[ { "id": "https://authors.library.caltech.edu/records/9pcz2-9nj34", "eprint_id": 121532, "eprint_status": "archive", "datestamp": "2023-08-22 20:52:44", "lastmod": "2023-10-20 15:37:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Alvarez-Carlos", "name": { "family": "Alvarez", "given": "Carlos" }, "orcid": "0000-0003-0815-7953" }, { "id": "Kassis-Marc", "name": { "family": "Kassis", "given": "Marc" } }, { "id": "Greffe-Timoth\u00e9e", "name": { "family": "Greffe", "given": "Timothee" }, "orcid": "0000-0003-4594-1827" }, { "id": "Smith-Roger-M", "name": { "family": "Smith", "given": "Roger" }, "orcid": "0000-0001-7062-9726" }, { "id": "Barillot-Marc", "name": { "family": "Barillot", "given": "Marc" } }, { "id": "Campbell-Randall-D", "name": { "family": "Campbell", "given": "Randall" }, "orcid": "0000-0002-3289-5203" }, { "id": "Gomez-Percy", "name": { "family": "Gomez", "given": "Percy" }, "orcid": "0000-0003-0408-9850" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Mawet-D", "name": { "family": "Mawet", "given": "Dimitri P." }, "orcid": "0000-0002-8895-4735" }, { "id": "Roberts-Mitsuko", "name": { "family": "Roberts", "given": "Mitsuko" } }, { "id": "Weber-Roberto-A", "name": { "family": "Weber", "given": "Roberto" } }, { "id": "Hale-David-D-S", "name": { "family": "Hale", "given": "David" } }, { "id": "Cavalieri-David", "name": { "family": "Cavalieri", "given": "David" } }, { "id": "Holewczynski-Joshua", "name": { "family": "Holewczynski", "given": "Joshua" } }, { "id": "Smous-James", "name": { "family": "Smous", "given": "James" } }, { "id": "Kwok-Shui-H", "name": { "family": "Kwok", "given": "Shui H." } }, { "id": "Chan-Dwight", "name": { "family": "Chan", "given": "Dwight" } }, { "id": "Dahler-Mike", "name": { "family": "Dahler", "given": "Mike" } } ] }, "title": "Upgrades to W. M. Keck observatory detector systems", "ispublished": "pub", "full_text_status": "public", "keywords": "Space and Planetary Science; Astronomy and Astrophysics", "note": "\u00a9 2023 Wiley-VCH. \n\nWe would like to thank the Mt. Cuba Astronomical Foundation for their support of the NIRES guider upgrade. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.", "abstract": "We report on our plans to upgrade the detector systems in the 2022\u20132024 time frame for three of the workhorse instruments (NIRC2, DEIMOS, and NIRES) operated by the W. M. Keck Observatory. The upgrades are done in collaboration with Observatory partner institutions and other Maunakea observatories. The main motivating factors behind these upgrades are to tackle obsolescence of hardware and software components, to boost observing efficiency, to enhance the instrument throughput, and to add new observing functionality.", "date": "2023-07-12", "date_type": "published", "publication": "Astronomische Nachrichten", "publisher": "Wiley", "pagerange": "Art. No. e20230062", "id_number": "CaltechAUTHORS:20230525-772698100.19", "issn": "0004-6337", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230525-772698100.19", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Mt. Cuba Astronomical Foundation" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.1002/asna.20230062", "resource_type": "article", "pub_year": "2023", "author_list": "Alvarez, Carlos; Kassis, Marc; et el." }, { "id": "https://authors.library.caltech.edu/records/37san-rnc03", "eprint_id": 121650, "eprint_status": "archive", "datestamp": "2023-08-22 20:55:11", "lastmod": "2023-10-20 15:41:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhuang-Zhuyun", "name": { "family": "Zhuang", "given": "Zhuyun" }, "orcid": "0000-0002-1945-2299" }, { "id": "Leethochawalit-Nicha", "name": { "family": "Leethochawalit", "given": "Nicha" }, "orcid": "0000-0003-4570-3159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Nightingale-James-W", "name": { "family": "Nightingale", "given": "J. W." }, "orcid": "0000-0002-8987-7401" }, { "id": "Steidel-C-C", "name": { "family": "Steidel", "given": "Charles C." }, "orcid": "0000-0002-4834-7260" }, { "id": "Glazebrook-Karl", "name": { "family": "Glazebrook", "given": "Karl" }, "orcid": "0000-0002-3254-9044" }, { "id": "Barone-Tania-M", "name": { "family": "Barone", "given": "Tania M." }, "orcid": "0000-0002-2784-564X" }, { "id": "Skobe-Hannah", "name": { "family": "Skobe", "given": "Hannah" }, "orcid": "0000-0003-0516-3485" }, { "id": "Sweet-Sarah-M", "name": { "family": "Sweet", "given": "Sarah M." }, "orcid": "0000-0002-1576-2505" }, { "id": "Nanayakkara-Themiya", "name": { "family": "Nanayakkara", "given": "Themiya" }, "orcid": "0000-0003-2804-0648" }, { "id": "Allen-Rebecca-J", "name": { "family": "Allen", "given": "Rebecca J." }, "orcid": "0000-0002-7278-9528" }, { "id": "G-C-Keerthi-Vasan", "name": { "family": "G. C.", "given": "Keerthi Vasan" }, "orcid": "0000-0002-2645-679X" }, { "id": "Jones-Tucker-A", "name": { "family": "Jones", "given": "Tucker" }, "orcid": "0000-0001-5860-3419" }, { "id": "Kacprzak-Glenn-G", "name": { "family": "Kacprzak", "given": "Glenn G." }, "orcid": "0000-0003-1362-9302" }, { "id": "Tran-Kim-Vy-H", "name": { "family": "Tran", "given": "Kim-Vy H." }, "orcid": "0000-0001-9208-2143" }, { "id": "Jacobs-Colin", "name": { "family": "Jacobs", "given": "Colin" }, "orcid": "0000-0003-4239-4055" } ] }, "title": "A Glimpse of the Stellar Populations and Elemental Abundances of Gravitationally Lensed, Quiescent Galaxies at z \u2273 1 with Keck Deep Spectroscopy", "ispublished": "pub", "full_text_status": "public", "keywords": "Space and Planetary Science; Astronomy and Astrophysics", "note": "\u00a9 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nThe authors acknowledge the insightful and constructive feedback of the anonymous referee, which helped us improve the manuscript. We would also like to thank Meng Gu for helpful advice on full-spectrum fitting with alf and Allison Strom for useful discussions on MOSFIRE data reduction and analysis with MOSPEC. We gratefully thank the staff at the W. M. Keck Observatory, including support astronomers Luca Rizzi, Carlos Alvarez, and Jim Lyke and telescope operators Arina Rostopchina, Julie Renauld-Kim, and Heather Hershey, for assisting in the observations. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry, on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nThis material is based on work supported by the National Science Foundation under grant Nos. AST-2233781 (E.N.K.) and AST-2009278 (C.C.S.). Z.Z., E.N.K., and C.C.S. acknowledge financial support from National Aeronautics and Space Administration (NASA) through the FINESST program (No. 80NSSC22K1755). K.G., T.N. and C.J. acknowledge support from Australian Research Council (FL180100060). S.M.S. acknowledges funding from the Australian Research Council (DE220100003). T.J. and K.V.G.C. gratefully acknowledge financial support from NASA through grant No. HST-GO-16773, the Gordon and Betty Moore Foundation through grant No. GBMF8549, and the National Science Foundation through grant No. AST-2108515. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project No. CE170100013. \n\nThis work has made use of observations from the NASA/ESA Hubble Space Telescope obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Support for Program No. GO-16773 was provided through a grant from the STScI under NASA contract NAS5-26555. \n\nFacilities: Keck I (LRIS - , MOSFIRE) - , HST (WFC3). - \n\nSoftware: SExtractor (Bertin & Arnouts 1996), alf (Conroy et al. 2018), dynesty (Speagle 2020), PyAutoLens (Nightingale & Dye 2015; Nightingale et al. 2018, 2021a, 2021b), BAGPIPES (Carnall et al. 2018, 2019), Astropy (Astropy Collaboration et al. 2013, 2018), NumPy (Harris et al. 2020), SciPy (Virtanen et al. 2020).\n\n
Published - Zhuang_2023_ApJ_948_132.pdf
", "abstract": "Gravitational lenses can magnify distant galaxies, allowing us to discover and characterize the stellar populations of intrinsically faint, quiescent galaxies that are otherwise extremely difficult to directly observe at high redshift from ground-based telescopes. Here, we present the spectral analysis of two lensed, quiescent galaxies at z \u2273 1 discovered by the ASTRO 3D Galaxy Evolution with Lenses survey: AGEL1323 (M_* \u223c 10^(11.1)M_\u2299, z = 1.016, \u03bc \u223c 14.6) and AGEL0014 (M_* \u223c 10^(11.5)M_\u2299, z = 1.374, \u03bc \u223c 4.3). We measured the age, [Fe/H], and [Mg/Fe] of the two lensed galaxies using deep, rest-frame-optical spectra (S/N \u2273 40 \u00c5\u207b\u00b9) obtained on the Keck I telescope. The ages of AGEL1323 and AGEL0014 are 5.6^(+0.8)_(\u22120.8) Gyr and 3.1^(+0.8)_(\u22120.3) Gyr, respectively, indicating that most of the stars in the galaxies were formed less than 2 Gyr after the Big Bang. Compared to nearby quiescent galaxies of similar masses, the lensed galaxies have lower [Fe/H] and [Mg/H]. Surprisingly, the two galaxies have comparable [Mg/Fe] to similar-mass galaxies at lower redshifts, despite their old ages. Using a simple analytic chemical evolution model connecting the instantaneously recycled element Mg with the mass-loading factors of outflows averaged over the entire star formation history, we found that the lensed galaxies may have experienced enhanced outflows during their star formation compared to lower-redshift galaxies, which may explain why they quenched early.", "date": "2023-05-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "948", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 132", "id_number": "CaltechAUTHORS:20230531-151922700.2", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230531-151922700.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-2233781" }, { "agency": "NSF", "grant_number": "AST-2009278" }, { "agency": "NASA Earth and Space Science and Technology Fellowship", "grant_number": "80NSSC22K1755" }, { "agency": "Australian Research Council", "grant_number": "FL180100060" }, { "agency": "Australian Research Council", "grant_number": "DE220100003" }, { "agency": "NASA", "grant_number": "HST-GO-16773" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF8549" }, { "agency": "NSF", "grant_number": "AST-2108515" }, { "agency": "Australian Research Council", "grant_number": "CE170100013" }, { "agency": "NASA", "grant_number": "NAS5-26555" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/acc79b", "primary_object": { "basename": "Zhuang_2023_ApJ_948_132.pdf", "url": "https://authors.library.caltech.edu/records/37san-rnc03/files/Zhuang_2023_ApJ_948_132.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Zhuang, Zhuyun; Leethochawalit, Nicha; et el." }, { "id": "https://authors.library.caltech.edu/records/v5c61-v0406", "eprint_id": 117668, "eprint_status": "archive", "datestamp": "2023-08-22 17:57:57", "lastmod": "2023-10-24 22:37:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Savino-Alessandro", "name": { "family": "Savino", "given": "Alessandro" }, "orcid": "0000-0002-1445-4877" }, { "name": { "family": "Weisz", "given": "Daniel R." }, "orcid": "0000-0002-6442-6030" }, { "name": { "family": "Skillman", "given": "Evan D." }, "orcid": "0000-0003-0605-8732" }, { "name": { "family": "Dolphin", "given": "Andrew E." }, "orcid": "0000-0001-8416-4093" }, { "name": { "family": "Kallivayalil", "given": "Nitya" }, "orcid": "0000-0002-3204-1742" }, { "name": { "family": "Wetzel", "given": "Andrew" }, "orcid": "0000-0003-0603-8942" }, { "name": { "family": "Anderson", "given": "Jay" }, "orcid": "0000-0003-2861-3995" }, { "name": { "family": "Besla", "given": "Gurtina" }, "orcid": "0000-0003-0715-2173" }, { "name": { "family": "Boylan-Kolchin", "given": "Michael" }, "orcid": "0000-0002-9604-343X" }, { "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "name": { "family": "Cole", "given": "Andrew A." }, "orcid": "0000-0003-0303-3855" }, { "name": { "family": "Collins", "given": "Michelle L. M." }, "orcid": "0000-0002-1693-3265" }, { "name": { "family": "Cooper", "given": "M. C." }, "orcid": "0000-0003-1371-6019" }, { "name": { "family": "Deason", "given": "Alis J." }, "orcid": "0000-0001-6146-2645" }, { "name": { "family": "Dotter", "given": "Aaron L." }, "orcid": "0000-0002-4442-5700" }, { "name": { "family": "Fardal", "given": "Mark" }, "orcid": "0000-0003-4207-3788" }, { "name": { "family": "Ferguson", "given": "Annette M. N." }, "orcid": "0000-0001-7934-1278" }, { "name": { "family": "Fritz", "given": "Tobias K." }, "orcid": "0000-0002-3122-300X" }, { "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "name": { "family": "Ibata", "given": "Rodrigo" }, "orcid": "0000-0002-3292-9709" }, { "name": { "family": "Irwin", "given": "Michael J." }, "orcid": "0000-0002-2191-9038" }, { "name": { "family": "Jeon", "given": "Myoungwon" }, "orcid": "0000-0001-6529-9777" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "name": { "family": "Lewis", "given": "Geraint F." }, "orcid": "0000-0003-3081-9319" }, { "name": { "family": "Mackey", "given": "Dougal" }, "orcid": "0000-0002-6529-8093" }, { "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "name": { "family": "Martin", "given": "Nicolas" }, "orcid": "0000-0002-1349-202X" }, { "name": { "family": "McConnachie", "given": "Alan" }, "orcid": "0000-0003-4666-6564" }, { "name": { "family": "Patel", "given": "Ekta" }, "orcid": "0000-0002-9820-1219" }, { "name": { "family": "Rich", "given": "R. Michael" }, "orcid": "0000-0003-0427-8387" }, { "name": { "family": "Simon", "given": "Joshua D." }, "orcid": "0000-0002-4733-4994" }, { "name": { "family": "Sohn", "given": "Sangmo Tony" }, "orcid": "0000-0001-8368-0221" }, { "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "name": { "family": "van der Marel", "given": "Roeland P." }, "orcid": "0000-0001-7827-7825" } ] }, "title": "The Hubble Space Telescope Survey of M31 Satellite Galaxies. I. RR Lyrae-based Distances and Refined 3D Geometric Structure", "ispublished": "pub", "full_text_status": "public", "keywords": "Space and Planetary Science; Astronomy and Astrophysics", "note": "A.S. thanks Y. Zheng for useful discussions at various stages of this work. Support for this work was provided by NASA through grants GO-13768, GO-15746, GO-15902, AR-16159, and GO-16273 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. M.C.C. acknowledges support though NSF grant AST-1815475. M.B.K. acknowledges support from NSF CAREER award AST-1752913, NSF grants AST-1910346 and AST-2108962, NASA grant NNX17AG29G, and HST-AR-15006, HST-AR-15809, HST-GO-15658, HST-GO-15901, HST-GO-15902, HST-AR-16159, and HST-GO-16226 from STScI. A.S. wishes to thank M. Marconi and R. Molinaro for providing the PWZ scaling relations used in this paper. This research has made use of NASA's Astrophysics Data System Bibliographic Services. All of the HST data used in this paper can be found in MAST:10.17909/jb41-ex86.", "abstract": "We measure homogeneous distances to M31 and 38 associated stellar systems (\u221216.8 \u2264 M_V \u2264 \u22126.0), using time-series observations of RR Lyrae stars taken as part of the Hubble Space Telescope Treasury Survey of M31 Satellites. From >700 orbits of new/archival Advanced Camera for Surveys imaging, we identify >4700 RR Lyrae stars and determine their periods and mean magnitudes to a typical precision of 0.01 day and 0.04 mag. Based on period\u2013Wesenheit\u2013metallicity relationships consistent with the Gaia eDR3 distance scale, we uniformly measure heliocentric and M31-centric distances to a typical precision of \u223c20 kpc (3%) and \u223c10 kpc (8%), respectively. We revise the 3D structure of the M31 galactic ecosystem and: (i) confirm a highly anisotropic spatial distribution such that \u223c80% of M31's satellites reside on the near side of M31; this feature is not easily explained by observational effects; (ii) affirm the thin (rms 7\u201323 kpc) planar \"arc\" of satellites that comprises roughly half (15) of the galaxies within 300 kpc from M31; (iii) reassess the physical proximity of notable associations such as the NGC 147/185 pair and M33/AND xxii; and (iv) illustrate challenges in tip-of-the-red-giant branch distances for galaxies with M_V > \u2212 9.5, which can be biased by up to 35%. We emphasize the importance of RR Lyrae for accurate distances to faint galaxies that should be discovered by upcoming facilities (e.g., Rubin Observatory). We provide updated luminosities and sizes for our sample. Our distances will serve as the basis for future investigation of the star formation and orbital histories of the entire known M31 satellite system.", "date": "2022-10-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "938", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 101", "id_number": "CaltechAUTHORS:20221031-575177800.33", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221031-575177800.33", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "HST-GO-13768" }, { "agency": "NASA", "grant_number": "HST-GO-15746" }, { "agency": "NASA", "grant_number": "HST-GO-15902" }, { "agency": "NASA", "grant_number": "HST-AR-16159" }, { "agency": "NASA", "grant_number": "HST-GO-16273" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "NSF", "grant_number": "AST-1815475" }, { "agency": "NSF", "grant_number": "AST-1752913" }, { "agency": "NSF", "grant_number": "AST-1910346" }, { "agency": "NSF", "grant_number": "AST-2108962" }, { "agency": "NASA", "grant_number": "NNX17AG29G" }, { "agency": "NASA", "grant_number": "HST-AR-15006" }, { "agency": "NASA", "grant_number": "HST-AR-15809" }, { "agency": "NASA", "grant_number": "HST-GO-15658" }, { "agency": "NASA", "grant_number": "HST-GO-15901" }, { "agency": "NASA", "grant_number": "HST-GO-15902" }, { "agency": "NASA", "grant_number": "HST-AR-16159" }, { "agency": "NASA", "grant_number": "HST-GO-16226" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ac91cb", "resource_type": "article", "pub_year": "2022", "author_list": "Savino, Alessandro; Weisz, Daniel R.; et el." }, { "id": "https://authors.library.caltech.edu/records/bf5a8-xwj63", "eprint_id": 112427, "eprint_status": "archive", "datestamp": "2023-08-20 08:17:24", "lastmod": "2023-10-23 15:11:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Buttry-Rachel", "name": { "family": "Buttry", "given": "Rachel" }, "orcid": "0000-0001-5501-7609" }, { "id": "Pace-Andrew-B", "name": { "family": "Pace", "given": "Andrew B." }, "orcid": "0000-0002-6021-8760" }, { "id": "Koposov-Sergey-E", "name": { "family": "Koposov", "given": "Sergey E." }, "orcid": "0000-0003-2644-135X" }, { "id": "Walker-Matthew-G", "name": { "family": "Walker", "given": "Matthew G." }, "orcid": "0000-0003-2496-1925" }, { "id": "Caldwell-Nelson", "name": { "family": "Caldwell", "given": "Nelson" }, "orcid": "0000-0003-2352-3202" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Martin-Nicolas-F", "name": { "family": "Martin", "given": "Nicolas F." }, "orcid": "0000-0002-1349-202X" }, { "id": "Mateo-Mario", "name": { "family": "Mateo", "given": "Mario" }, "orcid": "0000-0002-3856-232X" }, { "id": "Olszewski-Edward-W", "name": { "family": "Olszewski", "given": "Edward W." }, "orcid": "0000-0002-7157-500X" }, { "id": "Starkenburg-Else", "name": { "family": "Starkenburg", "given": "Else" }, "orcid": "0000-0003-4501-103X" }, { "id": "Badenes-Carles", "name": { "family": "Badenes", "given": "Carles" }, "orcid": "0000-0003-3494-343X" }, { "id": "Daher-Christine-M", "name": { "family": "Daher", "given": "Christine Mazzola" }, "orcid": "0000-0003-2116-2159" } ] }, "title": "Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II", "ispublished": "pub", "full_text_status": "public", "keywords": "binaries: spectroscopic \u2013galaxies: kinematics and dynamics", "note": "\u00a9 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). \n\nAccepted 2022 May 14. Received 2022 May 13; in original form 2021 August 25. Published: 30 May 2022. \n\nThis work is supported in part by National Science Foundation (NSF) grants AST-1813881 and AST-1909584. ENK is supported by NSF grant AST-1847909, and he gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement. EO is partially supported by NSF grant AST-1815767. NC is supported by NSF grant AST-1812461. MM is supported by U.S. NSF grants AST-1312997, AST-1726457 and AST-1815403. ES acknowledges funding through VIDI grant 'Pushing Galactic Archaeology to its limits' (with project number VI.Vidi.193.093), which is funded by the Dutch Research Council (NWO). CB and CMD are supported by NSF grant AST-1909022. \n\nThis work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. \n\nThe Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. \n\nThis research has made use of NASA's Astrophysics Data System Bibliographic Services. This paper made use of the Whole Sky Database (wsdb) created by Sergey Koposov and maintained at the Institute of Astronomy, Cambridge by Sergey Koposov, Vasily Belokurov, and Wyn Evans with financial support from the Science & Technology Facilities Council (STFC) and the European Research Council (ERC). \n\nObservations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nFor the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission. \n\nNew observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nData Availability: The processed MMT/Hectochelle catalog for Tri II targets are publicly available at the Zenodo database, https://doi.org/10.5281/zenodo.6561483.\n\nPublished - stac1441.pdf
