { "id": "authors:rxmhm-e8f03", "collection": "authors", "collection_id": "rxmhm-e8f03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150227-151024707", "type": "article", "title": "Multicolor Observations of the GRB 000926 Afterglow", "author": [ { "family_name": "Price", "given_name": "P. A.", "clpid": "Price-P-A" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Reichart", "given_name": "D. E.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Axelrod", "given_name": "T. S.", "clpid": "Axelrod-T-S" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Busche", "given_name": "J.", "clpid": "Busche-J" }, { "family_name": "Cline", "given_name": "T.", "clpid": "Cline-T" }, { "family_name": "Dierks", "given_name": "A.", "clpid": "Dierks-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Gal-Yam", "given_name": "A.", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Halpern", "given_name": "J.", "clpid": "Halpern-J-P" }, { "family_name": "Holtzman", "given_name": "J. A.", "clpid": "Holtzman-J-A" }, { "family_name": "Hunt", "given_name": "M.", "clpid": "Hunt-M" }, { "family_name": "Hurley", "given_name": "K.", "clpid": "Hurley-K-C" }, { "family_name": "Jacoby", "given_name": "B.", "clpid": "Jacoby-B-A" }, { "family_name": "Kimble", "given_name": "R.", "clpid": "Kimble-Randy-A" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Mirabal", "given_name": "N.", "clpid": "Mirabal-N" }, { "family_name": "Morrison", "given_name": "G.", "clpid": "Morrison-G" }, { "family_name": "Ofek", "given_name": "E.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Pevunova", "given_name": "O.", "clpid": "Pevunova-O" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Turnshek", "given_name": "D.", "clpid": "Turnshek-D" }, { "family_name": "Yost", "given_name": "S.", "clpid": "Yost-S-A" } ], "abstract": "We present multicolor light curves of the optical afterglow of gamma-ray burst (GRB) 000926. Beginning\n~1.5 days after the burst, the light curves of this GRB steepen measurably. The existence of such achromatic breaks\nis usually taken to be an important observational signature that the ejecta are not expanding isotropically but rather\nhave a collimated jetlike geometry. If we interpret the data in this context, we derive an opening angle of 5\u00b0, which\nreduces the energy release compared with an isotropic model by a factor of ~275, to 1.7x10^(51) ergs. To fit\nthe data with a simple jet model requires extinction along the line of sight. The derived A_V is in the range \n0.11\u20130.82 mag, depending on the adopted extinction law and whether the electrons giving rise to the optical emission\nare undergoing synchrotron cooling or not. Since this is in excess of the expected extinction from our Galaxy, we\nattribute this to the GRB host. We note that this extinction is typical of a galactic disk, and therefore the event\nlikely took place in the disk of its host.", "doi": "10.1086/319152", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2001-03-01", "series_number": "1", "volume": "549", "issue": "1", "pages": "L7-L10" }, { "id": "authors:zn6g7-8wg83", "collection": "authors", "collection_id": "zn6g7-8wg83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-153557859", "type": "article", "title": "The evolutionary history of early-type galaxies as derived from the fundamental plane", "author": [ { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "abstract": "The fundamental plane (FP) scaling relations and their evolution are a powerful tool for studying the global properties of early-type galaxies and their evolutionary history. The form of the FP, as derived by surveys in the local Universe at wavelengths ranging from the U to the K band, cannot be explained by metallicity variations alone among early-type galaxies; systematic variations in age, dark matter content, or homology breaking are required. A large-scale study of early-type galaxies at 0.1 < z < 0.6demonstrates that the SB intercept of the FP, the rest frame (U-V) colour, and the absorption line strengths all evolve passively, thereby implying a high mean formation redshift for the stellar content. The slope of the FP evolves with redshift, which is broadly consistent with systematic age effects occurring along the early-type galaxy sequence. The implication that the least luminous early-type galaxies formed later than the luminous galaxies is discussed in the context of the evolution of thecolour\u2013magnitude relation, the Butcher\u2013Oemler effect and hierarchical galaxy formation models.", "doi": "10.1023/A:1017528430583", "issn": "0004-640X", "publisher": "Springer", "publication": "Astrophysics and Space Science", "publication_date": "2001-03", "series_number": "2-4", "volume": "276", "issue": "2-4", "pages": "983-990" }, { "id": "authors:5qwam-mef51", "collection": "authors", "collection_id": "5qwam-mef51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180306-111017080", "type": "article", "title": "Luminosity function of clusters of galaxies", "author": [ { "family_name": "Paolillo", "given_name": "M.", "orcid": "0000-0003-4210-7693", "clpid": "Paolillo-M" }, { "family_name": "Andreon", "given_name": "S.", "clpid": "Andreon-S" }, { "family_name": "Longo", "given_name": "G.", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" }, { "family_name": "Puddu", "given_name": "E.", "clpid": "Puddu-E" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Scaramella", "given_name": "R.", "clpid": "Scaramella-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "abstract": "The composite galaxy luminosity function (hereafter LF) of 39 Abell clusters of galaxies is derived by computing the statistical excess of galaxy counts in the cluster direction with respect to control fields. Due to the wide field coverage of the digitised POSS-II plates, we can measure field counts around each cluster in a fully homogeneous way. Furthermore, the availability of virtually unlimited sky coverage allows us to directly compute the LF errors without having to rely on the estimated variance of the background. The wide field coverage also allows us to derive the LF of the whole cluster, including galaxies located in the cluster outskirts. The global composite LF has a slope \u03b1 ~ -1.1 \u00b1 0.2 with minor variations from blue to red filters, and M* ~ -21.7, -22.2, -22.4 mag (H_0 = 50 km s^(-1) Mpc^(-1)) in g, r and i filters, respectively (errors are detailed in the text). These results are in quite good agreement with several previous determinations and in particular with the LF determined for the inner region of a largely overlapping set of clusters, but derived making use of a completely different method for background subtraction. The similarity of the two LFs suggests the existence of minor differences between the LF in the cluster outskirts and in the central region, or a negligible contribution of galaxies in the cluster outskirts to the global LF.", "doi": "10.1051/0004-6361:20000442", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy & Astrophysics", "publication_date": "2001-02-03", "series_number": "1", "volume": "367", "issue": "1", "pages": "59-71" }, { "id": "authors:r8qbr-vjw95", "collection": "authors", "collection_id": "r8qbr-vjw95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150224-160246756", "type": "book_section", "title": "The Digital Sky Project: Prototyping Virtual Observatory Technologies", "book_title": "Virtual Observatories of the Future", "author": [ { "family_name": "Brunner", "given_name": "R. J.", "clpid": "Brunner-R-J" }, { "family_name": "Prince", "given_name": "T.", "orcid": "0000-0002-8850-3627", "clpid": "Prince-T-A" }, { "family_name": "Good", "given_name": "J.", "clpid": "Good-J-C" }, { "family_name": "Handley", "given_name": "T. H.", "clpid": "Handley-T-H" }, { "family_name": "Lonsdale", "given_name": "C.", "orcid": "0000-0003-0898-406X", "clpid": "Lonsdale-C-J" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "Djorgovski", "given_name": "S. George", "clpid": "Djorgovski-S-G" }, { "family_name": "Szalay", "given_name": "Alex S.", "clpid": "Szalay-A-S" } ], "abstract": "Astronomy is entering a new era as multiple, large area,\ndigital sky surveys are in production. The resulting datasets are truly remarkable in their own right; however, a revolutionary step arises in the aggregation of complimentary multi-wavelength surveys (i.e., the crossidentification of a billion sources) . The federation of these large datasets is already underway, and is producing a major paradigm shift as Astronomy has suddenly become an immensely data-rich field. This new paradigm\nwill enable quantitatively and qualitatively new science, from statistical studies of our Galaxy and the large-scale structure in the universe, to discoveries of rare, unusual, or even completely new types of astronomical objects and phenomena. Federating and then exploring these large\ndatasets, however, is an extremely challenging task. The Digital Sky project was initiated with this task in mind and is working to develop the techniques and technologies necessary to solve the problems inherent in federating these large databases, as well as the mining of the resultant aggregate data.", "isbn": "1-58381-057-9", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "2001", "pages": "135-141" }, { "id": "authors:0cbxq-s8r44", "collection": "authors", "collection_id": "0cbxq-s8r44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-160758075", "type": "book_section", "title": "Exploration of Large Digital Sky Surveys", "book_title": "Mining the Sky", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Brunner", "given_name": "R. J.", "clpid": "Brunner-R-J" }, { "family_name": "Mahabal", "given_name": "A. A.", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Stolorz", "given_name": "P.", "clpid": "Stolorz-P" }, { "family_name": "Granat", "given_name": "R.", "clpid": "Granat-R" }, { "family_name": "Curkendall", "given_name": "D.", "clpid": "Curkendall-D-W" }, { "family_name": "Jacob", "given_name": "J.", "clpid": "Jacob-J" }, { "family_name": "Castro", "given_name": "S.", "clpid": "Castro-S" } ], "contributor": [ { "family_name": "Banday", "given_name": "Anthony J.", "clpid": "Banday-A-J" }, { "family_name": "Zaroubi", "given_name": "Saleem", "clpid": "Zaroubi-S" }, { "family_name": "Bartelmann", "given_name": "Matthias", "clpid": "Bartelmann-M" } ], "abstract": "We review some of the scientific opportunities and technical challenges posed by the exploration of the large digital sky surveys, in the context of a Virtual Observatory (VO). The VO paradigm will profoundly change the way observational astronomy is done. Clustering analysis techniques can be used to discover samples of rare, unusual, or even previously unknown types of astronomical objects and phenomena. Exploration of the previously poorly probed portions of the observable parameter space are especially promising. We illustrate some of the possible types of studies with examples drawn from DPOSS; much more complex and interesting applications are forthcoming. Development of the new tools needed for an efficient exploration of these vast data sets requires a synergy between astronomy and information sciences, with great potential returns for both fields.", "doi": "10.1007/10849171_37", "isbn": "978-3-540-42468-0", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "2001", "pages": "305-322" }, { "id": "authors:qvtgm-1yn04", "collection": "authors", "collection_id": "qvtgm-1yn04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-155408196", "type": "book_section", "title": "Automated Search of LSB Galaxies in DPOSS (CRoNaRio Project): Method and First Results from Follow-Ups", "book_title": "Mining the Sky", "author": [ { "family_name": "Testa", "given_name": "Vincenzo", "clpid": "Testa-V" }, { "family_name": "Sabatini", "given_name": "Sabina", "clpid": "Sabatini-S" }, { "family_name": "Scaramella", "given_name": "Roberto", "clpid": "Scaramella-R" }, { "family_name": "Longo", "given_name": "Giuseppe", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gal", "given_name": "Roy R.", "clpid": "Gal-R-R" }, { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "de Carvalho", "given_name": "Reinaldo R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "contributor": [ { "family_name": "Banday", "given_name": "Anthony J.", "clpid": "Banday-A-J" }, { "family_name": "Zaroubi", "given_name": "Saleem", "clpid": "Zaroubi-S" }, { "family_name": "Bartelmann", "given_name": "Matthias", "clpid": "Bartelmann-M" } ], "abstract": "We developed an algorithm to search automatically for LSB galaxies in the DPOSS plate scans. The algorithm consists of three different steps in which: i) the original image is processed with a standard image analysis package (e.g. SExtractor) and normal high surface brightness objects are removed; ii) a series of filters with an exponential compensated profile are applied at different scales; iii) significance maps are pruned by selecting, for each detection, the characteristic scale and significance; iv) candidates are then trimmed by measuring them on the original image with a fit with an exponential profile. Multicolor optical follow-up with CCD has begun on some of the best candidates.", "doi": "10.1007/10849171_72", "isbn": "978-3-540-42468-0", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "2001", "pages": "557-563" }, { "id": "authors:7yn86-6h687", "collection": "authors", "collection_id": "7yn86-6h687", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-160211878", "type": "book_section", "title": "The Northern Sky Optical Cluster Survey", "book_title": "Mining the Sky", "author": [ { "family_name": "Gal", "given_name": "Roy R.", "clpid": "Gal-R-R" }, { "family_name": "de Carvalho", "given_name": "Reinaldo R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Odewahn", "given_name": "Stephen C.", "clpid": "Odewahn-S-C" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Brunner", "given_name": "Robert J.", "clpid": "Brunner-R-J" }, { "family_name": "Margoniner", "given_name": "Vera E.", "clpid": "Margoniner-V-E" } ], "contributor": [ { "family_name": "Banday", "given_name": "Anthony J.", "clpid": "Banday-A-J" }, { "family_name": "Zaroubi", "given_name": "Saleem", "clpid": "Zaroubi-S" }, { "family_name": "Bartelmann", "given_name": "Matthias", "clpid": "Bartelmann-M" } ], "abstract": "The Northern Sky Optical Cluster Survey aims to create an objective catalog of galaxy clusters over the entire high-galactic-latitude Northern sky. We use the catalogs generated from the Digitized Second Palomar Sky Survey (DPOSS, Djorgovski et al. 1999) as the basis for this survey. We apply a color criterion to select against field galaxies, and use a simple adaptive kernel technique to create galaxy density maps, combined with the bootstrap technique to make significance maps, from which density peaks are selected. We find a mean surface density of \u223c1.5 clusters per square degree, consistent with the detection of richness class 0 and higher clusters to z\u223c0.3. In addition, we demonstrate an effective photometric redshift estimator for our clusters.", "doi": "10.1007/10849171_12", "isbn": "978-3-540-42468-0", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "2001", "pages": "160-167" }, { "id": "authors:b5wjb-wyz73", "collection": "authors", "collection_id": "b5wjb-wyz73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-154113446", "type": "book_section", "title": "The GRB Host Galaxies and Redshifts", "book_title": "Gamma-Ray Bursts in the Afterglow Era", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Reichart", "given_name": "D.", "orcid": "0000-0002-5060-3673", "clpid": "Reichart-D-E" }, { "family_name": "Castro", "given_name": "S. M.", "clpid": "Castro-S-M" }, { "family_name": "Fox", "given_name": "D.", "orcid": "0000-0002-3714-672X", "clpid": "Fox-D-B" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Price", "given_name": "P.", "clpid": "Price-P-A" }, { "family_name": "Yost", "given_name": "S.", "clpid": "Yost-S-A" }, { "family_name": "Goodrich", "given_name": "R.", "clpid": "Goodrich-R-W" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F-H" } ], "contributor": [ { "family_name": "Costa", "given_name": "Enrico", "clpid": "Costa-E" }, { "family_name": "Frontera", "given_name": "Filippo", "clpid": "Frontera-F" }, { "family_name": "Hjorth", "given_name": "Jens", "clpid": "Hjorth-J" } ], "abstract": "Observations of GRB host galaxies and their environments in general can provide valuable clues about the nature of progenitors. Bursts are associated with faint, \u27e8R\u27e9\u223c25 mag, galaxies at cosmological redshifts, \u27e8z\u27e9\u223c1. The host galaxies span a range of luminosities and morphologies, and appear to be broadly typical for the normal, evolving, actively star-forming galaxy populations at comparable redshifts and magnitudes, but may have somewhat elevated SFR per unit luminosity. There are also spectroscopic hints of massive star formation, from the ratios of [Ne III] and [O II] lines. The observed, unobscured star formation rates are typically a few M\u2299/yr, but a considerable fraction of the total star formation in the hosts may be obscured by dust. A census of detected optical afterglows provides a powerful new handle on the obscured fraction of star formation in the universe; the current results suggest that at most a half of the massive star formation was hidden by dust.", "doi": "10.1007/10853853_60", "isbn": "978-3-540-42771-1", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "2001", "pages": "218-225" }, { "id": "authors:6reps-nx144", "collection": "authors", "collection_id": "6reps-nx144", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KULaipcp00c", "type": "book_section", "title": "The afterglows of gamma-ray bursts", "book_title": "Gamma Ray Bursts: 5th Huntsville Symposium, Huntsville, AL, 18-22 October 1999", "author": [ { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F" }, { "family_name": "Diercks", "given_name": "A.", "clpid": "Diercks-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Goodrich", "given_name": "R. W.", "clpid": "Goodrich-R-W" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" } ], "contributor": [ { "family_name": "Kippen", "given_name": "R. Marc" }, { "family_name": "Mallozzi", "given_name": "Robert S." }, { "family_name": "Fishman", "given_name": "Gerald J." } ], "abstract": "Gamma-ray burst astronomy has undergone a revolution in the last three years, spurred by the discovery of fading long-wavelength counterparts. We now know that at least the long-duration GRBs lie at cosmological distances with estimated electromagnetic energy release of 10^51\u201310^53 erg, making these the brightest explosions in the Universe. In this article we review the current observational state, beginning with the statistics of X-ray, optical, and radio afterglow detections. We then discuss the insights these observations have given to the progenitor population, the energetics of the GRB events, and the physics of the afterglow emission. We focus particular attention on the evidence linking GRBs to the explosion of massive stars. Throughout, we identify remaining puzzles and uncertainties, and emphasize promising observational tools for addressing them. The imminent launch of HETE-2 and the increasingly sophisticated and coordinated ground-based and space-based observations have primed this field for fantastic growth.", "doi": "10.1063/1.1361549", "isbn": "1-56396-947-5", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2000-09-08", "pages": "277-297" }, { "id": "authors:z32fp-atg15", "collection": "authors", "collection_id": "z32fp-atg15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180629-132701664", "type": "book_section", "title": "Afterglows of gamma-ray bursts", "book_title": "Discoveries and Research Prospects from 8- to 10-Meter-Class Telescopes", "author": [ { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F-H" }, { "family_name": "Diercks", "given_name": "A.", "clpid": "Diercks-A-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Goodrich", "given_name": "R. W.", "clpid": "Goodrich-R-W" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" } ], "contributor": [ { "family_name": "Bergeron", "given_name": "Jacqueline", "clpid": "Bergeron-J" } ], "abstract": "Gamma-ray burst astronomy has undergone a revolution in the last three years, spurred by the discover of fading long- wavelength counterparts. We now know that at least the long duration GRBs lie at cosmological distances with estimated electromagnetic energy release of 10^(51)-10^(53) erg, making these the brightest explosions in the Universe. In this article we review the current observational state of the long-lived 'afterglow' emission that accompanies GRBs at X-ray, optical, and radio afterglow wavelengths. We then discuss the insights these observations have given to the progenitor population, the energetics of the GRB events, and the physics of the afterglow emission. We focus particular attention on the evidence linking GRBs to the explosion of massive stars. Throughout, we identify remaining puzzles and uncertainties, and emphasize promising observations tools for addressing them. The imminent launch of HETE-2, the increasingly sophisticated and coordinated ground-based and space-based observations, and the increasing availability of 10-m class optical telescopes have primed this field for fantastic growth.", "doi": "10.1117/12.390135", "isbn": "0819436305", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2000-06-29", "pages": "9-21" }, { "id": "authors:t7n41-x6b11", "collection": "authors", "collection_id": "t7n41-x6b11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KULaipcp00b", "type": "book_section", "title": "The afterglows of gamma-ray bursts", "book_title": "Cosmic Explosions: Tenth Astrophysics Conference, College Park, MD, 11-13 October 1999", "author": [ { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Berger", "given_name": "E.", "orcid": "0000-0002-9392-9681", "clpid": "Berger-Edo" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Chaffee", "given_name": "F.", "clpid": "Chaffee-F" }, { "family_name": "Diercks", "given_name": "A.", "clpid": "Diercks-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Galama", "given_name": "T. J.", "clpid": "Galama-T-J" }, { "family_name": "Goodrich", "given_name": "R. W.", "clpid": "Goodrich-R-W" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Yost", "given_name": "S. A.", "clpid": "Yost-S-A" } ], "contributor": [ { "family_name": "Holt", "given_name": "Stephen S." }, { "family_name": "Zhang", "given_name": "William W." } ], "abstract": "Gamma-ray burst astronomy has undergone a revolution in the last three years, spurred by the discovery of fading long-wavelength counterparts. We now know that at least the long duration GRBs lie at cosmological distances with estimated electromagnetic energy release of 10^51\u201310^53 erg, making these the brightest explosions in the Universe. In this article we review the current observational state, beginning with the statistics of X-ray, optical, and radio afterglow detections. We then discuss the insights these observations have given to the progenitor population, the energetics of the GRB events, and the physics of the afterglow emission. We focus particular attention on the evidence linking GRBs to the explosion of massive stars. Throughout, we identify remaining puzzles and uncertainties, and emphasize promising observational tools for addressing them. The imminent launch of HETE-2 and the increasingly sophisticated and coordinated ground-based and space-based observations have primed this field for fantastic growth.", "doi": "10.1063/1.1291715", "isbn": "1-56396-943-2", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2000-06-23", "pages": "191-212" }, { "id": "authors:xvc9g-ynj83", "collection": "authors", "collection_id": "xvc9g-ynj83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170223-133457249", "type": "article", "title": "3 Micron Imaging of the Hubble Deep Field", "author": [ { "family_name": "Hogg", "given_name": "David W.", "orcid": "0000-0003-2866-9403", "clpid": "Hogg-D-W" }, { "family_name": "Neugebauer", "given_name": "Gerry", "clpid": "Neugebauer-G" }, { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "Dickinson", "given_name": "Mark", "orcid": "0000-0001-5414-5131", "clpid": "Dickinson-Mark-E" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Matthews", "given_name": "Keith", "clpid": "Matthews-Keith-Astronomy" }, { "family_name": "Soifer", "given_name": "B. T.", "orcid": "0000-0002-8112-1132", "clpid": "Soifer-B-T" } ], "abstract": "Images of the Hubble Deep Field (HDF) at 3.2 \u03bcm, taken with the 10 m Keck Telescope, are presented. The images cover a total area of ~2.5 arcmin^2. To a 5 \u03c3 limit of [3.2]_(tot) \u2248 17.5 mag (Vega relative), 11 sources are detected, nine of which are extragalactic. The integrated galaxy number counts are therefore ~1.3 \u00d7 10^4 deg^(-2) to this depth. The galaxies detected at 3.2 \u03bcm have a median redshift of z = 0.56. All 3.2 \u03bcm sources have 1.6 \u03bcm, 1.1 \u03bcm, and visual counterparts, all of fairly regular morphology; several also have 6.7 \u03bcm, 15 \u03bcm, 850 \u03bcm, 8.5 GHz, or 1.4 GHz counterparts. No sources are found that are either anomalously red or anomalously blue in their H-[3.2] color, and there are significant detections of most of the known near-infrared HDF sources for which detection in these 3.2 \u03bcm data seemed likely.", "doi": "10.1086/301309", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2000-04", "series_number": "4", "volume": "119", "issue": "4", "pages": "1519-1525" }, { "id": "authors:y8dqv-4ys46", "collection": "authors", "collection_id": "y8dqv-4ys46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190524-141458208", "type": "article", "title": "A New Spin on the Problem of Horizontal\u2010Branch Gaps: Stellar Rotation along the Blue Horizontal Branch of Globular Cluster M13", "author": [ { "family_name": "Behr", "given_name": "Bradford B.", "clpid": "Behr-B-B" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "McCarthy", "given_name": "James K.", "clpid": "McCarthy-J-K" }, { "family_name": "C\u00f4t\u00e9", "given_name": "Patrick", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Piotto", "given_name": "Giampaolo", "clpid": "Piotto-G" }, { "family_name": "Zoccali", "given_name": "Manuela", "clpid": "Zoccali-M" } ], "abstract": "We have determined the projected rotational velocities of 13 blue horizontal-branch (BHB) stars in the globular cluster M13 via rotational broadening of metal absorption lines. Our sample spans the photometric gap observed in the horizontal-branch distribution at T_(eff) 11,000 K and reveals a pronounced difference in stellar rotation on either side of this feature\u2014blueward of the gap, all the stars show modest rotations, v sin i < 10 km s^(-1), while to the red side of the gap, we confirm the more rapidly rotating population (v sin i \u2243 40 km s^(-1)) previously observed by R. C. Peterson and coworkers. Taken together with these prior results, our measurements indicate that a star's rotation is indeed related to its location along the HB, although the mechanism behind this correlation remains unknown. We explore possible connections between stellar rotation and mass-loss mechanisms which influence the photometric morphology of globular cluster HBs.", "doi": "10.1086/308219", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2000-01-10", "series_number": "2", "volume": "528", "issue": "2", "pages": "849-853" }, { "id": "authors:k56mj-kym98", "collection": "authors", "collection_id": "k56mj-kym98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150218-142510130", "type": "article", "title": "Optical and Radio Observations of the Afterglow from GRB 990510: Evidence for a Jet", "author": [ { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Sari", "given_name": "P.", "clpid": "S\u00e1ri-P" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Axelrod", "given_name": "T.", "clpid": "Axelrod-T" }, { "family_name": "Mould", "given_name": "J.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Wieringa", "given_name": "M. H.", "clpid": "Wieringa-M-H" }, { "family_name": "Wark", "given_name": "R. M.", "clpid": "Wark-R-M" }, { "family_name": "Subrahmanyan", "given_name": "R.", "clpid": "Subrahmanyan-R" }, { "family_name": "McConnell", "given_name": "D.", "clpid": "McConnell-D" }, { "family_name": "McCarthy", "given_name": "P. J.", "clpid": "McCarthy-P-J" }, { "family_name": "Schaefer", "given_name": "B. E.", "clpid": "Schaefer-B-E" }, { "family_name": "McMahon", "given_name": "R. G.", "clpid": "McMahon-R-G" }, { "family_name": "Markze", "given_name": "R. O.", "clpid": "Markze-R-O" }, { "family_name": "Firth", "given_name": "E.", "clpid": "Firth-E" }, { "family_name": "Soffitta", "given_name": "P.", "orcid": "0000-0003-1252-4891", "clpid": "Soffitta-P" }, { "family_name": "Amati", "given_name": "L.", "clpid": "Amati-L" } ], "abstract": "We present multicolor optical and two-frequency radio observations of the bright BeppoSAX event GRB 990510. Neither the well-sampled optical decay nor the radio observations are consistent with simple spherical afterglow models. The achromatic steepening in the optical band and the early decay of the radio afterglow, which both occur at t ~ 1 day, are evidence for hydrodynamical evolution of the source and can be most easily interpreted by models in which the gamma-ray burst ejecta are collimated in a jet. Employing a simple jet model to explain the observations, we derive a jet opening angle of \u03b8_0 = 0.08(n/1 cm^(-3))^(1/8), reducing the isotropic gamma-ray energy release of 2.9 \u00d7 10^(53) ergs by a factor of ~300.", "doi": "10.1086/312282", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1999-10-01", "series_number": "2", "volume": "523", "issue": "2", "pages": "L121-L124" }, { "id": "authors:kb23w-j2h81", "collection": "authors", "collection_id": "kb23w-j2h81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130416-105100568", "type": "article", "title": "The unusual afterglow of the \u03b3-ray burst of 26 March 1998 as evidence for a supernova connection", "author": [ { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Eichelberger", "given_name": "A. C.", "clpid": "Eichelberger-A-C" }, { "family_name": "C\u00f4t\u00e9", "given_name": "P.", "orcid": "0000-0003-1184-8114", "clpid": "C\u00f4t\u00e9-P" }, { "family_name": "Blakeslee", "given_name": "J. P.", "clpid": "Blakeslee-J-P" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Filippenko", "given_name": "A. V.", "orcid": "0000-0003-3460-0103", "clpid": "Filippenko-A-V" }, { "family_name": "Leonard", "given_name": "D. C.", "clpid": "Leonard-D-C" }, { "family_name": "Riess", "given_name": "A. G.", "clpid": "Riess-A-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "Stern", "given_name": "D.", "orcid": "0000-0003-2686-9241", "clpid": "Stern-D" }, { "family_name": "Bunker", "given_name": "A.", "clpid": "Bunker-A-J" }, { "family_name": "Dey", "given_name": "A.", "orcid": "0000-0002-4928-4003", "clpid": "Dey-A" }, { "family_name": "Grossan", "given_name": "B.", "clpid": "Grossan-B" }, { "family_name": "Perlmutter", "given_name": "S.", "clpid": "Perlmutter-S" }, { "family_name": "Knop", "given_name": "R. A.", "clpid": "Knop-R-A" }, { "family_name": "Hook", "given_name": "I. M.", "orcid": "0000-0002-2960-978X", "clpid": "Hook-I-M" }, { "family_name": "Feroci", "given_name": "M.", "clpid": "Feroci-M" } ], "abstract": "Cosmic \u03b3-ray bursts have now been firmly established as one of the most powerful phenomena in the Universe, releasing almost the rest-mass energy of a neutron star within the space of a few seconds (ref. 1). The two most popular models to explain \u03b3-ray bursts are the coalescence of two compact objects such as neutron stars or black holes, or the catastrophic collapse of a massive star in a very energetic supernova-like explosion. Here we show that, about three weeks after the gamma-ray burst of 26 March 1998, the transient optical source associated with the burst brightened to about 60 times the expected flux, based upon an extrapolation of the initial light curve. Moreover, the spectrum changed dramatically, with the colour becoming extremely red. We argue that the new source is an underlying supernova. If our hypothesis is true then this provides evidence linking cosmologically located \u03b3-ray bursts with deaths of massive stars.", "doi": "10.1038/46744", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1999-09-30", "series_number": "6752", "volume": "401", "issue": "6752", "pages": "453-456" }, { "id": "authors:kffqy-v5338", "collection": "authors", "collection_id": "kffqy-v5338", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170223-070422097", "type": "article", "title": "The Host Galaxy of GRB 990123", "author": [ { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Harrison", "given_name": "F. A.", "orcid": "0000-0002-4226-8959", "clpid": "Harrison-F-A" }, { "family_name": "Koresko", "given_name": "C.", "clpid": "Koresko-C-D" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Armus", "given_name": "L.", "orcid": "0000-0003-3498-2973", "clpid": "Armus-L" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Sari", "given_name": "R.", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" }, { "family_name": "Squires", "given_name": "G.", "orcid": "0000-0002-1977-5717", "clpid": "Squires-G-K" }, { "family_name": "Illingworth", "given_name": "G.", "orcid": "0000-0002-8096-2837", "clpid": "Illingworth-G-D" }, { "family_name": "Kelson", "given_name": "D.", "clpid": "Kelson-D-D" }, { "family_name": "Chaffee", "given_name": "F. H.", "clpid": "Chaffee-F-H-Jr" }, { "family_name": "Goodrich", "given_name": "R.", "clpid": "Goodrich-R-W" }, { "family_name": "Feroci", "given_name": "M.", "clpid": "Feroci-M" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" }, { "family_name": "Piro", "given_name": "L.", "clpid": "Piro-L" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Mao", "given_name": "S.", "orcid": "0000-0001-8317-2788", "clpid": "Mao-Shude" }, { "family_name": "Akerlof", "given_name": "C.", "clpid": "Akerlof-C-W" }, { "family_name": "McKay", "given_name": "T. A.", "clpid": "McKay-T-A" } ], "abstract": "We present deep images of the field of GRB 990123 obtained in a broadband UV/visible bandpass with the Hubble Space Telescope (HST) and deep near-infrared images obtained with the Keck I 10 m telescope. The HST image reveals that the optical transient (OT) is offset by 0farcs67 (5.8 kpc in projection) from an extended, apparently interacting galaxy. This galaxy, which we conclude is the host galaxy of GRB 990123, is the most likely source of the absorption lines of metals at a redshift of z=1.6 seen in the spectrum of the OT. With magnitudes of Gunn-r = 24.5 \u00b1 0.2 and K = 22.1\u00b10.3 mag, this corresponds to an L ~ 0.5L$\\mathstrut{_{*}}$ galaxy, assuming that it is located at z = 1.6. The estimated unobscured star formation rate is \u22484 M_\u2609 yr^(\u22121), which is typical for normal galaxies at comparable redshifts. There is no evidence for strong gravitational lensing magnification of this burst, and some alternative explanation for its remarkable energetics (such as beaming) may therefore be required. The observed offset of the OT from the nominal host center, the absence of broad absorption lines in the afterglow spectrum, and the relatively blue continuum of the host do not support the notion that gamma-ray bursts (GRBs) originate from active galactic nuclei or massive black holes. Rather, the data are consistent with models of GRBs that involve the death and/or merger of massive stars. Indeed, the HST image suggests an intimate connection between GRB 990123 and a star-forming region.", "doi": "10.1086/312059", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1999-06-10", "series_number": "1", "volume": "518", "issue": "1", "pages": "L1-L4" }, { "id": "authors:3a6s7-ajm31", "collection": "authors", "collection_id": "3a6s7-ajm31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190528-140622271", "type": "article", "title": "Striking Photospheric Abundance Anomalies in Blue Horizontal-Branch Stars in Globular Cluster M13", "author": [ { "family_name": "Behr", "given_name": "Bradford B.", "clpid": "Behr-B-B" }, { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "McCarthy", "given_name": "James K.", "clpid": "McCarthy-J-K" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "High-resolution optical spectra of 13 blue horizontal-branch stars in the globular cluster M13 show enormous deviations in element abundances from the expected cluster metallicity. In the hotter stars (T_(eff) > 12,000 K), helium is depleted by factors of 10-100 below solar, while iron is enhanced to 3 times the solar abundance, 2 orders of magnitude above the canonical metallicity of [Fe/H] \u2243-1.5 dex for this globular cluster. Nitrogen, phosphorus, and chromium exhibit even more pronounced enhancements, and other metals are also mildly overabundant, with the exception of magnesium, which stays very near the expected cluster metallicity. These photospheric anomalies are most likely due to diffusion\u2014the gravitational settling of helium and the radiative levitation of the other elements\u2014in the stable radiative atmospheres of these hot stars. The effects of these mechanisms may have some impact on the photometric morphology of the cluster's horizontal branch and on estimates of its age and distance.", "doi": "10.1086/312052", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1999-06-01", "series_number": "2", "volume": "517", "issue": "2", "pages": "L135-L138" }, { "id": "authors:h4ctz-9tg61", "collection": "authors", "collection_id": "h4ctz-9tg61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150624-153310995", "type": "article", "title": "The energetic afterglow of the big \u03b3-ray burst of 14 December 1997", "author": [ { "family_name": "Ramaprakash", "given_name": "A. N.", "clpid": "Ramaprakash-A-N" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Koresko", "given_name": "C.", "clpid": "Koresko-C" }, { "family_name": "Kuchner", "given_name": "M.", "clpid": "Kuchner-M" }, { "family_name": "Goodrich", "given_name": "R.", "clpid": "Goodrich-R" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Murphy", "given_name": "T.", "orcid": "0000-0002-2686-438X", "clpid": "Murphy-T" }, { "family_name": "Eikenberry", "given_name": "S.", "clpid": "Eikenberry-S" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Waxman", "given_name": "E.", "orcid": "0000-0002-9038-5877", "clpid": "Waxman-E" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Feroci", "given_name": "M.", "clpid": "Feroci-M" }, { "family_name": "Nicastro", "given_name": "L.", "clpid": "Nicastro-L" } ], "abstract": "The discovery of fading but relatively long-lived X-ray emission accompanying \u03b3-ray bursts has revolutionized the study of these objects. This 'afterglow' is most easily explained by models similar to those describing supernovae, but with relativistic ejecta. And as with supernovae, afterglow measurements should in principle provide important constraints on burst properties, permitting, for example, estimates of the amount of energy released, the geometry of the emitting surface and the density of the ambient medium. Here we report infrared observations of the fading optical transient associated with the burst of 14 December 1997 (GRB971214). We detect a 'break' in the broad-band spectrum, as predicted by afterglow models, which constrains the total energy in the burst to be >10^(51) erg. Combining the fluence of optical afterglow with the redshift (z = 3.42), we estimate that the energy released in the afterglow alone was 2 x 10^(51) erg. Estimates of afterglow energetics are less likely to be subject to geometric effects\u2014such as beaming\u2014that render uncertain estimates of the total burst energy, but it nevertheless appears from our measurements that \u03b3-ray bursts may be much more energetic than the 10^(51) erg usually assumed.", "doi": "10.1038/29941", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1998-05-07", "series_number": "6680", "volume": "393", "issue": "6680", "pages": "43-46" }, { "id": "authors:6xg65-27664", "collection": "authors", "collection_id": "6xg65-27664", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150617-154004613", "type": "article", "title": "Identification of a host galaxy at redshift z = 3.42 for the big \u03b3-ray burst of 14 December 1997", "author": [ { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ramaprakash", "given_name": "A. N.", "clpid": "Ramaprakash-A-N" }, { "family_name": "Goodrich", "given_name": "R.", "clpid": "Goodrich-R" }, { "family_name": "Bloom", "given_name": "J. S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Adelberger", "given_name": "K. L.", "clpid": "Adelberger-K-L" }, { "family_name": "Kundic", "given_name": "T.", "clpid": "Kundic-T" }, { "family_name": "Lubin", "given_name": "L.", "clpid": "Lubin-L-M" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" }, { "family_name": "Feroci", "given_name": "M.", "clpid": "Feroci-M" }, { "family_name": "Nicastro", "given_name": "L.", "clpid": "Nicastro-L" }, { "family_name": "Barth", "given_name": "A. J.", "orcid": "0000-0002-3026-0562", "clpid": "Barth-A-J" }, { "family_name": "Davis", "given_name": "M.", "clpid": "Davis-M-E-Astro" }, { "family_name": "Filippenko", "given_name": "A. V.", "orcid": "0000-0003-3460-0103", "clpid": "Filippenko-A-V" }, { "family_name": "Newman", "given_name": "J.", "clpid": "Newman-J" } ], "abstract": "Knowledge of the properties of \u03b3-ray bursts has increased substantially following recent detections of counterparts at X-ray, optical and radio wavelengths. But the nature of the underlying physical mechanism that powers these sources remains unclear. In this context, an important question is the total energy in the burst, for which an accurate estimate of the distance is required. Possible host galaxies have been identified for the first two optical counterparts discovered, and a lower limit obtained for the redshift of one of them, indicating that the bursts lie at cosmological distances. A host galaxy of the third optically detected burst has now been identified and its redshift determined to be z = 3.42. When combined with the measured flux of \u03b3-rays from the burst, this large redshift implies an energy of 3 10^(53) erg in the \u03b3-rays alone, if the emission is isotropic. This is much larger than the energies hitherto considered, and it poses a challenge for theoretical models of the bursts.", "doi": "10.1038/29927", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1998-05-07", "series_number": "6680", "volume": "393", "issue": "6680", "pages": "35-39" }, { "id": "authors:a8mr1-26v46", "collection": "authors", "collection_id": "a8mr1-26v46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-161537020", "type": "book_section", "title": "Cataloging of the Digitized Poss-II: Initial Scientific Results", "book_title": "New Horizons from Multi-Wavelength Sky Surveys", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Scaramella", "given_name": "R.", "clpid": "Scaramella-R" }, { "family_name": "Longo", "given_name": "G.", "orcid": "0000-0002-9182-8414", "clpid": "Longo-G" } ], "contributor": [ { "family_name": "McLean", "given_name": "Brian J.", "clpid": "McLean-B-J" } ], "abstract": "The Second Palomar Sky Survey (POSS-II) is now nearing completion. It will cover the entire northern sky with 894 fields (6.5\u00b0 square) at 5\u00b0 spacings, with no gaps in the coverage. Plates are taken in three bands: IIIa-J + GG395, \u03bb_(eff) \u223c 480 nm; IIIa-F + RG610, \u03bb_(eff) \u223c 650 nm; and IV-N + RG9, \u03bb_(eff) \u223c 850 nm. Typical limiting magnitudes reached are B_J \u223c 22.5, R_F \u223c 20.8, and I_N \u223c 19.5, i.e., \u223c 1m \u22121.5m deeper than the POSS-I. The image quality is improved relative to the POSS-I, and is comparable to the southern photographic sky surveys. For more details, see Reid et al. (1987), and Reid & Djorgovski (1993).", "doi": "10.48550/arXiv.9612108", "isbn": "9780792348023", "publisher": "Kluwer", "place_of_publication": "Dordrecht", "publication_date": "1998", "pages": "424-430" }, { "id": "authors:wsbxg-smv82", "collection": "authors", "collection_id": "wsbxg-smv82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-101525969", "type": "book_section", "title": "Data mining a large digital sky survey: from the challenges to the scientific results", "book_title": "Applications of Digital Image Processing XX", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Roden", "given_name": "J.", "clpid": "Roden-J-C" }, { "family_name": "Stolorz", "given_name": "P.", "clpid": "Stolorz-P" }, { "family_name": "Gray", "given_name": "A.", "clpid": "Gray-A" } ], "contributor": [ { "family_name": "Tescher", "given_name": "Andrew G.", "clpid": "Tescher-A-G" } ], "abstract": "The analysis and an efficient scientific exploration of the digital Palomar observatory sky survey represents a major technical challenge. The input data set consists of 3 Terabytes of pixel information, and contains a few billion sources. We describe some of the specific scientific problems posed by the data, including searches for distant quasars and clusters of galaxies, and the data-mining techniques we are exploring in addressing them Machine- assisted discovery methods may become essential for the analysis of such multi-Terabyte data sets. New and future approaches involve unsupervised classification and clustering analysis in the Giga-object data space, including various Bayesian techniques. In addition to the searches for known types of objects in this database, these techniques may also offer the possibility of discovering previously unknown, rare types of astronomical objects.", "doi": "10.1117/12.292750", "isbn": "9780819425867", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1997-10-30", "pages": "98-109" }, { "id": "authors:zp5kq-wg591", "collection": "authors", "collection_id": "zp5kq-wg591", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190205-142100455", "type": "article", "title": "Discovery of Extended Blue Horizontal Branches in Two Metal-rich Globular Clusters", "author": [ { "family_name": "Rich", "given_name": "R. Michael", "orcid": "0000-0003-0427-8387", "clpid": "Rich-R-M" }, { "family_name": "Sosin", "given_name": "Craig", "clpid": "Sosin-C" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Piotto", "given_name": "Giampaolo", "clpid": "Piotto-G" }, { "family_name": "King", "given_name": "Ivan R.", "clpid": "King-I-R" }, { "family_name": "Renzini", "given_name": "Alvio", "orcid": "0000-0002-7093-7355", "clpid": "Renzini-A" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Dorman", "given_name": "Ben", "clpid": "Dorman-B" }, { "family_name": "Liebert", "given_name": "James", "clpid": "Liebert-J" }, { "family_name": "Meylan", "given_name": "Georges", "clpid": "Meylan-G" } ], "abstract": "We have used WFPC2 to construct B, V color-magnitude diagrams of four metal-rich globular clusters, NGC 104 (47 Tuc), NGC 5927, NGC 6388, and NGC 6441. All four clusters have well populated red horizontal branches (RHB), as expected for their metallicity. However, NGC 6388 and 6441 also exhibit a prominent blue horizontal-branch (BHB) extension, including stars reaching as faint in V as the turnoff luminosity. This discovery demonstrates directly for the first time that a major population of hot horizontal-branch (HB) stars can exist in old, metal-rich systems. This may have important implications for the interpretation of the integrated spectra of elliptical galaxies. \n\nThe cause of the phenomenon remains uncertain. We examine the possibility that NGC 6388 and 6441 are older than the other clusters, but a simple difference in age may not be sufficient to produce the observed distributions along the HB. The high central densities in NGC 6388 and 6441 suggest that the existence of the BHB tails might be caused by stellar interactions in the dense cores of these clusters, which we calculate to have two of the highest collision rates among globular clusters in the Galaxy. Tidal collisions might act in various ways to enhance loss of envelope mass and therefore populate the blue side of the HB. However, the relative frequency of tidal collisions does not seem large enough (compared to that of the clusters with pure RHBs) to account for such a drastic difference in HB morphology. While a combination of an age difference and dynamical interactions may help, prima facie the lack of a radial gradient in the BHB/RHB star ratio seems to argue against dynamical effects playing a role.", "doi": "10.1086/310758", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1997-07-20", "series_number": "1", "volume": "484", "issue": "1", "pages": "L25-L28" }, { "id": "authors:eyrmm-gsx68", "collection": "authors", "collection_id": "eyrmm-gsx68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150609-120007821", "type": "article", "title": "The optical counterpart to the \u03b3-ray burst GRB970508", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Metzger", "given_name": "M. R.", "clpid": "Metzger-M-R" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Odewahn", "given_name": "S. C.", "clpid": "Odewahn-S-C" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Feroci", "given_name": "M.", "clpid": "Feroci-M" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" }, { "family_name": "Palazzi", "given_name": "E.", "clpid": "Palazzi-E" } ], "abstract": "Understanding the nature of the gamma-ray burst phenomenon is one of the outstanding problems of modern astrophysics. The identification of counterparts at optical wavelengths is considered a crucial factor for determining the origin of these events. Here we report the detection and temporal properties of a variable optical source, which has been identified as the counterpart of the X-ray transient associated with the \u03b3-ray burst GRB970508 (ref. 3). The initial optical images were obtained only 5.8 hours after the initial gamma-ray burst, after which the optical source was observed to brighten over the next two days before declining in luminosity with a t-1 power law. The decline in brightness follows a form predicted by many relativistic fireball models for \u03b3-ray bursts, although the initial rise does not appear to be compatible with the simplest of these models. The observed fluence of the source at visible wavelengths over the period spanned by our observations is \u22654.6 times 10^(-8) erg cm^(-2), about 3% of the fluence of the gamma-ray burst itself.", "doi": "10.1038/43126", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1997-06-26", "series_number": "6636", "volume": "387", "issue": "6636", "pages": "876-878" }, { "id": "authors:39zgd-xp565", "collection": "authors", "collection_id": "39zgd-xp565", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130419-091322811", "type": "article", "title": "Spectral constraints on the redshift of the optical counterpart to the \u03b3-ray burst of 8 May 1997", "author": [ { "family_name": "Metzger", "given_name": "M. R.", "clpid": "Metzger-M-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Steidel", "given_name": "C. C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" }, { "family_name": "Adelberger", "given_name": "K. L.", "clpid": "Adelberger-K-L" }, { "family_name": "Frail", "given_name": "D. A.", "clpid": "Frail-D-A" }, { "family_name": "Costa", "given_name": "E.", "clpid": "Costa-E" }, { "family_name": "Frontera", "given_name": "F.", "clpid": "Frontera-F" } ], "abstract": "Brief, intense bursts of y-rays occur approximately daily from random directions in space, but their origin has remained unknown since their initial detection almost 25 years ago. Arguments based on their observed isotropy and apparent brightness distribution are not sufficient to constrain the location of the bursts to a local or cosmological origin. The recent detection of a counterpart to a y-ray burst at other wavelengths has therefore\nraised the hope that the sources of these energetic events might soon be revealed. Here we report spectroscopic observations of the possible optical counterpart to the y-ray burst GRB970508. The spectrum is mostly featureless, except for a few prominent absorption lines which we attribute to the presence of an absorption system along the line of sight at redshift z = 0.835. Coupled with the absence of Lyman-\u03b1 forest features in the spectra, our\nresults imply that the optical transient lies at 0.835 \u227e z \u227e 2.3. If the optical transient is indeed the counterpart of GRB970508, our results provide the first direct limits on the distance to a y-ray burst, confirming that at least some of these events lie at cosmological distances, and are thus highly energetic.", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1997-06-26", "series_number": "6636", "volume": "387", "issue": "6636", "pages": "878-880" }, { "id": "authors:r4qz1-22x10", "collection": "authors", "collection_id": "r4qz1-22x10", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190205-142100559", "type": "article", "title": "Peculiar Multimodality on the Horizontal Branch of the Globular Cluster NGC 2808", "author": [ { "family_name": "Sosin", "given_name": "Craig", "clpid": "Sosin-C" }, { "family_name": "Dorman", "given_name": "Ben", "clpid": "Dorman-B" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Piotto", "given_name": "Giampaolo", "clpid": "Piotto-G" }, { "family_name": "Rich", "given_name": "R. Michael", "orcid": "0000-0003-0427-8387", "clpid": "Rich-R-M" }, { "family_name": "King", "given_name": "Ivan R.", "clpid": "King-I-R" }, { "family_name": "Liebert", "given_name": "James", "clpid": "Liebert-J" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Renzini", "given_name": "Alvio", "orcid": "0000-0002-7093-7355", "clpid": "Renzini-A" } ], "abstract": "We present distributions of colors of stars along the horizontal branch (HB) of the globular cluster NGC 2808, from Hubble Space Telescope Wide Field Planetary Camera 2 imaging in B, V, and an ultraviolet filter (F218W). This cluster's HB is already known to be strongly bimodal, with approximately equal-sized HB populations widely separated in the color-magnitude diagram. Our images reveal a long blue tail with two gaps, for a total of four nearly distinct HB groups. These gaps are very narrow, corresponding to envelope-mass differences of only ~0.01 M_\u2609. This remarkable multimodality may be a signature of mass-loss processes, subtle composition variations, or dynamical effects; we briefly summarize the possibilities. The existence of narrow gaps between distinct clumps on the HB presents a challenge for models that attempt to explain HB bimodality or other peculiar HB structures.", "doi": "10.1086/310606", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1997-05-01", "series_number": "1", "volume": "480", "issue": "1", "pages": "L35-L38" }, { "id": "authors:2afps-55965", "collection": "authors", "collection_id": "2afps-55965", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190603-153225522", "type": "article", "title": "Dynamical Correlations for Globular Clusters in M31", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "McCarthy", "given_name": "J. K.", "clpid": "McCarthy-J-K" }, { "family_name": "Cohen", "given_name": "J. G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Bendinelli", "given_name": "O.", "clpid": "Bendinelli-O" }, { "family_name": "Parmeggiani", "given_name": "G.", "clpid": "Parmeggiani-G" } ], "abstract": "We present internal velocity dispersion measurements for a set of 21 globular clusters in the Andromeda galaxy (M31). We combine them with structural and photometric cluster parameters measured earlier with the Hubble Space Telescope and from the ground to explore correlations of cluster properties and to compare them with the equivalent correlations for the Galactic globular clusters. We find that the M31 globulars follow the same correlations between velocity dispersion and luminosity, central, and average surface brightness, as do their Galactic counterparts. This suggests a common physical origin for these correlations. They may be produced by the same astrophysical conditions and processes operating at the epoch of globular cluster formation in both galaxies. The very existence of these excellent correlations, and their quantitative form as scaling laws, represent challenges and constraints for theories of globular cluster formation. Preliminary estimates of the cluster M/L ratios show correlations with the cluster metallicity, in the sense of more metal-rich clusters having lower M/L, particularly in the near-infrared. At a given metallicity, there is no detectable systematic difference between the M31 globulars and their Galactic counterparts, which suggests a great similarity of their stellar populations. The observed scatter around these trends is comparable to the expected errors, which implies a small intrinsic scatter and thus which leaves little room for possible variations in the cluster age or stellar IMF at a given metallicity.", "doi": "10.1086/310423", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1997-01-01", "series_number": "1", "volume": "474", "issue": "1", "pages": "L19-L22" }, { "id": "authors:skfen-khc21", "collection": "authors", "collection_id": "skfen-khc21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-154010871", "type": "article", "title": "Sub-arcsecond imaging and spectroscopy of the radio-loud highly polarized quasar PKS 1610-771", "author": [ { "family_name": "Courbin", "given_name": "F.", "clpid": "Courbin-F" }, { "family_name": "Hutsem\u00e9kers", "given_name": "D.", "clpid": "Hutsem\u00e9kers-D" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Magain", "given_name": "P.", "clpid": "Magain-P" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report on imaging and spectroscopic observations of the radio-loud, highly polarized quasar PKS 1610-771 (z = 1.71). Our long-slit spectroscopy of the companion 4.55\" NW of the quasar confirms the stellar nature of this object, so ruling out the previously suspected gravitationally lensed nature of this system.\nPKS 1610-771 looks fuzzy on our sub-arcsecond R and I images and appears located in a rich environment of faint galaxies. Possible magnification, without image splitting of the quasar itself, by some of these maybe foreground galaxies cannot be excluded. The continuum fuzz (made of the closest two objects, viz. A and D) is elongated in a direction orthogonal to the E vector of the optical polarization, as in high-redshift radio-galaxies. The spectrum of PKS 1610-771 appears strongly curved, in a convex way, with a maximum of intensity at ~7,600 \u00c5 (2,800 \u00c5 rest frame), possibly indicating a strong ultraviolet absorption by dust.", "doi": "10.48550/arXiv.9606114", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "1997-01", "series_number": "3", "volume": "317", "issue": "3", "pages": "656-660" }, { "id": "authors:9z5p7-t8312", "collection": "authors", "collection_id": "9z5p7-t8312", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-074511280", "type": "book_section", "title": "Near-Infrared Fundamental Plane of Elliptical Galaxies and Its Evolution", "book_title": "Galaxy Scaling Relations: Origins, Evolution and Applications", "author": [ { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "contributor": [ { "family_name": "da Costa", "given_name": "Luiz Nicolaci", "clpid": "da-Costa-L-N" }, { "family_name": "Renzini", "given_name": "Alvio", "clpid": "Renzini-A" } ], "abstract": "We present the first Fundamental Plane (FP) that has been constructed in the K-band using near\u2014infrared imaging source data. The slope of this IR FP differs systematically both from the optical relation and the virial expectation (assuming homology and constant M/L) in a way that cannot be explained by stellar populations effects alone. We also show observations of the optical and IR FP at higher redshift which demonstrates the same effect. A slight but systematic breakdown of homology along the elliptical galaxy sequence, in addition to stellar populations effects, could explain the FP at all wavelengths.", "doi": "10.1007/978-3-540-69654-4_24", "isbn": "978-3-662-21934-8", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1997", "pages": "197-202" }, { "id": "authors:5yaed-tk497", "collection": "authors", "collection_id": "5yaed-tk497", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-075242320", "type": "book_section", "title": "Space Density of Z > 4 Quasars from the Second Palomar Sky Survey", "book_title": "Wide-Field Spectroscopy", "author": [ { "family_name": "Kennefick", "given_name": "J. D.", "clpid": "Kennefick-J-D" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "contributor": [ { "family_name": "Kontizas", "given_name": "E.", "clpid": "Kontizas-E" }, { "family_name": "Kontizas", "given_name": "M.", "clpid": "Kontizas-M" }, { "family_name": "Morgan", "given_name": "D. H.", "clpid": "Morgan-D-H" }, { "family_name": "Vettolani", "given_name": "G. P.", "clpid": "Vettolani-G-P" } ], "abstract": "In recent years, several groups have undertaken searches for quasars at very high redshifts with the aim of computing quasar space densities as well as providing quasars for studies of intervening material. Schmidt et al. (1995; SSG) have computed densities at 2.7 < z < 4.7 from 90 quasars discovered through their Ly\u03b1 emission. Warren et al. (1994; WHO) have computed densities at 2.2 < z < 4.5 using quasars discovered in a photographic multicolor survey. Irwin et al. (1991; IMH) have discovered 31 quasars in a photographic multicolor survey for bright quasars at z > 4.", "doi": "10.1007/978-94-011-5722-3_67", "isbn": "978-94-010-6413-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1997", "pages": "381-382" }, { "id": "authors:mar67-trq96", "collection": "authors", "collection_id": "mar67-trq96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-073811293", "type": "book_section", "title": "Towards an Objectively Defined Catalog of Galaxy Clusters from the Digitized POSS-II", "book_title": "Wide-Field Spectroscopy", "author": [ { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Pahre", "given_name": "M.", "clpid": "Pahre-M-A" }, { "family_name": "Gal", "given_name": "R. R.", "clpid": "Gal-R-R" }, { "family_name": "Gray", "given_name": "A.", "clpid": "Gray-A" }, { "family_name": "Roden", "given_name": "J.", "clpid": "Roden-J" } ], "contributor": [ { "family_name": "Kontizas", "given_name": "E.", "clpid": "Kontizas-E" }, { "family_name": "Kontizas", "given_name": "M.", "clpid": "Kontizas-M" }, { "family_name": "Morgan", "given_name": "D. H.", "clpid": "Morgan-D-H" }, { "family_name": "Vettolani", "given_name": "G. P.", "clpid": "Vettolani-G-P" } ], "abstract": "The subjective nature of the Abell catalog has been widely recognized as its major limitation. We report on the preliminary results of an effort to create an unbiased catalog of clusters of galaxies from the galaxy catalogs derived from the digitized POSS-II (DPOSS).", "doi": "10.1007/978-94-011-5722-3_51", "isbn": "978-94-010-6413-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1997", "pages": "285-286" }, { "id": "authors:kqa01-mpz04", "collection": "authors", "collection_id": "kqa01-mpz04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150610-133832770", "type": "article", "title": "Identification of a galaxy responsible for a high-redshift Lyman-\u03b1 absorption system", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Bechtold", "given_name": "J.", "clpid": "Bechtold-J" } ], "abstract": "Damped Lyman-\u03b1 systems are high-column-density intergalactic clouds of hydrogen, the existence of which is inferred from absorption lines appearing in the emission spectra of distant quasars. The galaxies believed to be responsible for these absorption systems have been suggested as possible progenitors of the normal disk galaxies observed in the local Universe. Indeed, Lyman-\u03b1 systems appear to contain a substantial fraction of the baryons known to exist in galaxies today. Here we report the optical detection of a galaxy (designated DLA2233 + 131) associated with a known damped Lyman-\u03b1 absorption system at a redshift of z = 3.150. The properties of this galaxy correspond closely to those expected of a young disk galaxy in the early stages of formation, and show no evidence for an active nucleus. This finding gives strong support to the idea that damped Lyman-\u03b1 systems represent a population of young galaxies at high red-shifts.", "doi": "10.1038/382234a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1996-07-18", "series_number": "6588", "volume": "382", "issue": "6588", "pages": "234-236" }, { "id": "authors:67k4r-xzt76", "collection": "authors", "collection_id": "67k4r-xzt76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-153250341", "type": "article", "title": "A Tolman Surface Brightness Test for Universal Expansion and the Evolution of Elliptical Galaxies in Distant Clusters", "author": [ { "family_name": "Pahre", "given_name": "Michael A.", "clpid": "Pahre-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "abstract": "We use the intercept of the elliptical galaxy radius-surface brightness (SB) relation at a fixed metric radius as the standard condition for the Tolman SB test of the universal expansion. We use surface photometry in the optical and near-infrared of elliptical galaxies in Abell 2390 (z = 0.23) and Abell 851 (z = 0.41) and compare them to the Coma Cluster at z \u2248 0. The photometric data for each cluster are well described by the Kormendy relation r_e \u221d \u2211_e^A, where A = -0.9 in the optical and A = -1.0 in the near-infrared. The scatter about this near-infrared relation is only 0.076 in log r_e at the highest redshift, which is much smaller than at low redshifts, suggesting a remarkable homogeneity of the cluster elliptical population at z = 0.41. We use the intercept of these fixed-slope correlations at R_e = 1 kpc (assuming H_0 = 75 km s^(-1) Mpc^(-1), \u03a9_0 = 0.2, and \u039b_0 = 0, where the results are only weakly dependent on the cosmology) to construct the Tolman SB test for these three clusters. The data are fully consistent with universal expansion if we assume simple models of passive evolution for elliptical galaxies but are inconsistent with a nonexpanding geometry (the tired-light cosmology) at the 5 \u03c3 confidence level at z = 0.41. These results suggest luminosity evolution in the rest-frame Kband of 0.36 \u00b1 0.14 mag from z = 0.41 to the present and are consistent with the elliptical galaxies' having formed at high redshift. The SB intercept in elliptical galaxy correlations is thus a powerful tool for investigating models of their evolution for significant look-back times.", "doi": "10.1086/309872", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-01-10", "series_number": "2", "volume": "456", "issue": "2", "pages": "L79-L82" }, { "id": "authors:0p7m4-zdx94", "collection": "authors", "collection_id": "0p7m4-zdx94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-081120947", "type": "book_section", "title": "The B3-VLA Sample", "book_title": "Extragalactic Radio Sources", "author": [ { "family_name": "Vigotti", "given_name": "M.", "clpid": "Vigotti-M" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Gregorini", "given_name": "L.", "clpid": "Gregorini-L" }, { "family_name": "Klein", "given_name": "U.", "clpid": "Klein-U" }, { "family_name": "Mack", "given_name": "K. H.", "clpid": "Mack-K-H" }, { "family_name": "Maxfield", "given_name": "L.", "clpid": "Maxfield-L" }, { "family_name": "Reuter", "given_name": "H. P.", "clpid": "Reuter-H-P" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" } ], "contributor": [ { "family_name": "Ekers", "given_name": "R.", "clpid": "Ekers-R" }, { "family_name": "Fanti", "given_name": "C.", "clpid": "Fanti-C" }, { "family_name": "Padrielli", "given_name": "L.", "clpid": "Padrielli-L" } ], "abstract": "The use of radio sources to identify the most distant object in the Universe has been proved to be a very successful approach in observational cosmology. Studies of high flux, powerful 3CR and 1-Jy galaxies show dramatic evidence for color and luminosity evolution, reaching to look-back times 80% of the Hubble time. In order to disentangle the selection effect, correlation with redshift, and correlation with radio power, it is necessary to obtain well defined, complete samples of radio galaxies at a large range of redshifts, and with a wide baseline of radio power. We need the identifications of complete samples in the flux range of a factor 10 smaller than 3CR sample. The B3VLA sample (Vigotti et al. 1989) is a subset of 1050 sources selected in restricted areas at high galactic from the B3 survey, which is complete down to S(408 MHz)= 100mJy. For the B3VLA sample detailed VLA maps were obtained at 1.4GHz using A, C and D arrays. We are conducting a long-term effort to provide optical ID's and redshifts for well-defined, complete subsamples of the B3VLA survey (Djorgovski et al. 1990, Vigotti et al. 1990, Thompson et al., 1994), a similar effort is being conducted independently by others. We present here the \"status of the art\" for the B3VLA sample: a new low flux sample of 124 QSS selected at meter wavelength, a sample of 194 radio galaxies (77 with measured redshift) and a sample of 732 Empty Fields (EF : no optical counterpart on POSS I plate).", "doi": "10.1007/978-94-009-0295-4_187", "isbn": "978-0-7923-4122-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1996", "pages": "519-521" }, { "id": "authors:102r0-j5e56", "collection": "authors", "collection_id": "102r0-j5e56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190605-134717870", "type": "book_section", "title": "1608+656: A Quadruple Lens System Found in the Class Gravitational Lens Survey", "book_title": "Astrophysical Applications of Gravitational Lensing", "author": [ { "family_name": "Myers", "given_name": "Steven T.", "clpid": "Myers-Steven-Theodore" }, { "family_name": "Fassnacht", "given_name": "C. D.", "orcid": "0000-0002-4030-5461", "clpid": "Fassnacht-C-D" }, { "family_name": "Pearson", "given_name": "T. J.", "orcid": "0000-0001-5213-6231", "clpid": "Pearson-T-J" }, { "family_name": "Readhead", "given_name": "A. C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Shepherd", "given_name": "M. C.", "clpid": "Shepherd-Martin-C" }, { "family_name": "Blandford", "given_name": "R. D.", "orcid": "0000-0002-1854-5506", "clpid": "Blandford-R-D" }, { "family_name": "Browne", "given_name": "I. W. A.", "clpid": "Browne-I-W-A" }, { "family_name": "Jackson", "given_name": "N.", "clpid": "Jackson-N-J" }, { "family_name": "Muxlow", "given_name": "T.", "clpid": "Muxlow-T-W-B" }, { "family_name": "Nair", "given_name": "S.", "clpid": "Nair-S" }, { "family_name": "Sykes", "given_name": "C.", "clpid": "Sykes-C-M" }, { "family_name": "Wilkinson", "given_name": "P. N.", "clpid": "Wilkinson-P-N" }, { "family_name": "de