Submitted - 2108.10867.pdf
", "abstract": "We present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultrafaint dwarf galaxy Triangulum II (Tri II). Combining results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Tri II, with up to 10 independent redshift measurements per star. To this multi-epoch kinematic data set, we apply methodology that we develop in order to infer binary orbital parameters from sparsely sampled radial velocity curves with as few as two epochs. For a previously identified (spatially unresolved) binary system in Tri II, we infer an orbital solution with period 296.0^(+3.8)_(\u22123.3)\u2060, semimajor axis 1.12^(+0.41)_(\u22120.24)\u2060, and systemic velocity \u2212380.0\u00b11.7 km s\u207b\u00b9 that we then use in the analysis of Tri II's internal kinematics. Despite this improvement in the modelling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Tri II. We instead find a 95 per\u2009cent confidence upper limit of \u03c3_v\u22723.4 km s\u207b\u00b9.", "date": "2022-08", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "514", "number": "2", "publisher": "Royal Astronomical Society", "pagerange": "1706-1719", "id_number": "CaltechAUTHORS:20211214-190053191", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211214-190053191", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1813881" }, { "agency": "NSF", "grant_number": "AST-1909584" }, { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "NSF", "grant_number": "AST-1815767" }, { "agency": "NSF", "grant_number": "AST-1812461" }, { "agency": "NSF", "grant_number": "AST-1312997" }, { "agency": "NSF", "grant_number": "AST-1726457" }, { "agency": "NSF", "grant_number": "AST-1815403" }, { "agency": "Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)", "grant_number": "VI.Vidi.193.093" }, { "agency": "NSF", "grant_number": "AST-1909022" }, { "agency": "Gaia Multilateral Agreement" }, { "agency": "NASA", "grant_number": "NNX08AR22G" }, { "agency": "NSF", "grant_number": "AST-1238877" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Science and Technology Facilities Council (STFC)" }, { "agency": "European Research Council (ERC)" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.1093/mnras/stac1441", "primary_object": { "basename": "stac1441.pdf", "url": "https://authors.library.caltech.edu/records/bf5a8-xwj63/files/stac1441.pdf" }, "related_objects": [ { "basename": "2108.10867.pdf", "url": "https://authors.library.caltech.edu/records/bf5a8-xwj63/files/2108.10867.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Buttry, Rachel; Pace, Andrew B.; et el." }, { "id": "https://authors.library.caltech.edu/records/b4feh-vjy61", "eprint_id": 115908, "eprint_status": "archive", "datestamp": "2023-08-22 16:50:07", "lastmod": "2023-10-24 20:54:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Richstein-Hannah", "name": { "family": "Richstein", "given": "Hannah" }, "orcid": "0000-0002-3188-2718" }, { "id": "Patel-Ekta", "name": { "family": "Patel", "given": "Ekta" }, "orcid": "0000-0002-9820-1219" }, { "id": "Kallivayalil-Nitya", "name": { "family": "Kallivayalil", "given": "Nitya" }, "orcid": "0000-0002-3204-1742" }, { "id": "Simon-Joshua-D", "name": { "family": "Simon", "given": "Joshua D." }, "orcid": "0000-0002-4733-4994" }, { "id": "Zivick-Paul", "name": { "family": "Zivick", "given": "Paul" }, "orcid": "0000-0001-9409-3911" }, { "id": "Tollerud-Erik-J", "name": { "family": "Tollerud", "given": "Erik" }, "orcid": "0000-0002-9599-310X" }, { "id": "Fritz-Tobias", "name": { "family": "Fritz", "given": "Tobias" }, "orcid": "0000-0002-3122-300X" }, { "id": "Warfield-Jack-T", "name": { "family": "Warfield", "given": "Jack T." }, "orcid": "0000-0003-1634-4644" }, { "id": "Besla-Gurtina", "name": { "family": "Besla", "given": "Gurtina" }, "orcid": "0000-0003-0715-2173" }, { "id": "van-der-Marel-Roland-P", "name": { "family": "van der Marel", "given": "Roeland P." }, "orcid": "0000-0001-7827-7825" }, { "id": "Wetzel-Andrew-R", "name": { "family": "Wetzel", "given": "Andrew" }, "orcid": "0000-0003-0603-8942" }, { "id": "Choi-Yumi", "name": { "family": "Choi", "given": "Yumi" }, "orcid": "0000-0003-1680-1884" }, { "id": "Deason-Alis-J", "name": { "family": "Deason", "given": "Alis" }, "orcid": "0000-0001-6146-2645" }, { "id": "Geha-Marla-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Guhathakurta-Puragra", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Jeon-Myoungwon", "name": { "family": "Jeon", "given": "Myoungwon" }, "orcid": "0000-0001-6529-9777" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Libralato-Mattia", "name": { "family": "Libralato", "given": "Mattia" }, "orcid": "0000-0001-9673-7397" }, { "id": "Sacchi-Elena", "name": { "family": "Sacchi", "given": "Elena" }, "orcid": "0000-0001-5618-0109" }, { "id": "Sohn-Sangmo-Tony", "name": { "family": "Sohn", "given": "Sangmo Tony" }, "orcid": "0000-0001-8368-0221" } ] }, "title": "Structural Parameters and Possible Association of the Ultra-faint Dwarfs Pegasus III and Pisces II from Deep Hubble Space Telescope Photometry", "ispublished": "pub", "full_text_status": "public", "keywords": "Dwarf galaxies; Local Group; Galaxy structure; Space and Planetary Science; Astronomy and Astrophysics", "note": "\u00a9 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2022 April 4; revised 2022 May 9; accepted 2022 May 19; published 2022 July 15. \n\nWe would like to thank the anonymous referee for their thorough reading of this manuscript and comments that have led to its improvement and clarification. These data are associated with the HST Treasury Program 14734 (PI: N. Kallivayalil). Support for this program was provided by NASA through grants from the Space Telescope Science Institute. This material is based upon work supported by the National Science Foundation under grant No. AST-1847909. H.R. acknowledges support from the Virginia Space Grant Consortium Graduate Research STEM Fellowship. E.P. acknowledges support from the Miller Institute for Basic Research in Science at the University of California Berkeley. This research has made use of NASA's Astrophysics Data System. \n\nFacility: HST (ACS, WFC3), \n\nSoftware: Aplpy (Robitaille & Bressert 2012); Astrodrizzle (Fruchter & Hook 2002); Astropy (Astropy Collaboration et al. 2013, 2018); corner.py (Foreman-Mackey 2016); dustmaps (Green 2018); emcee (Foreman-Mackey et al. 2013); Jupyter Notebook (Kluyver et al. 2016); Matplotlib (Hunter 2007); NumPy (Harris et al. 2020); photutils (Bradley et al. 2020); scikitlearn (Pedregosa et al. 2012); SciPy (Virtanen et al. 2020); stsynphot (STScI Development Team 2010); synphot (STScI Development Team 2018),\n\nPublished - Richstein_2022_ApJ_933_217.pdf
Submitted - 2204.01917.pdf
", "abstract": "We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf (UFD) galaxies Pegasus III (Peg III) and Pisces II (Psc II), two of the most distant satellites in the halo of the Milky Way (MW). We measure the structure of both galaxies, derive mass-to-light ratios with newly determined absolute magnitudes, and compare our findings to expectations from UFD-mass simulations. For Peg III, we find an elliptical half-light radius of a\u2095 = 1.\u203288_(-0.33)^(+0.42) (118\u208b\u2083\u2080\u207a\u00b3\u00b9 pc) and M\u1d65 = -4.17_(-0.22)^(+0.19); for Psc II, we measure a\u2095 = 1.\u203231_(\u22120.09)^(+0.10) (69 \u00b1 8 pc) and M\u1d65 = \u22124.28_(-0.16)^(+0.19). We do not find any morphological features that indicate a significant interaction between the two has occurred, despite their close separation of only \u223c40 kpc. Using proper motions (PMs) from Gaia early Data Release 3, we investigate the possibility of any past association by integrating orbits for the two UFDs in an MW-only and a combined MW and Large Magellanic Cloud (LMC) potential. We find that including the gravitational influence of the LMC is crucial, even for these outer-halo satellites, and that a possible orbital history exists where Peg III and Psc II experienced a close (\u223c10\u201320 kpc) passage about each other just over \u223c1 Gyr ago, followed by a collective passage around the LMC (\u223c30\u201360 kpc) just under \u223c1 Gyr ago. Considering the large uncertainties on the PMs and the restrictive priors imposed to derive them, improved PM measurements for Peg III and Psc II will be necessary to clarify their relationship. This would add to the rare findings of confirmed pairs of satellites within the Local Group.", "date": "2022-07-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "933", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 217", "id_number": "CaltechAUTHORS:20220727-37608000", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220727-37608000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Virginia Space Grant Consortium" }, { "agency": "Miller Institute for Basic Research in Science" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ac7226", "primary_object": { "basename": "2204.01917.pdf", "url": "https://authors.library.caltech.edu/records/b4feh-vjy61/files/2204.01917.pdf" }, "related_objects": [ { "basename": "Richstein_2022_ApJ_933_217.pdf", "url": "https://authors.library.caltech.edu/records/b4feh-vjy61/files/Richstein_2022_ApJ_933_217.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Richstein, Hannah; Patel, Ekta; et el." }, { "id": "https://authors.library.caltech.edu/records/e6nbf-yb608", "eprint_id": 113773, "eprint_status": "archive", "datestamp": "2023-10-09 20:58:49", "lastmod": "2023-10-24 16:29:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nu\u00f1ez-Evan-H", "name": { "family": "Nu\u00f1ez", "given": "Evan H." }, "orcid": "0000-0001-5595-757X" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Steidel-C-C", "name": { "family": "Steidel", "given": "Charles C." }, "orcid": "0000-0002-4834-7260" } ] }, "title": "Empirical Constraints on Core-collapse Supernova Yields Using Very Metal-poor Damped Ly\u03b1 Absorbers", "ispublished": "pub", "full_text_status": "public", "keywords": "Core-collapse supernovae; Damped Lyman-alpha systems; Quasar absorption line spectroscopy; Population III stars; Nucleosynthesis; Space and Planetary Science; Astronomy and Astrophysics", "note": "\u00a9 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2021 August 1; revised 2021 November 29; accepted 2021 December 7; published 2022 March 4. \n\nWe thank Tuguldur Sukhbold for in-depth comments and correspondence that significantly improved this work. We thank Ryan Cooke, Louise Welsh, Donatella Romano, Carl Fields, Lynne Hillenbrand, and Sanjana Curtis for thoughtful conversations and for sharing information and data that improved the quality of this work. We thank our referee for helpful comments that improved this paper. E.H.N. acknowledges the support of the NSF Graduate Research Fellowship Program. This material is based upon work supported by the National Science Foundation under grant No. AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement. \n\nSoftware: Astropy (Astropy Collaboration et al. 2013, 2018).\n\nPublished - Nunez_2022_ApJ_927_64.pdf
Submitted - 2108-00659.pdf
", "abstract": "We place empirical constraints on the yields from zero- and low-metallicity core-collapse supernovae (CCSNe) using abundances measured in very metal-poor (VMP; [Fe/H] \u2264 \u22122) damped Ly\u03b1 absorbers (DLAs). For some abundance ratios ([N,Al,S/Fe]), VMP DLAs constrain the metal yields of the first SNe more reliably than VMP stars. We compile a large sample of high-S/N VMP DLAs from over 30 yr of literature, most with high-resolution spectral measurements. We infer the initial-mass-function-averaged CCSNe yield from the median values from the DLA abundance ratios of C, N, O, Al, Si, S, and Fe (over Fe and O). We assume that the DLAs are metal-poor enough that they represent galaxies in their earliest stages of evolution, when CCSNe are the only nucleosynthetic sources of the metals we analyze. We compare five sets of zero- and low-metallicity theoretical yields to the empirical yields derived in this work. We find that the five models agree with the DLA yields for ratios containing Si and S. Only one model (Heger & Woosley 2010, hereafter HW10) reproduced the DLA values for N, and one other model (Limongi & Chieffi 2018, hereafter LC18) reproduced [N/O]. We found little change in the theoretical yields with the adoption of an SN explosion landscape (where certain progenitor masses collapse into black holes, contributing no yields) onto HW10, but fixing explosion energy to progenitor mass results in wide disagreements between the predictions and DLA abundances. We investigate the adoption of a simple, observationally motivated initial distribution of rotational velocities for LC18 and find a slight improvement.", "date": "2022-03-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "927", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 64", "id_number": "CaltechAUTHORS:20220307-189105000", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220307-189105000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" } ] }, "doi": "10.3847/1538-4357/ac470e", "primary_object": { "basename": "2108-00659.pdf", "url": "https://authors.library.caltech.edu/records/e6nbf-yb608/files/2108-00659.pdf" }, "related_objects": [ { "basename": "Nunez_2022_ApJ_927_64.pdf", "url": "https://authors.library.caltech.edu/records/e6nbf-yb608/files/Nunez_2022_ApJ_927_64.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Nu\u00f1ez, Evan H.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/vwpvr-tne67", "eprint_id": 112103, "eprint_status": "archive", "datestamp": "2023-08-22 13:24:25", "lastmod": "2023-10-23 20:53:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "de-los-Reyes-Mithi-A-C", "name": { "family": "de los Reyes", "given": "Mithi A. C." }, "orcid": "0000-0002-4739-046X" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Ji-Alexander-P", "name": { "family": "Ji", "given": "Alexander P." }, "orcid": "0000-0002-4863-8842" }, { "id": "Nu\u00f1ez-Evan-H", "name": { "family": "Nu\u00f1ez", "given": "Evan H." }, "orcid": "0000-0001-5595-757X" } ] }, "title": "Simultaneous Constraints on the Star Formation History and Nucleosynthesis of Sculptor dSph", "ispublished": "pub", "full_text_status": "public", "keywords": "Dwarf galaxies; Dwarf spheroidal galaxies; Sculptor dwarf elliptical galaxy; Star formation; Nucleosynthesis; Stellar nucleosynthesis; Galaxies; Galaxy spectroscopy", "note": "\u00a9 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2021 August 2; revised 2021 September 23; accepted 2021 October 24; published 2022 January 26. \n\nThis material is based upon work supported by the National Science Foundation under grant No. AST-1847909. M.A.d.l.R. and E.H.N. acknowledge the financial support of the NSF Graduate Research Fellowship Program. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement. A.P.J. acknowledges support from a Carnegie Fellowship and the Thacher Research Award in Astronomy. \n\nThere are many communities without whom this work would not have been possible. We thank the anonymous reviewer for comments that helped improve the paper. We acknowledge that this work is rooted in Western scientific practices and is the material product of a long and complex history of settler-colonialism. M.A.d.l.R., E.N.K., E.H.N., and A.P.J. wish to recognize their status as settlers on the traditional and unceded territory of the Tongva peoples, and to recognize that the astronomical observations described in this paper were only possible because of the dispossession of Maunakea from ${\\rm{K}}\\bar{{\\rm{a}}}$naka Maoli. We hope to work toward a scientific practice guided by pono and a future in which we all honor the land. \n\nFinally, we would like to express our deep gratitude to the staff at academic and telescope facilities, particularly those whose communities are excluded from the academic system but whose labor maintains spaces for scientific inquiry. \n\nFacility: Keck:II (DEIMOS). - \n\nSoftware: Matplotlib (Hunter 2007), Astropy (Robitaille et al. 2013), Scipy (Jones et al. 2001), emcee (Foreman-Mackey et al. 2013).\n\nPublished - de_los_Reyes_2022_ApJ_925_66.pdf
Accepted Version - 2110.01690.pdf
", "abstract": "We demonstrate that using up to seven stellar abundance ratios can place observational constraints on the star formation histories (SFHs) of Local Group dSphs, using Sculptor dSph as a test case. We use a one-zone chemical evolution model to fit the overall abundance patterns of \u03b1 elements (which probe the core-collapse supernovae that occur shortly after star formation), s-process elements (which probe AGB nucleosynthesis at intermediate delay times), and iron-peak elements (which probe delayed Type Ia supernovae). Our best-fit model indicates that Sculptor dSph has an ancient SFH, consistent with previous estimates from deep photometry. However, we derive a total star formation duration of \u223c0.9 Gyr, which is shorter than photometrically derived SFHs. We explore the effect of various model assumptions on our measurement and find that modifications to these assumptions still produce relatively short SFHs of duration \u22721.4 Gyr. Our model is also able to compare sets of predicted nucleosynthetic yields for supernovae and AGB stars, and can provide insight into the nucleosynthesis of individual elements in Sculptor dSph. We find that observed [Mn/Fe] and [Ni/Fe] trends are most consistent with sub-MCh Type Ia supernova models, and that a combination of \"prompt\" (delay times similar to core-collapse supernovae) and \"delayed\" (minimum delay times \u227350 Myr) r-process events may be required to reproduce observed [Ba/Mg] and [Eu/Mg] trends.", "date": "2022-01-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "925", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 66", "id_number": "CaltechAUTHORS:20211130-215710052", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211130-215710052", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Carnegie Institution of Washington" }, { "agency": "Carnegie Observatories" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ac332b", "primary_object": { "basename": "2110.01690.pdf", "url": "https://authors.library.caltech.edu/records/vwpvr-tne67/files/2110.01690.pdf" }, "related_objects": [ { "basename": "de_los_Reyes_2022_ApJ_925_66.pdf", "url": "https://authors.library.caltech.edu/records/vwpvr-tne67/files/de_los_Reyes_2022_ApJ_925_66.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "de los Reyes, Mithi A. C.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/c0qqx-d9g27", "eprint_id": 111423, "eprint_status": "archive", "datestamp": "2023-08-22 11:33:41", "lastmod": "2023-10-23 20:34:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhuang-Zhuyun", "name": { "family": "Zhuang", "given": "Zhuyun" }, "orcid": "0000-0002-1945-2299" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Leethochawalit-N", "name": { "family": "Leethochawalit", "given": "Nicha" }, "orcid": "0000-0003-4570-3159" }, { "id": "de-los-Reyes-Mithi-A-C", "name": { "family": "de los Reyes", "given": "Mithi A. C." }, "orcid": "0000-0002-4739-046X" } ] }, "title": "NGC 147 Corroborates the Break in the Stellar Mass\u2013Stellar Metallicity Relation for Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "Local Group; Galaxy abundances; Metallicity; Chemical abundances; Stellar abundances; Dwarf elliptical galaxies", "note": "\u00a9 2021. The American Astronomical Society. \n\nReceived 2021 May 28; revised 2021 July 2; accepted 2021 July 8; published 2021 October 13. \n\nThe authors acknowledge the constructive feedback from the anonymous referee, which helped us improve the manuscript. We thank Yuguang Chen, Donal O'Sullivan, and James (Don) Neill for useful discussions on PCWI data reduction and covariance correction. We gratefully thank the staff at the Palomar Observatory, including support astronomers Carolyn Heffner and Kevin Rykoski, and telescope operator Kajsa Peffer, for assisting in the observations. \n\nThis material is based on work supported by the National Science Foundation (NSF) under grant No. AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar Award administered by the Research Corporation for Science Advancement. M.A.C.d.l.R. acknowledges the financial support of the NSF Graduate Research Fellowship Program. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry, on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. This research has made use of the Keck Observatory Archive, which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute, under a contract with the National Aeronautics and Space Administration. \n\nFacilities: Hale (CWI) - , Keck II (DEIMOS) - . \n\nSoftware: CWITools (O'Sullivan & Chen 2020), FSPS (Conroy et al. 2009), alf (Conroy et al. 2018), MPFIT (Markwardt 2012), Astropy (Astropy Collaboration et al. 2013, 2018), NumPy (Harris et al. 2020), SciPy (Virtanen et al. 2020), pPXF (Cappellari 2017).\n\nPublished - Zhuang_2021_ApJ_920_63.pdf