Bruyn", "given_name": "A. G.", "clpid": "de-Bruyn-A-G" }, { "family_name": "Bremer", "given_name": "M.", "clpid": "Bremer-M-N" }, { "family_name": "Miley", "given_name": "G. K.", "clpid": "Miley-G-K" }, { "family_name": "Schilizzi", "given_name": "R. T.", "clpid": "Schilizzi-R-T" }, { "family_name": "Snellen", "given_name": "I. A. G.", "clpid": "Snellen-I-A-G" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-Keith-Astronomy" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Womble", "given_name": "D. S.", "clpid": "Womble-D-S" }, { "literal": "CLASS Team" } ], "contributor": [ { "family_name": "Kochanek", "given_name": "C. S.", "clpid": "Kochanek-C-S" }, { "family_name": "Hewitt", "given_name": "J. N.", "clpid": "Hewitt-J-N" } ], "abstract": "The first phase of a large gravitational lens survey using the Very Large Array at a wavelength of 3.6 cm has been completed, yielding images for 3258 radio sources. The Cosmic Lens All-Sky Survey, or CLASS, is designed to locate gravitational lens systems consisting of multiply-imaged compact components with separations > 0\u2033.2. From this first phase has come the discovery of 1608+656, a quadruply-imaged object with maximum separation of 2\u2033.1. Images from the Palomar 5-m and Keck 10-m telescopes show the lensed images and the lensing galaxy. An optical spectrum obtained with the Palomar 5-m Telescope indicates a redshift of z = 0.63 for the lensing galaxy, and a newly-obtained Palomar spectrum indicates a redshift of z = 1.39 for the lensed source, which appears to be a galaxy. A simple single-galaxy lens model derived from the radio image reproduces the observed configuration and relative fluxes of the images, as well as the position, shape, and orientation of the lensing galaxy. Because a simple mass model is able to fit the observations, we argue that this lens system is promising for determining H_0. CLASS has also yielded the new double image lens system 1600+434. The second phase of the survey is scheduled for August and September 1995 on the VLA, and should yield images for an additional 5000+ targets, bringing the CLASS total to over 8000.", "doi": "10.1007/978-94-009-0221-3_90", "isbn": "978-0-7923-3955-7", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1996", "pages": "317-322" }, { "id": "authors:tdtj6-hs976", "collection": "authors", "collection_id": "tdtj6-hs976", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-080007477", "type": "book_section", "title": "Optical and IR Properties of Radio Galaxies as a Function of Their Radio Power", "book_title": "New Light on Galaxy Evolution", "author": [ { "family_name": "Maxfield", "given_name": "L.", "clpid": "Maxfield-L" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Vigotti", "given_name": "M.", "clpid": "Vigotti-M" }, { "family_name": "Grueff", "given_name": "G.", "clpid": "Grueff-G" } ], "contributor": [ { "family_name": "Bender", "given_name": "Ralf", "clpid": "Bender-R" }, { "family_name": "Davies", "given_name": "Roger L.", "clpid": "Davies-R-L" } ], "abstract": "We compare optical and infrared photometric and spectroscopic properties of high-redshift radio galaxies from the 3CR and B3 surveys. At a given redshift and a fixed restframe frequency, the two samples differ on average by an order of magnitude in radio power, thus providing a fair baseline in radio powerfor a range of redshift s. We present new optical and IR photometry and spectrosopy for a number of B3 sources. We combine these data with the existing corresponding information on B3 and 3CR sources, in order to explore different correlations of source properties with redshift, and among themselves. B3 sources follow the same trend as 3CR's in the K band Hubble diagram, although they do seem to be slightly fainter on average at a given redshift. This trend is slightly more prominent in the Gunn r band. This suggests that some fraction of the observed light in the r and K bands is contributed by an active nucleus, which also powers the radio lobes. The B3's also tend to have lower emission line luminosities than 3CR's at any given redshift, suggesting that there may be a correlation between line luminosity and radio power. Such a correlation is clearly seen and is followed by both samples. It suggests that the UV emission lines are largely powered by the active nucleus, ostensibly a hidden quasar, which is also responsible for the radio emission. We also examine the behavior of the optical and radio PA alignments for the combined B3+3CR data set.", "doi": "10.1007/978-94-009-0229-9_126", "isbn": "978-0-7923-3976-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1996", "pages": "414-414" }, { "id": "authors:j6b0z-hth29", "collection": "authors", "collection_id": "j6b0z-hth29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-080635149", "type": "book_section", "title": "The Quest for Protogalaxies", "book_title": "New Light on Galaxy Evolution", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Bender", "given_name": "Ralf", "clpid": "Bender-R" }, { "family_name": "Davies", "given_name": "Roger L.", "clpid": "Davies-R-L" } ], "abstract": "The current state and the future prospects of searches for protogalaxies (PGs) are reviewed. Many high-redshift objects are now known, mostly associated in some way with AGN, and at least some of them may be young galaxies. Quasars at z > 4 and high-z quasar pairs may mark galaxy formation sites. Deep field surveys for Ly\u03b1 luminous galaxies powered by star formation alone have failed so far to reveal a large population of such objects, and the observed limits are in conflict with simple model predictions by three orders of magnitude. Some extinction by dust can account for this. However, strong limits from COBE place severe constraints on models of completely obscured PGs. New searches in the near IR are now beginning to probe the relevant line flux and number density regime, and first interesting PG candidates are being discovered. Searches from mid-IR to mm wavelengths would complement these efforts.", "doi": "10.1007/978-94-009-0229-9_41", "isbn": "978-0-7923-3976-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1996", "pages": "277-286" }, { "id": "authors:yv7xy-40c35", "collection": "authors", "collection_id": "yv7xy-40c35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170409-080326932", "type": "article", "title": "The discovery of two giant arcs in the rich cluster A2219 with the Keck telescope", "author": [ { "family_name": "Smail", "given_name": "Ian", "orcid": "0000-0003-3037-257X", "clpid": "Smail-I" }, { "family_name": "Hogg", "given_name": "David W.", "orcid": "0000-0003-2866-9403", "clpid": "Hogg-D-W" }, { "family_name": "Blandford", "given_name": "Roger", "orcid": "0000-0002-1854-5506", "clpid": "Blandford-R-D" }, { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "Edge", "given_name": "Alastair C.", "clpid": "Edge-A-C" }, { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report the discovery with the Keck telescope of two new multiply imaged arcs in the luminous X-ray cluster A2219 (z = 0.225). The brighter arc in the field is red and we use spectroscopic and photometric information to identify it as a z ~ 1 moderately star-forming system. The brightness of this arc suggests that it is formed from two merging images of the background source, and we identify possible candidates for the third image of this source. The second giant arc in this cluster is blue and, while fainter than the red arc, it has a similarly large angular extent (32 arcsec). This arc comprises three images of a single nucleated source - the relative parities of the three images are discernible in our best-resolution images. The presence of several bright multiply imaged arcs in a single cluster allows detailed modelling of the cluster mass distribution, especially when redshift information is available. We present a lensing model of the cluster, which explains the properties of the various arcs, and we contrast this model with the optical and X-ray information available on the cluster. We uncover significant differences between the distributions of mass and X-ray gas in the cluster. We suggest that such discrepancies may indicate an on-going merger event in the cluster core, possibly associated with a group around the second brightest cluster member. The preponderance of similar merger signatures in a large fraction of the moderate-redshift clusters would indicate their dynamical immaturity.", "doi": "10.1093/mnras/277.1.1", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "1995-11-01", "series_number": "1", "volume": "277", "issue": "1", "pages": "1-10" }, { "id": "authors:xk7ew-0hc69", "collection": "authors", "collection_id": "xk7ew-0hc69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-150450958", "type": "article", "title": "Near-Infrared Fundamental Plane of Elliptical Galaxies", "author": [ { "family_name": "Pahre", "given_name": "Michael A.", "clpid": "Pahre-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "abstract": "We present results from a near-infrared K-band imaging survey of 59 elliptical galaxies in five nearby clusters. We measure photometric parameters for each galaxy using surface photometry and draw velocity dispersions from the literature. Three observables define a near-infrared fundamental plane (FP) of elliptical galaxies with R_e \u221d \u03c3^(1.44\u00b10.04)\u03a3_e^(\u22120.79\u00b10.04). The scatter in the near-infrared relation is small at 16.5% in distance, which is equivalent to, or less than, the scatter of the optical FP. We suggest that the small deviation of the near-infrared FP relation from the optical FP is due to the reduction of metallicity effects in the near-infrared bandpass. While the small scatter of the optical FP could be consistent with compensating effects of age and metallicity, the similarly small scatter of the near-infrared FP is nearly independent of metallicity and hence places a strong constraint on possible age spreads among elliptical galaxies at every point along the FP. We suggest that the departure of the near-infrared FP from the pure virial form Re \u221d \u03c3^2\u03a3_e^(\u22121), and the corresponding observed relation (M/L) \u221d M^(0.16 \u00b1 0.01), may be explained by slight systematic departures of the structure and dynamics of elliptical galaxies from a homology.", "doi": "10.1086/309740", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-11-01", "series_number": "1", "volume": "453", "issue": "1", "pages": "L17-L20" }, { "id": "authors:ds16f-zk353", "collection": "authors", "collection_id": "ds16f-zk353", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-145114139", "type": "article", "title": "A Near-Infrared Search for Line Emission from Protogalaxies Using the W. M. Keck Telescope", "author": [ { "family_name": "Pahre", "given_name": "Michael A.", "clpid": "Pahre-M-A" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present the first results from a near-infrared narrowband search for primeval galaxies (PGs) using the Keck 10 m telescope. We have targeted our fields for three QSOs and one radio galaxy at redshifts z = 2.28 to z = 4.70. We selected narrowband filters in the K band centered on strong emission lines at the redshift of the targets. We reach limiting fluxes between 1.6 \u00d7 10^(-17) and 1.0 \u00d7 10^(-16) ergs s^(-1) cm^(-2), and cover a total area of ~4 arcmin2. At the redshifts of interest, these flux limits correspond to typical rest-frame line luminosities of ~10^(42)-10^(43) ergs s^(-1), unobscured star formation rates of ~1-100 M\u2609 yr^(-1), and a sampled comoving volume of several tens of Mpc^3. We have found no candidate PGs at a 2 \u03c3 confidence level. We demonstrate that for moderate dust absorption (A_V 2 mag) in a simple dust-screen model, our preliminary survey puts a strong constraint on intrinsic PG luminosities during an initial burst of star formation. In the case of the QSOs, we have used point-spread function subtraction to search for the presence of faint, extended line emission surrounding these radio-quiet active galactic nuclei. We find no evidence for extended emission down to 3.7 \u00d7 10^(-17) ergs s^(-1) cm^(-2). This imposes limits on the reprocessed fraction of the QSO continuum emission ranging between 0.02% and 0.29%; if beaming effects are not important, then this implies similarly small covering factors for clouds optically thick to the QSO continuum emission.", "doi": "10.1086/309632", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-08-10", "series_number": "1", "volume": "449", "issue": "1", "pages": "L1-L4" }, { "id": "authors:24rf3-q5351", "collection": "authors", "collection_id": "24rf3-q5351", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150817-154138504", "type": "article", "title": "1608+656: A Quadruple-Lens System Found in the CLASS Gravitational Lens Survey", "author": [ { "family_name": "Myers", "given_name": "S. T.", "clpid": "Myers-Steven-Theodore" }, { "family_name": "Fassnacht", "given_name": "C. D.", "orcid": "0000-0002-4030-5461", "clpid": "Fassnacht-C-D" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Blandford", "given_name": "R. D.", "orcid": "0000-0002-1854-5506", "clpid": "Blandford-R-D" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-K" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Pearson", "given_name": "T. J.", "orcid": "0000-0001-5213-6231", "clpid": "Pearson-T-J" }, { "family_name": "Readhead", "given_name": "A. C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Womble", "given_name": "D. S.", "clpid": "Womble-D-S" }, { "family_name": "Browne", "given_name": "I. W. A.", "clpid": "Browne-I-W-A" }, { "family_name": "Wilkinson", "given_name": "P. N.", "clpid": "Wilkinson-P-N" }, { "family_name": "Nair", "given_name": "S.", "clpid": "Nair-S" }, { "family_name": "Jackson", "given_name": "N.", "clpid": "Jackson-N" }, { "family_name": "Snellen", "given_name": "I. A. G.", "clpid": "Snellen-I-A-G" }, { "family_name": "Miley", "given_name": "G. K.", "clpid": "Miley-G-K" }, { "family_name": "de Bruyn", "given_name": "A. G.", "clpid": "de-Bruyn-A-G" }, { "family_name": "Schilizzi", "given_name": "R. T.", "clpid": "Schilizzi-R-T" } ], "abstract": "The first phase of a large gravitational lens survey using the Very Large Array at a wavelength of 3.6 cm has been completed, yielding images for 3258 radio sources. The Cosmic Lens All-Sky Survey (CLASS) is designed to locate gravitational lens systems consisting of multiply imaged compact components with separations greater than 0.\"2. We report here the first discovery of a gravitational lens from the survey: 1608+656, a quadruply imaged object with a maximum separation of 2.\"1. Images from the Palomar 5 m and Keck 10 m telescopes show the lensed images and the lensing galaxy. An optical spectrum obtained with the Palomar 5 m telescope indicates a redshift of z=0.6304 for the lensing galaxy. No conclusive redshift for the lensed object has been determined, although a single strong emission line is found at 9240 \u00c5 in the Keck low-resolution imaging spectrograph spectrum. The two most likely identifications for this line are H\u03b2 (z=0.90) and Mg II (z=2.30). The preliminary lens model derived from the radio image reproduces the observed configuration and relative fluxes of the images, as well as the position, shape, and orientation of the lensing galaxy. Because a simple mass model is able to fit the observations, we argue that this lens system is promising for determining H_0.", "doi": "10.1086/309556", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-07-01", "series_number": "1", "volume": "447", "issue": "1", "pages": "L5-L8" }, { "id": "authors:1ppfs-kty97", "collection": "authors", "collection_id": "1ppfs-kty97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170228-140004588", "type": "article", "title": "Deep galaxy counts in the K band with the Keck telescope", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Soifer", "given_name": "B. T.", "orcid": "0000-0002-8112-1132", "clpid": "Soifer-B-T" }, { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Larkin", "given_name": "J. E.", "orcid": "0000-0001-7687-3965", "clpid": "Larkin-J-E" }, { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Smail", "given_name": "I.", "orcid": "0000-0003-3037-257X", "clpid": "Smail-Ian-R" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-Keith-Astronomy" }, { "family_name": "Hogg", "given_name": "D. W.", "orcid": "0000-0003-2866-9403", "clpid": "Hogg-D-W" }, { "family_name": "Blandford", "given_name": "R. D.", "orcid": "0000-0002-1854-5506", "clpid": "Blandford-R-D" }, { "family_name": "Cohen", "given_name": "J. G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "Harrison", "given_name": "W.", "clpid": "Harrison-W" }, { "family_name": "Nelson", "given_name": "J.", "clpid": "Nelson-J" } ], "abstract": "We present deep galaxy counts in the K (\u22cb 2.2 micrometer) band, obtained at the W. M. Keck 10 m telescope. The data reach limiting magnitudes K approximately 24 mag, about 5 times deeper than the deepest published K-band images to date. The counts are performed in three small (approximately 1 min), widely separated high-latitude fields. Extensive Monte Carlo tests were used to derive the completeness corrections and minimize photometric biases. The counts continue to rise, with no sign of a turnover, down to the limits of our data, with the logarithmic slope of d log N/dm = 0.315 +/- 0.02 between K = 20 and 24 mag. This implies a cumulative surface density of approximately 5 x 10^5 galaxies/sq deg, or approximately 2 x 10^10 over the entire sky, down to K = 24 mag. Our counts are in good agreement with, although slightly lower than, those from the Hawaii Deep Survey by Cowie and collaborators; the discrepancies may be due to the small differences in the aperture corrections. We compare our counts with some of the available theoretical predictions. The data do not require models with a high value of Omega_0, but can be well fitted by models with no (or little) evolution, and cosmologies with a low value of Omega_0. Given the uncertainties in the models, it may be premature to put useful constrains on the value of Omega_0 from the counts alone. Optical-to-IR colors are computed, using CCD data obtaind previously at Palomar. We find a few red galaxies with (r-K) approximately greater than 5 mag, or (i-K) approximately greater than 5 mag; these may be ellipticals at z approximately 1. While the redshift distribution of galaxies in our counts is still unknown, the flux limits reached would allow us to detect unobscured L_* galaxies out to substantial redshifts (z greater than 3?)", "doi": "10.1086/187703", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-01-01", "series_number": "1", "volume": "438", "issue": "1", "pages": "L13-L16" }, { "id": "authors:41grz-rf118", "collection": "authors", "collection_id": "41grz-rf118", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-074142687", "type": "article", "title": "Automated analysis and exploration of image databases: Results, progress, and challenges", "author": [ { "family_name": "Fayyad", "given_name": "Usama M.", "clpid": "Fayyad-U-M" }, { "family_name": "Smyth", "given_name": "Padhraic", "clpid": "Smyth-P" }, { "family_name": "Weir", "given_name": "Nicholas", "clpid": "Weir-N" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "In areas as diverse as earth remote sensing, astronomy, and medical imaging, image acquisition technology has undergone tremendous improvements in recent years. The vast amounts of scientific data are potential treasure-troves for scientific investigation and analysis. Unfortunately, advances in our ability to deal with this volume of data in an effective manner have not paralleled the hardware gains. While special-purpose tools for particular applications exist, there is a dearth of useful general-purpose software tools and algorithms which can assist a scientist in exploring large scientific image databases. This paper presents our recent progress in developing interactive semi-automated image database exploration tools based on pattern recognition and machine learning technology. We first present a completed and successful application that illustrates the basic approach: the SKICAT system used for the reduction and analysis of a 3 terabyte astronomical data set. SKICAT integrates techniques from image processing, data classification, and database management. It represents a system in which machine learning played a powerful and enabling role, and solved a difficult, scientifically significant problem. We then proceed to discuss the general problem of automated image database exploration, the particular aspects of image databases which distinguish them from other databases, and how this impacts the application of off-the-shelf learning algorithms to problems of this nature. A second large image database is used to ground this discussion: Magellan's images of the surface of the planet Venus. The paper concludes with a discussion of current and future challenges.", "doi": "10.1007/bf00962819", "issn": "0925-9902", "publisher": "Springer", "publication": "Journal of Intelligent Information Systems", "publication_date": "1995-01", "series_number": "1", "volume": "4", "issue": "1", "pages": "7-25" }, { "id": "authors:a2kgd-g0q37", "collection": "authors", "collection_id": "a2kgd-g0q37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-082224078", "type": "book_section", "title": "Observational Cosmology With Faint Galaxies and a (9\u00b11)-meter Telescope", "book_title": "Science with the VLT", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Walsh", "given_name": "Jeremy R.", "clpid": "Walsh-J-R" }, { "family_name": "Danziger", "given_name": "Ivan J.", "clpid": "Danziger-I-J" } ], "abstract": "The new generation of 8 to 10-meter class telescopes opens exciting new possibilities for observational cosmology. A brief overview is given of several types of studies of galaxy formation and evolution. Deep galaxy counts and redshift surveys will probe the evolution of normal field galaxies out to redshifts well in excess of 1, and L\u2217 galaxies should be detectable in the infrared out to z ~ 4\u20135. It is possible that new types of galaxies or AGN may be found in the deep infrared surveys. Detailed studies of galaxian properties and their correlations (e.g., the fundamental plane correlations for ellipticals) may be possible out to z ~ 1. Infrared Hubble diagrams for brightest cluster ellipticals and moderate-power radio galaxies may again become a viable cosmological test. Finally, a population of primeval galaxies undergoing their first major bursts of star formation should be detectable, possibly through their nebular oxygen and hydrogen Balmer line emission, now redshifted to the near infrared.", "doi": "10.1007/978-3-540-49215-3_44", "isbn": "978-3-662-22397-0", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1995", "pages": "351-360" }, { "id": "authors:47ppd-zy221", "collection": "authors", "collection_id": "47ppd-zy221", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190530-103644055", "type": "book_section", "title": "Near-IR Imaging of Elliptical Galaxies", "book_title": "Stellar Populations", "author": [ { "family_name": "Pahre", "given_name": "M. A.", "clpid": "Pahre-M-A" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-Keith-Astronomy" }, { "family_name": "Shupe", "given_name": "D.", "orcid": "0000-0003-4401-0430", "clpid": "Shupe-David-L" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" } ], "contributor": [ { "family_name": "van der Kruit", "given_name": "P. C.", "clpid": "van-der-Kruit-P-C" }, { "family_name": "Gilmore", "given_name": "C.", "clpid": "Gilmore-C" } ], "abstract": "We have imaged more than thirty early-type galaxies in the K-band to investigate their stellar populations. Our surface brightness fluctuations (SBF) measurements for the nearest 14 galaxies produce a mean fluctuations magnitude in the K-band of M_K = \u22125.8 \u00b1 0.2 mag. The scatter in the Virgo cluster is small at 0.18 mag, which implies that infrared SBF is potentially a good distance indicator (Pahre & Mould 1994). Inspection of the simple stellar population tracks of Worthey (1994) suggests that a plot of the fluctuation color (\u012a\u2014 K) against broadband color (V \u2014 I) might be useful in discriminating between age and metallicity effects in elliptical galaxies. We have measured (r \u2014 K) color gradients for the entire sample utilizing three methods, two of them independent of sky-subtraction errors, as found in Sparks & J\u00f8rgensen (1993). Our color gradients are consistent with a mean metallicity gradient of 0.14 mag dex^(-1), which is somewhat smaller than that implied by optical color and line gradients alone, suggesting that age gradients may also be important. Finally, we have constructed an infrared Fundamental Plane (FP) which is consistent with its optical counterpart; continued work will determine if there is a significant change in the tilt of the FP between the optical and infrared.", "doi": "10.1007/978-94-011-0125-7_112", "isbn": "9780792335382", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1995", "pages": "443-443" }, { "id": "authors:s4q8s-abq96", "collection": "authors", "collection_id": "s4q8s-abq96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170213-133303949", "type": "article", "title": "Multicolor detection of high-redshift quasars, II. Five objects with z \u2273 4\"", "author": [ { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Brisken", "given_name": "W. F.", "clpid": "Brisken-W-F" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-K" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" }, { "family_name": "Suntzeff", "given_name": "N. B.", "clpid": "Suntzeff-N-B" } ], "abstract": "We report the results of a multicolor wide-field CCD survey designed to rediscover several BRI quasars\npreviously found in a photographic survey by Irwin et al [ASPCS, 21, 117 (1991)], but not fully documented in the literature. Here we provide spectra, redshifts, finding charts, magnitudes, and coordinates for four such BRI quasars. Follow-up observations were obtained for BRI 2235\u201403, a borderline BAL object. Amoderate resolution absorption line spectrum for the object shows a very dense Lya forest and two CIV doublets at z>3. Its visible spectrum is redder than those of the other quasars presented, although it is similar in the infrared. J, H, and K magnitudes are presented for this quasar, showing it to be one of the most luminous objects known. New J, H, and K photometry is presented for PC 1247+3406, the most\ndistant quasar known. In the course of the survey we also discovered a new quasar with z=4.042. Its spectrum, coordinates, magnitudes, and finding chart are presented here as well.", "doi": "10.1086/117143", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1994-10", "series_number": "1", "volume": "110", "issue": "1", "pages": "1147-1155" }, { "id": "authors:kr60j-19174", "collection": "authors", "collection_id": "kr60j-19174", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150513-103241631", "type": "article", "title": "Digitizing the skies", "author": [ { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Charting the skies is the most ancient of\nastronomical pursuits. Now, in the spirit\nof the age, astronomers are busily paving\ntheir own information superhighways,\nand compiling digital road maps to guide\nthem along. This happy activity was very\napparent at a recent meeting, where we\nlearned that numerous ambitious projects\nare being planned or are underway to map\nthe sky at wavelengths ranging\nfrom the radio to the X-ray. Each\ndigital survey will produce a census\nof all sources detected down to\nits appropriate flux limit, numbering\nthousands, millions or even\nbillions.", "doi": "10.1038/370018a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1994-07-07", "series_number": "6484", "volume": "370", "issue": "6484", "pages": "18-19" }, { "id": "authors:p40fk-7sk18", "collection": "authors", "collection_id": "p40fk-7sk18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170228-145632512", "type": "article", "title": "Deep imaging of the field of the Z = 4.9 quasar PC 1247+3406, and faint galaxy counts in the K band with the Keck telescope", "author": [ { "family_name": "Soifer", "given_name": "B. T.", "orcid": "0000-0002-8112-1132", "clpid": "Soifer-B-T" }, { "family_name": "Matthews", "given_name": "K.", "clpid": "Matthews-Keith-Astronomy" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Larkin", "given_name": "J.", "orcid": "0000-0001-7687-3965", "clpid": "Larkin-J-E" }, { "family_name": "Graham", "given_name": "J. R.", "clpid": "Graham-J-R" }, { "family_name": "Harrison", "given_name": "W.", "clpid": "Harrison-W" }, { "family_name": "Jernigan", "given_name": "G.", "clpid": "Jernigan-G" }, { "family_name": "Lin", "given_name": "S.", "clpid": "Lin-S" }, { "family_name": "Nelson", "given_name": "J.", "clpid": "Nelson-J" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Smith", "given_name": "G.", "clpid": "Smith-Gene" }, { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" }, { "family_name": "Ziomkowski", "given_name": "C.", "clpid": "Ziomkowski-C" } ], "abstract": "We present deep images in the K. band of the field of the quasar PC 1247 + 3406 at z = 4.897, obtained using the near-infrared camera on the W. M. Keck telescope. A number of faint sources have been detected, some of which appear to be quite red. Their nature and redshifts remain uncertain at this time. These data are combined with deep Keck infrared images of five additional fields and present galaxy counts reaching down to K_s = 22 mag, comparable to the deepest K-band surveys to date. The data presented here are in good agreement with the Hawaii Deep Survey and represent the first independent verification of those results. The slope of the log N-log S relation derived from these data agrees well with the Hawaii Deep Survey, while the counts are slightly higher, especially at the faintest levels probed here. This may be due to a presence of groups or clusters around the target objects at high redshifts.", "doi": "10.1086/187148", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1994-01-01", "series_number": "1", "volume": "420", "issue": "1", "pages": "L1-L4" }, { "id": "authors:22v5r-kx516", "collection": "authors", "collection_id": "22v5r-kx516", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-085714246", "type": "book_section", "title": "Structural and dynamical forms of elliptical and dwarf galaxies", "book_title": "Ergodic Concepts in Stellar Dynamics", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Gurzadyan", "given_name": "V. G.", "clpid": "Gurzadyan-V-G" }, { "family_name": "Pfenniger", "given_name": "D.", "clpid": "Pfenniger-D" } ], "abstract": "This review discusses two intriguing problems posed by observations of early-type galaxies: First, the existence of a so-called fundamental plane of elliptical galaxies and its thickness impose strong constraints on their global dynamical structures, stellar populations, and the relation of dark to visible matter in them. Second, the prevalence of extreme core-halo structures among the nucleated dwarf galaxies. Finally, some general remarks are made about the standard density forms of galactic subsystems, including dark halos. These empirical findings provide strong constraints and valuable clues for models of galaxy formation. They may point towards the existence of preferred dynamical structures in galaxies, perhaps globally stable or maximum entropy states, reached through different formative histories.", "doi": "10.1007/BFb0058086", "isbn": "978-3-540-57929-8", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1994", "pages": "3-21" }, { "id": "authors:n7986-m5q35", "collection": "authors", "collection_id": "n7986-m5q35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-082815448", "type": "book_section", "title": "Globular Clusters in M31 with the Hubble Space Telescope", "book_title": "Frontiers of Space And Ground-Based Astronomy", "author": [ { "family_name": "Cacciari", "given_name": "C.", "clpid": "Cacciari-C" }, { "family_name": "Federici", "given_name": "L.", "clpid": "Federici-L" }, { "family_name": "Ferraro", "given_name": "F. R.", "clpid": "Ferraro-F-R" }, { "family_name": "Fusi Pecci", "given_name": "F.", "clpid": "Fusi-Pecci-F" }, { "family_name": "Parmeggiani", "given_name": "G.", "clpid": "Parmeggiani-G" }, { "family_name": "Bendinelli", "given_name": "O.", "clpid": "Bendinelli-O" }, { "family_name": "Zavatti", "given_name": "F.", "clpid": "Zavatti-F" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" } ], "contributor": [ { "family_name": "Wamsteker", "given_name": "W.", "clpid": "Wamsteker-W" }, { "family_name": "Longair", "given_name": "M. S.", "clpid": "Longair-M-S" }, { "family_name": "Kondo", "given_name": "Y.", "clpid": "Kondo-Yoji" } ], "abstract": "The study of the globular clusters in the Galaxy has provided a wealth of essential information on stellar evolution and dynamics, as well as on the formation and early evolutionary stages of the Galaxy itself. \n\nWith the use of the Hubble Space Telescope for the first time the same type of studies can be applied to a globular cluster system beyond the halo of our Galaxy, namely to the closest giant spiral galaxy M31. Because of the HST optical aberration, however, accurate photometry of individual stars for a Colour-Magnitude Diagram has not been possible so far, and only surface brightness profiles could be obtained. \n\nWe have observed thirteen globular clusters in M31 with the HST FOC/96 and F430W (B band) filter. Excellent surface brightness photometry was obtained. Accurate profiles and structural parameters were derived using three independent PSF deconvolution methods (i.e. Regularized Multi-Gaussian, Richardson-Lucy and Maximum Entropy). Our conclusions are: \n1. The three deconvolution methods yield perfectly consistent results as far as the surface brightness profiles are concerned. This opens the possibility of morphological studies of M31 globular clusters comparable to the ground-based studies of globulars in the Galaxy. \n \n2. Care must be taken for the conservation of flux when absolute photometry is performed. \n \n3. One of our M31 clusters shows a clear PCC morphology: this is the first such detection outside the immediate vicinity of the Galaxy, and was made possible by the superior HST space resolution (see Bendinelli et al. 1993 for more details). \n \n4. The structural parameters (i.e. core radius, half-light radius and central surface brightness) derived for the 13 globulars in M31 have been compared with: a) the results obtained from ground-based observations. The ground-based core radii tend to be systematically larger by ~ 30% or more, unless accurate seeing deconvolution is performed; b) the parameters obtained for Galactic globular clusters. They all agree very well, suggesting that the two families of clusters consist of very similar objects. The complete results and detailed analysis and discussion are presented in a forthcoming paper (Fusi Pecci et al. 1993).", "doi": "10.1007/978-94-011-0794-5_104", "isbn": "978-94-010-4341-0", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1994", "pages": "661-661" }, { "id": "authors:9qgzg-21137", "collection": "authors", "collection_id": "9qgzg-21137", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-084632067", "type": "book_section", "title": "Cataloging the Northern Sky Using a new Generation of Software Technology", "book_title": "Astronomy from Wide-Field Imaging", "author": [ { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fayyad", "given_name": "U.", "clpid": "Fayyad-U" }, { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" }, { "family_name": "Roden", "given_name": "J.", "clpid": "Roden-J-C" } ], "contributor": [ { "family_name": "MacGillivray", "given_name": "H. T.", "clpid": "MacGillivray-H-T" }, { "family_name": "Thomson", "given_name": "E. B.", "clpid": "Thomson-E-B" }, { "family_name": "Lasker", "given_name": "B. M.", "clpid": "Lasker-B-M" }, { "family_name": "Reid", "given_name": "I. N.", "clpid": "Reid-I-N" }, { "family_name": "Malin", "given_name": "D. F.", "clpid": "Malin-D-F" }, { "family_name": "West", "given_name": "R. M.", "clpid": "West-R-M" }, { "family_name": "Lorenz", "given_name": "H.", "clpid": "Lorenz-H" } ], "abstract": "We have developed a system, called SKICAT, for producing, managing and analyzing catalogs from the digitized POSS-II survey. The system classifies and matches catalogs from multiple, overlapping plate scans as well as CCD calibration sequences; and it can be used for the scientific analysis of the resulting catalogs. It incorporates a number of novel machine-learning and AI tools, including the star/galaxy classification using decision tree algorithms. This results in star/galaxy separation accurate to 90% or better down to B_j, \u223c 21^m, i.e. \u223c 1^m above the plate limit The final catalog is expected to contain at least 5 x 10^7 galaxies and > 2 x 10^9 stars. We present preliminary results on galaxy counts from a test region near the NGP. We find a mild excess over the no-evolution models, smaller than previously found by the APM group. A search for z > 4 quasars and the two-point correlation analysis of this data set are in progress.", "doi": "10.1007/978-94-011-1146-1_43", "isbn": "978-0-7923-2879-7", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1994", "pages": "205-212" }, { "id": "authors:kzy29-gxr16", "collection": "authors", "collection_id": "kzy29-gxr16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161013-133506418", "type": "book_section", "title": "Automated cataloging and analysis of sky survey image databases: the SKICAT system", "book_title": "CIKM '93 Proceedings of the second international conference on Information and knowledge management", "author": [ { "family_name": "Fayyad", "given_name": "Usama M.", "clpid": "Fayyad-U-M" }, { "family_name": "Weir", "given_name": "Nicholas", "clpid": "Weir-N" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Bhargava", "given_name": "Bharat", "clpid": "Bhargava-B" }, { "family_name": "Finin", "given_name": "Tim", "clpid": "Finin-T" }, { "family_name": "Yesha", "given_name": "Yelena", "clpid": "Yesha-Y" } ], "abstract": "We describe the application of machine learning and\nstate-of-the-art database management technology to\nthe development of an automated tool for the\nreduction and analysis of a large astronomical data set.\nThe 3 terabytes worth of images are expected to\ncontain on the order of 5 x 10^7 galaxies and 5 x 10^8\nstars. For the primary scientific analysis of these\ndata, it is necessary to detect, measure, and classify\nevery sky object. The size of the complete data set\nprecludes manual reduction, requiring an automated\napproach. SKICAT integrates techniques for image\nprocessing, data classification, and database\nmanagement. Once sky objects are detected, a set of\nbasic features for each object are computed. The\nlearning algorithms are trained to classify the detected\nobjects and can classify objects too faint for visual\nclassification with an accuracy level of about 941Z0.\nThis increases the number of classified objects in the\nfinal catalog three-fold relative to the best results from\ndigitized photographic sky surveys to date. The tasks\nof managing and matching the resulting hundreds of\nplate catalogs is accomplished using custom software\nand the Sybase relational DBMS. A full array of\nscientific analysis tools are provided for filtering,\nmanipulating, plotting, and listing the data in the sky\nobject database. We are currently experimenting with\nthe use of machine discovery tools, such as the\nAUTOCLASS unsupervised classification program,\non the data. SKICAT represents a system in which\nmachine learning played a powerful and enabling role,\nand solved a difficult, scientifically significant\nproblem. The primary benefits of our overall approach\nare increased data reduction throughput consistency of\nclassification; and the ability to easily access, analyze,\nand create new information from an otherwise\nunfathomable data set.", "doi": "10.1145/170088.170414", "isbn": "0-89791-626-3", "publisher": "ACM", "place_of_publication": "New York, NY", "publication_date": "1993-11", "pages": "527-536" }, { "id": "authors:th3wj-wnp28", "collection": "authors", "collection_id": "th3wj-wnp28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151109-111429841", "type": "article", "title": "Limits on Lyman-alpha Luminous Protogalaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S. George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Smith", "given_name": "J. D.", "orcid": "0000-0003-1545-5078", "clpid": "Smith-J-D-T" } ], "abstract": "The bulk of the energy released from protogalaxies, defined here as young ellipticals and bulges undergoing their first major bursts of star formation at large redshifts, is from the nuclear burning in massive stars. This may amount to ~ 10^(61) erg per an average (L_*) galaxy, which is at least an order of magnitude higher than the amount of binding energy released in the protogalactic collapse; an active nucleus, if present, could contribute a comparable amount of energy. If released over a period of ~ 10^8 -10^9 years, this corresponds to protogalaxy (hereafter PG) luminosities of ~ 10^(11) -10^(12) L_\u2609. For unobscured protogalaxies, a few percent of this energy is expected to emerge in the form of recombination lines, primarily Ly\u0251. Star formation\nrate of 100 M_\u2609/yr would power a restframe Ly\u0251 line luminosity of ~ 10^(44) erg/s. At the redshifts of interest, for a range of standard cosmologies, the\nluminosity distances are ~ 10^(29) - 10^(30) cm, and thus the expected observable Ly\u0251 line fluxes from unobscured PGs are ~ 10^(-16\u00b11) erg/cm^2 /s, which is detectable with present-day technology. Thus, most PG searches to date\nemployed the Lyn line as the observable signature of young galaxies powered by star formation. More details can be found in our recent reviews and references therein.", "doi": "10.1111/j.1749-6632.1993.tb43926.x", "issn": "0077-8923", "publisher": "New York Academy of Sciences", "publication": "Annals of the New York Academy of Sciences", "publication_date": "1993-06", "series_number": "1", "volume": "688", "issue": "1", "pages": "515-518" }, { "id": "authors:gyw1t-6mt23", "collection": "authors", "collection_id": "gyw1t-6mt23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150609-112744901", "type": "article", "title": "Rates of collapse and evaporation of globular clusters", "author": [ { "family_name": "Hut", "given_name": "Piet", "clpid": "Hut-P" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Of the known galactic globular clusters, ~ 140 in number, about one-fifth have undergone core collapse, and an unknown number have evaporated altogether. From observational estimates of the dynamical relaxation times of globular clusters, measured at their cores and at their half-light radii, we estimate here the present rates at which core collapse and evaporation are occurring. We find a core collapse rate of 2 \u00b1 1 per Gyr, which for a galactic age of ~ 12 Gyr agrees well with the fact that 27 clusters have surface brightness profiles with the morphology expected for the post-collapse phase. We find a destruction and evaporation rate of 5\u00b13 per Gyr, suggesting that a significant fraction of the Galaxy's original complement of globular clusters have perished, through the combined effects of mechanisms such as relaxation-driven evaporation and shocking due to interaction with the galactic disk and bulge.", "doi": "10.1038/359806a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1992-10-29", "series_number": "6398", "volume": "359", "issue": "6398", "pages": "806-808" }, { "id": "authors:32epw-hgp44", "collection": "authors", "collection_id": "32epw-hgp44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190605-131407195", "type": "book_section", "title": "A search for the optical counterpart of the Einstein ring PKS 1830-211", "book_title": "Gravitational Lenses", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Thompson", "given_name": "D.", "clpid": "Thompson-D" }, { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Swarup", "given_name": "G.", "clpid": "Swarup-G" }, { "family_name": "Rao", "given_name": "P.", "clpid": "Rao-P" }, { "family_name": "Subrahmanyan", "given_name": "R.", "clpid": "Subrahmanyan-R" }, { "family_name": "Smette", "given_name": "A.", "clpid": "Smette-A" } ], "contributor": [ { "family_name": "Kayser", "given_name": "Rainer", "clpid": "Kayser-R" }, { "family_name": "Schramm", "given_name": "Thomas", "clpid": "Schramm-T" }, { "family_name": "Nieser", "given_name": "Lars", "clpid": "Nieser-L" } ], "abstract": "We report the results of deep optical and IR imaging, astrometry, and spectroscopy of the recently identified Einstein ring source PKS 1830-211. (Rao & Subrahmanyan 1988, Swarup et al. 1989, Subrahmanyan et al. 1990). We made several attempts to secure an optical or IR ID of this object, using observations from Palomar and ESO, May 1988 \u2013 May 1990. Several objects are visible within the 2-\u03c3 error circle in our CCD images, including the \u2248 22^m object (which may be extended, or a close double) proposed as the tentative counterpart by Subrahmanyan et al. 1990. This, and another object \u2248 1.2\u2033 NE from it may represent the optical counterparts of the two major radio source components. We cannot yet unambiguously determine which one(s), if any, of these objects represent the correct ID. The lensing galaxy is likely to be at a redshift of at least a few tenths. A full account of this work will be submitted for publication shortly. Some of the data used here were obtained as a part of the ESO Key Project on Gravitational Lenses. S.D. acknowledges a partial support from the Alfred P. Sloan Foundation, and the NSF PYI award AST-9157412.", "doi": "10.1007/3-540-55797-0_129", "isbn": "978-3-540-55797-5", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1992", "pages": "367" }, { "id": "authors:kz4j1-rff88", "collection": "authors", "collection_id": "kz4j1-rff88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-083117821", "type": "book_section", "title": "Properties of Dwarf Spheroidals", "book_title": "Morphological and Physical Classification of Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "contributor": [ { "family_name": "Longo", "given_name": "G.", "clpid": "Longo-G" }, { "family_name": "Capaccioli", "given_name": "M.", "clpid": "Capaccioli-M" }, { "family_name": "Busarello", "given_name": "G.", "clpid": "Busarello-G" } ], "abstract": "Low surface brightness dwarf galaxies (at least the gas-poor variety) represent a fundamentally distinct family of objects, rather than just a low luminosity extension of the Hubble sequence; they are not \"dwarf ellipticals\" (Wirth and Gallagher, 1984; Kormendy, 1985; see Kormendy and Djorgovski, 1989 for a brief discussion and further references). Kormendy (1985) has demonstrated that dwarfs obey simple scaling laws and correlations which are quite different from those of normal ellipticals, pointing towards different formation histories. We extended this line of inquiry to multivariate correlations, using the sample of Local Group dwarf spheroidals (dSph), and samples of low surface brightness dwarfs (LSBD) in the Virgo and Fornax clusters. Whereas normal ellipticals form a statistically two-dimensional family in the parameter space of observables (Djorgovski, this volume, and references therein), dwarfs form nearly one-dimensional families; i.e., all of their properties seem to be well correlated (Djorgovski and de Carvalho, 1990). The only exception are velocity dispersion (only 5 available) , which do not correlate with any other observed properties. Furthermore, the corresponding correlations for dSph's and ellipticals often have the opposite signs. Some examples are shown in figures 1 and 2. These results are only preliminary: selection effects are notoriously difficult.", "doi": "10.1007/978-94-011-2522-2_31", "isbn": "978-94-010-5113-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "379-380" }, { "id": "authors:mcvbw-j7b44", "collection": "authors", "collection_id": "mcvbw-j7b44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-100716861", "type": "book_section", "title": "Galaxy Manifolds and Galaxy Formation", "book_title": "Morphological and Physical Classification of Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Longo", "given_name": "G.", "clpid": "Longo-G" }, { "family_name": "Capaccioli", "given_name": "M.", "clpid": "Capaccioli-M" }, { "family_name": "Busarello", "given_name": "G.", "clpid": "Busarello-G" } ], "abstract": "We are witnessing the emergence of a physical classification of galaxies. New methods of inquiry, including multivariate statistical analysis of galaxy manifolds, scaling laws and correlations provide important clues towards understanding the formative mechanisms and evolutionary histories of galaxies. Galaxies of different families form two-dimensional sequences in the parameter spaces of their many (but not all) global observable properties; this relative simplicity probably reflects the regularities and feedbacks in the processes of galaxy formation. A minimal three-dimensional parameter space, whose axes include measures of galaxy size, density, and kinetic temperature promises to become the equivalent of an H-R diagram for galaxies.", "doi": "10.1007/978-94-011-2522-2_27", "isbn": "978-94-010-5113-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "337-356" }, { "id": "authors:n5hdx-cyg59", "collection": "authors", "collection_id": "n5hdx-cyg59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-160710185", "type": "book_section", "title": "Systematic Differences Between the Field and Cluster Ellipticals", "book_title": "The Stellar Populations of Galaxies", "author": [ { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Barbuy", "given_name": "B.", "clpid": "Barbuy-B" }, { "family_name": "Renzini", "given_name": "A.", "clpid": "Renzini-A" } ], "abstract": "We applied multivariate statistical techniques to study the possible systematic differences between the field and cluster ellipticals, in the framework of the fundamental plane (FP) of elliptical galaxies on the samples of elliptical galaxies from the general field and loose groups, and from rich clusters. The data set used here are the ellipticals from the \"7 Samurai\" (Burstein et al. 1987; Davies et al. 1987), limited to cz < 6000 km/s. There are 55 galaxies in the cluster sample (mostly from the Coma and Virgo clusters), and 57 galaxies in the field sample, which may include galaxies in loose and poor groups. We have also used the data set from Djorgovski & Davis (1987), with very similar results.", "doi": "10.1007/978-94-011-2434-8_67", "isbn": "978-0-7923-1699-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "400" }, { "id": "authors:db9k6-4g103", "collection": "authors", "collection_id": "db9k6-4g103", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-074631256", "type": "book_section", "title": "Properties of Brightest Cluster Members", "book_title": "Morphological and Physical Classification of Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Shlosman", "given_name": "I.", "clpid": "Shlosman-I" }, { "family_name": "Schombert", "given_name": "J.", "clpid": "Schombert-J" } ], "contributor": [ { "family_name": "Longo", "given_name": "G.", "clpid": "Longo-G" }, { "family_name": "Capaccioli", "given_name": "M.", "clpid": "Capaccioli-M" }, { "family_name": "Busarello", "given_name": "G.", "clpid": "Busarello-G" } ], "abstract": "Are the brightest cluster members (BCMs) somehow different from the \"normal\" ellipticals, or are their properties in accord with the high luminosity extension of the global properties and scaling laws of the family of ellipticals? We examined the behavior of BCMs in the parameter space defined by the luminosity (L), radius (R), surface brightness (\u03bc), and velocity dispersion (\u03c3), i.e., the so-called Fundamental Plane (FP) variables. We used the data from Malumuth and Kirshner, for both the core and the half-light parameters; the results on both radial scales were qualitatively the same.", "doi": "10.1007/978-94-011-2522-2_53", "isbn": "978-94-010-5113-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "427-428" }, { "id": "authors:9c3vj-2f760", "collection": "authors", "collection_id": "9c3vj-2f760", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-090410376", "type": "book_section", "title": "Stellar Population Changes in Post-Core-Collapse Globular Clusters", "book_title": "The Stellar Populations of Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" } ], "contributor": [ { "family_name": "Barbuy", "given_name": "B.", "clpid": "Barbuy-B" }, { "family_name": "Renzini", "given_name": "A.", "clpid": "Renzini-A" } ], "abstract": "Color gradients, in the sense of becoming bluer inwards, are found in postcore-collapse (PCC) clusters. No gradients are seen in clusters with King-model morphology. The gradients seem to be caused by the demise of red giants and/or subgiants, and possibly an increased number of blue stragglers or some other population of faint, blue objects. Practically all PCC clusters have blue horizontal branches, with faint blue tails. Bright red giants are clearly underabundant in the central regions of PCC clusters, whereas HB stars seem to be unaffected. At a. fixed metallicity, PCC clusters also show blue FUV colors, as seen in the archival data from the IUE and ANS (Figure 1). This is consistent with our observations of their HB morphologies, but a presence of an additional hot population cannot be excluded. The gradients may be a consequence of stellar interactions during and after the core collapse, and the mechanism may be important for the formation of millisecond and binary pulsars and LMXB's. These effects represent a strong evidence that dynamical evolution of star clusters can physically modify their stellar populations. It is possible that similar effects may operate in at least some galactic nuclei. More details and further references are given by Djorgovski et al. 1991, ApJ, 372, L41.", "doi": "10.1007/978-94-011-2434-8_80", "isbn": "978-0-7923-1699-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "413" }, { "id": "authors:6wkjq-bnv12", "collection": "authors", "collection_id": "6wkjq-bnv12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-083737347", "type": "book_section", "title": "Searches for Primeval Galaxies", "book_title": "The Stellar Populations of Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" } ], "contributor": [ { "family_name": "Barbuy", "given_name": "B.", "clpid": "Barbuy-B" }, { "family_name": "Renzini", "given_name": "A.", "clpid": "Renzini-A" } ], "abstract": "We review primeval galaxy searches based on the Ly\u03b1 line emission. Simple arguments are given which suggest that primeval galaxies (interpreted here as ellipticals and bulges undergoing their first major bursts of star formation) should be detectable with present-day technology. Many active objects are now known at large redshifts, which may be plausibly interpreted as young galaxies, but there is so far no convincing detection of a field population of forming normal galaxies. This suggests that either primeval galaxies were obscured, and/or are to be found at higher redshifts, z_(gf) > 5.", "doi": "10.1007/978-94-011-2434-8_44", "isbn": "978-0-7923-1699-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "337-347" }, { "id": "authors:57yyx-eq956", "collection": "authors", "collection_id": "57yyx-eq956", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-075849971", "type": "book_section", "title": "NGC 205 and the Nature of Compact Nuclei in Dwarf Galaxies", "book_title": "Morphological and Physical Classification of Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bendinelli", "given_name": "O.", "clpid": "Bendinelli-O" }, { "family_name": "Parmeggiani", "given_name": "G.", "clpid": "Parmeggiani-G" }, { "family_name": "Zavatti", "given_name": "F.", "clpid": "Zavatti-F" } ], "contributor": [ { "family_name": "Longo", "given_name": "G.", "clpid": "Longo-G" }, { "family_name": "Capaccioli", "given_name": "M.", "clpid": "Capaccioli-M" }, { "family_name": "Busarello", "given_name": "G.", "clpid": "Busarello-G" } ], "abstract": "Compact nuclei are both a ubiquitous and a striking feature in low-surface brightness dwarf galaxies, sometimes containing a large fraction of the total light. Yet, their nature and origin are still a mystery. Spectroscopic and photometric observations suggest that the nuclei contain an intermediate-age stellar population. Their structural and dynamical parameters are still very poorly known, due to their compactness: essentially all an unresolved. The Local Group dwarf galaxy NGC 205 contains the nearest, albeit an unimpressive and relatively faint example. Even in this nearby case, the nucleus is almost unresolved, making the estimates of its structural and dynamical parameters difficult. The situation can be helped somewhat by seeing deconvolution.", "doi": "10.1007/978-94-011-2522-2_59", "isbn": "978-94-010-5113-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1992", "pages": "439-440" }, { "id": "authors:zfhae-xvb72", "collection": "authors", "collection_id": "zfhae-xvb72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-081805716", "type": "book_section", "title": "A search for gravitational lenses using sky survey plate scans", "book_title": "Gravitational Lenses", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Pirenne", "given_name": "B.", "clpid": "Pirenne-B" }, { "family_name": "Weir", "given_name": "W. N.", "clpid": "Weir-W-N" }, { "family_name": "Beaulieu", "given_name": "S.", "clpid": "Beaulieu-S" } ], "contributor": [ { "family_name": "Kayser", "given_name": "Rainer", "clpid": "Kayser-R" }, { "family_name": "Schramm", "given_name": "Thomas", "clpid": "Schramm-T" }, { "family_name": "Nieser", "given_name": "Lars", "clpid": "Nieser-L" } ], "abstract": "We used scans of sky survey plates available at STScl to look for the presence of multiple-image QSOs which could be due to gravitational lensing. We extracted about 1500 fields, each having 5 arcmin in size, around QSOs brighter than m_v = 18. No lenses have been found so far. We found several cases of galaxies close in projection (within a few arcsec) from QSOs.", "doi": "10.1007/3-540-55797-0_118", "isbn": "978-3-540-55797-5", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1992", "pages": "323-327" }, { "id": "authors:gmsgq-9fw66", "collection": "authors", "collection_id": "gmsgq-9fw66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-150502036", "type": "article", "title": "High-resolution imaging of the double QSO 2345 + 007", "author": [ { "family_name": "Weir", "given_name": "Nicholas", "clpid": "Weir-N" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present raw and maximum entropy restored images of the quasar pair (gravitational lens candidate) 2345 + 007 A and B. Restorations are performed using an implementation of the Gull-Skilling MEMSYS-3 package of maximum entropy method subroutines designed to achieve subpixel resolution in certain data regimes. Extensive simulations of our data imply that we are able to detect structure in the restored images down to the 0.4\" level. Using this method, we qualitatively confirm that component B is resolved and, at least at visual and red wavelengths, elongated in a direction almost perpendicular to the line joining A and B. We also find evidence for a color difference and variation in the magnitude difference between the two components. We believe these data, in conjunction with recent spectroscopic results, more likely favor the multiple quasar rather than gravitational lens interpretation of the objects.", "doi": "10.1086/115666", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1991-01", "series_number": "1", "volume": "101", "issue": "1", "pages": "66-70" }, { "id": "authors:ds1hf-7d351", "collection": "authors", "collection_id": "ds1hf-7d351", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-155323960", "type": "book_section", "title": "Color and population gradients in globular clusters", "book_title": "The Formation and Evolution of Star Clusters", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" }, { "family_name": "Mallen-Ornelas", "given_name": "G.", "clpid": "Mallen-Ornelas-G" } ], "contributor": [ { "family_name": "Janes", "given_name": "Kenneth", "clpid": "Janes-K" } ], "abstract": "We present preliminary results from a survey for color and population gradients in globular cluster cores. Color gradients, in the sense of becoming bluer inwards, are always found in post-core-collapse clusters. They seem to be caused by the demise of red giants, and possibly an increased number of blue stragglers. This may be a consequence of stellar interactions during and after the core collapse. No gradients are seen in clusters with King-model morphology.", "isbn": "0-937707-32-5", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1991", "pages": "262-264" }, { "id": "authors:ffvg7-dtp27", "collection": "authors", "collection_id": "ffvg7-dtp27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190610-123510979", "type": "book_section", "title": "A Subpixel Deconvolution Method for Astronomical Images", "book_title": "Maximum Entropy and Bayesian Methods", "author": [ { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Grandy", "given_name": "W. T., Jr.", "clpid": "Grandy-W-T-Jr" }, { "family_name": "Schick", "given_name": "L. H.", "clpid": "Schick-L-H" } ], "abstract": "We present results from the use of an image deconvolution method for achieving subpixel resolution in certain data regimes. Restorations are performed using a shell which utilizes the Gull-Skilling MEMSYS-3 package. We have performed extensive tests using the method and have determined general limits of its applicability and resolving power. We present results from applying the technique to simulated and real images of sparse and closely crowded astronomical fields. Specific projects involved in this study include a search for close companions to quasars and the structural investigation of star cluster cores.", "doi": "10.1007/978-94-011-3460-6_26", "isbn": "978-94-010-5531-4", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1991", "pages": "275-283" }, { "id": "authors:xafvf-rfy08", "collection": "authors", "collection_id": "xafvf-rfy08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190827-084837062", "type": "article", "title": "Extended Ly\u03b1 emission associated with 3C 294", "author": [ { "family_name": "McCarthy", "given_name": "Patrick J.", "clpid": "McCarthy-P-J" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "van Breugel", "given_name": "Wil", "clpid": "van-Breugel-W" }, { "family_name": "Liebert", "given_name": "James", "clpid": "Liebert-J" }, { "family_name": "Dickinson", "given_name": "Mark", "clpid": "Dickinson-M" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Eisenhardt", "given_name": "Peter", "clpid": "Eisenhardt-P-R-M" } ], "abstract": "We report the discovery of a large cloud of ionized gas associated with the radio galaxy 3C 294 at a redshift of 1.786. The radio source is a powerful double with a weak core. We detect Ly\u03b1 emission with a total monochromatic luminosity of L_(Ly\u03b1) = 7.6 x 10^(44) ergs s^(-1) extended over ~100 x 170 kpc. The emission-line cloud is highly elongated and is well aligned with the inner radio source axis. Long-slit spectra, taken along the major axis, show spatially extended emission lines of N v \u03bb1240, C IV \u03bb1550, He II \u03bb1640, and C III \u03bb1909. The extended Ly\u03b1 emission shows a large, smooth velocity gradient (1500 km s^(-1) and large intrinsic line widths (700-2600 km s^(-1)). The high-ionization lines, particularly C IV, show large velocity changes that are systematically different from those of Ly\u03b1. \n\n3C 294 appears to be another, even more spectacular member of a class of powerful radio galaxies at high redshift typified by 3C 326.1. We discuss our observations from the point of view of star formation and the interaction of nuclear activity with ambient material. We consider two scenarios for the ionization of the Ly\u03b1 cloud: ionization by a population of extremely massive stars and ionization by a non thermal continuum from the radio nucleus. Stellar photoionization appears to be insufficient in both the total number of ionizing photons and its ability to produce highly ionized species. We propose that the 150 kpc cloud of gas is photoionized by a central nonstellar source. We detect a very red compact object at 2.2 \u03bcm nearly coincident with the radio core. It is unclear whether the light from this object is primarily stellar or nonstellar.", "doi": "10.1086/169503", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1990-12-20", "volume": "365", "pages": "487-501" }, { "id": "authors:j9mqw-k8665", "collection": "authors", "collection_id": "j9mqw-k8665", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190827-090330444", "type": "article", "title": "High-resolution imaging of globular cluster cores", "author": [ { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Piotto", "given_name": "G.", "clpid": "Piotto-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Practically all of ground-based astronomy can benefit from improved angular resolution. Whereas specialized techniques exist (e.g., speckle) or are being developed (e.g., optical interferometry), they are often limited in field size and/or by the available signal level. A significant fraction of optical work relies on CCD imagery of fields of several arcmin, and will probably continue to do so for quite some time. Recent advances in telescope technology (the ESO NTT being the foremost example), careful selection of telescope sites, etc., can do a lot to improve the seeing. But once the hardware is firmly in place, and the data are taken, the only way to improve the resolution is by some image deconvolution technique. Possibly the best among them is the Maximum Entropy Method.", "issn": "0722-6691", "publisher": "European Southern Observatory", "publication": "Messenger", "publication_date": "1990-12", "volume": "62", "pages": "48-50" }, { "id": "authors:d3bke-j5224", "collection": "authors", "collection_id": "d3bke-j5224", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190827-084114558", "type": "article", "title": "Miscellaneous spectroscopic observations of quasars and quasar candidates", "author": [ { "family_name": "V\u00e9ron", "given_name": "P.", "clpid": "V\u00e9ron-P" }, { "family_name": "V\u00e9ron-Cetty", "given_name": "M.