Accepted Version - 2107.04067.pdf
", "abstract": "The stellar mass\u2013stellar metallicity relation (MZR) is an essential approach to probing the chemical evolution of galaxies. It reflects the balance between galactic feedback and gravitational potential as a function of stellar mass. However, the current MZR of local dwarf satellite galaxies (M* \u2272 10\u2078 M_\u2299; measured from resolved stellar spectroscopy) may not be reconcilable with that of more massive galaxies (M* \u2273 10^(9.5) M_\u2299; measured from integrated-light spectroscopy). Such a discrepancy may result from a systematic difference between the two methods, or it may indicate a break in the MZR around 10\u2079 M_\u2299. To address this question, we measured the stellar metallicity of NGC 147 from integrated light using the Palomar Cosmic Web Imager. We compared the stellar metallicity estimates from integrated light with measurements from resolved stellar spectroscopy and found them to be consistent within 0.1 dex. On the other hand, the high-mass MZR overpredicts the metallicity by 0.6 dex at the mass of NGC 147. Therefore, our results tentatively suggest that the discrepancy between the low-mass MZR and high-mass MZR should not be attributed to a systematic difference in techniques. Instead, real physical processes cause the transition in the MZR. In addition, we discovered a positive age gradient in the innermost region and a negative metallicity gradient from the resolved stars at larger radii, suggesting a possible outside-in formation of NGC 147.", "date": "2021-10-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "920", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 63", "id_number": "CaltechAUTHORS:20211014-170544433", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211014-170544433", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NASA/JPL/Caltech" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ac1340", "primary_object": { "basename": "2107.04067.pdf", "url": "https://authors.library.caltech.edu/records/c0qqx-d9g27/files/2107.04067.pdf" }, "related_objects": [ { "basename": "Zhuang_2021_ApJ_920_63.pdf", "url": "https://authors.library.caltech.edu/records/c0qqx-d9g27/files/Zhuang_2021_ApJ_920_63.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Zhuang, Zhuyun; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/yjh2e-6b234", "eprint_id": 111434, "eprint_status": "archive", "datestamp": "2023-08-22 11:33:47", "lastmod": "2023-10-23 20:34:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sacchi-Elena", "name": { "family": "Sacchi", "given": "Elena" }, "orcid": "0000-0001-5618-0109" }, { "id": "Richstein-Hannah", "name": { "family": "Richstein", "given": "Hannah" } }, { "id": "Kallivayalil-Nitya", "name": { "family": "Kallivayalil", "given": "Nitya" }, "orcid": "0000-0002-3204-1742" }, { "id": "van-der-Marel-Roeland-P", "name": { "family": "van der Marel", "given": "Roeland" }, "orcid": "0000-0001-7827-7825" }, { "id": "Libralato-Mattia", "name": { "family": "Libralato", "given": "Mattia" }, "orcid": "0000-0001-9673-7397" }, { "id": "Zivick-Paul", "name": { "family": "Zivick", "given": "Paul" }, "orcid": "0000-0001-9409-3911" }, { "id": "Besla-Gurtina", "name": { "family": "Besla", "given": "Gurtina" }, "orcid": "0000-0003-0715-2173" }, { "id": "Brown-Thomas-M", "name": { "family": "Brown", "given": "Thomas M." }, "orcid": "0000-0002-1793-9968" }, { "id": "Choi-Yumi", "name": { "family": "Choi", "given": "Yumi" }, "orcid": "0000-0003-1680-1884" }, { "id": "Deason-Alis-J", "name": { "family": "Deason", "given": "Alis" }, "orcid": "0000-0001-6146-2645" }, { "id": "Fritz-Tobias", "name": { "family": "Fritz", "given": "Tobias" }, "orcid": "0000-0002-3122-300X" }, { "id": "Geha-Marla-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Guhathakurta-Puragra", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Jeon-Myoungwon", "name": { "family": "Jeon", "given": "Myoungwon" }, "orcid": "0000-0001-6529-9777" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Majewski-Steven-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Patel-Ekta", "name": { "family": "Patel", "given": "Ekta" }, "orcid": "0000-0002-9820-1219" }, { "id": "Simon-Joshua-D", "name": { "family": "Simon", "given": "Joshua D." }, "orcid": "0000-0002-4733-4994" }, { "id": "Sohn-Sangmo-Tony", "name": { "family": "Sohn", "given": "Sangmo Tony" }, "orcid": "0000-0001-8368-0221" }, { "id": "Tollerud-Erik-J", "name": { "family": "Tollerud", "given": "Erik" }, "orcid": "0000-0002-9599-310X" }, { "id": "Wetzel-Andrew-R", "name": { "family": "Wetzel", "given": "Andrew" }, "orcid": "0000-0003-0603-8942" } ] }, "title": "Star Formation Histories of Ultra-faint Dwarf Galaxies: Environmental Differences between Magellanic and Non-Magellanic Satellites?", "ispublished": "pub", "full_text_status": "public", "keywords": "Dwarf galaxies; Galaxy evolution; Galaxy dynamics; Galaxy stellar content; Galaxy kinematics; Star formation; Local Group; Magellanic Clouds", "note": "\u00a9 2021. The American Astronomical Society. \n\nReceived 2021 August 9; revised 2021 September 27; accepted 2021 September 27; published 2021 October 8. \n\nThese data are associated with the HST Treasury Program 14734 (PI Kallivayalil). Support for this program was provided by NASA through grants from the Space Telescope Science Institute. A.W. received support from NASA ATP grant Nos. 80NSSC18K1097 and 80NSSC20K0513; a Scialog Award from the Heising-Simons Foundation; and a Hellman Fellowship. This material is based upon work supported by the National Science Foundation under grant No. AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement. \n\nBased on observations obtained with the NASA/ESA Hubble Space Telescope at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA Contract NAS 5-26555.\n\nPublished - Sacchi_2021_ApJL_920_L19.pdf
Accepted Version - 2108.04271.pdf
", "abstract": "We present the color\u2013magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix 2, Reticulum 2, Sagittarius 2, Triangulum 2, and Tucana 2, derived from high-precision Hubble Space Telescope photometry. We find that the SFH of each galaxy is consistent with them having created at least 80% of the stellar mass by z \u223c 6. For all galaxies, we find quenching times older than 11.5 Gyr ago, compatible with the scenario in which reionization suppresses the star formation of small dark matter halos. However, our analysis also reveals some differences in the SFHs of candidate Magellanic Cloud satellites, i.e., galaxies that are likely satellites of the Large Magellanic Cloud and that entered the Milky Way potential only recently. Indeed, Magellanic satellites show quenching times about 600 Myr more recent with respect to those of other Milky Way satellites, on average, even though the respective timings are still compatible within the errors. This finding is consistent with theoretical models that suggest that satellites' SFHs may depend on their host environment at early times, although we caution that within the error bars all galaxies in our sample are consistent with being quenched at a single epoch.", "date": "2021-10-10", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "920", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 19", "id_number": "CaltechAUTHORS:20211014-170553664", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211014-170553664", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "80NSSC18K1097" }, { "agency": "NASA", "grant_number": "80NSSC20K0513" }, { "agency": "Heising-Simons Foundation", "grant_number": "Scialog Award" }, { "agency": "Hellman Fellowship" }, { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/2041-8213/ac2aa3", "primary_object": { "basename": "2108.04271.pdf", "url": "https://authors.library.caltech.edu/records/yjh2e-6b234/files/2108.04271.pdf" }, "related_objects": [ { "basename": "Sacchi_2021_ApJL_920_L19.pdf", "url": "https://authors.library.caltech.edu/records/yjh2e-6b234/files/Sacchi_2021_ApJL_920_L19.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Sacchi, Elena; Richstein, Hannah; et el." }, { "id": "https://authors.library.caltech.edu/records/x4j4v-m3a50", "eprint_id": 109770, "eprint_status": "archive", "datestamp": "2023-08-22 10:40:50", "lastmod": "2023-10-23 18:09:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Escala-Ivanna", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Gilbert-Karoline-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Wojno-Jennifer", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-Puragra", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Elemental Abundances in M31: Gradients in the Giant Stellar Stream", "ispublished": "pub", "full_text_status": "public", "keywords": "Stellar abundances; Galaxy abundances; Stellar streams; Galaxy stellar halos; Andromeda Galaxy; Galaxy formation", "note": "\u00a9 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2021 March 15; revised 2021 May 4; accepted 2021 May 5; published 2021 July 6. \n\nWe thank the anonymous referee, whose careful reading of this paper improved its clarity. We thank Emily C. Cunningham for helpful comments on the manuscript and Stephen Gwyn for reducing the photometry for slitmask f123_1. I.E. was generously supported by a Carnegie-Princeton Fellowship through the Carnegie Observatories. This material is based upon work supported by the NSF under grants Nos. AST-1614081 (E.N.K.), AST-1614569 (K.M.G, J.W.), and AST-1412648 (P.G.). E.N.K gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement, as well as funding from generous donors to the California Institute of Technology. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nFacility: Keck (DEIMOS).\nSoftware: Astropy (Astropy Collaboration et al. 2013, 2018),\nemcee (Foreman-Mackey et al. 2013).\n\nPublished - Escala_2021_AJ_162_45.pdf
Accepted Version - 2105.02339.pdf
", "abstract": "We analyze existing measurements of [Fe/H] and [\u03b1/Fe] for individual red giant branch (RGB) stars in the Giant Stellar Stream (GSS) of M31 to determine whether spatial abundance gradients are present. These measurements were obtained from low- (R ~ 3000) and moderate- (R ~ 6000) resolution Keck/DEIMOS spectroscopy using spectral synthesis techniques as part of the Elemental Abundances in M31 survey. From a sample of 62 RGB stars spanning the GSS at 17, 22, and 33 projected kpc, we measure a [Fe/H] gradient of \u22120.018 \u00b1 0.003 dex kpc\u207b\u00b9 and negligible [\u03b1/Fe] gradient with M31-centric radius. We investigate GSS abundance patterns in the outer halo using additional [Fe/H] and [\u03b1/Fe] measurements for six RGB stars located along the stream at 45 and 58 projected kpc. These abundances provide tentative evidence that the trends in [Fe/H] and [\u03b1/Fe] beyond 40 kpc in the GSS are consistent with those within 33 kpc. We also compare the GSS abundances to 65 RGB stars located along the possibly related Southeast (SE) shelf substructure at 12 and 18 projected kpc. The abundances of the GSS and SE shelf are consistent, supporting a common origin hypothesis, although this interpretation may be complicated by the presence of [Fe/H] gradients in the GSS. We discuss the abundance patterns in the context of photometric studies from the literature and explore implications for the properties of the GSS progenitor, suggesting that the high \u3008[\u03b1/Fe]\u3009 of the GSS (+0.40 \u00b1 0.05 dex) favors a major merger scenario for its formation.", "date": "2021-08", "date_type": "published", "publication": "Astronomical Journal", "volume": "162", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 45", "id_number": "CaltechAUTHORS:20210709-222308921", "issn": "0004-6256", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210709-222308921", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Carnegie-Princeton Fellowship" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-3881/abfec4", "primary_object": { "basename": "2105.02339.pdf", "url": "https://authors.library.caltech.edu/records/x4j4v-m3a50/files/2105.02339.pdf" }, "related_objects": [ { "basename": "Escala_2021_AJ_162_45.pdf", "url": "https://authors.library.caltech.edu/records/x4j4v-m3a50/files/Escala_2021_AJ_162_45.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Escala, Ivanna; Gilbert, Karoline M.; et el." }, { "id": "https://authors.library.caltech.edu/records/s9h4b-46t33", "eprint_id": 107276, "eprint_status": "archive", "datestamp": "2023-08-22 08:04:43", "lastmod": "2023-10-23 15:42:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zheng-Yong", "name": { "family": "Zheng", "given": "Yong" }, "orcid": "0000-0003-4158-5116" }, { "id": "Emerick-Andrew", "name": { "family": "Emerick", "given": "Andrew" }, "orcid": "0000-0003-2807-328X" }, { "id": "Putman-Mary-E", "name": { "family": "Putman", "given": "Mary E." }, "orcid": "0000-0002-1129-1873" }, { "id": "Werk-Jessica-K", "name": { "family": "Werk", "given": "Jessica K." }, "orcid": "0000-0002-0355-0134" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Peek-Joshua-E-G", "name": { "family": "Peek", "given": "Joshua" }, "orcid": "0000-0003-4797-7030" } ] }, "title": "Characterizing the Circumgalactic Medium of the Lowest-mass Galaxies: A Case Study of IC 1613", "ispublished": "pub", "full_text_status": "public", "keywords": "Circumgalactic medium; Local Group; Magellanic Stream; Metallicity; Dwarf irregular galaxies", "note": "\u00a9 2020. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2020 August 11; revised 2020 October 26; accepted 2020 November 6; published 2020 December 22. \n\nWe thank R. Bordoloi for sharing his python code of escape velocity calculation, E. Patel for discussing the projection effect between the Magellanic System and the LG galaxies using hydrodynamic simulations and HST/Gaia proper motion measurements, and D. Weisz for discussing many aspects of this paper and for his great support as a faculty mentor to Y.Z. at Miller Institute at UC Berkeley. We also thank A. Fox and P. Richter for helpful discussion on the manuscript. Y.Z. acknowledges support from the Miller Institute for Basic Research in Science. Support for Program number HST-GO-15156 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. This material is based upon work supported by the National Science Foundation under grant No. AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement. This research has made use of the HSLA database, developed and maintained at STScI, Baltimore, USA. \n\nFacilities: Hubble Space Telescope/Cosmic Origins Spectrograph - , Mikulski Archive for Space Telescopes (MAST). - \n\nSoftware: Astropy (The Astropy Collaboration et al. 2018), Numpy (Harris et al. 2020), Matplotlib (Hunter 2007), CLOUDY (Ferland et al. 2017), IDL, the gala package (Price-Whelan et al. 2017).\n\nPublished - pdf
Submitted - 2010.15645.pdf
", "abstract": "Using 10 sight lines observed with the Hubble Space Telescope/Cosmic Origins Spectrograph, we study the circumgalactic medium (CGM) and outflows of IC 1613, which is a low-mass (M_* ~ 10\u2078 M_\u2299), dwarf irregular galaxy on the outskirts of the Local Group. Among the sight lines, four are pointed toward UV-bright stars in IC 1613, and the other six sight lines are background QSOs at impact parameters from 6 kpc (<0.1R_(200)) to 61 kpc (0.6R_(200)). We detect a number of Si ii, Si iii, Si iv, C ii, and C iv absorbers, most of which have velocities less than the escape velocity of IC 1613 and thus are gravitationally bound. The line strengths of these ion absorbers are consistent with the CGM absorbers detected in dwarf galaxies at low redshifts. Assuming that Si ii, Si iii, and Si iv comprise nearly 100% of the total silicon, we find 3% (~8 \u00d7 10\u00b3 M_\u2299), 2% (~7 \u00d7 10\u00b3 M_\u2299), and 32%\u201342% [~(1.0\u20131.3) \u00d7 10\u2075 M_\u2299] of the silicon mass in the stars, interstellar medium, and within 0.6R_(200) of the CGM of IC 1613. We also estimate the metal outflow rate to be \u1e40_(out,Z) \u2a7e 1.1 x 10\u207b\u2075 M_\u2299 yr\u207b\u00b9 and the instantaneous metal mass loading factor to be \u03b7_Z \u2265 0.004, which are in broad agreement with available observation and simulation values. This work is the first time a dwarf galaxy of such low mass is probed by a number of both QSO and stellar sight lines, and it shows that the CGM of low-mass, gas-rich galaxies can be a large reservoir enriched with metals from past and ongoing outflows.", "date": "2020-12-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "905", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 133", "id_number": "CaltechAUTHORS:20201224-085807319", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201224-085807319", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Miller Institute for Basic Research in Science" }, { "agency": "NASA", "grant_number": "HST-GO-15156" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" } ] }, "local_group": { "items": [ { "id": "TAPIR" }, { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/abc875", "primary_object": { "basename": "2010.15645.pdf", "url": "https://authors.library.caltech.edu/records/s9h4b-46t33/files/2010.15645.pdf" }, "related_objects": [ { "basename": "pdf", "url": "https://authors.library.caltech.edu/records/s9h4b-46t33/files/pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Zheng, Yong; Emerick, Andrew; et el." }, { "id": "https://authors.library.caltech.edu/records/w6szj-rrv54", "eprint_id": 105807, "eprint_status": "archive", "datestamp": "2023-08-22 07:10:31", "lastmod": "2023-10-20 22:27:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Belland-B-R", "name": { "family": "Belland", "given": "Brent" }, "orcid": "0000-0003-1950-448X" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Boylan-Kolchin-M", "name": { "family": "Boylan-Kolchin", "given": "Michael" }, "orcid": "0000-0002-9604-343X" }, { "id": "Wheeler-Coral", "name": { "family": "Wheeler", "given": "Coral" } } ] }, "title": "NGC 6822 as a Probe of Dwarf Galactic Evolution", "ispublished": "pub", "full_text_status": "public", "keywords": "Dwarf irregular galaxies; Stellar kinematics", "note": "\u00a9 2020 The American Astronomical Society. \n\nReceived 2020 July 8; revised 2020 September 4; accepted 2020 September 5; published 2020 October 26. \n\nThe data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. \n\nThe authors thank the anonymous referee for the input which improved this paper. \n\nThis material is based upon work supported by the National Science Foundation under grant Nos. AST-1636426 and AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement, as well as funding from generous donors to the California Institute of Technology. M.B.K. acknowledges support from NSF CAREER award AST-1752913, NSF grant AST-1910346, NASA grant NNX17AG29G, and HST-AR-15006, HST-AR-15809, HST-GO-15658, HST-GO-15901, and HST-GO-15902 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. Support for C.W. was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51449.001-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nFacility: Keck:II (DEIMOS). -\n\nPublished - Belland_2020_ApJ_903_10.pdf
Submitted - 2009.04555.pdf