-P.", "clpid": "V\u00e9ron-Cetty-M-P" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Magain", "given_name": "P.", "clpid": "Magain-P" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" } ], "abstract": "We report about new spectroscopic observations of 11 quasar candidates, 19 quasars with uncertain redshift and three BL Lac candidates, and 11 objects located within few arcseconds from a quasar.", "issn": "0365-0138", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics Supplement Series", "publication_date": "1990-12", "series_number": "3", "volume": "86", "issue": "3", "pages": "543-553" }, { "id": "authors:szmrq-94628", "collection": "authors", "collection_id": "szmrq-94628", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190827-083603535", "type": "article", "title": "Spectroscopy of radio sources from the Parkes 2700 MHz survey", "author": [ { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "abstract": "We present the results of long-slit CCD spectroscopy on 37 objects from the Parkes 2700 MHz survey, with data for an additional two companion objects. Eight of the objects are quasars, six more are AGNs, and five more are radio galaxies. Seventeen of the objects observed are stars and, thus, probable misidentifications. Three objects show featureless spectra and are identified as possible BL Lac objects. Spectra are presented for a total of 20 objects.", "doi": "10.1086/132758", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1990-11", "series_number": "657", "volume": "102", "issue": "657", "pages": "1235-1240" }, { "id": "authors:bwvxj-0zg30", "collection": "authors", "collection_id": "bwvxj-0zg30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190822-083224114", "type": "article", "title": "A rich, nearby galaxy cluster in Sagittarius", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" } ], "abstract": "We report on the existence of a rich, heavily obscured galaxy cluster (or a set of clusters) in Sagittarius, centered near l_(II) \u2243 359\u00b0, b_(II) \u2243 8\u00b0. About 30 objects, originally identified by Terzan and his collaborators, were imaged and followed up spectroscopically. We present here redshifts for 21 galaxies found among them. There is a pronounced concentration at cz \u2243 8600 km/s (containing 14 out of the 21 galaxies), and another possible concentration near cz \u2243 11 340 km/s (five out of 21). This putative Sagittarius cluster is probably part of a larger system, involving the Ophiuchus cluster at l_(II) \u2243 1\u00b0, b_(II) \u2243 9\u00b0, cz \u2243 8400 km/s, previously identified by Johnston et al. and Wakamatsu and Malkan. The heavy extinction on this line of sight (we estimate A_v ~ 5^m from the observed Balmer decrements) suggests that there is a much larger, as yet undetected number of galaxies in this direction. We propose that the Sagittarius-Ophiuchus concentration may be a massive cluster, or even a supercluster, comparable in richness to the Coma-A 1367 system, and at a comparable distance. The existence of this concentration serves as a reminder that some possibly dynamically important constituents of the local large-scale structure may be absent from the galaxy .catalogs available now, and the dynamical analyses based on them.", "doi": "10.1086/115544", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1990-09", "series_number": "3", "volume": "100", "issue": "3", "pages": "599-603" }, { "id": "authors:vt5pa-72561", "collection": "authors", "collection_id": "vt5pa-72561", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190827-082632491", "type": "article", "title": "Spectroscopy of quasar candidates from the University of Michigan low-dispersion survey", "author": [ { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present the results of long-slit CCD spectroscopy on 39 objects and four close companions from the University of Michigan objective-prism survey lists. Twelve of them are quasars with redshifts ranging from 0.326 to 2.852, and an additional 12 objects (including companions) are Seyferts or active galaxies ranging in redshift from 0.0365 to 0.227. UM 443 may be a broad absorption-line quasar. UM 565 is a star with a puzzling spectrum. Spectra are presented for a total of 25 objects.", "doi": "10.1086/132723", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1990-09", "series_number": "655", "volume": "102", "issue": "655", "pages": "959-965" }, { "id": "authors:8e4xs-m1q12", "collection": "authors", "collection_id": "8e4xs-m1q12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190822-082453577", "type": "article", "title": "An optical study of the possible proto-starburst galaxy VII ZW 31", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" } ], "abstract": "We present an optical imaging and spectroscopic study of an ultraluminous, gas-rich Infrared Astronomical Satellite (IRAS) galaxy, VII Zw 31. Sage and Solomon proposed earlier that this object may be interpreted as a protogalactic disk at low redshift, on account of its large mass fraction of molecular gas. Our data suggest that the object is a merger-induced starburst, and in that respect similar to many other ultraluminous IRAS galaxies. Asymmetries and distortions are seen in the visible light, and a prominent dust lane is detected near the nucleus. The spectra show strong, low-ionization line emission, consistent with photoionization by young stars, and substantial internal extinction. Absorption spectra suggest a presence of both young and old stellar populations. We interpret the object as an old galaxy, rejuvenated by a recent starburst. Since the large molecular gas content (~ 50% of the total mass) is the main distinguishing characteristic of this object, the starburst must be just in its initial stages. VII Zw 31 may thus be a low-redshift analog of at least some protogalaxies at large redshifts.", "doi": "10.1086/115424", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1990-05", "series_number": "5", "volume": "99", "issue": "5", "pages": "1414-1420" }, { "id": "authors:0g7jk-y0e79", "collection": "authors", "collection_id": "0g7jk-y0e79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190819-160929683", "type": "article", "title": "The cosmic submillimeter background as a possible signature of the initial burst of galaxy formation", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "Nicholas", "clpid": "Weir-N" } ], "abstract": "We propose a heuristic model for the origin of the cosmic submillimeter background (SMB), reported by the Nagoya-Berkeley collaboration. The SMB is interpreted as a direct signature of an epoch of (initial) galaxy formation at z ~ 10-15. The sources of the SMB are proposed to be dust-shrouded starburst protogalaxies, similar to the luminous IRAS galaxies at low redshifts. We interpret them as the progenitors of old stellar populations at low redshifts, ellipticals, bulges, and stellar components of the halos. The derived redshift of the galaxy formation is directly dependent on the dust temperatures assumed for these objects. The corresponding look-back times are -11.5h_(75)^(-1) Gyr for \u03a9_0 = 0.1, or ~ 8.5h_(75)^(-1) Gyr for \u03a9_0 = 1. The star formation history in an element of comoving volume was assumed to be a Gaussian in the rest frame, but this form is not critical for the models. Model spectra of the SMB were computed for the values of cosmological density parameter \u03a9_0 = 0.1 and 1, and the dust emissivity index n = 1 and 2. The largest allowed time scales for the star formation in these models (expressed as the FWHM of the luminosity history) are in the range FWHM ~ 0.2-0.6 Gyr for the low-density models (\u03a9_0 = 0.1); for the high-density models (\u03a9_0 = 1), the allowed widths are about a factor\nof 2 lower. These widths are comparable to, or slightly larger than, the free-fall times for normal galaxies. In order not to overproduce the baryonic mass density, it is necessary that the initial mass function (IMF) in these starbursts is biased toward high-mass stars; however, a substantial range in the IMF parameters is allowed. This postulated population of protogalaxies may be an important contributor to the diffuse soft X-ray background. Leaked (unobscured) starlight from these objects may give rise to a near-infrared background, at about the level detected by Matsumoto, Akiba, and Murakami. The predicted surface density of protogalaxies would be in the range ~10-100 arcsec^(-2), which is consistent with all relevant anisotropy measurements\navailable at this time. The model also predicts that a considerable fraction of the mass density in the bulge and halo of our Galaxy would be provided by old white dwarfs, which may be detectable in deep surveys (a similar prediction was already made by Silk). Spectroscopic signatures of this population may be detectable with future space missions, e.g., with SIRTF or LDR, and possibly also from the ground in the near-infrared and millimeter/submillimeter regions.", "doi": "10.1086/168470", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1990-03-10", "volume": "351", "pages": "343-355" }, { "id": "authors:94x12-ncb41", "collection": "authors", "collection_id": "94x12-ncb41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190819-145431938", "type": "article", "title": "Seeing deconvolution of globular clusters in M31", "author": [ { "family_name": "Bendinelli", "given_name": "O.", "clpid": "Bendinelli-O" }, { "family_name": "Zavatti", "given_name": "F.", "clpid": "Zavatti-F" }, { "family_name": "Parmeggiani", "given_name": "G.", "clpid": "Parmeggiani-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Seeing deconvolution of surface-brightness profiles using the regularized multi-Gaussian method is potentially a powerful method for extraction of morphological information from digital images. Here we illustrate this method by applying it to CCD images of six globular clusters in M31. We demonstrate that it is possible to make some judgments about the dynamical structure of M31 globulars, using good-seeing, deconvolved CCD images obtained from the ground; for example, whether they have post-core-collapse morphology or not. The effective resolution limit of the method is about 0.1-0.3 arcsec, for the CCD images obtained in FWHM \u2243 1 arcsec seeing, and sampling of 0.3 arcsec/pixel. We also demonstrate the robustness of the method, i.e., its insensivity to the exact choices of the functional representation of the point-spread function, details of the deconvolution technique, etc. The situation is equivalent in terms of angular resolution and sampling to observing globular clusters in the Virgo Cluster (e.g., around M87) with the Hubble Space Telescope, and the methods demonstrated here may be applied to HST data in the future. Dynamical structure of globular clusters, e.g., propensity for the post-core-collapse morphology as a function of position in the host galaxy, reflects the global dynamical evolution of a globular cluster system, as was already demonstrated for our galaxy. Similar studies of large samples of globulars in M31 and other Local Group galaxies from the ground, and out to Virgo with the HST, can provide valuable insights about the mass distribution in galaxies, and the formation and evolution of their globular cluster systems. This pilot study is a step in this direction.", "doi": "10.1086/115373", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1990-03", "series_number": "3", "volume": "99", "issue": "3", "pages": "774-783" }, { "id": "authors:8ag2r-9s750", "collection": "authors", "collection_id": "8ag2r-9s750", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190820-151419801", "type": "article", "title": "PHL 1222: an Interacting Quasar Pair?", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Shaver", "given_name": "P.", "clpid": "Shaver-P" } ], "abstract": "The \"By-Product\" of a Survey: The origin of quasars and Active Galactic Nuclei (AGN) is one of the outstanding problems of modern extragalactic astronomy. Mergers and gravitational interactions between galaxies are probably more frequent at large redshifts, and may lead to the appearance of quasars and other AGN. As a matter of fact, there is now an increasing body of evidence - from observations and computer simulations - that gravitational interactions between galaxies may be somehow responsible for the onset and fueling of the nuclear activity (e.g., Hernquist 1989, and references therein).", "issn": "0722-6691", "publisher": "European Southern Observatory", "publication": "Messenger", "publication_date": "1990-03", "volume": "59", "pages": "47-49" }, { "id": "authors:86pgj-0dc76", "collection": "authors", "collection_id": "86pgj-0dc76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-142949859", "type": "article", "title": "The deep luminosity function of the globular cluster M30", "author": [ { "family_name": "Piotto", "given_name": "Giampaolo", "clpid": "Piotto-G" }, { "family_name": "King", "given_name": "Ivan R.", "clpid": "King-I-R" }, { "family_name": "Capaccioli", "given_name": "Massimo", "clpid": "Capaccioli-M" }, { "family_name": "Ortolani", "given_name": "Sergio", "clpid": "Ortolani-S" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "This paper is aimed at determining the mass function in the low-metallicity, post-core collapse globular cluster NGC 7099 = M30, and analyzing its radial trend. New deep CCD photometry is presented in two fields centered at r = 2'.9 and 4'.4 from the center, respectively. We confirm that a good representation of the color-magnitude diagrams is obtained by oxygen-enhanced isochrones (as used by Capaccioli, Ortolani, and Piotto). The best fit yields (m - M)_v = 14.65, E(B-V) = 0.05, and an age of 16 Gyr. \n\nLuminosity functions down to V\u224325 (M_v\u224310.3) are constructed and carefully corrected for contamination by field objects and for incompleteness (see Appendix). Comparison with standard theoretical luminosity functions shows that the mass function, modeled with a power law, has an index x\u22431, at variance with the x\u22430 found by Richer, Fahlman, and VandenBerg for a field centered at r = 3'.4. An even steeper slope is given by the photometry in an outer field of M30 studied with the 4 m CTIO CCD camera (Piotto et al.).\nAll together, our data agree with the trend of x found by Pryor, Smith, and McClure for a multimass King-Michie model (with or without velocity anisotropy), yielding a global slope x_0 ~0.7. Mass segregation is implied, though marginally, given the errors and the small variation of x expected on theoretical grounds in the radial range explored by our observations. M30 is found to deviate strongly from the mass-function slope versus metallicity relation (McClure et al.); its mass function is as fiat as that of intermediate-metallicity clusters.", "doi": "10.1086/168418", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1990-02-20", "volume": "350", "pages": "662-671" }, { "id": "authors:s3007-dgq09", "collection": "authors", "collection_id": "s3007-dgq09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-125503655", "type": "article", "title": "Classification of Very Red Stars Using Narrowband Colors", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Greenstein", "given_name": "J. L.", "clpid": "Greenstein-J-L" } ], "abstract": "A classification technique for faint, very red stars is described, based on two composite colors, derived from flux measurements in six narrowbands in the visual and red parts of the spectrum. One of the composite colors, ST, is an M spectral type indicator, common to both dwarfs and giants. It can be used to predict the spectral types to within half a class. The other color, DG, is a dwarf-giant discriminator for spectral types later than about M4, and whose power increases for the later types, where most other methods fail. It reflects the differences in blanketing between the late-M type dwarfs and the giants. The method can be generalized to other, similar colors, depending on the data and task at hand. It should be useful in surveys for extreme low-mass dwarfs, or alternatively, for luminous red giants, or other kinds of objects. We illustrate the application of the method on an example of a very red star identified earlier by Blair and Long, and show it to be a distant red giant.", "doi": "10.1086/115364", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1990-02", "series_number": "2", "volume": "99", "issue": "2", "pages": "684-690" }, { "id": "authors:7t3qh-pnn06", "collection": "authors", "collection_id": "7t3qh-pnn06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190819-130419500", "type": "article", "title": "Spectroscopy of radio sources from the third Bologna survey", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Vigotti", "given_name": "M.", "clpid": "Vigotti-M" }, { "family_name": "Grueff", "given_name": "G.", "clpid": "Grueff-G" } ], "abstract": "We present long-slit CCD spectroscopy of eleven optical candidates for selected radio sources from the third Bologna survey (B3). One object (0141+398) is a probable misidentification, a foreground star. The remaining ones are a mixture of quasars and active galaxies, ranging in redshift from 0.11 to 0.85. B3 0219+443 is a steep-spectrum quasar. B3 1141+374 is identified with an interacting galaxy pair, with the southern component harboring an active nucleus.", "doi": "10.1086/132615", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1990-02", "series_number": "648", "volume": "102", "issue": "648", "pages": "113-116" }, { "id": "authors:9mryx-ysy92", "collection": "authors", "collection_id": "9mryx-ysy92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-135718671", "type": "article", "title": "A preliminary optical study of the intergalactic H I cloud in Virgo", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "A possible optical counterpart of the intergalactic H I cloud in the Virgo Cluster, discovered by Giovanelli and Haynes, is reported. It is a blue, 17 mag, irregular galaxy, and it is located near the peak of the H I emission. No other optical objects which can be obviously associated with the. cloud are found m the area from which the H I emission was detected, and no extended, low surface brightness counterpart is seen in these data. If the irregular galaxy is really associated with the H I cloud, the overall properties of the system would be similar to those of a number of other known gas-rich dwarf galaxies. However, the system has an unusually large hydrogen to light ratio, and a large spatial extent, and it could be dynamically young. Optical spectroscopy is needed in order to establish whether the proposed optical counterpart is indeed correct, and if so, to determine the stage of its chemical evolution.", "doi": "10.1086/115308", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1990-01", "series_number": "1", "volume": "99", "issue": "1", "pages": "31-36" }, { "id": "authors:y0ax8-65w07", "collection": "authors", "collection_id": "y0ax8-65w07", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-103242934", "type": "article", "title": "New radio maps and optical identifications of distant 3 CR galaxies", "author": [ { "family_name": "Strom", "given_name": "R. G.", "clpid": "Strom-R-G" }, { "family_name": "Riley", "given_name": "J. M.", "clpid": "Riley-J-M" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "van Breugel", "given_name": "W. J. M.", "clpid": "van-Breugel-W-J-M" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Liebert", "given_name": "J.", "clpid": "Liebert-J" }, { "family_name": "McCarthy", "given_name": "P. J.", "clpid": "McCarthy-P-J" } ], "abstract": "We have made radio observations with both high angular resolution and sensitivity at 6 and 11 cm of thirteen 3 CR radio sources. In eleven of these we have detected compact or fairly compact central components enabling us to pinpoint the location of the optical object and to confirm some previously suggested identifications. We have obtained optical images of 3C114, 3C277, and 3C437, which were previously unidentified, and have measured redshifts for 3C114, 3C272, 3C277, and 3C437. Optical information on the remaining sources has been or is being published elsewhere. All of the sources are associated with galaxies, with redshifts ranging from 0.165 to nearly 1.8. The newly identified sources have redshifts greater than 0.6. All the sources display some form of double structure, about half of them being symmetrical, classical doubles. It is pointed out that the higher redshift (z > 0.8) sources in this group have relatively weak bridges, although the high redshift sources with extended Ly\u03b1 display strong bridge emission. In one case (3C114) we have evidence that the flux density of the central radio core varies.", "issn": "0004-6361", "publisher": "EDP Sciences", "publication": "Astronomy and Astrophysics", "publication_date": "1990-01", "series_number": "1", "volume": "227", "issue": "1", "pages": "19-29" }, { "id": "authors:0cdyj-5hp16", "collection": "authors", "collection_id": "0cdyj-5hp16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-104502407", "type": "book_section", "title": "Optical Properties of Early-Type Galaxies", "book_title": "Windows on Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "contributor": [ { "family_name": "Fabbiano", "given_name": "Giuseppina", "clpid": "Fabbiano-G" }, { "family_name": "Gallagher", "given_name": "John S.", "clpid": "Gallagher-J-S" }, { "family_name": "Renzini", "given_name": "Alvio", "clpid": "Renzini-A" } ], "abstract": "We review the systematics of optical properties of elliptical and dwarf spheroidal galaxies. The scaling laws and correlations among the global properties of these systems can be used to deduce some information about their formation. Both dissipation and mergers appear to be important in the formation of elliptical galaxies. Small, but systematic differences between cluster and field ellipticals are detected, and also between normal ellipticals and brightest cluster members. The scaling laws for dwarf galaxies are very different from those of normal ellipticals, and point to a formation dominated by a single process.", "doi": "10.1007/978-94-009-0543-6_3", "isbn": "978-94-010-6731-7", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1990", "pages": "9-21" }, { "id": "authors:eg5w8-ex187", "collection": "authors", "collection_id": "eg5w8-ex187", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190605-123824473", "type": "book_section", "title": "A search for gravitational lenses and quasar pairs and the discovery of a new multiple QSO system", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Shaver", "given_name": "P.", "clpid": "Shaver-P" } ], "contributor": [ { "family_name": "Mellier", "given_name": "Yannick", "clpid": "Mellier-Y" }, { "family_name": "Fort", "given_name": "Bernard", "clpid": "Fort-B" }, { "family_name": "Soucail", "given_name": "Genevi\u00e8ve", "clpid": "Soucail-G" } ], "abstract": "We are conducting an optical imaging survey for lensed quasars, with a spectroscopic follow-up for the promising cases. A sample of known QSOs has been selected on the basis of apparently large absolute luminosities and high redshifts. So far, this survey has yielded one close pair of possibly interacting quasars, PKS 1145-071, one very probable gravitational lens, UM 425, several other promising lens candidates, and several cases of foreground or associated galaxies within a few arcsec from the quasars. Recently, we have discovered another interesting system, PHL 1222, probably a close physical pair of QSOs with similar redshifts, z\u22431.91, and separated by 3.3 arcsec. At least three other foreground faint objects (R~24 mag) are observed inside a circle of 7 arcsec around the quasar. In PHL 1222 we may be witnessing a triggering event responsible for the nonthermal activity in both objects, i.e., the birth of a quasar pair at a redshift where the comoving density of quasars was close to its maximum.", "doi": "10.1007/BFb0009243", "publisher": "Springer", "publication_date": "1990" }, { "id": "authors:eryvq-8n076", "collection": "authors", "collection_id": "eryvq-8n076", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190605-111346363", "type": "book_section", "title": "Application of image processing techniques in a search for gravitational lenses and quasar pairs", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "N.", "clpid": "Weir-N" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" } ], "contributor": [ { "family_name": "Mellier", "given_name": "Yannick", "clpid": "Mellier-Y" }, { "family_name": "Fort", "given_name": "Bernard", "clpid": "Fort-B" }, { "family_name": "Soucail", "given_name": "Genevi\u00e8ve", "clpid": "Soucail-G" } ], "abstract": "We discuss application of two image processing techniques to high-resolution imaging of quasars, in a search for multiple images or companion objects: PSF subtraction, and MEM seeing deconvolution, on the examples of QSO 2300-352, and QQ 2345+007.", "doi": "10.1007/BFb0009242", "publisher": "Springer", "publication_date": "1990" }, { "id": "authors:mf37w-ddz43", "collection": "authors", "collection_id": "mf37w-ddz43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-144638150", "type": "book_section", "title": "The cosmic submillimeter background - A signature of the initial burst of galaxy formation?", "book_title": "Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "W. N.", "clpid": "Weir-W-N" } ], "contributor": [ { "family_name": "Kron", "given_name": "Richard G.", "clpid": "Kron-R-G" } ], "abstract": "We propose a heuristic model for the origin of the cosmic submillimeter background (SMB), reported by the Nagoya-Berkeley\ncollaboration. The SMB is interpreted as a direct signature of an epoch of (initial) galaxy formation at z_(gf) ~ 10 - 15. The sources of the SMB are proposed to be dust-shrouded starburst protogalaxies, similar to the luminous IRAS galaxies at low redshifts. We interpret them as the progenitors of old stellar populations at low redshifts, ellipticals, bulges, and stellar components of the halos. The largest allowed time scales for the star formation in these models are in the range FWHM ~ 0.2 - 0.6 Gyr, for \u03a9 _0 = 0.1; for \u03a9 _0 = 1, the allowed widths are about a factor of two lower. In order not to overproduce the baryonic mass density, it is necessary that the IMF in these starbursts is biased towards high-mass stars; however, a substantial range in the IMF parameters is allowed. This postulated population of protogalaxies may be an important contributor to the diffuse soft x-ray background. The predicted surface density of protogalaxies would be in the range ~10-100 arcsec^(-2), which is consistent with all relevant anisotropy measurements available at this time.", "isbn": "0-937707-28-7", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1990", "pages": "228-230" }, { "id": "authors:tmtn5-f4q21", "collection": "authors", "collection_id": "tmtn5-f4q21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-141451441", "type": "book_section", "title": "The mass-metallicity - Luminosity density relation for elliptical galaxies", "book_title": "Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium", "author": [ { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Kron", "given_name": "Richard G.", "clpid": "Kron-R-G" } ], "abstract": "Global properties of elliptical galaxies form a two-dimensional family. One aspect of this 'fundamental plane' of ellipticals is a bivariate relation between the mass or luminosity, surface brightness or luminosity density, and a metallicity indicator (e.g., the M g line strength index, or a color). There is a second parameter in the mass-metallicity relation, identified here as the luminosity density. The existence of this relation can be understood in the context of dissipative galaxy formation, reflecting both the effect of galatic winds, and an analog of the Schmidt law for star formation for protoelliptical galaxies. Small, but systematic differences are found in the solutions for the field and for the cluster ellipticals, suggesting a systematic difference in their formative histories.", "isbn": "0-937707-28-7", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1990", "pages": "106-108" }, { "id": "authors:tpwat-efb18", "collection": "authors", "collection_id": "tpwat-efb18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-145724015", "type": "book_section", "title": "Infrared Images of Distant 3C Radio Galaxies", "book_title": "Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium", "author": [ { "family_name": "Eisenhardt", "given_name": "P.", "clpid": "Eisenhardt-P-R-M" }, { "family_name": "Chokshi", "given_name": "A.", "clpid": "Chokshi-A" }, { "family_name": "Dickinson", "given_name": "M.", "clpid": "Dickinson-M" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "McCarthy", "given_name": "P.", "clpid": "McCarthy-P-J" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" } ], "contributor": [ { "family_name": "Kron", "given_name": "Richard G.", "clpid": "Kron-R-G" } ], "abstract": "We have obtained J and K images of radio galaxies with redshifts of up to 3.4, including 3C 41, 54, 124, 194, 256, 257, 265, 294, 326.1, 356, 437, 441, & 454.1, and B2 0902+34. The observations were made using the Infrared Imager (IRIM) on the KPNO 4m telescope. Stellar image sizes (FWHM) are from 0.85 to 1.2 arcseconds, roughly 10 kpc for H_0=50. The limiting sensitivity (3\u03c3 in 1 square arcsecond) of the deepest images is approximately K=21 (2.7\u03bcJy).", "isbn": "0-937707-28-7", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1990", "pages": "371-372" }, { "id": "authors:3d439-48n21", "collection": "authors", "collection_id": "3d439-48n21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-145249267", "type": "book_section", "title": "Evolutionary model uncertainties in the K-band Hubble diagram", "book_title": "Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium", "author": [ { "family_name": "Weir", "given_name": "W. N.", "clpid": "Weir-W-N" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Bruzual A.", "given_name": "Gustavo", "clpid": "Bruzual-A-G" } ], "contributor": [ { "family_name": "Kron", "given_name": "Richard G.", "clpid": "Kron-R-G" } ], "abstract": "We explore the effects of variations in evolutionary model parameters on the K-band Hubble diagram, and compare the prediction of the older and the newer population synthesis models. The predictions of the old and the new Bruzual models differ significantly; this is tractable to a problem in combining the input stellar libraries. The new models are sensitive to a number of evolutionary parameters, and there is some coupling with the cosmological parameters. Therefore, the K-band Hubble diagram still cannot be used as a reliable cosmological tool with the state-of-the-art evolutionary population synthesis models.", "isbn": "0-937707-28-7", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1990", "pages": "356-358" }, { "id": "authors:ahmkb-hsh23", "collection": "authors", "collection_id": "ahmkb-hsh23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-102943527", "type": "book_section", "title": "Optical and X-Ray Properties of Elliptical Galaxies", "book_title": "Windows on Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" } ], "contributor": [ { "family_name": "Fabbiano", "given_name": "Giuseppina", "clpid": "Fabbiano-G" }, { "family_name": "Gallagher", "given_name": "John S.", "clpid": "Gallagher-J-S" }, { "family_name": "Renzini", "given_name": "Alvio", "clpid": "Renzini-A" } ], "abstract": "We compare and correlate the x-ray properties of early-type galaxies with their optical properties, using the data from extensive, homogeneous optical photometry surveys. Bivariate scaling solutions are found for the x-ray luminosities in terms of the optical surface brightness and velocity dispersion. A new quantity, the anisotropy index (AI) is defined. X-ray luminosities are found to correlate well with the AI. This is tentatively interpreted as a suggestion that mergers and tidal interactions played an important role in generation of the x-ray coronae in elliptical galaxies.", "doi": "10.1007/978-94-009-0543-6_40", "isbn": "978-94-010-6731-7", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1990", "pages": "307-310" }, { "id": "authors:6hmdt-2mv03", "collection": "authors", "collection_id": "6hmdt-2mv03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-110754715", "type": "article", "title": "Spectroscopy of quasar candidates from the case low-dispersion survey", "author": [ { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Weir", "given_name": "W. N.", "clpid": "Weir-W-N" } ], "abstract": "Case Low-Dispersion Northern Sky Survey. Thirteen of them are quasars, ranging in redshift from 0.0786 to 2.67, with a median redshift of 2. CSO 203 is a broad absorption-line quasar, and CSO 38 may have substantial associated absorption in the cores of emission lines. Several other objects show some intervening absorption, and all of them are bright enough to make the follow-up studies practical. CSO 251 is a bright (~15m), previously uncataloged quasar. The remaining objects are Galactic stars, five subdwarfs, and one hot white dwarf (CSO 160).", "doi": "10.1086/132577", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1989-12", "series_number": "646", "volume": "101", "issue": "646", "pages": "1065-1071" }, { "id": "authors:2g9kp-tsa16", "collection": "authors", "collection_id": "2g9kp-tsa16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161021-155705985", "type": "article", "title": "Surface Photometry and the Structure of Elliptical Galaxies", "author": [ { "family_name": "Kormendy", "given_name": "John", "clpid": "Kormendy-J" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "This paper reviews surface photometry of bulges and elliptical galaxies. Work prior to 1982 is discussed by Kormendy (1982a; hereafter K82). Since then, the subject has gone through a revolution. CCD detectors have come into common use, providing photometry accurate enough to measure new classes of subtle properties of ellipticals. Together with improvements in seeing, CCDs have allowed the resolution and study of galaxy cores\nand nuclei (Section 2). Newly discovered structural details, such as dust, shells, and dynamical subsystems, show the importance of accretion events in galaxy evolution (Sections 3-6). Better measurements of parameter scaling laws have led to improved constraints on galaxy formation (Section 8). Finally, CCDs provide accurate measurements of departures from elliptical isophotes (Section 9) and color gradients (Section 10). These observations are currently producing a quantum jump in our understanding\nof elliptical galaxies. \nSome of the present subjects are discussed in more detail in recent reviews by Kormendy (1987a; hereafter K87), Okamura (1988), and Nieto (1988). Techniques are discussed by de Vaucouleurs (1979, 1984), Nieto (1982), Capaccioli & de Vaucouleurs (1983), Capaccioli (1985, 1987,\n1988a,b), Okamura (1988), and Djorgovski & Dickinson (1989). Compilations of photometry references for individual galaxies are found in Davoust & Pence (1982) and Pence & Davoust (1985).\n\nUnless otherwise noted, we assume that the Hubble constant is H_0 = 50 km s^(-1) Mpc^(-1).", "doi": "10.1146/annurev.aa.27.090189.001315", "issn": "0066-4146", "publisher": "Annual Reviews", "publication": "Annual Review of Astronomy and Astrophysics", "publication_date": "1989-09", "series_number": "1", "volume": "27", "issue": "1", "pages": "235-277" }, { "id": "authors:9jej5-05s28", "collection": "authors", "collection_id": "9jej5-05s28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-105623193", "type": "article", "title": "A new family of distance indicator relations for elliptical galaxies", "author": [ { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We describe a new family of distance indicator relations for elliptical galaxies. Distance-dependent quantities, i.e., radius or luminosity, are expressed as distance-independent combinations of the mean surface brightness and a color, or any other metallicity indicator. Our preliminary results, based on a somewhat heterogeneous collection of published data, indicate that the typical relative distance errors to individual galaxies derived from new relations are ~25%, and the accuracy of ~15% may be achievable with more homogeneous data sets. This is comparable to the accuracy obtained from the Tully-Fisher and D_n - \u03c3 relations. The importance of the new relations is that the necessary data are derived from photometry only and thus can be obtained relatively quickly for large numbers of galaxies. This can lead to a more efficient and detailed mapping of the large-scale velocity field and streaming motions. A preliminary application of the new relations gives for the relative distance modulus between the Virgo and Coma clusters \u0394(m-M) = 3.95 \u00b1 0.25, in a good agreement with measurements obtained using other methods. The new relations are interpreted in terms of the \"fundamental plane\" of elliptical galaxies, and imply the existence of a second parameter in the mass-metallicity relation, identified here as the internal luminosity density.", "doi": "10.1086/185452", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1989-06-15", "volume": "341", "pages": "L37-L40" }, { "id": "authors:1fnzv-7eh53", "collection": "authors", "collection_id": "1fnzv-7eh53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-101503972", "type": "article", "title": "The warp of the Galactic stellar disk detected in IRAS source counts", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Sosin", "given_name": "Craig", "clpid": "Sosin-C" } ], "abstract": "We investigate the tentative evidence for a warp in the Galactic stellar disk, similar to the well-known warp seen in the H I gas, using a sample of ~ 90,000 IRAS point sources as disk tracers. The IRAS sources were selected on the basis of infrared colors, and most of them are probably evolved, dust-shell stars. Analysis of their distribution near the Galactic plane shows a systematic variation of characteristic latitude with the longitude. The sources are found preferentially above the plane near l^(II) ~ 90\u00b0-100\u00b0, and below the plane near l^(II) ~ 240\u00b0-270\u00b0, with the amplitude of the deviation increasing at the fainter flux levels (i.e., for more distant sources). Simple sine-wave models provide good fits to the data, whereas the null hypothesis (no variation with the longitude) can be rejected with a high degree of significance. This behavior is at least qualitatively as expected, if the IRAS sources follow the H I warp. We conclude that the stellar disk of our Galaxy is warped at large radii in a way similar to the H I layer, and that the warp is an important characteristic of our Galaxy as a whole. Since most of the IRAS stars are relatively old (several Gyr), we propose that the warp is a long-lasting phenomenon, possibly caused by asymmetries of the mass distribution in the outer regions of the Galactic dark halo. The projected amplitude of the IRAS warp may be lower than expected if the stars and the gas trace each other at all radii. We tentatively explain this as a signature of the radial truncation of the Galactic stellar disk. We also find that the mean disk plane, as delineated by the IRAS sources, is ~ 0\u00b01-0\u00b02 below b^(II) = 0\u00b0; this may reflect the z-distance of the Sun above the disk plane.", "doi": "10.1086/185446", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1989-06-01", "volume": "341", "pages": "L13-L16" }, { "id": "authors:8z0g2-ymt52", "collection": "authors", "collection_id": "8z0g2-ymt52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-085154076", "type": "conference_item", "title": "A rich nearby cluster in Sagittarius", "author": [ { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Thompson", "given_name": "D. J.", "clpid": "Thompson-D-J" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" } ], "abstract": "In a series of ESO Messenger and Comptes Rendu papers (1978 - 1985), Terzan, Bernard, and Ju discovered some 45 diffuse objects in the general direction of the Galactic Bulge, viz., Sagittarius bright cloud B, \u03b1 range 17^h04^m \u2013 17^h42^m, \u03b4 range -24\u00b0 to -33\u00b0. This region, centered near 1_(II) ~358\u00b0, b_(II) ~ +7\u00b0, has a patchy, but obviously very heavy extinction (we estimate A_v > 3^m \u2013 4^m). These TBJ objects are a mixed bag; in the discovery papers, some were tentatively classified as galaxies, some as possible globular clusters, others as planetary nebulae. During an imaging search for obscured globular clusters, one of us (SGD) obtained images of 14 of them. Out of those, two turned out to be probable globular clusters (TJ 5 and TJ 23), one planetary nebula. (TBJ 41), and the rest were obviously galaxies. A dozen of the remaining objects may be classified as galaxies from their appearance on the SRC/I sky survey films. The magnitudes of detected galaxies are typically in the range R ~17^m \u2013 18^m, within 10 - 20 arcsec apertures (the measurements are difficult and still very preliminary, because of the heavy stellar foreground). The occurrence of so many background galaxies in a. relatively small and heavily obscured area is remarkable. These objects must be luminous ellipticals and/or bright S0 or Sp bulges: anything with a lower surface brightness would not be detected through the heavy extinction and foreground. (None of the TBJ galaxies and possible galaxies a.re detected in the IRAS PSC, which corroborates their identification as early types.) Thus, this concentration of galaxies must be just the very tip of an iceberg. Terzan et al. apparently discovered a major rich cluster, hidden behind the Galactic Bulge, in the heart of \"zone of avoidance\".", "publisher": "Caltech Library", "publication_date": "1989-05" }, { "id": "authors:d5zmv-mag75", "collection": "authors", "collection_id": "d5zmv-mag75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-083113838", "type": "conference_item", "title": "A photometric distance-indicator relation for low surface brightness dwarfs", "author": [ { "family_name": "de Carvalho", "given_name": "R. R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Djorgovski", "given_name": "S. G.