", "abstract": "NGC 6822 is the closest isolated dwarf irregular galaxy to the Milky Way. Its proximity and stellar mass (10\u2078 M_\u2299, large for a dwarf galaxy) allow for a detailed study of its kinematic properties. The red giant branch (RGB) stars at the galaxy's center are particularly interesting because they are aligned on an axis perpendicular to the galaxy's more extended H I disk. We detected a velocity gradient among the RGB population using spectra from Keck/Deep Imaging Multi-Object Spectrograph (DEIMOS). This rotation is aligned with the H I disk, but the sense of rotation is about the major axis of the central RGB population. We measured the rotation velocity (v) and velocity dispersion (\u03c3) of the RGB population in five metallicity bins. We found an increase of rotation support (v/\u03c3) with increasing metallicity, driven primarily by decreasing dispersion. We also deduced an increasing radial distance for lower metallicity stars at \u22120.5 kpc dex\u207b\u00b9 by relating the observed stellar kinematics to position via NGC 6822's H I velocity curve. While the inverted metallicity gradient-like distribution could be interpreted as evidence for an outside-in formation scenario, it may instead indicate that stellar feedback disturbed a centrally star-forming galaxy over time.", "date": "2020-11-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "903", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 10", "id_number": "CaltechAUTHORS:20201005-134507051", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201005-134507051", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "W. M. Keck Foundation" }, { "agency": "NSF", "grant_number": "AST-1636426" }, { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "NSF", "grant_number": "AST-1752913" }, { "agency": "NSF", "grant_number": "AST-1910346" }, { "agency": "NASA", "grant_number": "NNX17AG29G" }, { "agency": "NASA", "grant_number": "HST-AR-15006" }, { "agency": "NASA", "grant_number": "HST-AR-15809" }, { "agency": "NASA", "grant_number": "HST-GO-15658" }, { "agency": "NASA", "grant_number": "HST-GO-15901" }, { "agency": "NASA", "grant_number": "HST-GO-15902" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF2-51449.001-A" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/abb5f4", "primary_object": { "basename": "2009.04555.pdf", "url": "https://authors.library.caltech.edu/records/w6szj-rrv54/files/2009.04555.pdf" }, "related_objects": [ { "basename": "Belland_2020_ApJ_903_10.pdf", "url": "https://authors.library.caltech.edu/records/w6szj-rrv54/files/Belland_2020_ApJ_903_10.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Belland, Brent; Kirby, Evan; et el." }, { "id": "https://authors.library.caltech.edu/records/yxv8e-wa091", "eprint_id": 105478, "eprint_status": "archive", "datestamp": "2023-08-22 06:55:17", "lastmod": "2023-10-20 22:02:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Cunningham-E-C", "name": { "family": "Cunningham", "given": "Emily C." }, "orcid": "0000-0002-6993-0826" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Elemental Abundances in M31: Properties of the Inner Stellar Halo", "ispublished": "pub", "full_text_status": "public", "keywords": "Andromeda galaxy; Galaxy stellar halos; Stellar abundances; Galaxy abundances; Galaxy formation", "note": "\u00a9 2020 The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2020 May 2; revised 2020 August 28; accepted 2020 August 31; published 2020 October 12. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nWe thank the referee for their comments, which improved this paper. The authors would additionally like to thank Miles Cranmer and Erik Tollerud for insightful discussions regarding statistics and David Nidever for providing a catalog of APOGEE data for the Magellanic Clouds. We also thank Stephen Gwyn for reducing the photometry for slitmasks f109_1 and f123_1, and Jason Kalirai for the reduction of f130_1. \n\nI.E. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship under grant No. DGE-1745301, in addition to a Carnegie-Princeton Fellowship through the Carnegie Observatories. This material is based upon work supported by the NSF under grants No. AST-1614081 (E.N.K., I.E.) AST-1614569 (K.M.G, J.W.), and AST-1412648 (P.G.). E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement, as well as funding from generous donors to the California Institute of Technology. E.C.C. is supported by a Flatiron Research Fellowship at the Flatiron Institute. The Flatiron Institute is supported by the Simons Foundation. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST- 0071048. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nFacility: Keck II/DEIMOS. - \n\nSoftware: astropy (Astropy Collaboration et al. 2013, 2018), emcee (Foreman-Mackey et al. 2013).\n\nPublished - Escala_2020_ApJ_902_51.pdf
Submitted - 2009.00529.pdf
", "abstract": "We present measurements of [Fe/H] and [\u03b1/Fe] for 128 individual red giant branch stars (RGB) in the stellar halo of M31, including its Giant Stellar Stream (GSS), obtained using spectral synthesis of low- and medium-resolution Keck/DEIMOS spectroscopy (R\u223c3000 and 6000, respectively). We observed four fields in M31's stellar halo (at projected radii of 9, 18, 23, and 31 kpc), as well as two fields in the GSS (at 33 kpc). In combination with existing literature measurements, we have increased the sample size of [Fe/H] and [\u03b1/Fe] measurements from 101 to a total of 229 individual M31 RGB stars. From this sample, we investigate the chemical abundance properties of M31's inner halo, finding \u27e8[Fe/H]\u27e9 = \u22121.08 \u00b1 0.04 and \u27e8[\u03b1/Fe]\u27e9 = 0.40 \u00b1 0.03. Between 8 and 34 kpc, the inner halo has a steep [Fe/H] gradient (\u22120.025 \u00b1 0.002 dex kpc\u207b\u00b9) and negligible [\u03b1/Fe] gradient, where substructure in the inner halo is systematically more metal-rich than the smooth component of the halo at a given projected distance. Although the chemical abundances of the inner stellar halo are largely inconsistent with that of present-day dwarf spheroidal (dSph) satellite galaxies of M31, we identified 22 RGB stars kinematically associated with the smooth component of the stellar halo that have chemical abundance patterns similar to M31 dSphs. We discuss formation scenarios for M31's halo, concluding that these dSph-like stars may have been accreted from galaxies of similar stellar mass and star formation history, or of higher stellar mass and similar star formation efficiency.", "date": "2020-10-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "902", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 51", "id_number": "CaltechAUTHORS:20200922-145833729", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200922-145833729", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "W. M. Keck Foundation" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "Carnegie-Princeton Fellowship" }, { "agency": "Carnegie Observatories" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "Flatiron Institute" }, { "agency": "Simons Foundation" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/abb474", "primary_object": { "basename": "2009.00529.pdf", "url": "https://authors.library.caltech.edu/records/yxv8e-wa091/files/2009.00529.pdf" }, "related_objects": [ { "basename": "Escala_2020_ApJ_902_51.pdf", "url": "https://authors.library.caltech.edu/records/yxv8e-wa091/files/Escala_2020_ApJ_902_51.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Escala, Ivanna; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/cd7qp-z6m88", "eprint_id": 104070, "eprint_status": "archive", "datestamp": "2023-08-22 05:30:49", "lastmod": "2023-10-20 19:03:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" } ] }, "title": "Elemental Abundances in M31: Iron and Alpha Element Abundances in M31's Outer Halo", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxies; Local Group; Andromeda Galaxy; Galaxy stellar halos; Stellar abundances", "note": "\u00a9 2020. The American Astronomical Society. \n\nReceived 2020 January 21; revised 2020 May 1; accepted 2020 May 21; published 2020 June 25. \n\nThe authors recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We thank the anonymous referee, whose careful reading of the manuscript improved the clarity of the paper. \n\nSupport for this work was provided by NSF grants AST-1614569 (K.M.G., J.W.), AST-1614081 (E.N.K., I.E.), AST-1847909 (E.N.K.), and AST-1909497 (S.R.M.). P.G. acknowledges support from NSF grants AST-1412648, AST-1010039, AST-0607852, and AST-0307966. S.R.M. and R.L.B. acknowledge support from NSF grants AST-1413269, AST-1009882, AST-0607726, and AST-0307842. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement as well as funding from generous donors to the California Institute of Technology. I.E. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship under grant No. DGE-1745301. Support for this work was provided by NASA through Hubble Fellowship grant #51386.01 awarded to R.L.B. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048. \n\nThe authors thank A. McConnachie for use of the PAndAS image. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018). \n\nFacility: Keck:II (DEIMOS). \n\nSoftware: Astropy (Astropy Collaboration et al. 2013), Matplotlib (Hunter 2007), numpy (van der Walt et al. 2011).\n\nPublished - Gilbert_2020_AJ_160_41.pdf
Accepted Version - 2006.05430.pdf
", "abstract": "We present [Fe/H] and [\u03b1/Fe] abundances, derived using spectral synthesis techniques, for stars in M31's outer stellar halo. The 21 [Fe/H] measurements and 7 [\u03b1/Fe] measurements are drawn from fields ranging from 43 to 165 kpc in projected distance from M31. We combine our measurements with existing literature measurements, and compare the resulting sample of 23 stars with [Fe/H] and 9 stars with [\u03b1/Fe] measurements in M31's outer halo with [\u03b1/Fe] and [Fe/H] measurements, also derived from spectral synthesis, in M31's inner stellar halo (r < 26 kpc) and dSph galaxies. The stars in M31's outer halo have [\u03b1/Fe] patterns that are consistent with the largest of M31's dSph satellites (And I and And VII). These abundances provide tentative evidence that the [\u03b1/Fe] abundances of stars in M31's outer halo are more similar to the abundances of Milky Way halo stars than to the abundances of stars in M31's inner halo. We also compare the spectral synthesis\u2013based [Fe/H] measurements of stars in M31's halo with previous photometric [Fe/H] estimates, as a function of projected distance from M31. The spectral synthesis\u2013based [Fe/H] measurements are consistent with a large-scale metallicity gradient previously observed in M31's stellar halo to projected distances as large as 100 kpc.", "date": "2020-07", "date_type": "published", "publication": "Astronomical Journal", "volume": "160", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 41", "id_number": "CaltechAUTHORS:20200626-103612106", "issn": "1538-3881", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200626-103612106", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "NSF", "grant_number": "AST-1909497" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0307966" }, { "agency": "NSF", "grant_number": "AST-1413269" }, { "agency": "NSF", "grant_number": "AST-1009882" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NSF", "grant_number": "AST-0307842" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51386.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-0071048" }, { "agency": "W. M. Keck Foundation" }, { "agency": "Carnegie-Princeton Fellowship" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-3881/ab9602", "primary_object": { "basename": "Gilbert_2020_AJ_160_41.pdf", "url": "https://authors.library.caltech.edu/records/cd7qp-z6m88/files/Gilbert_2020_AJ_160_41.pdf" }, "related_objects": [ { "basename": "2006.05430.pdf", "url": "https://authors.library.caltech.edu/records/cd7qp-z6m88/files/2006.05430.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Gilbert, Karoline M.; Wojno, Jennifer; et el." }, { "id": "https://authors.library.caltech.edu/records/8nz1w-hvg98", "eprint_id": 102517, "eprint_status": "archive", "datestamp": "2023-08-23 16:51:54", "lastmod": "2023-10-20 00:16:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pace-A-B", "name": { "family": "Pace", "given": "Andrew B." }, "orcid": "0000-0002-6021-8760" }, { "id": "Kaplinghat-M", "name": { "family": "Kaplinghat", "given": "Manoj" } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik" }, "orcid": "0000-0002-9599-310X" }, { "id": "Mu\u00f1oz-R-R", "name": { "family": "Mu\u00f1oz", "given": "Ricardo R." } }, { "id": "C\u00f4t\u00e9-P", "name": { "family": "C\u00f4t\u00e9", "given": "Patrick" }, "orcid": "0000-0003-1184-8114" }, { "id": "Djorgovski-S-G", "name": { "family": "Djorgovski", "given": "S. G." }, "orcid": "0000-0002-0603-3087" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" } ] }, "title": "Multiple Chemodynamic Stellar Populations of the Ursa Minor Dwarf Spheroidal Galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: evolution \u2013 galaxies: kinematics and dynamics \u2013 Local Group \u2013 cosmology: dark matter \u2013 galaxies: individual: Ursa Minor dSph", "note": "\u00a9 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). \n\nAccepted 2020 May 18. Received 2020 May 11; in original form 2020 February 21. Published: 22 May 2020. \n\nWe thank Matt Walker for sharing an earlier catalogue of the UMi MMT/Hectochelle data. We thank James Bullock, Mike Cooper, Sergey Koposov, Jen Marshall, Louie Strigari, and Matt Walker for helpful comments and discussion. We also thank the referee for their helpful comments. \n\nABP was supported by a GAANN fellowship at UCI. ABP acknowledges generous support from the George P. and Cynthia Woods Institute for Fundamental Physics and Astronomy at Texas A&M University. ABP was supported by NSF grant AST-1813881. EK gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement and funding from generous donors to the California Institute of Technology. RRM acknowledges partial support from project BASAL AFB-170002 and FONDECYT project N\u00b01170364. SGD was supported in part by the NSF grants AST-1413600, AST-1518308, and AST-1749235. \n\nThe authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nFunding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the US Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/. \n\nSDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. \n\nThis work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. \n\nThis research has made use of NASA's Astrophysics Data System Bibliographic Services. \n\nDatabases and software: Besan\u00e7on model15 (Robin et al. 2003). PYTHON packages: ASTROPY16 (Astropy Collaboration 2013), NUMPY (Walt, Colbert & Varoquaux 2011), IPYTHON (P\u00e9rez & Granger 2007), SCIPY (Jones et al. 2001), MATPLOTLIB (Hunter 2007), CORNER.PY (Foreman-Mackey 2016), and EMCEE (Foreman-Mackey et al. 2013). \n\nThe data presented in this work were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W.M. Keck Foundation.\n\nPublished - staa1419.pdf
Submitted - 2002.09503.pdf
Supplemental Material - staa1419_supplemental_file.zip
", "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.", "date": "2020-07", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "495", "number": "3", "publisher": "Royal Astronomical Society", "pagerange": "3022-3040", "id_number": "CaltechAUTHORS:20200414-071817157", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200414-071817157", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "University of California, Irvine" }, { "agency": "Texas A&M University" }, { "agency": "NSF", "grant_number": "AST-1813881" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "BASAL-CATA", "grant_number": "AFB-170002" }, { "agency": "Fondo Nacional de Desarrollo Cient\u00edfico y Tecnol\u00f3gico (FONDECYT)", "grant_number": "1170364" }, { "agency": "NSF", "grant_number": "AST-1413600" }, { "agency": "NSF", "grant_number": "AST-1518308" }, { "agency": "NSF", "grant_number": "AST-1749235" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Participating Institutions" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Gaia Multilateral Agreement" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.1093/mnras/staa1419", "primary_object": { "basename": "staa1419.pdf", "url": "https://authors.library.caltech.edu/records/8nz1w-hvg98/files/staa1419.pdf" }, "related_objects": [ { "basename": "staa1419_supplemental_file.zip", "url": "https://authors.library.caltech.edu/records/8nz1w-hvg98/files/staa1419_supplemental_file.zip" }, { "basename": "2002.09503.pdf", "url": "https://authors.library.caltech.edu/records/8nz1w-hvg98/files/2002.09503.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Pace, Andrew B.; Kaplinghat, Manoj; et el." }, { "id": "https://authors.library.caltech.edu/records/6reav-9q951", "eprint_id": 103518, "eprint_status": "archive", "datestamp": "2023-08-22 05:17:28", "lastmod": "2023-10-20 16:27:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Elemental Abundances in M31: [Fe/H] and [\u03b1/Fe] in M31 Dwarf Galaxies Using Coadded Spectra", "ispublished": "pub", "full_text_status": "public", "keywords": "Andromeda Galaxy; Chemical abundances", "note": "\u00a9 2020 The American Astronomical Society. \n\nReceived 2019 November 30; revised 2020 April 20; accepted 2020 April 21; published 2020 May 28. \n\nWe thank the anonymous referee for thorough comments and suggestions, which have greatly improved the quality of the manuscript. \n\nThis material is based upon work supported by the National Science Foundation under grant Nos. AST-1614569 (J.W., K.M.G.) and AST-1614081 (E.N.K., I.E.). E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement as well as funding from generous donors to the California Institute of Technology. I.E. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship under grant No. DGE-1745301. R.L.B. and S.R.M. thank NSF grants AST-0307842, AST-0607726, AST-1009882, and AST-1413269. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nThe authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nThis research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018).11\n\nFacility: Keck:II (DEIMOS). - \n\nSoftware: Astropy (Astropy Collaboration et al. 2013), Matplotlib (Hunter 2007), numpy (van der Walt et al. 2011), scipy (Virtanen et al. 2020), emcee (Foreman-Mackey et al. 2013).\n\nPublished - Wojno_2020_ApJ_895_78.pdf
Submitted - 2004.03425.pdf
", "abstract": "We present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system of Andromeda (M31), using spectral synthesis of medium-resolution (R ~ 6000) spectra obtained with the Keck II telescope and Deep Imaging Multi-Object Spectrometer spectrograph via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We coadd stars according to their similarity in photometric metallicity or effective temperature to obtain a signal-to-noise ratio (S/N) high enough to measure average [Fe/H] and [\u03b1/Fe] abundances. We validate our method using high S/N spectra of RGB stars in Milky Way globular clusters, as well as deep observations for a subset of the M31 dSphs in our sample. For this set of validation coadds, we compare the weighted average abundance of the individual stars with the abundance determined from the coadd. We present individual and coadded measurements of [Fe/H] and [\u03b1/Fe] for stars in 10 M31 dSphs, including the first [\u03b1/Fe] measurements for And IX, XIV, XV, and XVIII. These fainter, less massive dSphs show declining [\u03b1/Fe] relative to [Fe/H], implying an extended star formation history (SFH). In addition, these dSphs also follow the same mass\u2013metallicity relation found in other Local Group satellites. The conclusions we infer from coadded spectra agree with those from previous measurements in brighter M31 dSphs with individual abundance measurements, as well as conclusions from photometric studies. These abundances greatly increase the number of spectroscopic measurements of the chemical composition of M31's less massive dwarf satellites, which are crucial to understanding their SFH and interaction with the M31 system.", "date": "2020-06-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "895", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 78", "id_number": "CaltechAUTHORS:20200528-105015601", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200528-105015601", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-0307842" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NSF", "grant_number": "AST-1009882" }, { "agency": "NSF", "grant_number": "AST-1413269" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab8ccb", "primary_object": { "basename": "2004.03425.pdf", "url": "https://authors.library.caltech.edu/records/6reav-9q951/files/2004.03425.pdf" }, "related_objects": [ { "basename": "Wojno_2020_ApJ_895_78.pdf", "url": "https://authors.library.caltech.edu/records/6reav-9q951/files/Wojno_2020_ApJ_895_78.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Wojno, Jennifer; Gilbert, Karoline M.; et el." }, { "id": "https://authors.library.caltech.edu/records/bcgx3-3n290", "eprint_id": 101746, "eprint_status": "archive", "datestamp": "2023-08-22 04:17:49", "lastmod": "2023-10-19 23:08:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "de-los-Reyes-Mithi-A-C", "name": { "family": "de los Reyes", "given": "Mithi A. C." }, "orcid": "0000-0002-4739-046X" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Seitenzahl-Ivo-R", "name": { "family": "Seitenzahl", "given": "Ivo R." }, "orcid": "0000-0002-5044-2988" }, { "id": "Shen-Kevin-J", "name": { "family": "Shen", "given": "Ken J." }, "orcid": "0000-0002-9632-6106" } ] }, "title": "Manganese Indicates a Transition from Sub- to Near-Chandrasekhar Type Ia Supernovae in Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "Dwarf spheroidal galaxies; Dwarf galaxies; Sculptor dwarf elliptical galaxy; SNe Ia; Chemical abundances; Galaxy abundances; Stellar abundances", "note": "\u00a9 2020. The American Astronomical Society. \n\nReceived 2019 October 11; revised 2020 February 4; accepted 2020 February 5; published 2020 March 6. \n\nThe authors thank I. Escala and G. Duggan for informing parts of the data pipeline, as well as A. Piro and A. McWilliam for helpful discussions and comments. This material is based upon work supported by the National Science Foundation under grant No. AST-1847909. M.A.dl.R. acknowledges the financial support of the NSF Graduate Research Fellowship Program. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement as well as funding from generous donors to the California Institute of Technology. I.R.S. was supported by the Australian Research Council through grant No. FT160100028. \n\nThe authors wish to recognize and acknowledge the deep cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this sacred mountain. Finally, we would like to express our deep gratitude to the staff at academic and telescope facilities, particularly those whose communities are excluded from the academic system, but whose labor maintains spaces for scientific inquiry. \n\nFacility: Keck:II (DEIMOS). - \n\nSoftware: spec2d (Cooper et al. 2012; Newman et al. 2013), Matplotlib (Hunter 2007), Astropy (Robitaille et al. 2013), Scipy (Jones et al. 2001), MOOG (Sneden et al. 2012), ATLAS9 (Castelli & Kurucz 2003).\n\nPublished - de_los_Reyes_2020_ApJ_891_85.pdf