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Recently, dwarf elliptical galaxies have received a great deal of attention and some of the points to be addressed in future investigations include metallicities of the stellar population, structural properties, and the large scale distribution (Caldwell and Bothun 1987; Impey et al. 1988; Eder et al. 1989). Here we are more concerned with the large scale structure for this class of galaxies. Recent analysis by Eder et al. (1989) has indicated that dwarf galaxies seem to trace the large scale structures in the same way as bright ones. Another important characteristic of dwarfs is that they are more populous in clusters than bright elliptical galaxies. The ratio dE/E (dwarf/normal) in Fomax is around 4, and in Virgo 17, which means that if we can define a distance indicator relation for dwarfs with at least the same accuracy as we have for normal ellipticals, we can substantially improve our distance measurement for clusters, thus mapping the large-scale velocity field more efficiently.", "publisher": "Caltech Library", "publication_date": "1989-05" }, { "id": "authors:dpsy4-zz265", "collection": "authors", "collection_id": "dpsy4-zz265", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-081605918", "type": "article", "title": "An analysis of the distribution of globular clusters with postcollapse cores in the Galaxy", "author": [ { "family_name": "Chernoff", "given_name": "David F.", "clpid": "Chernoff-D-F" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present a new compilation of structural parameters for Galactic globular clusters, based on the data from the complete survey published by Djorgovski, King, and collaborators in 1984, 1986, and 1987 and the literature. We find that the distribution of the post-core-collapsed (PCC) clusters is much more concentrated about the Galactic center than the distribution of the King model (KM) clusters. Within the KM family, a similar trend exists: centrally condensed KM clusters are found, on average, at smaller galactocentric radii. To deal with the problem of Galactic obscuration, we used a distance-independent analysis, similar to one developed and published by Frenk and White in 1982. We analyzed the shapes of the KM and PCC cluster systems; they are each consistent with a symmetrical distribution of the clusters about the Galactic center. At fixed distance from the center, the clusters at smaller heights above the plane (and thus the less inclined orbits)\nare marginally more concentrated. The data indicate that the more concentrated KM clusters tend to have higher luminosities. On the other hand, the PCC clusters are less luminous than the highest concentration KM clusters. The PCC clusters show signs of tidal distortions in their envelopes: their major axes tend to point toward the Galactic center; the KM clusters show no such effect. There is a very slight difference in the average metallicities of the two families, in the sense that PCC clusters have slightly lower metal abundances, but there is no significant trend with the concentration within the KM family. The fact that some internal properties of clusters correlate well with global variables, such as the galactocentric radius, suggests that some external effects are important in cluster evolution. These include the average cluster density, set by the mean tidal field of the Galaxy, and, perhaps, the strength of tidal shocks.", "doi": "10.1086/167344", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1989-04-15", "volume": "339", "pages": "904-918" }, { "id": "authors:zamhc-hpn29", "collection": "authors", "collection_id": "zamhc-hpn29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-074238924", "type": "article", "title": "UM 425 - A new gravitational lens candidate", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report the discovery of a probable new gravitational lens, associated with the quasar UM 425 = QSO 1120 + 019. This object was specifically selected in an optical imaging survey for gravitational lenses because of its relatively high redshift and apparently high luminosity. Multicolor (BVR) images were obtained with a charge-coupled device (CCD) at the Cerro Tololo Interamerican Observatory (CTIO) 60 inch (1.5 m) telescope in 1987 March, showing three close companions around the bright image of the quasar. The follow-up spectroscopy in marginal weather conditions, with the Mount Palomar 200 inch (5 m) and Las Campanas 100 inch (2.5 m) telescopes (in 1988 March and April), suggested that the brightest companion has the same emission lines as the quasar. Additional spectra and additional imaging were obtained with the European Southern Observatory (ESO) 3.6 m telescope at La Silla, in 1988 May. UM 425 and its brightest companion (which we denote as components A and B) have similar BVR colors. Spectra of both objects, in the range 3600-8000 \u00c5, with resolution of about 7 \u00c5 pixel^(-1), show the same emission lines, i.e., C IV 1549, C III] 1909, and Mg II 2799, with the same redshift z = 1.465 \u00b1 0.005. The spectra are also similar in shape and in some details, including, possibly some associated absorption in the Mg II 2799 and C IV 1549 lines. The velocity difference between the two brightest components from the cross-correlation technique is \u0394V(A-B) = 200 \u00b1 100 km s^(-1) and is consistent with zero. Subtracting a scaled spectrum of the brighter component (A) from that of the brightest companion (B), leaves a residual which may be interpreted as the spectrum of a lensing galaxy at z \u2243 0.6. Whereas we cannot exclude the possibility that we are seeing a pair of physically distinct AGNs, the overall data are in favor of the gravitational lens hypothesis.", "doi": "10.1086/185386", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1989-03-01", "volume": "338", "pages": "L1-L4" }, { "id": "authors:8ate8-g1r52", "collection": "authors", "collection_id": "8ate8-g1r52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-075639450", "type": "article", "title": "Profiles of a Key Programme: Gravitational Lensing", "author": [ { "family_name": "Surdej", "given_name": "J.", "orcid": "0000-0002-7005-1976", "clpid": "Surdej-J" }, { "family_name": "Arnaud", "given_name": "J.", "clpid": "Arnaud-J" }, { "family_name": "Borgeest", "given_name": "U.", "clpid": "Borgeest-U" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fleischmann", "given_name": "F.", "clpid": "Fleischmann-F" }, { "family_name": "Hammer", "given_name": "F.", "clpid": "Hammer-F" }, { "family_name": "Hutsem\u00e9kers", "given_name": "D.", "clpid": "Hutsem\u00e9kers-D" }, { "family_name": "Kayser", "given_name": "R.", "clpid": "Kayser-R" }, { "family_name": "Le Fevre", "given_name": "O.", "orcid": "0000-0001-5891-2596", "clpid": "Le-F\u00e8vre-O" }, { "family_name": "Nottale", "given_name": "L.", "clpid": "Nottale-L" }, { "family_name": "Magain", "given_name": "P.", "clpid": "Magain-P" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Refsdal", "given_name": "S.", "clpid": "Refsdal-S" }, { "family_name": "Remy", "given_name": "M.", "clpid": "Remy-M" }, { "family_name": "Shaver", "given_name": "P.", "clpid": "Shaver-P" }, { "family_name": "Smette", "given_name": "A.", "clpid": "Smette-A" }, { "family_name": "Swings", "given_name": "J. P.", "clpid": "Swings-J-P" }, { "family_name": "Vanderriest", "given_name": "C.", "clpid": "Vanderriest-C" }, { "family_name": "van Drom", "given_name": "E.", "clpid": "van-Drom-E" }, { "family_name": "V\u00e9ron-Cetty", "given_name": "M.", "clpid": "V\u00e9ron-Cetty-M" }, { "family_name": "V\u00e9ron", "given_name": "P.", "clpid": "V\u00e9ron-P" }, { "family_name": "Weigelt", "given_name": "G.", "clpid": "Weigelt-G" } ], "abstract": "Prior to Professor van der Laan's enquiry, in the March 1988 issue of the Messenger, on the general interest among astronomers from the European community to possibly participate in Key Programmes (KPs) at the European 80uthern Observatory, at least three distinct groups (including more than half of the above authors) were already involved in the study of \"gravitational lensing\" effects (see box on pages 10-11). Observations were being performed with the help of various telescopes on La 8illa as weil as at other observatories (VLA, CFHT, Palomar, Kitt Peak, etc.).", "issn": "0722-6691", "publisher": "European Southern Observatory", "publication": "Messenger", "publication_date": "1989-03", "volume": "55", "pages": "8-12" }, { "id": "authors:d7rdy-0sm68", "collection": "authors", "collection_id": "d7rdy-0sm68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190605-104442161", "type": "book_section", "title": "An optical imaging survey for gravitational lenses and the discovery of a new lens candidate", "book_title": "Gravitational Lenses", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" } ], "contributor": [ { "family_name": "Moran", "given_name": "J. M.", "clpid": "Moran-J-M" }, { "family_name": "Hewitt", "given_name": "J. N.", "clpid": "Hewitt-J-N" }, { "family_name": "Lo", "given_name": "K. Y.", "clpid": "Lo-K-Y" } ], "abstract": "We are conducting an optical imaging search for gravitational lenses. A sample of known quasars was selected on the basis of high redshifts and apparently large absolute luminosities; these selection criteria significantly enhance the probability that a given QSO is gravitationally magnified. So far, our search has yielded at least one new gravitational lens system, associated with the quasar UM 425 = 1120+019,,one binary quasar, PKS 1145-071, and several other promising candidates that still need spectroscopic confirmation. In addition, we found several cases of foreground galaxies within a few arcsec from the quasars, which should be useful for absorption line studies. The optical image of the UM 425 system consists of four or more components, at least two of which have identical spectra. There are many faint galaxies in the field, suggestive of a lensing cluster at a redshift of several tenths, and tentative evidence for a z \u2245 0.6 galaxy underlying the second-brightest quasar image. We conclude that the heuristically designed optical searches for gravitational lenses can successfully complement the radio-based surveys.", "doi": "10.1007/3-540-51061-3_51", "isbn": "978-3-540-51061-1", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1989", "pages": "173-178" }, { "id": "authors:bg7gf-vmd92", "collection": "authors", "collection_id": "bg7gf-vmd92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-105232292", "type": "book_section", "title": "CCD Data Taking Modes and Flatfielding Problems", "book_title": "Highlights of Astronomy", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Dickinson", "given_name": "M.", "clpid": "Dickinson-M" } ], "contributor": [ { "family_name": "McNally", "given_name": "Derek", "clpid": "McNally-D" } ], "abstract": "We briefly review some problems in the flatfielding of CCD images, in the context of three data-taking modes: stare, short scan, and drift scan. The principal sources of flatfielding imperfections are: (1) mismatch in the spectra of the astronomical sources of interest and the flatfleld illumination; (2) a variety of low-level additive errors; and (3) nonlinearities of the CCD response. Residual flatfielding errors are probably the limiting factor in high-precision astronomical photometry. Flatfielding accuracies of the order of 1 \u2013 2% per pixel are commonly achieved; with some effort, accuracies of ~ 0.1% can be reached; higher accuracies require a substantial effort, or improvements in the quality of CCD chips. In general, scanning data taking modes outperform the \"standard\" stare mode.", "doi": "10.1007/978-94-009-0977-9_115", "isbn": "978-0-7923-0281-0", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1989", "pages": "645-650" }, { "id": "authors:gsmpj-6qk72", "collection": "authors", "collection_id": "gsmpj-6qk72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-160707984", "type": "book_section", "title": "An Optical Imaging Search for Gravitational Lenses", "book_title": "Active Galactic Nuclei", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" } ], "contributor": [ { "family_name": "Osterbrock", "given_name": "D. E.", "clpid": "Osterbrock-D-E" }, { "family_name": "Miller", "given_name": "J. S.", "clpid": "Miller-J-S" } ], "abstract": "We are conducting an optical imaging search for gravitational lenses. A sample of known quasars was selected on the basis of high redshifts and apparently large absolute luminosities; these selection criteria significantly enhance the probability that a given QSO is gravitationally magnified. Our search has yielded so far at least one lensed QSO, and several promissing candidates.", "doi": "10.1017/S0074180900141038", "isbn": "9780792302568", "publisher": "Kluwer", "place_of_publication": "Dordrecht", "publication_date": "1989", "pages": "269-270" }, { "id": "authors:xgrfh-zxa90", "collection": "authors", "collection_id": "xgrfh-zxa90", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-073308925", "type": "book_section", "title": "Discovery of a Probable Gravitational Lens", "book_title": "Active Galactic Nuclei", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Osterbrock", "given_name": "D. E.", "clpid": "Osterbrock-D-E" }, { "family_name": "Miller", "given_name": "J. S.", "clpid": "Miller-J-S" } ], "abstract": "We report the discovery of a new probable gravitational lens system, associated with the quasar UM 425 = 1120+019, at z = 1.465. The optical image of the system consists of 4 or more components. The two well-observed brightest components have very similar spectra. The difference of the two spectra (scaled appropriately) is consistent with a spectrum of a galaxy at z \u2243 0.6. There is a large number of faint galaxies in the field, suggestive of a lensing cluster at that redshift.", "doi": "10.1017/S007418090014104X", "isbn": "9780792302568", "publisher": "Kluwer", "place_of_publication": "Dordrecht", "publication_date": "1989", "pages": "271-272" }, { "id": "authors:wjm51-mmr09", "collection": "authors", "collection_id": "wjm51-mmr09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-154125598", "type": "article", "title": "Photometry and the light curve of the optical counterpart of the eclipsing millisecond pulsar 1957+20", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Evans", "given_name": "Charles R.", "clpid": "Evans-C-R" } ], "abstract": "We confirm the discovery of the optical counterpart to the eclipsing millisecond pulsar 1957 + 20 recently reported by Fruchter, Stinebring, and Taylor and identified earlier by Kulkarni et al. and Fruchter and colleagues. A nearly complete light curve derived from 58 CCD images taken in the Gunn r band has been obtained and found to match the 9.17 hr orbital period of the pulsar. As expected, minimum and maximum light correspond to orbital phases 0.25 and 0.75, respectively. The amplitude of the variation is 0.85 mag with apparent magnitudes of Gunn-Thuan r = 19.36, or V \u2243 19.7, and colors (g - r) = 0.66, or (B -V) \u2243 1.2, at maximum light, and uncorrected for interstellar extinction. However, the centroid of the previously proposed optical counterpart displays a 9.17 hr periodic wobble with amplitude of ~0.\"5, indicating the presence of a field star separated by \u2243 1\". Assuming that minimum light is due entirely to the field star, the pulsar companion would have peak apparent magnitudes of r = 20.05, or V \u2243 20.3, and colors (g - r) = 0.45, or (B - V) \u2243 1.0, again not including extinction. If the extinction is assumed to be = 1 mag, the corrected color is found to be (g - r) = 0.11, or (B - V) \u2243 0.7, which corresponds to an effective temperature of 5800 K. Based on modeling the heating of and reradiation from the companion, we obtain a synthetic light curve that matches the observed sharp rise to maximum light and flat, broad minimum. By matching the model to the observed brightness and color of the counterpart it is possible to rule out a high extinction (A_V \u2243 3 mag) to the source due to the high luminosity required. For A_V between 1 and 2 mag the inferred stellar radius lies between 0.07 R\u2299 and 0.2 R\u2299, depending on distance. Assuming the distance 0.9 kpc derived from the radio dispersion measure, and an extinction of A_V = 1 mag, we derive an absolute visual magnitude of the pulsar companion of 10.5 and its radius to be \u2243 0.16 R_\u2299, close to that of a degenerate hydrogen dwarf.", "doi": "10.1086/185340", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1988-12-15", "volume": "335", "pages": "L61-L65" }, { "id": "authors:c29r1-38s98", "collection": "authors", "collection_id": "c29r1-38s98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-155745491", "type": "article", "title": "UM 425: a New Gravitational Lens Candidate", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Since the first theoretical discussions more than 50 years ago on the phenomenon of light rays bent by intervening mass in the universe (Eddington 1920, Einstein 1936, Zwicky 1937 a, b), gravitational lensing has steadily grown to become one of the most active fields of research in extragalactic astronomy today. There are numerous theoretical investigations (Refsdal 1964, 1966, Turner et al. 1984, Blandford and Narayan 1986, Blandford and Kochanek 1987a, b), but the observations of good gravitationallens candidates are still rare. It is only during the last decade that a few quasar systems have been found in reasonable agreement with the gravitational lensing interpretation, viz., 0957 + 561 (Walsh et al. 1979), 1115 + 080 (Weymann et al. 1980), 2016 + 112 (Lawrence et al. 1983), 2237 + 030 (Huchra et al. 1985), 0142-100 (Surdej et al. 1987), and 1413+ 117 (Magain et al. 1988). In other possible cases, e.g., 2345+007 ryveedman et al. 1982), and 1635+267 (Djorgovski and Spinrad 1984), there has so far been no detection of lensing galaxies, and thus they should possibly be considered as genuine pairs of interacting quasars, similar to the probable binary quasar PKS 1145-071 (Djorgovski et al. 1987). Recently, so-called giant luminous arcs have been observed in a few clusters of galaxies. They are interpreted as segments of Einstein rings, created because of an almost perfect alignment of the lensing cluster potential well with the lensed background object (Soucail et al. 1988, Lynds and Petrosian 1988). Blandford and Kochanek (1987) provide the most comprehensive and updated review on these subjects.", "issn": "0722-6691", "publisher": "European Southern Observatory", "publication": "Messenger", "publication_date": "1988-12", "volume": "54", "pages": "39-42" }, { "id": "authors:kysv0-gza66", "collection": "authors", "collection_id": "kysv0-gza66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-153202765", "type": "article", "title": "Color and population gradients in the core of the postcollapse globular cluster M30", "author": [ { "family_name": "Piotto", "given_name": "Giampaolo", "clpid": "Piotto-G" }, { "family_name": "King", "given_name": "Ivan R.", "clpid": "King-I-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We have developed a new technique for seeking color gradients in multicolor CCD images of a globular cluster. Application of this technique to M30 confirms the radial color gradient reported by others. The B - V and V - R colors show linear gradients, when plotted against log r, that are many times their statistical errors. In the radial range ~ 3-100 arcsec, the B - V and V - R colors increase outwards by about (0.18 \u00b1 0.015) mag/dex and (0.09 \u00b1 0.01) mag/dex, respectively. Color-magnitude arrays of the central region show that the Balmer-line strength that accompanies the central blueness is due to an increased proportion of blue-horizontal-branch starlight in the center. This excess does not appear to be statistically significant in terms of star numbers, even though the color gradient is so highly significant. \n\nThe authors are divided among themselves as to whether the color and spectrum gradients observed here and in other clusters are due only to random statistical fluctuations, or whether they might have a\nphysical significance.", "doi": "10.1086/114937", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1988-12", "series_number": "6", "volume": "96", "issue": "6", "pages": "1918-1924" }, { "id": "authors:tbvfh-y5s15", "collection": "authors", "collection_id": "tbvfh-y5s15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-145426168", "type": "article", "title": "Further redshifts of 1-Jy radio sources", "author": [ { "family_name": "Allington-Smith", "given_name": "J. R.", "clpid": "Allington-Smith-J-R" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Liebert", "given_name": "J.", "clpid": "Liebert-J" } ], "abstract": "We have firm redshifts for a further 12 faint radio source identifications from the '1-Jy' complete radio-selected sample, two of which are galaxies with redshifts z > 1.5. Another object has a provisional redshift that requires confirmation. Five of these identifications had previously been classified as QSOs on the basis of their optical morphology. Our spectroscopy shows that of these, one is definitely a galaxy and two have characteristics intermediate between those of 'normal' radio galaxies and those of 'normal' quasars, for instance broad Balmer emission but an extended optical image. Two of the eight identifications previously classified as galaxies have similar 'intermediate' properties. The remaining identifications have low-excitation narrow emission-line systems of the type seen in other 1-Jy radio sources by Allington-Smith et al. We confirm that the 1-Jy emission lines are a factor 2 weaker than those of 3C galaxies in the same redshift interval.", "doi": "10.1093/mnras/234.4.1091", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "1988-10-01", "series_number": "4", "volume": "234", "issue": "4", "pages": "1091-1103" }, { "id": "authors:yrmy0-80p34", "collection": "authors", "collection_id": "yrmy0-80p34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-152259381", "type": "article", "title": "A search for the Perseus flasher and the limits on optical burst rates", "author": [ { "family_name": "Tokarz", "given_name": "Susan", "clpid": "Tokarz-S" }, { "family_name": "Browne", "given_name": "Stanley", "clpid": "Browne-S" }, { "family_name": "Klemola", "given_name": "A. R.", "clpid": "Klemola-A-R" }, { "family_name": "McCrosky", "given_name": "Richard", "clpid": "McCrosky-R" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We conducted a study of the error box of the possible optical burster, reported by Katz et al. (1986). This \"Perseus Flasher\" was subsequently identified with satellite glints by Maley (1987), a conclusion with which we fully concur. Our study, completed before Maley's report, involved a search for highly-variable objects on archival and newly-taken plates, with a total integration time of about 260 hours, a proper-motion survey of the area, deep optical imaging with a CCD, and a single-dish radio monitoring. We found no optical or radio bursts or any other unusual objects in this area. Our upper limit to the optical flash rate from the error box of the flash photographed by Katz et al. is at least 20 times lower than the flash rate reported by those authors. Similar negative results were achieved independently by other groups; like them, we conclude that the photographed flash was most likely caused by an Earth-orbiting artifact and that most of the remaining, visually-detected flashes were spurious. From our data, we derive limits on the optical flash rates from astrophysically-interesting sources.", "doi": "10.1086/132308", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1988-10", "series_number": "632", "volume": "100", "issue": "632", "pages": "1228-1232" }, { "id": "authors:ddh9j-frj20", "collection": "authors", "collection_id": "ddh9j-frj20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-143354304", "type": "article", "title": "Identifications and redshifts of faint 3CR radio sources", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "McCarthy", "given_name": "P.", "clpid": "McCarthy-P-J" }, { "family_name": "Dickinson", "given_name": "M.", "orcid": "0000-0001-5414-5131", "clpid": "Dickinson-Mark-E" }, { "family_name": "van Breugel", "given_name": "W.", "clpid": "van-Breugel-W" }, { "family_name": "Strom", "given_name": "R. G.", "clpid": "Strom-R-G" } ], "abstract": "We report new and confirmed optical identifications of 12 3CR radio sources, and redshifts for nine of them. Seven have redshifts in excess of 1, with the highest being 1.841 for 3C 454.1; the remaining three sources are also likely to be at z > 1. One of the newly identified sources, 3C 194, shows a moderately strong Ly\u03b1 emission, and may be a member of the new class of objects, possible young/forming galaxies, typified by 3C 326.1 and 3C 294. The optical identifications of the 3CR sources are now complete, and only six are lacking redshifts. Practically all of the new identifications are galaxies whose light appears to be dominated by stars, rather than nonthermal active nuclei, although their powerful radio emission argues that they are likely to be highly unusual objects. Their observed properties are similar to those of previously identified high-redshift powerful radio galaxies.", "doi": "10.1086/114849", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1988-09", "series_number": "3", "volume": "96", "issue": "3", "pages": "836-840" }, { "id": "authors:tc7bj-4cp76", "collection": "authors", "collection_id": "tc7bj-4cp76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-160106243", "type": "article", "title": "Probable optical counterpart of the eclipsing millisecond pulsar system, 1957 + 20", "author": [ { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Fruchter", "given_name": "A. S.", "clpid": "Fruchter-A-S" } ], "abstract": "Following the discovery of an eclipsing, millisecond pulsar 1957+20 (ref. 1) we conducted a series of optical observations to identify the optical counterpart of the system. We report the detection of a probably variable object (hereafter star X) with a mean apparent V magnitude of \u223c20 within the astrometric error circle of the equatorial radio position of the pulsar. Star X appears fainter at orbital phase 0.21, the onset of the pulsar eclipse, compared with the quadrature position, suggesting that it is probably the optical counterpart. We argue that the secondary heated by the pulsar wind and not the pulsar itself makes the dominant contribution to the visible radiation from this system. The absolute magnitude of star X is M_v \u2248 10.5, assuming a distance of \u223c 0.8 kpc derived from the dispersion measure. The optical luminosity of the counterpart directly measures the fraction of the pulsar wind power responsible for heating the secondary. Future optical observations may be able to constrain the nature of the pulsar wind.", "doi": "10.1038/334504a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1988-08-11", "series_number": "6182", "volume": "334", "issue": "6182", "pages": "504-506" }, { "id": "authors:4rnkw-5qm49", "collection": "authors", "collection_id": "4rnkw-5qm49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-141501504", "type": "book_section", "title": "The universality(?) of distance-indicator relations", "book_title": "The Extragalactic Distance Scale: Proceedings of the ASP 100th Anniversary Symposium", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "de Carvalho", "given_name": "R.", "orcid": "0000-0002-1283-3363", "clpid": "de-Carvalho-R-R" }, { "family_name": "Han", "given_name": "M.-S.", "clpid": "Han-M-S" } ], "contributor": [ { "family_name": "van den Bergh", "given_name": "Sidney", "clpid": "van-den-Bergh-S" }, { "family_name": "Pritchet", "given_name": "Christopher J.", "clpid": "Pritchet-C-J" } ], "abstract": "The origin of distance-indicator relations for galaxies is examined, as well as the possibility that they may vary with the large-scale environment. The relations reflect formative and evolutionary process of galaxies, and contain some information about them. They are expected to depend on the environment in a complex manner. There are hints that both the Tully-Fisher relation for the spirals, and the Dn-sigma relation for the ellipticals may depend on the parent cluster properties such as richness, velocity dispersion, or galaxy number density, but these tentative dependences are hard to separate from the selection effects. If the distance-indicators vary from one cluster to another, some of the large peculiar motions claimed in the literature are partly spurious. Until the environmental effects on distance-indicator relations are better understood, their use for the mapping of large-scale velocity fields and measurements of the far-field Hubble constant may be premature.", "isbn": "0-937707-21-X", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1988-07", "pages": "329-343" }, { "id": "authors:567jc-pb459", "collection": "authors", "collection_id": "567jc-pb459", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190806-142508681", "type": "article", "title": "A search for features in early-type galaxies", "author": [ { "family_name": "Ebneter", "given_name": "Kate", "clpid": "Ebneter-K" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Davis", "given_name": "Marc", "clpid": "Davis-M-E-Astro" } ], "abstract": "We have conducted a search for dust lanes, incipient stellar disks, bars, shells, and other deviations from elliptical symmetry in a sample of 159 early-type galaxies. The data are from the CCD surface-photometry survey of Djorgovski (1985a), for which the selection effects are well understood. The image-processing technique used is division by a purely elliptical model image, constructed from the surfacephotometry profiles for a given object (best-fit surface brightness, ellipticity, and position angle as functions of semimajor axis). Our sample contains 116 elliptical galaxies, 33 SO galaxies, and ten intermediate types. Some galaxies that might better be classified as \"dusty ellipticals\" (in that they contain no obvious stellar disk) are included among the SOs. Forty-two of the ellipticals (36%) either definitely or very likely contain dust, either in patches or in well-defined lanes or rings. Five of the E/SO galaxies (50%) also show possible or definite dust, as do 15 (47%) of the SOs. Three of the elliptical galaxies definitely contain stellar disks, with several more possible candidates. Thus, approximately 50% of the elliptical galaxies show \"features\" of some kind. The detection of features is dependent on the signal-to-noise ratio of the data, so these numbers represent lower limits. The presence of dust in the galaxies classified as ellipticals does not seem to depend on any intrinsic characteristic of the galaxy. The dusty ellipticals do seem to prefer low-density environments. The \"elliptical\" galaxies with disks tend to have higher ellipticities and larger two-wave Fourier residuals, an effect also described by Carter ( 1987). These galaxies may be preferentially found in higher-density environments, and may be lower-luminosity systems, but these statements are based on very small-number statistics (ten galaxies out of a total of 116), and no strong conclusions may be drawn. However, our results clearly further blur the distinction between ellipticals and SOs.", "doi": "10.1086/114644", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1988-02", "series_number": "2", "volume": "95", "issue": "2", "pages": "422-437" }, { "id": "authors:ek9tf-bt423", "collection": "authors", "collection_id": "ek9tf-bt423", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-151050207", "type": "book_section", "title": "Limits on the Number of Close Optical Quasar Pairs", "book_title": "Proceedings of a Workshop on Optical Surveys for Quasars", "author": [ { "family_name": "Weedman", "given_name": "D. W.", "clpid": "Weedman-D-W" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Osmer", "given_name": "Patrick Stewart", "clpid": "Osmer-P-S" }, { "family_name": "Phillips", "given_name": "M. M.", "clpid": "Phillips-M-M" } ], "abstract": "A new search has been conducted for close pairs of quasars with identical spectra, including both emission line objects and blue stellar objects. Survey plates covering 3.9 deg^2 were selected for image quality, full image widths being 0.