Accepted Version - 2001.01716.pdf
", "abstract": "Manganese abundances are sensitive probes of the progenitors of Type Ia supernovae (SNe Ia). In this work, we present a catalog of manganese abundances in dwarf spheroidal satellites of the Milky Way, measured using medium-resolution spectroscopy. Using a simple chemical evolution model, we infer the manganese yield of SNe Ia in the Sculptor dwarf spheroidal galaxy (dSph) and compare to theoretical yields. The sub-solar yield from SNe Ia ([(Mn/Fe)_(Ia) = -0.30_(-0.03)^(+0.03) at [Fe/ H] = \u22121.5 dex, with negligible dependence on metallicity) implies that sub-Chandrasekhar-mass (sub-M_(Ch)) white dwarf progenitors are the dominant channel of SNe Ia at early times in this galaxy, although some fraction (\u2273 20%) of M_(Ch) Type Ia or Type Iax SNe are still needed to produce the observed yield. First-order corrections for deviations from local thermodynamic equilibrium increase the inferred [(Mn/Fe)]_Ia by as much as ~0.3 dex. However, our results also suggest that the nucleosynthetic source of SNe Ia may depend on environment. In particular, we find that dSphs with extended star formation histories (Leo I, Fornax dSphs) appear to have higher [Mn/Fe] at a given metallicity than galaxies with early bursts of star formation (Sculptor dSph), suggesting that M Ch progenitors may become the dominant channel of SNe Ia at later times in a galaxy's chemical evolution.", "date": "2020-03-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "891", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 85", "id_number": "CaltechAUTHORS:20200306-133727979", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200306-133727979", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "Australian Research Council", "grant_number": "FT160100028" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab736f", "primary_object": { "basename": "2001.01716.pdf", "url": "https://authors.library.caltech.edu/records/bcgx3-3n290/files/2001.01716.pdf" }, "related_objects": [ { "basename": "de_los_Reyes_2020_ApJ_891_85.pdf", "url": "https://authors.library.caltech.edu/records/bcgx3-3n290/files/de_los_Reyes_2020_ApJ_891_85.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "de los Reyes, Mithi A. C.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/74pnb-kvz47", "eprint_id": 101666, "eprint_status": "archive", "datestamp": "2023-08-22 04:17:26", "lastmod": "2023-10-19 22:56:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Duggan-G-E", "name": { "family": "Duggan", "given": "Gina" }, "orcid": "0000-0002-9256-6735" }, { "id": "Ramirez-Ruiz-E", "name": { "family": "Ramirez-Ruiz", "given": "Enrico" }, "orcid": "0000-0003-2558-3102" }, { "id": "Macias-P", "name": { "family": "Macias", "given": "Phillip" }, "orcid": "0000-0002-9946-4635" } ] }, "title": "The Stars in M15 Were Born with the r-process", "ispublished": "pub", "full_text_status": "public", "keywords": "Globular star clusters; R-process; Nucleosynthesis", "note": "\u00a9 2020 The American Astronomical Society.\n\nReceived 2019 December 2; revised 2020 February 13; accepted 2020 February 20; published 2020 March 2.\n\nWe are grateful to Marc Kassis, Carlos \u00c1lvarez, and Percy G\u00f3mez for their essential roles in providing DEIMOS with the 1200B diffraction grating. We thank Paz Beniamini, E. Sterl Phinney, and Shrinivas Kulkarni for directing us to the observational studies of merging times for binary neutron stars. We also thank Dan Kasen and Ryan Foley for helpful discussions, and the anonymous referee for a helpful report.\n\nThis material is based upon work supported by the National Science Foundation under grant No. AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement as well as funding from generous donors to the California Institute of Technology. E.R.-R. and P.M. thank the Heising\u2013Simons Foundation, the Danish National Research Foundation (DNRF132), and NSF (AST-1911206 and AST-1852393) for support.\n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible.\n\nFacility: Keck:II (DEIMOS) - KECK II Telescope.\n\nSoftware: spec2d (Cooper et al. 2012; Newman et al. 2013), MOOG (Sneden et al. 2012), MESA (Paxton et al. 2011).\n\nPublished - Kirby_2020_ApJL_891_L13.pdf
Accepted Version - 2002.09495.pdf
", "abstract": "High-resolution spectroscopy of stars on the red giant branch (RGB) of the globular cluster M15 has revealed a large (~1 dex) dispersion in the abundances of r-process elements such as Ba and Eu. Neutron star mergers (NSMs) have been proposed as a major source of the r-process. However, most NSM models predict a delay time longer than the timescale for cluster formation. One possibility is that a NSM polluted the surfaces of stars in M15 long after the cluster finished forming. In this case, the abundances of the polluting elements would decrease in the first dredge-up as stars turn on to the RGB. We present Keck/DEIMOS abundances of Ba in 66 stars along the entire RGB and the top of the main sequence. The Ba abundances have no trend with stellar luminosity (evolutionary phase). Therefore, the stars were born with the Ba that they have today, and Ba did not originate in a source with a delay time longer than the timescale for cluster formation. In particular, if the source of Ba was a NSM, it would have had a very short delay time. Alternatively, if Ba enrichment took place before the formation of the cluster, an inhomogeneity of a factor of 30 in Ba abundance needs to be able to persist over the length scale of the gas cloud that formed M15, which is unlikely.", "date": "2020-03-01", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "891", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. L13", "id_number": "CaltechAUTHORS:20200302-152240292", "issn": "2041-8213", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200302-152240292", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1847909" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "Heising-Simons Foundation" }, { "agency": "Danish National Research Foundation", "grant_number": "DNRF132" }, { "agency": "NSF", "grant_number": "AST-1911206" }, { "agency": "NSF", "grant_number": "AST-1852393" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/2041-8213/ab78a1", "primary_object": { "basename": "2002.09495.pdf", "url": "https://authors.library.caltech.edu/records/74pnb-kvz47/files/2002.09495.pdf" }, "related_objects": [ { "basename": "Kirby_2020_ApJL_891_L13.pdf", "url": "https://authors.library.caltech.edu/records/74pnb-kvz47/files/Kirby_2020_ApJL_891_L13.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Kirby, Evan N.; Duggan, Gina; et el." }, { "id": "https://authors.library.caltech.edu/records/xwc6r-k1t74", "eprint_id": 101166, "eprint_status": "archive", "datestamp": "2023-08-22 03:56:56", "lastmod": "2023-10-19 22:29:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Cunningham-E-C", "name": { "family": "Cunningham", "given": "Emily C." }, "orcid": "0000-0002-6993-0826" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Elemental Abundances in M31: A Comparative Analysis of Alpha and Iron Element Abundances in the the Outer Disk, Giant Stellar Stream, and Inner Halo of M31", "ispublished": "pub", "full_text_status": "public", "keywords": "Andromeda galaxy; Stellar abundances; Galaxy stellar halos; Local Group; Galaxy stellar disks; Galaxy formation", "note": "\u00a9 2020. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2019 July 30; revised 2019 December 20; accepted 2019 December 28; published 2020 February 5. \n\nThe authors thank the anonymous reviewer for a thorough reading of this manuscript and helpful comments. We also thank Stephen Gwyn for reducing the photometry for slitmasks H, S, and D and Jason Kalirai for the reductions of f130_2. I.E. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship under grant No. DGE-1745301. This material is based upon work supported by the NSF under grant Nos. AST-1614081 (E.N.K.), AST-1614569 (K.M.G, J.W.), and AST-1412648 (P.G.). E.N.K gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement, as well as funding from generous donors to the California Institute of Technology. E.C.C. was supported by an NSF Graduate Research Fellowship and an ARCS Foundation Fellowship, as well as NSF grant AST-1616540. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST- 0071048. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nFacility: Keck II/DEIMOS. - \n\nSoftware: astropy (Astropy Collaboration et al. 2013, 2018), emcee (Foreman-Mackey et al. 2013).\n\nPublished - Escala_2020_ApJ_889_177.pdf
Accepted Version - 1909.00006.pdf
", "abstract": "We measured [Fe/H] and [\u03b1/Fe] using spectral synthesis of low-resolution stellar spectroscopy for 70 individual red-giant-branch stars across four fields spanning the outer disk, Giant Stellar Stream (GSS), and inner halo of M31. Fields at M31-centric projected distances of 23 kpc in the halo, 12 kpc in the halo, 22 kpc in the GSS, and 26 kpc in the outer disk are \u03b1-enhanced, with \u27e8 [\u03b1/Fe]\u3009= 0.43, 0.50, 0.41, and 0.58, respectively. The 23 and 12 kpc halo fields are relatively metal-poor, with \u27e8 [Fe/H]\u27e9 = \u22121.54 and \u22121.30, whereas the 22 kpc GSS and 26 kpc outer disk fields are relatively metal-rich with \u27e8 [Fe/H]\u27e9 = \u22120.84 and \u22120.92, respectively. For fields with substructure, we separated the stellar populations into kinematically hot stellar halo components and kinematically cold components. We did not find any evidence of a radial [\u03b1/Fe] gradient along the high surface brightness core of the GSS between ~17 and 22 kpc. However, we found tentative suggestions of a negative radial [\u03b1/Fe] gradient in the stellar halo, which may indicate that different progenitor(s) or formation mechanisms contributed to the build up of the inner versus outer halo. Additionally, the [\u03b1/Fe] distribution of the metal-rich ([Fe/H] > \u22121.5), smooth inner stellar halo (r_(proj) \u227e 26 kpc) is inconsistent with having formed from the disruption of a progenitor(s) similar to present-day M31 satellite galaxies. The 26 kpc outer disk is most likely associated with the extended disk of M31, where its high \u03b1-enhancement provides support for an episode of rapid star formation in M31's disk possibly induced by a major merger.", "date": "2020-02-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "889", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 177", "id_number": "CaltechAUTHORS:20200206-125056795", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200206-125056795", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "ARCS Foundation" }, { "agency": "NSF", "grant_number": "AST-1616540" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab6659", "primary_object": { "basename": "1909.00006.pdf", "url": "https://authors.library.caltech.edu/records/xwc6r-k1t74/files/1909.00006.pdf" }, "related_objects": [ { "basename": "Escala_2020_ApJ_889_177.pdf", "url": "https://authors.library.caltech.edu/records/xwc6r-k1t74/files/Escala_2020_ApJ_889_177.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Escala, Ivanna; Gilbert, Karoline M.; et el." }, { "id": "https://authors.library.caltech.edu/records/zrnww-pa593", "eprint_id": 100637, "eprint_status": "archive", "datestamp": "2023-08-22 03:48:03", "lastmod": "2023-10-18 21:41:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" } ] }, "title": "Elemental Abundances in M31: The Kinematics and Chemical Evolution of Dwarf Spheroidal Satellite Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "Andromeda Galaxy; Dwarf galaxies; Stellar abundances; Local Group", "note": "\u00a9 2020 The American Astronomical Society. \n\nReceived 2019 August 29; revised 2019 December 1; accepted 2019 December 3; published 2020 January. \n\nWe are grateful to Luis Vargas for providing a data table of M31 dSph measurements, including effective temperature. We thank Brent Belland for helpful discussion on the rotation model and Alexander Ji for insightful conversation. \n\nThis material is based upon work supported by the National Science Foundation under grant Nos. AST-1614081 and AST-1614569. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement, as well as funding from generous donors to the California Institute of Technology. I.E. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship under grant No. DGE-1745301. P.G., S.R.M., and R.L.B. acknowledge prior funding from collaborative NSF grants AST-0307842, AST-0307851, AST-0607726, AST-0807945, AST-1009882, AST-1009973, and AST-1010039. Support for this work was provided by NASA through Hubble Fellowship grant #51386.01 awarded to R.L.B. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality, as well as to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. We also express our deep gratitude to the staff at academic and telescope facilities whose labor maintains spaces for scientific inquiry. \n\nFacility: Keck:II (DEIMOS). - \n\nSoftware: spec2d (Cooper et al. 2012; Newman et al. 2013), MOOG (Sneden 1973; Sneden et al. 2012), ATLAS9 (Kurucz 1993), MPFIT (Markwardt 2012).\n\nPublished - Kirby_2020_AJ_159_46.pdf
Accepted Version - 1912.02186.pdf
", "abstract": "We present deep spectroscopy from Keck/DEIMOS of Andromeda I, III, V, VII, and X, all of which are dwarf spheroidal satellites of M31. The sample includes 256 spectroscopic members across all five dSphs. We confirm previous measurements of the velocity dispersions and dynamical masses, and we provide upper limits on bulk rotation. Our measurements confirm that M31 satellites obey the same relation between stellar mass and stellar metallicity as Milky Way (MW) satellites and other dwarf galaxies in the Local Group. The metallicity distributions show trends with stellar mass that are similar to those of MW satellites, including evidence in massive satellites for external influence, like pre-enrichment or gas accretion. We present the first measurements of individual element ratios, like [Si/Fe], in the M31 system, as well as measurements of the average [\u03b1/Fe] ratio. The trends of [\u03b1/Fe] with [Fe/H] also follow the same galaxy mass\u2013dependent patterns as MW satellites. Less massive galaxies have more steeply declining slopes of [\u03b1/Fe] that begin at lower [Fe/H]. Finally, we compare the chemical evolution of M31 satellites to M31's Giant Stellar Stream and smooth halo. The properties of the M31 system support the theoretical prediction that the inner halo is composed primarily of massive galaxies that were accreted early. As a result, the inner halo exhibits higher [Fe/H] and [\u03b1/Fe] than surviving satellite galaxies.", "date": "2020-02", "date_type": "published", "publication": "Astronomical Journal", "volume": "159", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 46", "id_number": "CaltechAUTHORS:20200110-143403708", "issn": "1538-3881", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200110-143403708", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-0307842" }, { "agency": "NSF", "grant_number": "AST-0307851" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NSF", "grant_number": "AST-0807945" }, { "agency": "NSF", "grant_number": "AST-1009882" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51386.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-3881/ab5f0f", "primary_object": { "basename": "1912.02186.pdf", "url": "https://authors.library.caltech.edu/records/zrnww-pa593/files/1912.02186.pdf" }, "related_objects": [ { "basename": "Kirby_2020_AJ_159_46.pdf", "url": "https://authors.library.caltech.edu/records/zrnww-pa593/files/Kirby_2020_AJ_159_46.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Kirby, Evan N.; Gilbert, Karoline M.; et el." }, { "id": "https://authors.library.caltech.edu/records/sp2cm-4ed15", "eprint_id": 99666, "eprint_status": "archive", "datestamp": "2023-08-19 18:42:23", "lastmod": "2023-10-18 18:38:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Leethochawalit-N", "name": { "family": "Leethochawalit", "given": "Nicha" }, "orcid": "0000-0003-4570-3159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Ellis-R-S", "name": { "family": "Ellis", "given": "Richard S." }, "orcid": "0000-0001-7782-7071" }, { "id": "Moran-S-M", "name": { "family": "Moran", "given": "Sean M." }, "orcid": "0000-0002-9194-5071" }, { "id": "Treu-Tommaso", "name": { "family": "Treu", "given": "Tommaso" }, "orcid": "0000-0002-8460-0390" } ] }, "title": "Evolution of the Stellar Mass\u2013Metallicity Relation. II. Constraints on Galactic Outflows from the Mg Abundances of Quiescent Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: evolution \u2013 galaxies: stellar content", "note": "\u00a9 2019 The American Astronomical Society. \n\nReceived 2019 March 14; revised 2019 September 19; accepted 2019 September 24; published 2019 November 5. \n\nWe thank the referee for comments and suggestions that significantly improved the paper. The authors acknowledge Charlie Conroy, Philip Hopkins, and Gwen Rudie for useful feedback and the use of their models and fitting codes. \n\nFacilities: Keck:II (DEIMOS) - , Sloan - , GALEX - , HST (WFPC2) - , Subaru (Suprime-Cam) - , CFHT (CFH12k) - , Hale (WIRC). - \n\nSoftware: KCORRECT (Blanton & Roweis 2007), FSPS, (Conroy et al. 2009), alf (Conroy et al. 2018), MPFIT (Markwardt 2012).\n\nPublished - Leethochawalit_2019_ApJ_885_100.pdf
Accepted Version - 1909.11680.pdf
", "abstract": "We present the stellar mass\u2013[Fe/H] and mass\u2013[Mg/H] relation of quiescent galaxies in two galaxy clusters at z ~ 0.39 and z ~ 0.54. We derive the age, [Fe/H], and [Mg/Fe] for each individual galaxy using a full-spectrum fitting technique. By comparing with the relations for z ~ 0 Sloan Digital Sky Survey galaxies, we confirm our previous finding that the mass\u2013[Fe/H] relation evolves with redshift. The mass\u2013[Fe/H] relation at higher redshift has lower normalization and possibly steeper slope. However, based on our sample, the mass\u2013[Mg/H] relation does not evolve over the observed redshift range. We use a simple analytic chemical evolution model to constrain the average outflow that these galaxies experience over their lifetime, via the calculation of mass-loading factor. We find that the average mass-loading factor \u03b7 is a power-law function of galaxy stellar mass, \u03b7 \u221d M*^(\u22120.21\u00b10.09). The measured mass-loading factors are consistent with the results of other observational methods for outflow measurements and with the predictions where outflow is caused by star formation feedback in turbulent disks.", "date": "2019-11-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "885", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 100", "id_number": "CaltechAUTHORS:20191105-094725372", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191105-094725372", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab4809", "primary_object": { "basename": "1909.11680.pdf", "url": "https://authors.library.caltech.edu/records/sp2cm-4ed15/files/1909.11680.pdf" }, "related_objects": [ { "basename": "Leethochawalit_2019_ApJ_885_100.pdf", "url": "https://authors.library.caltech.edu/records/sp2cm-4ed15/files/Leethochawalit_2019_ApJ_885_100.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Leethochawalit, Nicha; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/tfdqw-pf008", "eprint_id": 100214, "eprint_status": "archive", "datestamp": "2023-08-19 18:33:09", "lastmod": "2023-10-18 19:11:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zheng-Yong", "name": { "family": "Zheng", "given": "Yong" }, "orcid": "0000-0003-4158-5116" }, { "id": "Putman-M-E", "name": { "family": "Putman", "given": "Mary E." } }, { "id": "Emerick-Andrew", "name": { "family": "Emerick", "given": "Andrew" }, "orcid": "0000-0003-2807-328X" }, { "id": "McQuinn-K-B-W", "name": { "family": "McQuinn", "given": "Kristen B. W." } }, { "id": "Werk-J-K", "name": { "family": "Werk", "given": "Jessica K." }, "orcid": "0000-0002-0355-0134" }, { "id": "Lockman-F-J", "name": { "family": "Lockman", "given": "Felix J." } }, { "id": "Oppenheimer-Benjamin-D", "name": { "family": "Oppenheimer", "given": "Benjamin D." }, "orcid": "0000-0003-4754-6863" }, { "id": "Fox-A-J", "name": { "family": "Fox", "given": "Andrew J." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Burchett-J-N", "name": { "family": "Burchett", "given": "Joseph N." }, "orcid": "0000-0002-1979-2197" } ] }, "title": "Tentative detection of the circumgalactic medium of the isolated low-mass dwarf galaxy WLM", "ispublished": "pub", "full_text_status": "public", "keywords": "techniques: spectroscopic \u2013 galaxies: dwarf (WLM) \u2013 galaxies: haloes \u2013 quasars: absorption lines", "note": "\u00a9 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). \n\nAccepted 2019 September 6. Received 2019 July 15; in original form 2019 April 3. Published: 13 September 2019. \n\nYZ is grateful to D. Weisz for many useful discussions during the preparation of this work. YZ thanks S. Albers for providing SFH estimates of WLM on combined UVIS/ACS fields, thanks C. F. McKee for his feedback on this manuscript, and thanks C. howk and N. Lehner for their comments on possible origin of the MW ionized high-velocity clouds. YZ acknowledges support from the Miller Institute for Basic Research in Science. AE was supported by the National Science Foundation (NSF) Blue Waters Graduate Fellowship. ENK acknowledges support by NASA through a grant (HST-GO-15156.004-A) from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS 5-26555. The UV spectrum presented in this work was obtained from the Mikulski Archive for Space Telescopes (MAST). Facilities: HST/COS, Green Bank Telescope. Software: ASTROPY (Astropy Collaboration et al. 2013), IDL, NUMPY (Oliphant 2007), MATPLOTLIB (Hunter 2007).\n\nPublished - stz2563.pdf
Accepted Version - 1909.05407.pdf
", "abstract": "We report a tentative detection of the circumgalactic medium (CGM) of Wolf\u2013Lundmark\u2013Melotte (WLM), an isolated, low-mass (logM*/M\u2299 \u2248 7.6), dwarf irregular galaxy in the Local Group (LG). We analyse an HST/COS archival spectrum of a quasar sightline (PHL2525), which is 45 kpc (0.5 virial radius) from WLM and close to the Magellanic Stream (MS). Along this sightline, two ion absorbers are detected in Si II, Si III, Si IV, C II, and C IV at velocities of \u223c\u2212220 km s\u207b\u00b9 (Component v-220) and \u223c\u2212150 km s\u207b\u00b9 (Component v-150). To identify their origins, we study the position\u2013velocity alignment of the components with WLM and the nearby MS. Near the magellanic longitude of PHL2525, the MS-related neutral and ionized gas moves at \u2272\u2212190 km s\u207b\u00b9, suggesting an MS origin for Component v-220, but not for Component v-150. Because PHL2525 passes near WLM and Component v-150 is close to WLM's systemic velocity (\u223c\u2212132 km s\u207b\u00b9), it is likely that Component v-150 arises from the galaxy's CGM. This results in a total Si mass in WLM's CGM of M^(CGM)_(Si)\u223c(0.2\u22121.0)\u00d710\u2075 M\u2299 using assumption from other COS dwarf studies. Comparing M^(CGM)_(Si) to the total Si mass synthesized in WLM over its lifetime (\u223c1.3 \u00d7 10\u2075 M\u2299), we find \u223c3 per\u2009cent is locked in stars, \u223c6 per\u2009cent in the ISM, \u223c15\u201377 per\u2009cent in the CGM, and the rest (\u223c14\u201376 per\u2009cent) is likely lost beyond the virial radius. Our finding resonates with other COS dwarf galaxy studies and theoretical predictions that low-mass galaxies can easily lose metals into their CGM due to stellar feedback and shallow gravitational potential.", "date": "2019-11", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "490", "number": "1", "publisher": "Royal Astronomical Society", "pagerange": "467-477", "id_number": "CaltechAUTHORS:20191205-151312615", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191205-151312615", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Miller Institute for Basic Research in Science" }, { "agency": "NSF" }, { "agency": "NASA", "grant_number": "HST-GO-15156.004-A" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.1093/mnras/stz2563", "primary_object": { "basename": "1909.05407.pdf", "url": "https://authors.library.caltech.edu/records/tfdqw-pf008/files/1909.05407.pdf" }, "related_objects": [ { "basename": "stz2563.pdf", "url": "https://authors.library.caltech.edu/records/tfdqw-pf008/files/stz2563.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Zheng, Yong; Putman, Mary E.; et el." }, { "id": "https://authors.library.caltech.edu/records/v8w3r-ejf88", "eprint_id": 98901, "eprint_status": "archive", "datestamp": "2023-08-19 18:10:50", "lastmod": "2023-10-18 17:43:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Elemental Abundances in M31: First Alpha and Iron Abundance Measurements in M31's Giant Stellar Stream", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: halos \u2013 galaxies: individual (M31) \u2013 stars: abundances \u2013 stars: kinematics and dynamics \u2013 techniques: spectroscopic", "note": "\u00a9 2019 The American Astronomical Society. \n\nReceived 2019 April 30; revised 2019 July 31; accepted 2019 July 31; published 2019 September 26. \n\nThe authors recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nThe authors thank M. Fardal, F. Hammer, Y. Yang, and S. Hasselquist for helpful conversations during the writing of this manuscript, and A. McConnachie for use of the PAndAS image. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018). \n\nSupport for this work was provided by NSF grants AST-1614569 (K.M.G., J.W.), AST-1614081 (E.N.K., I.E.), and AST-1412648 (P.G.). E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement as well as funding from generous donors to the California Institute of Technology. I.E. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship under grant No. DGE-1745301. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048. \n\nFacilities: Keck II (DEIMOS) - , CFHT (MegaCam). - \n\nSoftware: Astropy (Astropy Collaboration et al. 2013), Matplotlib (Hunter 2007), numpy (van der Walt et al. 2011), corner (Foreman-Mackey 2016; Foreman-Mackey et al. 2016a).\n\nPublished - Gilbert_2019_ApJ_883_128.pdf
Accepted Version - 1908.04429.pdf
", "abstract": "We present the first measurements of [Fe/H] and [\u03b1/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31's giant stellar stream (GSS). The spectroscopic observations, obtained at a projected distance of 17 kpc from M31's center, yielded 61 stars with [Fe/H] measurements, including 21 stars with [\u03b1/Fe] measurements, from 112 targets identified as M31 stars. The [Fe/H] measurements confirm the expectation from photometric metallicity estimates that stars in this region of M31's halo are relatively metal rich compared to stars in the Milky Way's inner halo: more than half the stars in the field, including those not associated with kinematically identified substructure, have [Fe/H] abundances >-1.0. The stars in this field are \u03b1-enhanced at lower metallicities, while [\u03b1/Fe] decreases with increasing [Fe/H] above metallicities of [Fe/H] \u2273 \u22120.9. Three kinematical components have been previously identified in this field: the GSS, a second kinematically cold feature of unknown origin, and M31's kinematically hot halo. We compare probabilistic [Fe/H] and [\u03b1/Fe] distribution functions for each of the components. The GSS and the second kinematically cold feature have very similar abundance distributions, while the halo component is more metal poor. Although the current sample sizes are small, a comparison of the abundances of stars in the GSS field with abundances of M31 halo and dSph stars from the literature indicate that the progenitor of the stream was likely more massive, and experienced a higher efficiency of star formation, than M31's existing dSphs or the dEs NGC 147 and NGC 185.", "date": "2019-10-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "883", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 128", "id_number": "CaltechAUTHORS:20190927-092802684", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190927-092802684", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab3807", "primary_object": { "basename": "1908.04429.pdf", "url": "https://authors.library.caltech.edu/records/v8w3r-ejf88/files/1908.04429.pdf" }, "related_objects": [ { "basename": "Gilbert_2019_ApJ_883_128.pdf", "url": "https://authors.library.caltech.edu/records/v8w3r-ejf88/files/Gilbert_2019_ApJ_883_128.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Gilbert, Karoline M.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/t66na-6pq26", "eprint_id": 105073, "eprint_status": "archive", "datestamp": "2023-08-22 02:23:42", "lastmod": "2023-10-20 21:20:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Belland-B", "name": { "family": "Belland", "given": "Brent" } }, { "id": "Gunn-J-E", "name": { "family": "Gunn", "given": "James" } }, { "id": "Reiley-D", "name": { "family": "Reiley", "given": "Dan" } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith" }, "orcid": "0000-0002-8039-4673" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "de-Oliveira-A-C", "name": { "family": "de Oliveira", "given": "Antonio Cesar" } }, { "id": "de-Oliveira-L-S", "name": { "family": "de Oliveira", "given": "Ligia Souza" }, "orcid": "0000-0001-7670-0204" }, { "id": "Roberts-Mitsuko", "name": { "family": "Roberts", "given": "Mitsuko" } }, { "id": "Seiffert-M", "name": { "family": "Seiffert", "given": "Michael" } } ] }, "title": "Focal Ratio Degradation for Fiber Positioner Operation in Astronomical Spectrographs", "ispublished": "pub", "full_text_status": "public", "keywords": "Focal ratio degradation; optical fiber; telescope; stress; misalignment", "note": "\u00a9 2019 The Author(s). This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. \n\nReceived August 8, 2018; Revised December 18, 2018; Accepted January 8, 2019; Published February 21, 2019. \n\nWe are grateful to the Kavli Institute for the Physics and Mathematics of the Universe, the National Astronomical Observatory of Japan, and the Subaru PFS collaboration for their feedback and recommendations throughout this project. We would especially like to thank Naoyuki Tamura and Yuki Moritani for discussions and direction for this project, as well as Leandro dos Santos for fiber preparation. This material is based upon work supported by the National Science Foundation under MSIP Grant No. 1636426. \n\nThis research has made use of NASA's Astrophysics Data System.\n\nPublished - s2251171719500077.pdf
Accepted Version - 2006.10902.pdf
", "abstract": "Focal ratio degradation (FRD), the decrease of light's focal ratio between the input into an optical fiber and the output, is important to characterize for astronomical spectrographs due to its effects on throughput and the point spread function. However, while FRD is a function of many fiber properties such as stresses, microbending, and surface imperfections, angular misalignments between the incoming light and the face of the fiber also affect the light profile and complicate this measurement. A compact experimental setup and a model separating FRD from angular misalignment was applied to a fiber subjected to varying stresses or angular misalignments to determine the magnitude of these effects. The FRD was then determined for a fiber in a fiber positioner that will be used in the Subaru Prime Focus Spectrograph (PFS). The analysis we carried out for the PFS positioner suggests that effects of angular misalignment dominate and no significant FRD increase due to stress should occur.", "date": "2019-09", "date_type": "published", "publication": "Journal of Astronomical Instrumentation", "volume": "8", "number": "3", "publisher": "World Scientific Publishing", "pagerange": "Art. No. 1950007", "id_number": "CaltechAUTHORS:20200824-122637398", "issn": "2251-1717", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200824-122637398", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1636426" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.1142/s2251171719500077", "primary_object": { "basename": "2006.10902.pdf", "url": "https://authors.library.caltech.edu/records/t66na-6pq26/files/2006.10902.pdf" }, "related_objects": [ { "basename": "s2251171719500077.pdf", "url": "https://authors.library.caltech.edu/records/t66na-6pq26/files/s2251171719500077.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Belland, Brent; Gunn, James; et el." }, { "id": "https://authors.library.caltech.edu/records/g59yv-1pc54", "eprint_id": 97706, "eprint_status": "archive", "datestamp": "2023-08-19 17:18:06", "lastmod": "2023-10-18 16:38:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Xie-Justin-L", "name": { "family": "Xie", "given": "Justin L." } }, { "id": "Guo-Rachel", "name": { "family": "Guo", "given": "Rachel" } }, { "id": "de-los-Reyes-M-A-C", "name": { "family": "de los Reyes", "given": "Mithi A. C." }, "orcid": "0000-0002-4739-046X" }, { "id": "Bergemann-M", "name": { "family": "Bergemann", "given": "Maria" }, "orcid": "0000-0002-9908-5571" }, { "id": "Kovalev-M", "name": { "family": "Kovalev", "given": "Mikhail" } }, { "id": "Shen-Ken-J", "name": { "family": "Shen", "given": "Ken J." } }, { "id": "Piro-A-L", "name": { "family": "Piro", "given": "Anthony L." }, "orcid": "0000-0001-6806-0673" }, { "id": "McWilliam-A", "name": { "family": "McWilliam", "given": "Andrew" } } ] }, "title": "Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar\n Abundances in Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: dwarf \u2013 Local Group \u2013 nuclear reactions, nucleosynthesis, abundances \u2013 supernovae: general", "note": "\u00a9 2019 The American Astronomical Society. \n\nReceived 2019 April 26; revised 2019 June 18; accepted 2019 June 22; published 2019 August 12. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nWe thank Marten van Kerkwijk, Julianne Dalcanton, Ivo Seitenzahl, Robert Fisher, Ken'ichi Nomoto, Mansi Kasliwal, Alex Ji, and Norbert Werner for insightful conversations. We also thank the anonymous referee for a helpful report. This material is based upon work supported by the National Science Foundation under grant No. AST-1614081. E.N.K. gratefully acknowledges support from a Cottrell Scholar award administered by the Research Corporation for Science Advancement as well as funding from generous donors to the California Institute of Technology. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. We express our deep gratitude to the staff at academic and telescope facilities whose labor maintains spaces for scientific inquiry. \n\nFacility: Keck:II (DEIMOS). - \n\nSoftware: MOOG (Sneden 1973; Sneden et al. 2012).\n\nPublished - Kirby_2019_ApJ_881_45.pdf
Accepted Version - 1906.10126.pdf
", "abstract": "There is no consensus on the progenitors of Type Ia supernovae (SNe Ia) despite their importance for cosmology and chemical evolution. We address this question using our previously published catalogs of Mg, Si, Ca, Cr, Fe, Co, and Ni abundances in dwarf galaxy satellites of the Milky Way (MW) to constrain the mass at which the white dwarf (WD) explodes during a typical SN Ia. We fit a simple bi-linear model to the evolution of [X/Fe] with [Fe/H], where X represents each of the elements mentioned above. We use the evolution of [Mg/Fe] coupled with theoretical supernova yields to isolate what fraction of the elements originated in SNe Ia. Then, we infer the [X/Fe] yield of SNe Ia for all of the elements except Mg. We compare these observationally inferred yields to recent theoretical predictions for two classes of Chandrasekhar-mass (M_(Ch)) SN Ia as well as sub-M_(Ch) SNe Ia. Most of the inferred SN Ia yields are consistent with all of the theoretical models, but [Ni/Fe] is consistent only with sub-M_(Ch) models. We conclude that the dominant type of SN Ia in ancient dwarf galaxies is the explosion of a sub-M_(Ch) WD. The MW and dwarf galaxies with extended star formation histories have higher [Ni/Fe] abundances, which could indicate that the dominant class of SN Ia is different for galaxies where star formation lasted for at least several Gyr.", "date": "2019-08-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "881", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 45", "id_number": "CaltechAUTHORS:20190807-125436624", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190807-125436624", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "W. M. Keck Foundation" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "Caltech" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab2c02", "primary_object": { "basename": "1906.10126.pdf", "url": "https://authors.library.caltech.edu/records/g59yv-1pc54/files/1906.10126.pdf" }, "related_objects": [ { "basename": "Kirby_2019_ApJ_881_45.pdf", "url": "https://authors.library.caltech.edu/records/g59yv-1pc54/files/Kirby_2019_ApJ_881_45.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Kirby, Evan N.; Xie, Justin L.; et el." }, { "id": "https://authors.library.caltech.edu/records/n4tkk-wg886", "eprint_id": 96387, "eprint_status": "archive", "datestamp": "2023-08-19 16:15:56", "lastmod": "2023-10-20 21:07:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Cunningham-E-C", "name": { "family": "Cunningham", "given": "Emily C." }, "orcid": "0000-0002-6993-0826" }, { "id": "Wojno-J", "name": { "family": "Wojno", "given": "Jennifer" }, "orcid": "0000-0002-3233-3032" } ] }, "title": "Elemental Abundances in M31: Alpha and Iron Element Abundances from Low-resolution Resolved Stellar Spectroscopy in the Stellar Halo", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: formation \u2013 galaxies: halos \u2013 Local Group \u2013 stars: abundances", "note": "\u00a9 2019 The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 2018 November 15; revised 2019 April 9; accepted 2019 April 30; published 2019 June 12. \n\nThe authors thank the anonymous reviewer for a careful reading of this manuscript and providing thoughtful feedback that improved this paper. We also thank Alis Deason for assistance in line-list vetting, Gina Duggan for useful discussions on generating grids of synthetic spectra, Raja Guha Thakurta for help with observations and insightful conversations, and Luis Vargas and Marla Geha for sharing their data for M31 outer halo RGB stars. I.E. acknowledges support from a Ford Foundation Predoctoral Fellowship and the NSF Graduate Research Fellowship under grant No. DGE-1745301, as well as the NSF under grant No. AST-1614081, along with E.N.K. K.M.G. and J.W. acknowledge support from NSF grant AST-1614569. E.C.C. was supported by an NSF Graduate Research Fellowship as well as NSF grant No. AST-1616540. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048.\n\nPublished - Escala_2019_ApJ_878_42.pdf
Accepted Version - 1811.09279.pdf
", "abstract": "Measurements of [Fe/H] and [\u03b1/Fe] can probe the minor merging history of a galaxy, providing a direct way to test the hierarchical assembly paradigm. While measurements of [\u03b1/Fe] have been made in the stellar halo of the Milky Way (MW), little is known about detailed chemical abundances in the stellar halo of M31. To make progress with existing telescopes, we apply spectral synthesis to low-resolution DEIMOS spectroscopy (R ~ 2500 at 7000 \u00c5) across a wide spectral range (4500 \u00c5 < \u03bb < 9100 \u00c5). By applying our technique to low-resolution spectra of 170 giant stars in five MW globular clusters, we demonstrate that our technique reproduces previous measurements from higher resolution spectroscopy. Based on the intrinsic dispersion in [Fe/H] and [\u03b1/Fe] of individual stars in our combined cluster sample, we estimate systematic uncertainties of ~0.11 dex and ~0.09 dex in [Fe/H] and [\u03b1/Fe], respectively. We apply our method to deep, low-resolution spectra of 11 red giant branch stars in the smooth halo of M31, resulting in higher signal-to-noise ratios per spectral resolution element compared to DEIMOS medium-resolution spectroscopy, given the same exposure time and conditions. We find \u3008[\u03b1/Fe]\u3009 = 0.49 \u00b1 0.29 dex and \u3008[Fe/H]\u3009 = \u22121.59 \u00b1 0.56 dex for our sample. This implies that\u2014much like the MW\u2014the smooth halo field of M31 is likely composed of disrupted dwarf galaxies with truncated star formation histories that were accreted early in the halo's formation.", "date": "2019-06-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "878", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 42", "id_number": "CaltechAUTHORS:20190613-111030848", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190613-111030848", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Ford Foundation" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1616540" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab1eac", "primary_object": { "basename": "1811.09279.pdf", "url": "https://authors.library.caltech.edu/records/n4tkk-wg886/files/1811.09279.pdf" }, "related_objects": [ { "basename": "Escala_2019_ApJ_878_42.pdf", "url": "https://authors.library.caltech.edu/records/n4tkk-wg886/files/Escala_2019_ApJ_878_42.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Escala, Ivanna; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/h7sbv-5j875", "eprint_id": 95395, "eprint_status": "archive", "datestamp": "2023-08-22 01:34:41", "lastmod": "2023-10-20 20:12:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cunningham-E-C", "name": { "family": "Cunningham", "given": "Emily C." }, "orcid": "0000-0002-6993-0826" }, { "id": "Deason-A-J", "name": { "family": "Deason", "given": "Alis J." }, "orcid": "0000-0001-6146-2645" }, { "id": "Rockosi-C-M", "name": { "family": "Rockosi", "given": "Constance M." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Jennings-Z-G", "name": { "family": "Jennings", "given": "Zachary G." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Toloba-E", "name": { "family": "Toloba", "given": "Elisa" }, "orcid": "0000-0001-6443-5570" }, { "id": "Barro-G", "name": { "family": "Barro", "given": "Guillermo" }, "orcid": "0000-0001-6813-875X" } ] }, "title": "HALO7D I. The Line-of-sight Velocities of Distant Main-sequence Stars in the Milky Way Halo", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxy: halo; Galaxy: kinematics and dynamics; methods: statistical; techniques: radial velocities", "note": "\u00a9 2019. The American Astronomical Society. \n\nReceived 2018 September 3; revised 2019 March 19; accepted 2019 April 4; published 2019 May 10. \n\nOver the course of this work, E.C. was supported by a National Science Foundation Graduate Research Fellowship and an ARCs Foundation Fellowship, as well as NSF grant AST-1616540. Partial support for this work was provided by NASA through grants for program AR-13272 from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. E.C. expresses her profound gratitude to Alexander Rudy, a conversation with whom sparked the radial velocity measurement technique outlined in this work. E.C. also thanks Tony Sohn for his help with Figure 1. A.D. is supported by a Royal Society University Research Fellowship. A.D. also acknowledges support from the STFC grant ST/P000451/1. P.G. and E.T. acknowledge support from the NSF grants AST-1010039 and AST-1412504. We thank the outstanding team at Keck Observatory for assisting us in our observations. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018). This work has made use of the Rainbow Cosmological Surveys Database, which is operated by the Universidad Complutense de Madrid (UCM), partnered with the University of California Observatories at Santa Cruz (UCO/Lick, UCSC). We recognize and acknowledge the significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - Cunningham_2019_ApJ_876_124.pdf