\"8 to l.\"2. Although 200 to 400 quasar spectral images should have been examined, no candidate pairs with separations < 4\" were found. Eight such pairs from 4\" to 10\" were found, but none were subsequently confirmed as lensed quasars. The selection bias is derived and applied to these limits. It is concluded that the absence of close pairs expected from gravitational lensing models cannot be explained by observational selection effects.", "isbn": "0-937707-19-8", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1988-01", "pages": "226-232" }, { "id": "authors:mnke3-cs664", "collection": "authors", "collection_id": "mnke3-cs664", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-111544165", "type": "book_section", "title": "Lyman-Alpha Galaxies at Large Redshifts", "book_title": "Towards Understanding Galaxies at Large Redshift", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Kron", "given_name": "Richard G.", "clpid": "Kron-R-G" }, { "family_name": "Renzini", "given_name": "Alvio", "clpid": "Renzini-A" } ], "abstract": "Strong Ly\u03b1 emission has been detected from several different types of distant galaxies, radio galaxies and their companions at z \u2243 1.8, and galaxy companions of quasars at z > 3. This line emission is a good way of detecting galaxies at very large redshifts, and a powerful probe of the physical conditions and processes in them. A subset of the Ly\u03b1 radio galaxies have photometric, spectroscopic, and morphological properties unlike those of any previously known class of objects, and may be interpreted as galaxies in the process of formation. These and other observations agree very well with some modern theoretical ideas, which predict that galaxy formation is an extended process which may begin at large redshifts, but culminate at z ~ 1\u20132. If this is the case, we may have already detected primeval galaxies. Searches can be (re)designed to test this notion.", "doi": "10.1007/978-94-009-2919-7_32", "isbn": "978-94-010-7814-6", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1988", "pages": "259-274" }, { "id": "authors:5n6j4-ty235", "collection": "authors", "collection_id": "5n6j4-ty235", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190610-104912920", "type": "book_section", "title": "Surface Photometry of Globular Clusters", "book_title": "The Harlow-Shapley Symposium on Globular Cluster Systems in Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Grindlay", "given_name": "Jonathan E.", "clpid": "Grindlay-J-E" }, { "family_name": "Philip", "given_name": "A. G. Davis", "clpid": "Philip-A-G-D" } ], "abstract": "Much of what we know about the structure, dynamics, and evolution of globular clusters derives from their observed density profiles, and their interpretations. In this review, I will briefly describe the problems and techniques specific to the surface photometry of globular clusters, show some new results, and offer suggestions for future ground-based work.", "doi": "10.1007/978-94-015-1104-9_47", "isbn": "978-90-277-2665-0", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1988", "pages": "333-345" }, { "id": "authors:4gszj-y1g26", "collection": "authors", "collection_id": "4gszj-y1g26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190610-110710421", "type": "book_section", "title": "A Search for Obscured Globular Clusters", "book_title": "The Harlow-Shapley Symposium on Globular Cluster Systems in Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Grindlay", "given_name": "Jonathan E.", "clpid": "Grindlay-J-E" }, { "family_name": "Philip", "given_name": "A. G. Davis", "clpid": "Philip-A-G-D" } ], "abstract": "It has been estimated that up to several tens of globular clusters in our Galaxy remain undiscovered, because they are hidden by the dust. Most of those clusters are expected to be in the bulge area, but some may be anywhere in the galactic plane. This search is based on the use of IRAS catalogs as candidate lists for the obscured globular clusters. It was found that the properties of detected known clusters are sufficiently distinct for a meaningful sifting through the PSC. A sequence of statistical \"filters\", described below, was applied on the PSC, until a couple of hundred most promising candidates were found in the bulge.", "doi": "10.1007/978-94-015-1104-9_93", "isbn": "978-90-277-2665-0", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1988", "pages": "527-528" }, { "id": "authors:b70ep-p3p84", "collection": "authors", "collection_id": "b70ep-p3p84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-110052568", "type": "book_section", "title": "Extended Emission-Line Gas in Distant 3CR Radio Galaxies", "book_title": "Cooling Flows in Clusters and Galaxies", "author": [ { "family_name": "McCarthy", "given_name": "Patrick J.", "clpid": "McCarthy-P-J" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Breugel", "given_name": "Wil", "clpid": "Breugel-W" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Strauss", "given_name": "Michael A.", "orcid": "0000-0002-0106-7755", "clpid": "Strauss-M-A" }, { "family_name": "Dickinson", "given_name": "M.", "clpid": "Dickinson-M" } ], "contributor": [ { "family_name": "Fabian", "given_name": "A. C.", "clpid": "Fabian-A-C" } ], "abstract": "We report on the results of long-slit spectroscopy and interference filter imaging of powerful 3CR radio galaxies. Narrow-band [OII]A3727 imaging often reveals extensive regions of extranuclear emission associated with these objects. The extended [OII] emission is distributed on scales of several tens of kpc, it is often more luminous than the nuclear emission, and shows large velocity gradients. We discuss the physical conditions in these nebulae and their relation to the radio source structure. In particular, we examine the ionization mechanism for the gas, and find that photoionization models reproduce the observed emission line strengths reasonably well. The source of the ionizing photons, however, is not clear; the large luminosities of the extended gas suggesting that some form of in situ ionization may be occurring. Compared to the low-z cooling flow filaments, the 3CR emission regions are larger, more luminous, and generally show higher excitation. Futhermore, the distant radio galaxies show evidence for much stronger interactions with their radio sources than is seen in nearby cooling flow filaments.", "doi": "10.1007/978-94-009-2953-1_40", "isbn": "978-94-010-7828-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1988", "pages": "325-329" }, { "id": "authors:0stzc-a2q62", "collection": "authors", "collection_id": "0stzc-a2q62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-103020356", "type": "article", "title": "A preliminary survey of collapsed cores in the Magellanic Clouds' globular clusters", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We present a preliminary report on a surface photometry survey for collapsed cores in the Magellanic Clouds' globular clusters. We give core morphology classifications for the 33 globular clusters examined so far. One cluster, NGC 2019, shows definite signs of a collapsed core, and two others, NGC 1774 and NGC 1951, appear\nas strong candidates. This detection of postcollapse cores outside the Milky Way opens some interesting prospects for future dynamical studies. However, the fraction of collapsed-core clusters appears to be smaller in the Magellanic Clouds than in the Galaxy. This may be due in part to their younger ages, or to the limitations\nimposed by the seeing effects. It is also possible that the relative scarcity reflects the physical difference in the tidal field environments between the Galaxy and the Clouds, in agreement with a trend found earlier, viz., that the tidal shocks from disk passages accelerate dynamical evolution and enhance the propensity for core collapse.", "doi": "10.1086/185042", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1987-11-15", "volume": "322", "pages": "L91-L94" }, { "id": "authors:xnhq2-ae464", "collection": "authors", "collection_id": "xnhq2-ae464", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-085434845", "type": "article", "title": "Discovery of a probable binary quasar", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Perley", "given_name": "R.", "clpid": "Perley-R-A" }, { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "McCarthy", "given_name": "P.", "clpid": "McCarthy-P-J" } ], "abstract": "We report discovery of a pair of quasars at a redshift of 1.345, separated by 4\".2 in projection, apparently associated with the radio source PKS 1145-071. The optical intensity ratio of the two images is approximately 2.5. The spectra are very similar, and all emission lines except for the C IV \u03bbI549 have the same equivalent widths, within the error bars. The redshift difference based on the C IV line alone, which is the strongest feature, and on the cross-correlation of the two spectra including the C IV line, is approximately 250 \u00b1 100 km s^(-1) in the rest frame. If this discrepant emission line is excluded, the redshift difference drops to approximately 100 \u00b1 100 km s^(-1), and is consistent with zero. Thus, on the basis of the optical data alone, we would have concluded that this double QSO is another example of gravitational lensing. However, the radio source is single and unresolved at all VLA frequencies, and positionally coincident with the brighter of the two optical images. The fainter of the two optical components is at least a factor of 500 fainter in the radio. This dramatic difference in L_(opt)/L_(radio) between the two components suggests that the system is a genuine binary quasar, and the first such well-documented case. Assuming that the two QSO's are gravitationally bound, we derive a lower limit to the total mass of the system of ~ 10^(11)h^(-1)M_\u2299 this is the first such direct determination of a quasar mass. The close projected separation of the pair (~ 20h^(-1) kpc) and the small velocity difference are suggestive of an interaction, which may be causally related to the QSO activity, and of the existence of a parent group or cluster, which would be a very interesting find in itself. In the view of this discovery, it is plausible that some other, previously reported gravitational lenses may be really pairs of physically distinct quasars.", "doi": "10.1086/184998", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1987-10-01", "volume": "321", "pages": "L17-L21" }, { "id": "authors:fzks6-7e563", "collection": "authors", "collection_id": "fzks6-7e563", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-100410954", "type": "article", "title": "A correlation between the radio and optical morphologies of distant 3Cr radio galaxies", "author": [ { "family_name": "McCarthy", "given_name": "Patrick J.", "clpid": "McCarthy-P-J" }, { "family_name": "van Breugel", "given_name": "Wil", "clpid": "van-Breugel-W" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We report the discovery of a strong correlation between the radio and optical morphologies of distant (z \u2265 0.6), powerful radio galaxies. The isophotal axes of highly elongated distant 3CR galaxies, measured both in the light of stellar continua and extranuclear emission lines, tend to align with the radio source axes. This correlation suggests that there is a profound relation between these extremely powerful radio sources and their host galaxies. We propose that the most natural explanation of the effect is that the radio jets and/or backflows from the radio lobes interact with the interstellar media of the gas-rich galaxies associated with 3CR sources and stimulate large-scale star formation. This proposed mechanism can provide a physical explanation for the high star formation and evolution rates of 3CR galaxies at large look-back times found in earlier photometric studies. Thus, the formation and evolution of powerful radio galaxies and radio-quiet giant ellipticals may differ substantially.", "doi": "10.1086/185000", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1987-10-01", "volume": "321", "pages": "L29-L33" }, { "id": "authors:p7y5r-q8m67", "collection": "authors", "collection_id": "p7y5r-q8m67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-084348232", "type": "article", "title": "Extended Lyman-\u03b1 emission in 3C 326.1 - A 100 kiloparsec cloud of ionized gas at a redshift of 1.82", "author": [ { "family_name": "McCarthy", "given_name": "Patrick J.", "clpid": "McCarthy-P-J" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Strauss", "given_name": "Michael A.", "orcid": "0000-0002-0106-7755", "clpid": "Strauss-M-A" }, { "family_name": "van Breugel", "given_name": "Wil", "clpid": "van-Breugel-W" }, { "family_name": "Liebert", "given_name": "James", "clpid": "Liebert-J" } ], "abstract": "We report the discovery of a large cloud of ionized gas associated with the high-redshift radio source 3C 326.1 New radio-frequency images made at 4.9 GHz and 15 GHz with the Very Large Array show the radio source to be a small double (~ 7\") without a detectable core at the level of ~ 0.5 mJy. Long-slit spectrograms and L\u03b3a imaging reveal a ~ 100 kpc diameter cloud of ionized gas with a redshift of 1.825 encompassing the radio source. Deep broad-band images show two faint (V = 23.5-24.5) blue objects located on the periphery of the cloud, as well as some very faint (V = 25-26) extremely blue diffuse objects roughly coincident with the brightest regions of the cloud. Long-slit CCD spectra suggest that the L\u03b3a emission from the cloud has a large intrinsic width (FWHM \u2248 1000 km s^(-1)). Spectra taken in the red show weak extended emission from C II] and C III], but C IV emission has not been detected. The large equivalent width of L\u03b3a and the relative strengths of the carbon lines are consistent with H n region-type photoionization. We tentatively propose that 3C 326.1 is a young and/or forming galaxy.", "doi": "10.1086/184951", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1987-08-15", "volume": "319", "pages": "L39-L44" }, { "id": "authors:mjad1-tz689", "collection": "authors", "collection_id": "mjad1-tz689", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-083142685", "type": "article", "title": "Discovery of three obscured globular clusters", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "I report discovery of three previously uncataloged globular clusters n a direction of the Galactic Bulge. The clusters appear under a heavy foreground and extinction and are probably located close to the Galactic center. They are not associated with any known X-ray, \u03b3-ray, or IR sources, including the IRAS point sources. One of the clusters may have a postcollapse core.", "doi": "10.1086/184903", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1987-06-01", "volume": "317", "pages": "L13-L14" }, { "id": "authors:hycdr-xse25", "collection": "authors", "collection_id": "hycdr-xse25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-160805378", "type": "article", "title": "Mergers and starbursts at large redshifts - The case of 3C 368", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "Pedelty", "given_name": "J.", "clpid": "Pedelty-J" }, { "family_name": "Rudnick", "given_name": "L.", "clpid": "Rudnick-L" }, { "family_name": "Stockton", "given_name": "A.", "clpid": "Stockton-A" } ], "abstract": "We report the results of a multiwavelength study of the high-redshift radio galaxy 3C 368, which is observed at a lookback time of about two-thirds of the present galaxian age. This galaxy has optical and spectroscopic properties that are perhaps typical for the powerful 3CR galaxies at large redshifts (z > 1 ), though it is probably more luminous than the most, both in continuum and [O II]. Its resolved, multicomponent morphology of the starlight continuum and the [O II] \u03bb 3727 emission-line gas, and the properties of the ionized-gas velocity field, are suggestive of a strong and highly dissipative merger. There is a good positional and morphological coincidence between the line emission and the optical continuum. The proposed merger is probably enhancing the star formation over the whole galaxy (as evidenced by the large luminosity and the blue colors of the optical continuum), and may be the primary source of the fuel for, or even the trigger of, the strong radio emission from the system. The morphological and spectroscopic similarities with other 3CR galaxies at z > 1 suggest that spectacular merging was a common process in such systems at early epochs. The mergers may be identified with the process of transformation of (large?) E galaxies into cD's, and the epoch of such \"secondary\" formation of gE/cD galaxies may be signalled by the appearance of powerful radio sources at z ~ 1-2. The galaxy evolution models with a continuing star formation, suggested by the colors and magnitudes of high-redshift 3CR galaxies, may be understood in terms of a declining sequence of starbursts, stimulated by gas-rich mergers. There are also some indications of an ongoing interaction between the radio lobes and the ambient gas: both radio lobes show a prominent Faraday rotation and depolarization, probably caused by the intervening plasma along the line of sight. There is also a reasonable positional coincidence between the southern radio lobe and the emission-line gas. However, the evidence for an interaction between the radio plasma and the gas in the host galaxy is neither clear nor unambiguous.", "doi": "10.1086/114413", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1987-06", "series_number": "6", "volume": "93", "issue": "6", "pages": "1307-1317" }, { "id": "authors:gn02g-wkt18", "collection": "authors", "collection_id": "gn02g-wkt18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-155306435", "type": "article", "title": "Discovery of a binary quasar", "author": [ { "family_name": "Meylan", "given_name": "G.", "clpid": "Meylan-G" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Perley", "given_name": "R.", "clpid": "Perley-R-A" }, { "family_name": "McCarthy", "given_name": "P.", "clpid": "McCarthy-P" } ], "abstract": "The paper reports the discovery of a pair of quasars with a redshift of 1.345, separated by 4.2 arcsec in projection, apparently associated with the radio source PKS 1145-071. The imaging CCD, spectroscopic, and radio observations are presented. The possibility that this pair is situated towards a high-redshift galaxy cluster is discussed.", "issn": "0722-6691", "publisher": "European Southern Observatory", "publication": "Messenger", "publication_date": "1987-06", "volume": "48", "pages": "34-37" }, { "id": "authors:h7p0f-z7w77", "collection": "authors", "collection_id": "h7p0f-z7w77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190801-161709869", "type": "article", "title": "A galaxy at a redshift of 3.215 - Further studies of the PKS 1614+051 system", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Strauss", "given_name": "Michael A.", "orcid": "0000-0002-0106-7755", "clpid": "Strauss-M-A" }, { "family_name": "Perley", "given_name": "R. A.", "clpid": "Perley-R-A" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "McCarthy", "given_name": "Patrick", "clpid": "McCarthy-P-J" } ], "abstract": "A narrow-emission-line companion of the quasar PKS 1614 + 051 was reported earlier as a probable galaxy at a redshift of 3.218, which would have made it by far the most distant galaxy known at the time. We report here on new radio and optical imaging, and optical and near-IR spectroscopy of the PKS 1614 + 051 system. We argue that the data support and reinforce the original interpretation of the companion object as a mildly active galaxy, possibly a marginal Seyfert.2. The object has a detectable and marginally resolved optical continuum, but was not detected at radio .wavelengths. The ionization state is low, and the emission lines are fairly narrow. The improved redshift for the companion, based on the Ly\u03b1 line alone, is 3.215 \u00b1 0.002. New Ly\u03b1 images show interesting morphology of extended emission-line gas, suggestive of a possible tidal interaction with the neighboring QSO. Two other, fainter objects in the immediate proximity of the QSO may also be associated with the system. If this is the case, we may be seeing a group of galaxies in the early stages of formation.", "doi": "10.1086/114414", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1987-06", "series_number": "6", "volume": "93", "issue": "6", "pages": "1318-1325" }, { "id": "authors:14yaq-x2n98", "collection": "authors", "collection_id": "14yaq-x2n98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-160036947", "type": "article", "title": "Fundamental properties of elliptical galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Davis", "given_name": "Marc", "clpid": "Davis-M-E-Astro" } ], "abstract": "The global properties of elliptical galaxies, such as luminosity, radius, projected velocity dispersion, projected luminosity, etc., form a two-dimensional family. This 'fundamental plane' of elliptical galaxies can be defined in observable terms by the velocity dispersion and mean surface brightness. Its thickness is given by the present measurement error bars, and there are no significant indications of nonlinearity or higher dimensionality. This is indicative of a strong regularity in the process of galaxy formation. The equations of the plane can be used as new, substantially improved distance indicators for elliptical galaxies. However, all morphological parameters which describe the shape of the light distribution (ellipticity, elippticity gradient, isophotal twist rate, slope of the surface brightness profile) and reflect dynamical anisotropies of stars are completely independent of this fundamental plane. Thus, the elliptical galaxies are actually a '2 + N' parameter family. The M/L ratios correlate only with the velocity dispersions and show a small intrinsic scatter, perhaps only ~ 30 percent, in a luminosity range spanning some four orders of magnitude; this suggests a constant fraction of the dark matter contribution in elliptical galaxies.", "doi": "10.1086/164948", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1987-02-01", "volume": "313", "pages": "59-68" }, { "id": "authors:vs31e-7xm45", "collection": "authors", "collection_id": "vs31e-7xm45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-112106594", "type": "book_section", "title": "The Manifold of Elliptical Galaxies", "book_title": "Structure and Dynamics of Elliptical Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "De Zeeuw", "given_name": "Tim", "clpid": "De-Zeeuw-T" } ], "abstract": "Global properties of elliptical galaxies, such as the luminosity, radius, projected velocity dispersion, projected luminosity density, etc., form a two-dimensional family. This \"fundamental plane\" of elliptical galaxies can be defined by the velocity dispersion and mean surface brightness, and its thickness is presently given by the measurement error-bars only. This is indicative of a strong regularity in the process of galaxy formation. However, all morphological parameters which describe the shape of the distribution of light, and reflect dynamical anisotropics of stars, are completely independent from each other, and independent of the fundamental plane. The M/L ratios show only a small intrinsic scatter in a luminosity range spanning some four orders of magnitude; this suggests a constant fraction of the dark matter contribution in elliptical galaxies.", "doi": "10.1007/978-94-009-3971-4_6", "isbn": "978-90-277-2586-8", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1987", "pages": "79-88" }, { "id": "authors:q6g5c-qg117", "collection": "authors", "collection_id": "q6g5c-qg117", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-134127912", "type": "book_section", "title": "Morphological Properties of Elliptical Galaxies", "book_title": "Structure and Dynamics of Elliptical Galaxies", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "De Zeeuw", "given_name": "Tim", "clpid": "De-Zeeuw-T" } ], "abstract": "In the poster as presented at the meeting, I described global morphological properties of elliptical galaxies, based on the data from a CCD surface photometry survey of ~ 200 ellipticals and ~ 50 S0's (Djorgovski 1985). In this brief summary, I emphasize two points: (1) there is a very weak and very noisy trend of radial shape with luminosity, in the sense that more luminous galaxies are less concentrated, and (2) there is no preference for low-luminosity ellipticals to show boxy isophotes, and they differ in that respect from the bulges.", "doi": "10.1007/978-94-009-3971-4_31", "isbn": "978-90-277-2586-8", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1987", "pages": "377-378" }, { "id": "authors:x5zjq-jr906", "collection": "authors", "collection_id": "x5zjq-jr906", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-133248082", "type": "book_section", "title": "The Status of the Hubble Diagram In 1986", "book_title": "Observational Cosmology", "author": [ { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Hewitt", "given_name": "Adelaide", "clpid": "Hewitt-A" }, { "family_name": "Burbidge", "given_name": "Geoffrey", "clpid": "Burbidge-G" }, { "family_name": "Fang", "given_name": "Li Zhi", "clpid": "Fang-Li-Zhi" } ], "abstract": "We present visual and near-infrared Hubble diagrams for first- ranked cluster galaxies, and moderate-flux and high-flux radio galaxies. The photometric improvements and the extension of the diagrams to large redshifts (up to z \u2243 1.8) for both 3CR and \"1 Jy\" class radio galaxies are highlighted. The absolute luminosities of these three types of \"standard candles\", where their redshifts overlap, agree adequately. The near-IR (2\u03bcm) Hubble diagrams may be used to determine the global deceleration parameter, q_O, and the current data favor q_O ~ +0.2 to +0.3. The sensitivity to evolutionary changes in the giant galaxies is quite modest at these long wavelengths. On the other hand, the visual regime (BV R) shows a dramatic dependence on differential evolution effects, which dominate over the cosmological model differences. Most radio galaxies apparently have had active star formation, with a continually declining rate, but a few are quite faint and red; they may have had a relatively passive evolution.", "doi": "10.1007/978-94-009-3853-3_11", "isbn": "978-90-277-2476-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1987", "pages": "129-141" }, { "id": "authors:qqymb-4xp55", "collection": "authors", "collection_id": "qqymb-4xp55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-113250234", "type": "book_section", "title": "Coherent Orientation Effects of Galaxies and Clusters", "book_title": "Nearly Normal Galaxies - From the Planck Time to the Present", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Faber", "given_name": "S. M.", "clpid": "Faber-S-M" } ], "abstract": "Properties and distribution of galaxies on large scales appear to be an exercise in randomness. Our favorite quantifiers of these things, the correlation functions, are a little more than noise spectrum descriptors. It is thus not surprising that we are suspicious about any signs or reports of systematic coherence in that noisy world. Galaxy alignments in particular are prone to evoke skepticism. This is in the best spirit of a healthy scientific conservativism, but with a smattering of hypocrisy as well. The order out of chaos is really what we are hoping for, after all. To be more specific, any systematic behavior of \"inborn\" galaxian properties (that is, not acquired by subsequent evolution, e.g., by the ram-pressure stripping and its consequences) that depend on the large-scale environment would be a strong evidence in favor of the top-down formation scenarios; at most, galaxies and their parent large-scale structure could form at the same time, but the bottom-up scenarios would be in great difficulty to explain any such phenomena. Therein lies the deeper reason why most reports of large-scale coherence were greeted with doubts or controversy: due to a misfortunate historical accident, the theoretical cosmogony in english-speaking countries was stuck upon the hierarchical, bottom-up formation scenarios, and there is perhaps some inertia of belief, which mere data cannot shake too easily. To be fair, the burden of the proof is with the observers.", "doi": "10.1007/978-1-4612-4762-3_28", "isbn": "978-1-4612-9145-9", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "1987", "pages": "227-233" }, { "id": "authors:gzvbs-2jz24", "collection": "authors", "collection_id": "gzvbs-2jz24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-132000680", "type": "book_section", "title": "Galaxies at Very High Redshifts (z > 1)", "book_title": "Nearly Normal Galaxies - From the Planck Time to the Present", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Faber", "given_name": "S. M.", "clpid": "Faber-S-M" } ], "abstract": "Observational cosmology is partly based upon wishful thinking. (I am not even going to hint on what is the theoretical cosmology based.) This is, perhaps, inevitable: most, if not all, cosmological tests seem to require idealized test particles or conditions, and there is much skill in coming up with a setup which is the least unrealistically oversimplified. Some classical tests, such as the m vs. z diagram, require the \"standard candles\", that is, sources of light whose intrinsic behavior is well understood, and which span a large baseline in redshift. QSO's are much too finicky, variable, and poorly understood to serve in this role; and ever since the days of Hubble, giant elliptical galaxies were a favorite choice. They seem to qualify, since they are luminous, and can be spotted at high redshifts; this is made easier by the facts that they are often found in rich clusters, and sometimes have powerful radio lobes. Moreover, here and now (z \u2243 0) they seem to live apparently clean and quiet lives, with no ongoing star formation, no optically thick dust, etc. On a closer look this simplicity disappears, but we cannot be too picky now.", "doi": "10.1007/978-1-4612-4762-3_34", "isbn": "978-1-4612-9145-9", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "1987", "pages": "290-299" }, { "id": "authors:348yr-2h492", "collection": "authors", "collection_id": "348yr-2h492", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-090635359", "type": "book_section", "title": "Enhancement Of Features In Galaxy Images", "book_title": "Instrumentation in Astronomy VI", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Crawford", "given_name": "David L.", "clpid": "Crawford-D-L" } ], "abstract": "I describe and compare several image enhancement techniques, useful for morphological analysis of galaxian (or cometary) images. Such techniques can be used to search for, and investigate the properties of dust lanes, stellar disks or rings, jets, shells, tidal distortions, etc. Applications of the techniques are illustrated on CCD images of the peculiar galaxy Arp 230; this object has a rich morphology, indicative of a merger of two disk galaxies.", "doi": "10.1117/12.968146", "isbn": "9780892526628", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1986-10-13", "pages": "674-679" }, { "id": "authors:c8p2z-v5q41", "collection": "authors", "collection_id": "c8p2z-v5q41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-153336036", "type": "article", "title": "Self-regulated cooling flows in elliptical galaxies and in cluster cores - Is exclusively low mass star formation really necessary?", "author": [ { "family_name": "Silk", "given_name": "Joseph", "clpid": "Silk-J" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Wyse", "given_name": "Rosemary F. G.", "clpid": "Wyse-R-F-G" }, { "family_name": "Bruzual A.", "given_name": "Gustavo", "clpid": "Bruzual-A-G" } ], "abstract": "A self-consistent treatment of the heating by supernovae associated with star formation in a spherically symmetric cooling flow in a cluster core or elliptical galaxy is presented. An initial stellar mass function similar to that in the solar neighborhood is adopted. Inferred star-formation rates, within the cooling region - typically the inner 100 kpc around dominant galaxies at the centers of cooling flows in XD clusters - are reduced by about a factor of 2, relative to rates inferred when the heat input from star formation is ignored. Truncated initial mass functions (IMFs) are also considered, in which massive star formation is suppressed in accordance with previous treatments, and colors are predicted for star formation in cooling flows associated with central dominant elliptical galaxies and with isolated elliptical galaxies surrounded by gaseous coronae. The low inferred cooling-flow rates around isolated elliptical galaxies are found to be insensitive to the upper mass cutoff in the IMF, provided that the upper mass cutoff exceeds 2 M\u2299. Comparison with observed colors favors a cutoff in the IMF above 1 M\u2299 in at least two well-studied cluster cooling flows, but a normal IMF cannot be excluded definitively. Models for NGC 1275 support a young (\u227e 3 Gyr) cooling flow. As for the isolated elliptical galaxies, the spread in colors is consistent with a normal IMF. A definitive test of the IMF arising via star formation in cooling flows requires either UV spectral data or supernova searches in the cooling-flow-centered galaxies.", "doi": "10.1086/164430", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1986-08-15", "volume": "307", "pages": "415-426" }, { "id": "authors:nc3gh-tw626", "collection": "authors", "collection_id": "nc3gh-tw626", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-152940078", "type": "article", "title": "A preliminary survey of collapsed cores in globular clusters", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "King", "given_name": "Ivan R.", "clpid": "King-I-R" } ], "abstract": "This is a preliminary report on surface photometry of the major fraction of known globular clusters, to see which of them show the signs of a collapsed core. The authors find more than 20 examples, or one-fifth of the total. Core classifications are given for all clusters examined. The fraction of collapsed-core clusters may be an index of how long a cluster takes to reexpand after collapse.", "doi": "10.1086/184685", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1986-06-15", "volume": "305", "pages": "L61-L65" }, { "id": "authors:qd6zm-vwc14", "collection": "authors", "collection_id": "qd6zm-vwc14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-141825769", "type": "article", "title": "No optical pulses from the Geminga candidate", "author": [ { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "We have conducted several optical studies of a 21 mag star suggested to be the optical counterpart of the pulsed x-ray source IE 0630 + 178 and the \u03b3-ray source 2CG 195 + 04 (Geminga). We report the absence of significant optical pulsed emission over the entire period range claimed from the analysis of high-energy data. We also