Submitted - 1809.04082.pdf
", "abstract": "The Halo Assembly in Lambda-CDM: Observations in 7 Dimensions (HALO7D) data set consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope\u2013measured proper motions of Milky Way halo main-sequence turnoff stars in the CANDELS fields. In this paper, we present the spectroscopic component of this data set and discuss target selection, observing strategy, and survey properties. We present a new method of measuring line-of-sight (LOS) velocities by combining multiple spectroscopic observations of a given star, utilizing Bayesian hierarchical modeling. We present the LOS velocity distributions of the four HALO7D fields and estimate their means and dispersions. All of the LOS distributions are dominated by the \"hot halo\": none of our fields are dominated by substructure that is kinematically cold in the LOS velocity component. Our estimates of the LOS velocity dispersions are consistent across the different fields, and these estimates are consistent with studies using other types of tracers. To complement our observations, we perform mock HALO7D surveys using the synthetic survey software Galaxia to \"observe\" the Bullock & Johnston accreted stellar halos. Based on these simulated data sets, the consistent LOS velocity distributions across the four HALO7D fields indicate that the HALO7D sample is dominated by stars from the same massive (or few relatively massive) accretion event(s).", "date": "2019-05-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "876", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 124", "id_number": "CaltechAUTHORS:20190510-105529766", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-105529766", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship" }, { "agency": "ARCS Foundation" }, { "agency": "NSF", "grant_number": "AST-1616540" }, { "agency": "NASA", "grant_number": "AR-13272" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "Royal Society" }, { "agency": "Science and Technology Facilities Council (STFC)", "grant_number": "ST/P000451/1" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1412504" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/ab16cb", "primary_object": { "basename": "1809.04082.pdf", "url": "https://authors.library.caltech.edu/records/h7sbv-5j875/files/1809.04082.pdf" }, "related_objects": [ { "basename": "Cunningham_2019_ApJ_876_124.pdf", "url": "https://authors.library.caltech.edu/records/h7sbv-5j875/files/Cunningham_2019_ApJ_876_124.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Cunningham, Emily C.; Deason, Alis J.; et el." }, { "id": "https://authors.library.caltech.edu/records/7wea3-qjz30", "eprint_id": 91692, "eprint_status": "archive", "datestamp": "2023-08-22 00:27:51", "lastmod": "2023-10-19 23:39:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Duggan-G-E", "name": { "family": "Duggan", "given": "Gina E." }, "orcid": "0000-0002-9256-6735" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Andrievsky-S-M", "name": { "family": "Andrievsky", "given": "Serge M." } }, { "id": "Korotin-S-A", "name": { "family": "Korotin", "given": "Sergey A." } } ] }, "title": "Neutron Star Mergers are the Dominant Source of the r-process in the Early Evolution of Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: evolution; Local Group; nuclear reactions, nucleosynthesis, abundances; stars: abundances", "note": "\u00a9 2018. The American Astronomical Society. \n\nReceived 2018 July 16; revised 2018 October 17; accepted 2018 October 20; published 2018 December 11. \n\nThis material is based upon work supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-1745301 and the National Science Foundation under grant No. AST-1614081. \n\nFacility: Keck:II (DEIMOS). - \n\nSoftware: MOOG (Sneden 1973), spec2d pipeline (Cooper et al. 2012; Newman et al. 2013), scipy (Jones et al. 2001).\n\nPublished - Duggan_2018_ApJ_869_50.pdf
Accepted Version - 1809.04597.pdf
", "abstract": "There are many candidate sites of the r-process: core-collapse supernovae (CCSNe; including rare magnetorotational core-collapse supernovae), neutron star mergers (NSMs), and neutron star/black hole mergers. The chemical enrichment of galaxies\u2014specifically dwarf galaxies\u2014helps distinguish between these sources based on the continual build-up of r-process elements. This technique can distinguish between the r-process candidate sites by the clearest observational difference\u2014how quickly these events occur after the stars are created. The existence of several nearby dwarf galaxies allows us to measure robust chemical abundances for galaxies with different star formation histories. Dwarf galaxies are especially useful because simple chemical evolution models can be used to determine the sources of r-process material. We have measured the r-process element barium with Keck/DEIMOS medium-resolution spectroscopy. We present the largest sample of barium abundances (almost 250 stars) in dwarf galaxies ever assembled. We measure [Ba/Fe] as a function of [Fe/H] in this sample and compare with existing [\u03b1/Fe] measurements. We have found that a large contribution of barium needs to occur at more delayed timescales than CCSNe in order to explain our observed abundances, namely the significantly more positive trend of the r-process component of [Ba/Fe] versus [Fe/H] seen for [Fe/H] \u227e -1.6 when compared to the [Mg/Fe] versus [Fe/H] trend. We conclude that NSMs are the most likely source of r-process enrichment in dwarf galaxies at early times.", "date": "2018-12-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "869", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 50", "id_number": "CaltechAUTHORS:20181211-140648144", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181211-140648144", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NSF", "grant_number": "AST-1614081" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aaeb8e", "primary_object": { "basename": "1809.04597.pdf", "url": "https://authors.library.caltech.edu/records/7wea3-qjz30/files/1809.04597.pdf" }, "related_objects": [ { "basename": "Duggan_2018_ApJ_869_50.pdf", "url": "https://authors.library.caltech.edu/records/7wea3-qjz30/files/Duggan_2018_ApJ_869_50.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Duggan, Gina E.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/nabkc-z5q34", "eprint_id": 91518, "eprint_status": "archive", "datestamp": "2023-08-22 00:25:05", "lastmod": "2023-10-19 22:33:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spencer-M-E", "name": { "family": "Spencer", "given": "Meghin E." }, "orcid": "0000-0003-1240-1939" }, { "id": "Mateo-M", "name": { "family": "Mateo", "given": "Mario" } }, { "id": "Olszewski-E-W", "name": { "family": "Olszewski", "given": "Edward W." } }, { "id": "Walker-M-G", "name": { "family": "Walker", "given": "Matthew G." }, "orcid": "0000-0003-2496-1925" }, { "id": "McConnachie-A-W", "name": { "family": "McConnachie", "given": "Alan W." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "The Binary Fraction of Stars in Dwarf Galaxies: The Cases of Draco and Ursa Minor", "ispublished": "pub", "full_text_status": "public", "keywords": "binaries: general; galaxies: dwarf; galaxies: individual (Draco, Ursa Minor); galaxies: kinematics and dynamics", "note": "\u00a9 2018. The American Astronomical Society. \n\nReceived 2018 June 25; revised 2018 August 27; accepted 2018 August 27; published 2018 November 9. \n\nThe Hectochelle observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. \n\nThe authors would like to thank Jan Kleyna and Mark Wilkinson for sharing their velocity data from K02, K03, and W04 with us. We would also like to thank Josh Simon for allowing us to use his Keck spectra to obtain velocities for the K10 data set. We warmly thank Andrew Szentgyorgyi, Nelson Caldwell, and the rest of the Hectochelle builders and staff. We also thank Marc Lacasse and the MMT operators, robot operators, and technical staff. We thank the anonymous referee for helpful comments that improved this work. \n\nM.E.S. is supported by the National Science Foundation Graduate Research Fellowship under grant number DGE1256260. M.M. acknowledges support from NSF grants AST-1312997 and AST-1815403. M.G.W. acknowledges support from National Science Foundation grants AST-1313045 and AST-1813881. E.O. acknowledges support from NSF grants AST-1313006 and AST-1815767.\n\nPublished - Spencer_2018_AJ_156_257.pdf
Accepted Version - 1811.06597.pdf
", "abstract": "Measuring the frequency of binary stars in dwarf spheroidal galaxies (dSphs) requires data taken over long time intervals. We combine radial velocity measurements from five literature sources taken over the course of ~30 years to yield the largest multi-epoch kinematic sample for stars in the dSphs Draco and Ursa Minor. With this data set, we are able to implement an improved version of the Bayesian technique described in Spencer et al. to evaluate the binary fraction of red giant stars in these dwarf galaxies. Assuming Duquennoy & Mayor period and mass ratio distributions, the binary fractions in Draco and Ursa Minor are 0.50_(-0.06)^(+0.04) and 0.78_(-0.08)^(+0.09), respectively. We find that a normal mass ratio distribution is preferred over a flat distribution, and that log-normal period distributions centered on long periods \u00b5_(log P > 3.5) are preferred over distributions centered on short ones. We reanalyzed the binary fractions in Leo II, Carina, Fornax, Sculptor, and Sextans, and find that there is <1% chance that binary fraction is a constant quantity across all seven dwarfs, unless the period distribution varies greatly. This indicates that the binary populations in Milky Way dSphs are not identical in regard to their binary fractions, period distributions, or both. We consider many different properties of the dwarfs (e.g., mass, radius, luminosity, etc.) and find that binary fraction might be larger in dwarfs that formed their stars quickly and/or have high velocity dispersions.", "date": "2018-12", "date_type": "published", "publication": "Astronomical Journal", "volume": "156", "number": "6", "publisher": "American Astronomical Society", "pagerange": "Art. No. 257", "id_number": "CaltechAUTHORS:20181205-145346940", "issn": "1538-3881", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181205-145346940", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1256260" }, { "agency": "NSF", "grant_number": "AST-1312997" }, { "agency": "NSF", "grant_number": "AST-1815403" }, { "agency": "NSF", "grant_number": "AST-1313045" }, { "agency": "NSF", "grant_number": "AST-1813881" }, { "agency": "NSF", "grant_number": "AST-1313006" }, { "agency": "NSF", "grant_number": "AST-1815767" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-3881/aae3e4", "primary_object": { "basename": "1811.06597.pdf", "url": "https://authors.library.caltech.edu/records/nabkc-z5q34/files/1811.06597.pdf" }, "related_objects": [ { "basename": "Spencer_2018_AJ_156_257.pdf", "url": "https://authors.library.caltech.edu/records/nabkc-z5q34/files/Spencer_2018_AJ_156_257.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Spencer, Meghin E.; Mateo, Mario; et el." }, { "id": "https://authors.library.caltech.edu/records/m1wdx-x2b49", "eprint_id": 88486, "eprint_status": "archive", "datestamp": "2023-08-21 23:37:01", "lastmod": "2023-10-18 22:05:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Xie-Justin-L", "name": { "family": "Xie", "given": "Justin L." } }, { "id": "Guo-Rachel", "name": { "family": "Guo", "given": "Rachel" } }, { "id": "Kovalev-M", "name": { "family": "Kovalev", "given": "Mikhail" } }, { "id": "Bergemann-M", "name": { "family": "Bergemann", "given": "Maria" }, "orcid": "0000-0002-9908-5571" } ] }, "title": "Catalog of Chromium, Cobalt, and Nickel Abundances in Globular Clusters and Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; Local Group; nuclear reactions, nucleosynthesis, abundances; supernovae", "note": "\u00a9 2018. The American Astronomical Society. \n\nReceived 2018 April 2; revised 2018 May 23; accepted 2018 May 28; published 2018 July 19. \n\nWe thank the anonymous referee for a constructive report. This material is based upon work supported by the National Science Foundation under grant No. AST-1614081. Support for this work was also provided by NASA through a grant (HST-GO-14734.011-A) from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. E.N.K. acknowledges funding from generous donors to the California Institute of Technology. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nSoftware: MOOG (Sneden 1973), MAFAGS-OS (Grupp 2004a, 2004b), MARCS (Gustafsson et al. 2008), spec2d pipeline (Cooper et al. 2012; Newman et al. 2013), MPFIT (Markwardt 2012). \n\nFacility: Keck:II (DEIMOS). -\n\nPublished - Kirby_2018_ApJS_237_18.pdf
Submitted - 1906.08284.pdf
", "abstract": "We present measurements of the abundances of chromium, cobalt, and nickel in 4113 red giants, including 2277 stars in globular clusters (GCs), 1820 stars in the Milky Way's dwarf satellite galaxies, and 16 field stars. We measured the abundances from mostly archival Keck/DEIMOS medium-resolution spectroscopy with a resolving power of R ~ 6500 and a wavelength range of approximately 6500\u20139000 \u00c5. The abundances were determined by fitting spectral regions that contain absorption lines of the elements under consideration. We used estimates of temperature, surface gravity, and metallicity that we previously determined from the same spectra. We estimated systematic error by examining the dispersion of abundances within mono-metallic GCs. The median uncertainties for [Cr/Fe], [Co/Fe], and [Ni/Fe] are 0.20, 0.20, and 0.13, respectively. Finally, we validated our estimations of uncertainty through duplicate measurements, and we evaluated the accuracy and precision of our measurements through comparison to high-resolution spectroscopic measurements of the same stars.", "date": "2018-07", "date_type": "published", "publication": "Astrophysical Journal Supplement Series", "volume": "237", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 18", "id_number": "CaltechAUTHORS:20180801-164036156", "issn": "0067-0049", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180801-164036156", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NASA", "grant_number": "HST-GO-14734.011-A" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "Caltech" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4365/aac952", "primary_object": { "basename": "1906.08284.pdf", "url": "https://authors.library.caltech.edu/records/m1wdx-x2b49/files/1906.08284.pdf" }, "related_objects": [ { "basename": "Kirby_2018_ApJS_237_18.pdf", "url": "https://authors.library.caltech.edu/records/m1wdx-x2b49/files/Kirby_2018_ApJS_237_18.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Kirby, Evan N.; Xie, Justin L.; et el." }, { "id": "https://authors.library.caltech.edu/records/6x0ab-brr83", "eprint_id": 85453, "eprint_status": "archive", "datestamp": "2023-08-19 08:23:18", "lastmod": "2023-10-18 18:14:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Leethochawalit-N", "name": { "family": "Leethochawalit", "given": "Nicha" }, "orcid": "0000-0003-4570-3159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Moran-S-M", "name": { "family": "Moran", "given": "Sean M." }, "orcid": "0000-0002-9194-5071" }, { "id": "Ellis-R-S", "name": { "family": "Ellis", "given": "Richard S." }, "orcid": "0000-0001-7782-7071" }, { "id": "Treu-Tommaso", "name": { "family": "Treu", "given": "Tommaso" }, "orcid": "0000-0002-8460-0390" } ] }, "title": "Evolution of the Stellar Mass\u2013Metallicity Relation. I. Galaxies in the z \u223c 0.4 Cluster Cl0024", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: evolution \u2013 galaxies: stellar content", "note": "\u00a9 2018 The American Astronomical Society. \n\nReceived 2017 November 9; revised 2018 February 20; accepted 2018 February 23; published 2018 March 21. \n\nThe authors thank the referee for a constructive and helpful report. We also thank Anna Gallazzi and Jieun Choi for kindly providing data, catalogs, and feedback to the paper, and thank Xiangcheng Ma, Yu Lu, Shea Garrison-Kimmel, and Robyn Sanderson for useful discussions. E.N.K. and N.L. acknowledge support from the National Science Foundation grant AST-1614081.\n\nPublished - Leethochawalit_2018_ApJ_856_15.pdf
Accepted Version - 1802.09560.pdf
", "abstract": "We present the stellar mass\u2013stellar metallicity relationship (MZR) in the galaxy cluster Cl0024+1654 at z ~ 0.4 using full-spectrum stellar population synthesis modeling of individual quiescent galaxies. The lower limit of our stellar mass range is M* = 10^(9.7) M \u2299, the lowest galaxy mass at which individual stellar metallicity has been measured beyond the local universe. We report a detection of an evolution of the stellar MZR with observed redshift at 0.037 \u00b1 0.007 dex per Gyr, consistent with the predictions from hydrodynamical simulations. Additionally, we find that the evolution of the stellar MZR with observed redshift can be explained by an evolution of the stellar MZR with the formation time of galaxies, i.e., when the single stellar population (SSP)-equivalent ages of galaxies are taken into account. This behavior is consistent with stars forming out of gas that also has an MZR with a normalization that decreases with redshift. Lastly, we find that over the observed mass range, the MZR can be described by a linear function with a shallow slope ([Fe/H] \u221d (0.16 \u00b1 0.03) log M*. The slope suggests that galaxy feedback, in terms of mass-loading factor, might be mass-independent over the observed mass and redshift range.", "date": "2018-03-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "856", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 15", "id_number": "CaltechAUTHORS:20180327-104247834", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180327-104247834", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614081" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aab26a", "primary_object": { "basename": "1802.09560.pdf", "url": "https://authors.library.caltech.edu/records/6x0ab-brr83/files/1802.09560.pdf" }, "related_objects": [ { "basename": "Leethochawalit_2018_ApJ_856_15.pdf", "url": "https://authors.library.caltech.edu/records/6x0ab-brr83/files/Leethochawalit_2018_ApJ_856_15.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Leethochawalit, Nicha; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/frfw8-45f69", "eprint_id": 84996, "eprint_status": "archive", "datestamp": "2023-08-21 22:54:59", "lastmod": "2023-10-18 17:02:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gennaro-M", "name": { "family": "Gennaro", "given": "Mario" }, "orcid": "0000-0002-5581-2896" }, { "id": "Tchemyshyov-K", "name": { "family": "Tchemyshyov", "given": "Kirill" } }, { "id": "Brown-T-M", "name": { "family": "Brown", "given": "Thomas M." }, "orcid": "0000-0002-1793-9968" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Avila-R-J", "name": { "family": "Avila", "given": "Roberto J." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Renzini-A", "name": { "family": "Renzini", "given": "Alvio" }, "orcid": "0000-0002-7093-7355" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Tumlinson-J", "name": { "family": "Tumlinson", "given": "Jason" }, "orcid": "0000-0002-7982-412X" }, { "id": "Vargas-L-C", "name": { "family": "Vargas", "given": "Luis C." }, "orcid": "0000-0001-7155-0040" } ] }, "title": "Evidence of a Non-universal Stellar Initial Mass Function. Insights from HST Optical Imaging of Six Ultra-faint Dwarf Milky Way Satellites", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: stellar content; Local Group; methods: statistical; stars: luminosity function, mass function", "note": "\u00a9 2018 American Astronomical Society. \n\nReceived 2017 December 12. Accepted 2018 January 18. Published 2018 February 28. \n\nWe would like to thank Professor Don Vandenberg (University of Victoria, British Columbia, Canada) for providing the oxygen-enhanced models used in this work, as well as the Fortran routines used for their interpolation.\n\nSupport for program GO-12549 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. \n\nThis work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute under RSA number 1474359. Data presented herein were obtained at the W.M. Keck Observatory from telescope time allocated to NASA through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nE.N.K. acknowledges support from NSF grant AST-1614081.\n\nPublished - Gennaro_2018_ApJ_855_20.pdf