find no significant variability on time scales from tens of minutes to a few months. We suggest that the true optical counterpart of the x-ray source is either one of the two fainter stars in the x-ray source error box or an as yet undetected fainter star. In either case, IE 0630 + 178 is a unique x-ray source because its ratio of L_x (0.2-2.0 keV)/L_v (3000-7000 \u00c5) is at least 1100, which is characteristic of galactic-bulge x-ray sources. However, its absolute magnitude is at least about M_v ~ 20 and not M_v ~ 3 mag, typical of the bulge sources.", "doi": "10.1086/113987", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1986-01", "series_number": "1", "volume": "91", "issue": "1", "pages": "98-106" }, { "id": "authors:pfspe-z4w82", "collection": "authors", "collection_id": "pfspe-z4w82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-135518536", "type": "article", "title": "Optical study of the Geminga candidate field", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" } ], "abstract": "We have observed the field of the x-ray source IE 0630 + 178, proposed as a probable counterpart of the \u03b3-ray source 2CG 195+04 (Geminga). Deep CCD images of the field show two very faint optical sources within the x-ray error circle, as well as the 21 mag star (hereafter referred to as the G candidate) proposed earlier as the possible optical counterpart. The G candidate does not have a proper motion greater than 0.15 arcsec yr^(-1). The spectrum of this object shows no strong emission or absorption features. We conclude that the G candidate is most probably a distant G dwarf or a nearby, cool, white dwarf. We believe that one of the fainter objects within the x-ray circle is more likely to be the true counterpart of the x-ray source, and possibly of the \u03b3-ray source as well. This result is consistent with the interpretation of Geminga as a nearby neutron star, if all the \u03b3 rays are generated by some nonthermal mechanism. Deep H\u03b1 images do not reveal presence of any emission-line nebulosity (e.g., a supernova remnant).", "doi": "10.1086/113986", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1986-01", "series_number": "1", "volume": "91", "issue": "1", "pages": "90-97" }, { "id": "authors:83h66-5ng31", "collection": "authors", "collection_id": "83h66-5ng31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-134431074", "type": "article", "title": "The redshift of the highly variable BL Lac object H0323+022", "author": [ { "family_name": "Filippenko", "given_name": "Alexei V.", "orcid": "0000-0003-3460-0103", "clpid": "Filippenko-A-V" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" } ], "abstract": "New optical spectra are used to derive the redshift of H0323 + 022, a bright, highly variable x-ray source whose nature has been the subject of controversy. Most of the spectra are dominated by a featureless nonstellar continuum, as found in BL Lac objects. Photometric variations of \u22732 mag have been seen over a time interval of only 2 days. The nonstellar light is sometimes faint enough to allow the detection of absorption lines at a redshift z = 0.1471 + 0.0005. These lines are clearly due to stars in the host galaxy, which is easily visible in deep images of the object. The galaxy is probably a relatively normal elliptical with M_v \u2248 -21 to -22, except that a noticeable extension is evident in one quadrant. On 24.15 February 1985 UT, the nonstellar continuum could be described by a power law of index a \u2248 0.6 (where f_v \u221d v -\u03b1); its relative strength in the nucleus (2\" X 5.2\") was ~62% at 5460 \u00c5, while M_v \u2248 -22 to -23. When the power-law component fades, its slope appears to steepen. There is now no doubt that H0323 + 022 is a BL Lac object, rather than a peculiar Galactic star. As discussed by Feigelson et al. (1986), its extremely rapid variability (\u0394L \u2248 1 X 10^(45) erg s^(-1) in \u0394t \u2248 30 s) is matched only by that of OJ 287, and the hard x rays must come from a region roughly a factor of 10^4 smaller than that which produces the radio emission.", "doi": "10.1086/113977", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1986-01", "series_number": "1", "volume": "91", "issue": "1", "pages": "49-55" }, { "id": "authors:sj0sf-4w336", "collection": "authors", "collection_id": "sj0sf-4w336", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-142850045", "type": "book_section", "title": "Surface Photometry Surveys of Galaxies with Small Telescopes", "book_title": "Instrumentation and Research Programmes for Small Telescopes", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Hearnshaw", "given_name": "J. B.", "clpid": "Hearnshaw-J-B" }, { "family_name": "Cottrell", "given_name": "P. L.", "clpid": "Cottrell-P-L" } ], "abstract": "Surface photometry of relatively bright galaxies is now becoming almost an exclusive province of small telescopes equipped with CCDs. I give a brief review of the scientific possibilities and problems of interest in this field. Small telescopes become tools of observational cosmology: they can provide large amounts of data necessary for the further understanding of fundamental properties of galaxies, clues to their formation, and their interactions with environment.", "doi": "10.1007/978-94-010-9433-7_41", "isbn": "978-90-277-2325-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "243-245" }, { "id": "authors:cpv1w-nrd47", "collection": "authors", "collection_id": "cpv1w-nrd47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-140306264", "type": "book_section", "title": "A Search for Features in Early-Type Galaxies", "book_title": "Instrumentation and Research Programmes for Small Telescopes", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ebneter", "given_name": "K.", "clpid": "Ebneter-K" } ], "contributor": [ { "family_name": "Hearnshaw", "given_name": "J. B.", "clpid": "Hearnshaw-J-B" }, { "family_name": "Cottrell", "given_name": "P. L.", "clpid": "Cottrell-P-L" } ], "abstract": "We are conducting a search for dust lanes, incipient stellar disks and bars, and other deviations from elliptical symmetry in a sample ~ 250 early-type galaxies. Division by a model galaxy image is a very powerful enhancement technique for this type of work.", "doi": "10.1007/978-94-010-9433-7_52", "isbn": "978-90-277-2325-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "277-279" }, { "id": "authors:1rqvw-sm030", "collection": "authors", "collection_id": "1rqvw-sm030", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-135459615", "type": "book_section", "title": "Galaxy Surface Brightness and Clustering: A Test for Biased Galaxy Formation Scenarios?", "book_title": "Galaxy Distances and Deviations from Universal Expansion", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Davis", "given_name": "Marc", "clpid": "Davis-M-E-Astro" } ], "contributor": [ { "family_name": "Madore", "given_name": "Barry F.", "clpid": "Madore-B-F" }, { "family_name": "Tully", "given_name": "R. Breant", "clpid": "Tully-R-B" } ], "abstract": "Davis & Djorgovski (1985) described a correlation, between the clustering properties and characteristic surface brightness of UGC galaxies. The existence of such an effect is of considerable importance for theories of galaxy formation. In this contribution., we are trying to clarify some questions and problems about this intriguing phenomenon.", "doi": "10.1007/978-94-009-4702-3_49", "isbn": "978-94-010-8591-5", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "291-294" }, { "id": "authors:42x6w-ew534", "collection": "authors", "collection_id": "42x6w-ew534", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-144844274", "type": "book_section", "title": "The Structure of Globular Clusters", "book_title": "Instrumentation and Research Programmes for Small Telescopes", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "King", "given_name": "I. R.", "clpid": "King-I-R" }, { "family_name": "Vuosalo", "given_name": "C.", "clpid": "Vuosalo-C" }, { "family_name": "Oren", "given_name": "A.", "clpid": "Oren-A" }, { "family_name": "Penner", "given_name": "H.", "clpid": "Penner-H" } ], "contributor": [ { "family_name": "Hearnshaw", "given_name": "J. B.", "clpid": "Hearnshaw-J-B" }, { "family_name": "Cottrell", "given_name": "P. L.", "clpid": "Cottrell-P-L" } ], "abstract": "We report the preliminary results of a CCD surface photometry survey of a large fraction of all known Galactic globular clusters. About 1/5 of all surveyed clusters show a characteristic post-core-collapse (PCC) morphology. The PCC clusters are on average closer to the Galactic center than the King-mode1\u20131ike clusters.", "doi": "10.1007/978-94-010-9433-7_53", "isbn": "978-90-277-2325-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "281-282" }, { "id": "authors:6vk58-9s429", "collection": "authors", "collection_id": "6vk58-9s429", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-134541007", "type": "book_section", "title": "An Improved Distance Indicator for Elliptical Galaxies", "book_title": "Galaxy Distances and Deviations from Universal Expansion", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Davis", "given_name": "Marc", "clpid": "Davis-M-E-Astro" } ], "contributor": [ { "family_name": "Madore", "given_name": "Barry F.", "clpid": "Madore-B-F" }, { "family_name": "Tully", "given_name": "R. Breant", "clpid": "Tully-R-B" } ], "abstract": "We present a new relation between velocity dispersion, surface brightness, and radius (or luminosity) for elliptical galaxies. Relative distances of galaxies can be estimated to within 0.13 in log D. Most or all of that uncertainity is due to the measurement errors, and it may be reduced further. Our analysis shows that the elliptical galaxies are at least a three-parameter family. We discuss briefly the implications for theories of galaxy formation.", "doi": "10.1007/978-94-009-4702-3_24", "isbn": "978-94-010-8591-5", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "135-138" }, { "id": "authors:kmffx-0a529", "collection": "authors", "collection_id": "kmffx-0a529", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-143015831", "type": "book_section", "title": "Surface Photometry Surveys of Galaxies with Small Telescopes", "book_title": "Instrumentation and Research Programmes for Small Telescopes", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "contributor": [ { "family_name": "Hearnshaw", "given_name": "J. B.", "clpid": "Hearnshaw-J-B" }, { "family_name": "Cottrell", "given_name": "P. L.", "clpid": "Cottrell-P-L" } ], "abstract": "Surface photometry of relatively bright galaxies is now becoming almost an exclusive province of small telescopes equipped with CCDs. I give a brief review of the scientific possibilities and problems of interest in this field. Small telescopes become tools of observational cosmology: they can provide large amounts of data necessary for the further understanding of fundamental properties of galaxies, clues to their formation, and their interactions with environment.", "doi": "10.1007/978-94-010-9433-7_41", "isbn": "978-90-277-2325-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "243-245" }, { "id": "authors:jxhfr-hv490", "collection": "authors", "collection_id": "jxhfr-hv490", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-143658143", "type": "book_section", "title": "A Search for Features in Early-Type Galaxies", "book_title": "Instrumentation and Research Programmes for Small Telescopes", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Ebneter", "given_name": "K.", "clpid": "Ebneter-K" } ], "contributor": [ { "family_name": "Hearnshaw", "given_name": "J. B.", "clpid": "Hearnshaw-J-B" }, { "family_name": "Cottrell", "given_name": "P. L.", "clpid": "Cottrell-P-L" } ], "abstract": "We are conducting a search for dust lanes, incipient stellar disks and bars, and other deviations from elliptical symmetry in a sample ~ 250 early-type galaxies. Division by a model galaxy image is a very powerful enhancement technique for this type of work.", "doi": "10.1007/978-94-010-9433-7_52", "isbn": "978-90-277-2325-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "277-279" }, { "id": "authors:38g8r-x7424", "collection": "authors", "collection_id": "38g8r-x7424", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-143608851", "type": "book_section", "title": "The Structure of Globular Clusters", "book_title": "Instrumentation and Research Programmes for Small Telescopes", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "King", "given_name": "I. R.", "clpid": "King-I-R" }, { "family_name": "Vuosalo", "given_name": "C.", "clpid": "Vuosalo-C" }, { "family_name": "Oren", "given_name": "A.", "clpid": "Oren-A" }, { "family_name": "Penner", "given_name": "H.", "clpid": "Penner-H" } ], "contributor": [ { "family_name": "Hearnshaw", "given_name": "J. B.", "clpid": "Hearnshaw-J-B" }, { "family_name": "Cottrell", "given_name": "P. L.", "clpid": "Cottrell-P-L" } ], "abstract": "We report the preliminary results of a CCD surface photometry survey of a large fraction of all known Galactic globular clusters. About 1/5 of all surveyed clusters show a characteristic post-core-collapse (PCC) morphology. The PCC clusters are on average closer to the Galactic center than the King-model\u2013like clusters.", "doi": "10.1007/978-94-010-9433-7_53", "isbn": "978-90-277-2325-3", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1986", "pages": "281-282" }, { "id": "authors:cn0k3-4nz37", "collection": "authors", "collection_id": "cn0k3-4nz37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-132121025", "type": "article", "title": "Galaxy clustering as a function of surface brightness", "author": [ { "family_name": "Davis", "given_name": "Marc", "clpid": "Davis-M-E-Astro" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Using diameters and magnitudes of galaxies listed in the Nilson catalog, the angular correlation properties of highand low-surface brightness galaxies are examined. The low-surface brightness galaxies are less tightly clumped than the higher surface brightness galaxies; they also fill in some conspicuous holes in the distribution of the high-surface brightness galaxies. The angular correlations are weaker and shallower for the low-surface brightness galaxies; when account is taken for the differing redshift distribution of the subsets, it is found that the spatial clustering length scale is a factor of two smaller than for the high-surface brightness galaxies. This finding demonstrates that galaxy formation must have been dependent on the large-scale clustering environment and suggests that the luminous galaxy distribution may not be a fair tracer of the mass distribution on any scale. Although the effect is apparent from the sky-projected angular correlations, the relative amplitudes of the spatial clustering must be regarded as preliminary because they are derived from an incomplete and possibly biased redshift sample.", "doi": "10.1086/163678", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1985-12-01", "volume": "299", "pages": "15-20" }, { "id": "authors:kprj0-k9m88", "collection": "authors", "collection_id": "kprj0-k9m88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-132632340", "type": "article", "title": "Discovery of a probable galaxy with a redshift of 3.218", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "McCarthy", "given_name": "Patrick", "clpid": "McCarthy-P-J" }, { "family_name": "Strauss", "given_name": "Michael A.", "orcid": "0000-0002-0106-7755", "clpid": "Strauss-M-A" } ], "abstract": "We report the discovery of a narrow emission line object, probably a galaxy, with a redshift of 3.218. The object is a companion to the quasar PKS 1614 + 051, which is at a redshift of 3.209. This is the most distant non-QSO, non-gravitationally lensed object presently known by a large margin. Its properties are consistent with those expected of a high-redshift galaxy. This object has an age of only a few percent of the present age of the universe. The object was discovered with a novel technique, which promises to push studies of distant galaxies to redshifts as high as those of the most distant quasars known, and which may eventually lead to the discovery of primeval galaxies. This discovery opens the way for studies of galaxies beyond z = 3, which should prove invaluable for observational cosmology.", "doi": "10.1086/184569", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1985-12-01", "volume": "299", "pages": "L1-L5" }, { "id": "authors:cyycm-nkw48", "collection": "authors", "collection_id": "cyycm-nkw48", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-125856656", "type": "article", "title": "Calibration of the Lick red CCD bandpasses", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Red bandpasses indigenous to the Lick Observatory CCD imaging and photometry are defined and described. A set of primary calibration standards which define the magnitude zero points is presented. Color equations, relating these bandpasses to the other, commonly used photometric systems are evaluated by numerical integration of stellar spectra, and compared to the real data. It is estimated that the present calibration is accurate and consistent to about 2-3 percent as a magnitude predictor, if the primary standards are used; this accuracy is only about 3-5 percent if VR photometry is used for calibration, and only about 5-8 percent if BV photometry is used. (These estimates do not include the errors of measurement). This is sufficient for most scientific applications of data taken in these bandpasses, although it may be improved somewhat in a future work.", "doi": "10.1086/131674", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1985-11", "series_number": "597", "volume": "97", "issue": "597", "pages": "1119-1126" }, { "id": "authors:9khhw-gxf27", "collection": "authors", "collection_id": "9khhw-gxf27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-124407658", "type": "article", "title": "A third update of the status of the 3CR sources - Further new redshifts and new identifications of distant galaxies", "author": [ { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Marr", "given_name": "J.", "clpid": "Marr-J" }, { "family_name": "Aguilar", "given_name": "L.", "clpid": "Aguilar-L" } ], "abstract": "We present the third major update of new optical and radio data for the strong sources in the Revised Third Cambridge Catalogue (hereafter 3CR). New positions, redshifts, magnitudes, and identifications have been included as well as some radio data for the sample of 298 extragalactic 3CR sources. A new and extended bibliography of optical and radio data is included. The 3CR sources have now reached an almost satisfactory state of optical identification; 91% of the sources at midbmid > 10\u00b0 now have firm identifications and we have spectra for most of them. The few remaining faint objects at high latitudes are, of course, important, as they tend to be the most luminous radio sources known. Full completion of the 3CR data will aid in reducing the residual uncertainties at the luminous end of the evolving radio luminosity ftinction. Finally, we present some new identifications and new spectroscopic data for 29 faint 3CR galaxies, and one quasar.", "doi": "10.1086/131647", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1985-10", "series_number": "596", "volume": "97", "issue": "596", "pages": "932-961" }, { "id": "authors:ebzw5-p7h83", "collection": "authors", "collection_id": "ebzw5-p7h83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-080907206", "type": "article", "title": "Surface photometry of comet P/Encke", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" } ], "abstract": "We have developed a scheme to clean cometary digital images from offending background-star trails, and applied this technique to a pair of deep Kitt Peak 4-m plates of comet P/Encke, taken in October 1980. Simultaneous and subsequent digital spectra have been obtained at Lick Observatory. The non-polluted coma images show a strong asymmetric sunward-oriented fan/jet, and an extended and\nrounder (mostly gaseous) main coma, out to ~ 10^5 km radius. The stellar-trail point-spread function has a narrow width (\u03c37~0.6 arcsec), so that spatial resolution better than ~300 km is achieved at the comet. The photometric gradient near the nucleus is very steep, strongly suggesting an icy-grain component which evaporates quickly (at radii \u2a7d 500 km) in the sunlight. Further from the nucleus, the profile becomes shallower, bluer, and more gas dominated. The effect of solar radiation pressure on C_2, CN, and other molecules is probably responsible for the rounding of the outer, faint isophotes. The source of the molecules is likely to be larger than the nucleus itself, and a substantial fraction may originate in the jet. The technique described here may also be applicable in surface photometry of galaxies, in cases where the heavy image pollution by foreground stars is present.", "doi": "10.1086/113795", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1985-05", "series_number": "5", "volume": "90", "issue": "5", "pages": "869-876" }, { "id": "authors:2d5mj-0p220", "collection": "authors", "collection_id": "2d5mj-0p220", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-080143308", "type": "book_section", "title": "A Search for Post-Collapse Cores", "book_title": "Dynamics of Star Clusters", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Penner", "given_name": "H.", "clpid": "Penner-H" } ], "contributor": [ { "family_name": "Goodman", "given_name": "Jeremy", "clpid": "Goodman-J" }, { "family_name": "Hut", "given_name": "Piet", "clpid": "Hut-P" } ], "abstract": "We report the preliminary results of a surface photometry survey of globular cluster cores. Two new cores with post-collapse morphology have been found, and two possible candidates. The estimated fraction of clusters with this core morphology in the Galaxy is only a few percent. Most clusters do not show a morphology similar to the predictions of the central black hole models.", "doi": "10.1007/978-94-009-5335-2_8", "isbn": "978-90-277-1965-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1985", "pages": "73-76" }, { "id": "authors:g10n5-y9g79", "collection": "authors", "collection_id": "g10n5-y9g79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-144230449", "type": "book_section", "title": "A Search for Post-Collapse Cores", "book_title": "Dynamics of Star Clusters", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Penner", "given_name": "H.", "clpid": "Penner-H" } ], "contributor": [ { "family_name": "Goodman", "given_name": "Jeremy", "clpid": "Goodman-J" }, { "family_name": "Hut", "given_name": "Piet", "clpid": "Hut-P" } ], "abstract": "We report the preliminary results of a surface photometry survey of globular cluster cores. Two new cores with post-collapse morphology have been found, and two possible candidates. The estimated fraction of clusters with this core morphology in the Galaxy is only a few percent. Most clusters do not show a morphology similar to the predictions of the central black hole models.", "doi": "10.1007/978-94-009-5335-2_8", "isbn": "978-90-277-1965-2", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "1985", "pages": "73-76" }, { "id": "authors:73wk8-d4m68", "collection": "authors", "collection_id": "73wk8-d4m68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-131706914", "type": "book_section", "title": "Observing the galaxy evolution at high redshifts", "book_title": "New Aspects of Galaxy Photometry", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" }, { "family_name": "Marr", "given_name": "J.", "clpid": "Marr-J" } ], "contributor": [ { "family_name": "Nieto", "given_name": "Jean-Luc", "clpid": "Nieto-J-L" } ], "abstract": "Magnitudes and colors for a sample of distant 3CR radio-galaxies, with redshifts up to z=1.82, show very dramatic evidence for luminosity and color evolution of these objects. Cosmological differences are small compared to the detected evolutionary effects. Elongated shapes and very extended (both in space and velocity) [0 II] emission lines suggest violent merging activity at the early epochs, and possibly mark the beginnings of activity of powerful radio-galaxies.", "doi": "10.1007/BFb0030942", "isbn": "978-3-540-15657-4", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1985", "pages": "193-198" }, { "id": "authors:q7atb-3ww02", "collection": "authors", "collection_id": "q7atb-3ww02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-092528442", "type": "book_section", "title": "Morphological investigation of elliptical galaxies", "book_title": "New Aspects of Galaxy Photometry", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Davis", "given_name": "M.", "clpid": "Davis-M" }, { "family_name": "Kent", "given_name": "S.", "clpid": "Kent-S" } ], "contributor": [ { "family_name": "Nieto", "given_name": "Jean-Luc", "clpid": "Nieto-J-L" } ], "abstract": "We describe the two large surface photometry surveys of elliptical galaxies, completed at Mt. Hopkins and Lick observatories. These comprise the largest such surveys of early-type galaxies to this date, and will provide us with a large set of uniform quality data for a variety of statistical and dynamical studies. We discuss briefly some results from the Mt. Hopkins survey.", "doi": "10.1007/bfb0030953", "isbn": "978-3-540-15657-4", "publisher": "Springer", "place_of_publication": "Berlin", "publication_date": "1985", "pages": "257-262" }, { "id": "authors:b21pq-ss873", "collection": "authors", "collection_id": "b21pq-ss873", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190731-075239616", "type": "article", "title": "Spectroscopy of extremely distant radio galaxies", "author": [ { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "In this Letter we report the firm identification of two faint radio galaxies, 3C 13 and 3C 256, and a spectroscopic survey of 13 faint 3CR galaxies. The emission-line redshifts now extend up to z = 1.82 (3C 256), and we here present a list and a preliminary spectrum summary of the character of 11 new radio galaxies with z > 0. 77. About half of these luminous galaxies show low ionization emission-line spectra. Their strong [O II] lines can have luminosities up to 9 x 10^(43) ergs s^(-1) ; the emitted UV spectra have a much \"softer\" ionizing radiation field than those of QSOs and Seyfert nuclei. The spectra are of the narrow-line variety, with FWHM \u2264 1000 km s^(-1). The strong [O II] emission is often much extended and inclined, showing a considerable velocity amplitude. The most extreme cases are 3C 324 and 3C 267 (both with z > 1.0), but the phenomenon is\nmoderately frequent. These are the most distant (non-QSO) galaxies known, and we can now extend the cosmological and galaxy evolution tests into previously unprobed territory.", "doi": "10.1086/184363", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1984-10-15", "volume": "285", "pages": "L49-L52" }, { "id": "authors:4pv0p-j6q12", "collection": "authors", "collection_id": "4pv0p-j6q12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-161718898", "type": "article", "title": "Discovery of a new gravitational lens", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" } ], "abstract": "The faint QSO pair 1635 + 267 A + B, discovered in a slitless spectroscopy survey by Weedman (1982), are found to be at practically the same redshift of 1.961 \u00b1 0.003. Their redshift difference, determined with a cross-correlation technique, is found to be (3.2 \u00b1 8.5) x 10^(-4), which corresponds to a rest-frame velocity difference of only (33 \u00b1 86) km s^(-1). This low value and the similarity of the spectra strongly argue that this is another case of a gravitational lens. Deep CCD images do not reveal the presence of a lensing object more than an arcsec away from either QSO image down to a red magnitude of 23.5. An absorption feature in the spectrum of the brighter QSO image may be a signature of the lens galaxy. This line is interpreted as the Mg II \u03bb 2799 doublet, seen at redshift z_(lens) = 1.118.", "doi": "10.1086/184291", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1984-07-01", "volume": "282", "pages": "L1-L4" }, { "id": "authors:0dq9m-m1g72", "collection": "authors", "collection_id": "0dq9m-m1g72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-160825334", "type": "article", "title": "3C 324 - an extremely distant cluster radio galaxy", "author": [ { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "The strong radio source 3C 324 is identified with a faint cluster galaxy, with V \u2248 22.6. Our new CCD spectroscopic data yield an emission-line redshift, z_e = 1.2063. The emission spectrum is narrow-line and shows a characteristic low-ionization level. The strong [O II] fine is both spatially and velocity resolved in 3C 324; a\nspeculative hypothesis on its origin in a rotating and possibly captured gas disk or an infalling galaxy is advanced. The detection of a cluster around 3C 324 is discussed.", "doi": "10.1086/184258", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1984-05-01", "volume": "280", "pages": "L9-L12" }, { "id": "authors:z7bxw-zq947", "collection": "authors", "collection_id": "z7bxw-zq947", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-091813861", "type": "article", "title": "Searches for optical counterparts of the two millisecond pulsars", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" } ], "abstract": "The first millisecond pulsar, 1937+214, has given rise to much observational and theoretical excitement (reviewed in ref. 2). A 20th magnitude red object was proposed earlier as a possible optical counterpart, but we show here that this is not the case: this object is probably a giant star at a distance of 5\u20136 kpc. There is no evidence for an optical source brighter than the 23rd red magnitude at the improved optical position. We also present results of the search for the optical counterpart of the new millisecond pulsar 1953+290. A grid of astrometric offset stars for this source is given, and possibility of optical detection discussed.", "doi": "10.1038/306569a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1983-12-08", "series_number": "5943", "volume": "306", "issue": "5943", "pages": "569-571" }, { "id": "authors:ks0ma-zad72", "collection": "authors", "collection_id": "ks0ma-zad72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-073459410", "type": "article", "title": "Modelling of seeing effects in extragalactic astronomy and cosmology", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Convolution methods for modelling of astronomical seeing effects have been investigated. The advantages and disadvantages of several techniques are discussed, and particular attention is given to the fast Fourier transform (FFT) method. This method is then applied to two classes of problems, the structure of cores of elliptical galaxies, appearance of distant galaxies and the consequences of seeing effects in some cosmological tests. Estimates are presented for dimming of the central surface brightness and changes in the apparent core radius for elliptical galaxies, as well as seeing-induced changes in ellipticity. Modelling of galaxies with stellar nuclei has also been performed. Some consequences of these effects in investigations of dynamics of elliptical galaxies are addressed briefly. The influence of seeing in observational cosmology is discussed in the context of Hubble diagram (m-z) tests. It is shown that inadequate compensation for seeing effects can seriously distort the conclusions in such tests. Some suggestions for future work in this direction are offered.", "doi": "10.1007/bf02714921", "issn": "0250-6335", "publisher": "Indian Academy of Sciences", "publication": "Journal of Astrophysics and Astronomy", "publication_date": "1983-12", "series_number": "4", "volume": "4", "issue": "4", "pages": "271-288" }, { "id": "authors:ccv9j-46h70", "collection": "authors", "collection_id": "ccv9j-46h70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-160032192", "type": "article", "title": "Alignment of galaxies in the Coma Cluster", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Analysis of photometry data of the Coma Cluster galaxies shows a prominent effect of galaxy alignment with the cluster itself. The effect shows strong dependence on galaxy position within the cluster, galaxy, luminosity, and, to a lesser degree, color. Galaxies also show a tendency to point toward their nearest neighbors. Quantitative analysis of these effects is presented. Independent measurements of position angles in a small subset of data have been performed. Possible spurious causes for anisotropy are discussed, and it is argued that the effect is real. Weak tendencies found by the earlier authors are in agreement with the results reported here. This effect gives strong support to the adiabatic (fragmentation) picture of galaxy and cluster formation.", "doi": "10.1086/184140", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1983-11-01", "volume": "274", "pages": "L7-L11" }, { "id": "authors:adgsc-pqm05", "collection": "authors", "collection_id": "adgsc-pqm05", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190723-091332594", "type": "article", "title": "Optical identification of the millisecond pulsar 1937+214", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" } ], "abstract": "Backer et al. have reported the discovery of a pulsar with the period of 1.558 ms, identified with the source 1937 + 214 (=4021.53). The extreme rotational velocity and high energy loss rate of this object make it a very interesting astrophysical phenomenum not only as an important clue for the physics of neutron stars and supernova remnants, but also as a potential strong emitter of gravitational radiation (S. White and J. Arons, personal communication). I present here an optical identification candidate for the millisecond pulsar: it is a 20th mag red object, undetectable on the Palomar Sky Survey prints. Finding charts and offsets from nearby stars are given.", "doi": "10.1038/300618a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1982-12-16", "series_number": "5893", "volume": "300", "issue": "5893", "pages": "618-619" }, { "id": "authors:b8yz1-n0g66", "collection": "authors", "collection_id": "b8yz1-n0g66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190730-155324109", "type": "article", "title": "Toward the application of metric size function in galactic evolution and cosmology", "author": [ { "family_name": "Djorgovski", "given_name": "S.", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-S-G" }, { "family_name": "Spinrad", "given_name": "H.", "clpid": "Spinrad-H" } ], "abstract": "We have measured the metric size function \u03b7(r) defined by Petrosian on a limited sample of luminous distant galaxies, up to a redshift of 1.175. Although our investigation has a preliminary character, we find some evidence for the evolution of elliptical galaxies. Using the Ostriker-Hausman theoretical models, we place some constraints on the rates of dynamical evolution. The eta function appears to be an extremely sensitive probe for the investigation of galactic evolution and potentially useful in cosmology. Some problems and directions for future work are outlined.", "doi": "10.1086/159478", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1981-12-15", "volume": "251", "pages": "417-423" } ]