Submitted - 1801.06195.pdf
", "abstract": "Using deep observations obtained with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST), we demonstrate that the sub-solar stellar initial mass function (IMF) of six ultra-faint dwarf Milky Way satellites (UFDs) is more bottom light than the IMF of the Milky Way disk. Our data have a lower-mass limit of ~0.45 M_\u2299, while the upper limit is ~0.8 M_\u2299, set by the turnoff mass of these old, metal-poor systems. If formulated as a single power law, we obtain a shallower IMF slope than the Salpeter value of \u22122.3, ranging from \u22121.01 for Leo IV to \u22121.87 for Bo\u00f6tes I. The significance of these deviations depends on the galaxy and is typically 95% or more. When modeled as a log-normal, the IMF fit results in a higher peak mass than in the Milky Way disk, but a Milky Way disk value for the characteristic system mass (~0.22 M_\u2299) is excluded at only 68% significance, and only for some UFDs in the sample. We find that the IMF slope correlates well with the galaxy mean metallicity, and to a lesser degree, with the velocity dispersion and the total mass. The strength of the observed correlations is limited by shot noise in the number of observed stars, but future space-based missions like the James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope ( WFIRST) will enhance both the number of dwarf Milky Way satellites that can be studied in such detail and the observation depth for individual galaxies.", "date": "2018-03-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "855", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 20", "id_number": "CaltechAUTHORS:20180228-094019082", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180228-094019082", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NASA", "grant_number": "1474359" }, { "agency": "W. M. Keck Foundation" }, { "agency": "NSF", "grant_number": "AST-1614081" } ] }, "local_group": { "items": [ { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" }, { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aaa973", "primary_object": { "basename": "1801.06195.pdf", "url": "https://authors.library.caltech.edu/records/frfw8-45f69/files/1801.06195.pdf" }, "related_objects": [ { "basename": "Gennaro_2018_ApJ_855_20.pdf", "url": "https://authors.library.caltech.edu/records/frfw8-45f69/files/Gennaro_2018_ApJ_855_20.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Gennaro, Mario; Tchemyshyov, Kirill; et el." }, { "id": "https://authors.library.caltech.edu/records/5bs7a-1yh40", "eprint_id": 82826, "eprint_status": "archive", "datestamp": "2023-08-19 07:54:15", "lastmod": "2023-10-17 22:42:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Escala-I", "name": { "family": "Escala", "given": "Ivanna" }, "orcid": "0000-0002-9933-9551" }, { "id": "Wetzel-A-R", "name": { "family": "Wetzel", "given": "Andrew" }, "orcid": "0000-0003-0603-8942" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Hopkins-P-F", "name": { "family": "Hopkins", "given": "Philip F." }, "orcid": "0000-0003-3729-1684" }, { "id": "Ma-Xiangcheng", "name": { "family": "Ma", "given": "Xiangcheng" }, "orcid": "0000-0001-8091-2349" }, { "id": "Wheeler-C", "name": { "family": "Wheeler", "given": "Coral" } }, { "id": "Kere\u0161-D", "name": { "family": "Kere\u0161", "given": "Du\u0161an" }, "orcid": "0000-0002-1666-7067" }, { "id": "Faucher-Gigu\u00e8re-C-A", "name": { "family": "Faucher-Gigu\u00e8re", "given": "Claude-Andr\u00e9" }, "orcid": "0000-0002-4900-6628" }, { "id": "Quataert-E", "name": { "family": "Quataert", "given": "Eliot" }, "orcid": "0000-0001-9185-5044" } ] }, "title": "Modelling chemical abundance distributions for dwarf galaxies in the Local Group: the impact of turbulent metal diffusion", "ispublished": "pub", "full_text_status": "public", "keywords": "diffusion, methods: numerical, galaxies: abundances, galaxies: dwarf, Local Group", "note": "\u00a9 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. \n\nAccepted 2017 November 1. Received 2017 October 31; in original form 2017 October 17. \n\nIE would like to thank the anonymous referee, in addition to Shea Garrison-Kimmel, Matthew Orr and Denise Schmitz, for helpful comments that improved this paper. Numerical calculations were run on the Caltech computing cluster 'Zwicky' (NSF MRI award #PHY-0960291) and allocation TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF. IE was supported by Caltech funds, in part through the Caltech Earle C. Anthony Fellowship, and a Ford Foundation Predoctoral Fellowship. AW was supported by a Caltech-Carnegie Fellowship, in part through the Moore Center for Theoretical Cosmology and Physics at Caltech, and by NASA through grants HST-GO-14734 and HST-AR-15057 from STScI. ENK was supported by NSF Grant AST-1614081. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. CW was supported by the Lee A. DuBridge Postdoctoral Scholarship in Astrophysics. DK was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. CAFG was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G, and by STScI through grant HST-AR-14293.001-A. EQ was supported in part by a Simons Investigator Award from the Simons Foundation and NSF grant AST-1715070.\n\nPublished - stx2858.pdf
Submitted - 1710.06533.pdf
", "abstract": "We investigate stellar metallicity distribution functions (MDFs), including Fe and \u03b1-element abundances, in dwarf galaxies from the Feedback in Realistic Environment (FIRE) project. We examine both isolated dwarf galaxies and those that are satellites of a Milky Way-mass galaxy. In particular, we study the effects of including a sub-grid turbulent model for the diffusion of metals in gas. Simulations that include diffusion have narrower MDFs and abundance ratio distributions, because diffusion drives individual gas and star particles towards the average metallicity. This effect provides significantly better agreement with observed abundance distributions in dwarf galaxies in the Local Group, including small intrinsic scatter in [\u03b1/Fe] versus [Fe/H] of \u22720.1 dex. This small intrinsic scatter arises in our simulations because the interstellar medium in dwarf galaxies is well mixed at nearly all cosmic times, such that stars that form at a given time have similar abundances to \u22720.1 dex. Thus, most of the scatter in abundances at z = 0 arises from redshift evolution and not from instantaneous scatter in the ISM. We find similar MDF widths and intrinsic scatter for satellite and isolated dwarf galaxies, which suggests that environmental effects play a minor role compared with internal chemical evolution in our simulations. Overall, with the inclusion of metal diffusion, our simulations reproduce abundance distribution widths of observed low-mass galaxies, enabling detailed studies of chemical evolution in galaxy formation.", "date": "2018-02-21", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "474", "number": "2", "publisher": "Royal Astronomical Society", "pagerange": "2194-2211", "id_number": "CaltechAUTHORS:20171031-190653134", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171031-190653134", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "PHY-0960291" }, { "agency": "Caltech Earle C. Anthony Fellowship" }, { "agency": "Ford Foundation" }, { "agency": "Caltech-Carnegie Fellowship" }, { "agency": "Moore Center for Theoretical Cosmology and Physics, Caltech" }, { "agency": "NASA", "grant_number": "HST-GO-14734" }, { "agency": "NASA", "grant_number": "HST-AR-15057" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "NASA", "grant_number": "NNX14AH35G" }, { "agency": "NSF", "grant_number": "AST-1411920" }, { "agency": "NSF", "grant_number": "AST-1455342" }, { "agency": "Lee A. DuBridge Foundation" }, { "agency": "NASA", "grant_number": "AST-1715101" }, { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "NSF", "grant_number": "AST-1412836" }, { "agency": "NSF", "grant_number": "AST-1517491" }, { "agency": "NASA", "grant_number": "NNX15AB22G" }, { "agency": "NASA", "grant_number": "HST-AR-14293.001-A" }, { "agency": "Simons Foundation" }, { "agency": "NSF", "grant_number": "AST-1715070" }, { "agency": "NSF", "grant_number": "TG-AST130039" } ] }, "collection": "CaltechAUTHORS", "local_group": { "items": [ { "id": "TAPIR", "value": "TAPIR" }, { "id": "Moore-Center-for-Theoretical-Cosmology-and-Physics", "value": "Moore Center for Theoretical Cosmology and Physics" }, { "id": "Astronomy-Department", "value": "Astronomy Department" } ] }, "doi": "10.1093/mnras/stx2858", "primary_object": { "basename": "1710.06533.pdf", "url": "https://authors.library.caltech.edu/records/5bs7a-1yh40/files/1710.06533.pdf" }, "related_objects": [ { "basename": "stx2858.pdf", "url": "https://authors.library.caltech.edu/records/5bs7a-1yh40/files/stx2858.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Escala, Ivanna; Wetzel, Andrew; et el." }, { "id": "https://authors.library.caltech.edu/records/qy3p4-snd59", "eprint_id": 84430, "eprint_status": "archive", "datestamp": "2023-08-19 07:25:29", "lastmod": "2023-10-18 16:12:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Komiyama-Yutaka", "name": { "family": "Komiyama", "given": "Yutaka" } }, { "id": "Chiba-Masashi", "name": { "family": "Chiba", "given": "Masashi" }, "orcid": "0000-0002-9053-860X" }, { "id": "Tanaka-Mikito", "name": { "family": "Tanaka", "given": "Mikito" } }, { "id": "Tanaka-Masayuki", "name": { "family": "Tanaka", "given": "Masayuki" }, "orcid": "0000-0002-5011-5178" }, { "id": "Kirihara-Takanobu", "name": { "family": "Kirihara", "given": "Takanobu" } }, { "id": "Miki-Yohei", "name": { "family": "Miki", "given": "Yohei" } }, { "id": "Mori-Masao", "name": { "family": "Mori", "given": "Masao" } }, { "id": "Lupton-R-H", "name": { "family": "Lupton", "given": "Robert H." }, "orcid": "0000-0003-1666-0962" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline" }, "orcid": "0000-0003-0394-8377" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Lee-Myun-Gyoon", "name": { "family": "Lee", "given": "Myun Gyoon" } }, { "id": "Jang-In-Sung", "name": { "family": "Jang", "given": "In Sung" } }, { "id": "Sharma-Sanjib", "name": { "family": "Sharma", "given": "Sanjib" }, "orcid": "0000-0002-0920-809X" }, { "id": "Hayashi-Kohei", "name": { "family": "Hayashi", "given": "Kohei" }, "orcid": "0000-0002-8758-8139" } ] }, "title": "Stellar Stream and Halo Structure in the Andromeda Galaxy from a Subaru/Hyper Suprime-Cam Survey", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: halos \u2013 galaxies: individual (M31) \u2013 galaxies: structure", "note": "\u00a9 2018 The American Astronomical Society. \n\nReceived 2017 June 27; revised 2017 November 9; accepted 2017 December 8; published 2018 January 19. \n\nThis work is supported in part by the JSPS Grant-in-Aid for Scientific Research (No. JP25287062, JP15K05037, JP25800098, JP25400222, and JP17H01101), MEXT Grant-in-Aid for Scientific Research on Innovative Areas (No. JP15H05892, JP16H01090 for K.H., JP16H01086 for M.C.), and Grant-in-Aid for JSPS Fellows (TK 26.348). P.G. was supported by NSF grant AST-1412648. M.G.L. and I.S.J. were supported by the National Research Foundation (NRF) grant funded by the Korea Government (NRF-2017R1A2B4004632). \n\nWe would like to thank all the staff of Subaru Telescope, in particular Drs. Fumiaki Nakata, Tsuyoshi Terai, Shintaro Koshida, Francois Finet, and Akito Tajitsu for their excellent support during the observation, and all the staff of the HSC software developing group, in particular Dr. Hisanori Furusawa and Dr. Naoki Yasuda, for their advice during the processing of our M31 data. We would like to express our appreciation to Dr. Satoshi Kawanomoto for his effort in developing the NB515 filter. We are grateful to Dr. Paul Price for his kind support in calibrating our data to the PS1 system. We appreciate the many valuable comments and suggestions from the referee, which have improved this paper significantly. \n\nThe numerical computations were carried out on the HA-PACS System in the Center for Computational Sciences, University of Tsukuba, Japan. \n\nThe HSC collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University. The HSC instrumentation and software were developed by the National Astronomical Observatory of Japan (NAOJ), the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), the University of Tokyo, the High Energy Accelerator Research Organization (KEK), the Academia Sinica Institute for Astronomy and Astrophysics in Taiwan (ASIAA), and Princeton University. Funding was contributed by the FIRST program from the Japanese Cabinet Office, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Japan Society for the Promotion of Science (JSPS), Japan Science and Technology Agency (JST), the Toray Science Foundation, NAOJ, Kavli IPMU, KEK, ASIAA, and Princeton University. This paper makes use of software developed for the Large Synoptic Survey Telescope. We thank the LSST Project for making their code freely available. The Pan-STARRS1 (PS1) Surveys have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy and the Max Planck Institute for Extraterrestrial Physics, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE).\n\nPublished - Komiyama_2018_ApJ_853_29.pdf
Submitted - 1712.03654.pdf
", "abstract": "We present wide and deep photometry of the northwestern part of the halo of the Andromeda galaxy (M31) using Hyper Suprime-Cam on the Subaru Telescope. The survey covers a 9.2 deg^2 field in the g, i, and NB515 bands and shows a clear red giant branch (RGB) of M31's halo stars and a pronounced red clump (RC) feature. The spatial distribution of RC stars shows a prominent stream feature, the Northwestern (NW) Stream, and a diffuse substructure in the southern part of our survey field. We estimate the distances based on the RC method and obtain (m-M) = 24.63 \u00b1 0.191 (random) \u00b1 0.057 (systematic) and 24.29 \u00b1 0.211 (random) \u00b1 0.057 (systematic) mag for the NW Stream and diffuse substructure, respectively, implying that the NW Stream is located behind M31, whereas the diffuse substructure is located in front of it. We also estimate line-of-sight distances along the NW Stream and find that the southern part of the stream is ~20 kpc closer to us relative to the northern part. The distance to the NW Stream inferred from the isochrone fitting to the color\u2013magnitude diagram favors the RC-based distance, but the tip of the RGB (TRGB)-based distance estimated for NB515-selected RGB stars does not agree with it. The surface number density distribution of RC stars across the NW Stream is found to be approximately Gaussian with an FWHM of ~25 arcmin (5.7 kpc), with a slight skew to the southwest side. That along the NW Stream shows a complicated structure, including variations in number density and a significant gap in the stream.", "date": "2018-01-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "853", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 29", "id_number": "CaltechAUTHORS:20180119-143958173", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180119-143958173", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "JP25287062" }, { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "JP15K05037" }, { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "JP25800098" }, { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "JP25400222" }, { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "JP17H01101" }, { "agency": "Ministry of Education, Culture, Sports, Science and Technology (MEXT)", "grant_number": "JP15H05892" }, { "agency": "Ministry of Education, Culture, Sports, Science and Technology (MEXT)", "grant_number": "JP16H01090" }, { "agency": "Ministry of Education, Culture, Sports, Science and Technology (MEXT)", "grant_number": "JP16H01086" }, { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "TK 26.348" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "National Research Foundation of Korea", "grant_number": "NRF-2017R1A2B4004632" }, { "agency": "NASA", "grant_number": "NNX08AR22G" }, { "agency": "NSF", "grant_number": "AST-1238877" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aaa129", "primary_object": { "basename": "1712.03654.pdf", "url": "https://authors.library.caltech.edu/records/qy3p4-snd59/files/1712.03654.pdf" }, "related_objects": [ { "basename": "Komiyama_2018_ApJ_853_29.pdf", "url": "https://authors.library.caltech.edu/records/qy3p4-snd59/files/Komiyama_2018_ApJ_853_29.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Komiyama, Yutaka; Chiba, Masashi; et el." }, { "id": "https://authors.library.caltech.edu/records/715v3-mn306", "eprint_id": 84360, "eprint_status": "archive", "datestamp": "2023-08-19 07:21:18", "lastmod": "2023-10-18 16:09:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gilbert-Karoline-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Tollerud-Erik-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Beaton-Rachael-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Guhathakurta-Puragra", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Bullock-James-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Chiba-Masashi", "name": { "family": "Chiba", "given": "Masashi" }, "orcid": "0000-0002-9053-860X" }, { "id": "Kalirai-Jason-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Majewski-Steven-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Tanaka-Mikito", "name": { "family": "Tanaka", "given": "Mikito" } } ] }, "title": "Global Properties of M31's Stellar Halo from the SPLASH Survey. III. Measuring the Stellar Velocity Dispersion Profile", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 The American Astronomical Society. \n\nReceived 2017 April 30. Accepted 2017 November 20. Published 2018 January 15. \n\nSupport for this work was provided by NASA through a Giacconi Fellowship (E.J.T.) and Hubble Fellowship grants 51316.01 and 51386.01 awarded to E.J.T. and R.L.B. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. K.M.G. and E.N.K. acknowledge support from NSF grants AST-1614569 and AST-1614081. R.L.B. and S.R.M. acknowledge support from NSF grants AST-1413269 and AST-1009882. P.G. and J.S.B. acknowledge support from collaborative NSF grants AST-1412648, AST-1010039, AST-1009973. M.T. and M.C. acknowledge support from Grant-in-Aid for Scientific Research (2580098 for M.T., 16H01086 and 17H01101 for M.C.) of the Ministry of Education, Culture, Sports, Science, and Technology of Japan. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048.\n\nPublished - Gilbert_2018_ApJ_852_128.pdf
Submitted - 1711.02700.pdf
", "abstract": "We present the velocity dispersion of red giant branch stars in M31's halo, derived by modeling the line-of-sight velocity distribution of over 5000 stars in 50 fields spread throughout M31's stellar halo. The data set was obtained as part of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) Survey, and covers projected radii of 9 to 175 kpc from M31's center. All major structural components along the line of sight in both the Milky Way (MW) and M31 are incorporated in a Gaussian Mixture Model, including all previously identified M31 tidal debris features in the observed fields. The probability that an individual star is a constituent of M31 or the MW, based on a set of empirical photometric and spectroscopic diagnostics, is included as a prior probability in the mixture model. The velocity dispersion of stars in M31's halo is found to decrease only mildly with projected radius, from 108 km s_(\u22121) in the innermost radial bin (8.2 to 14.1 kpc) to ~80 to 90 km s^(\u22121) at projected radii of ~40\u2013130 kpc, and can be parameterized with a power law of slope \u22120.12 \u00b1 0.05. The quoted uncertainty on the power-law slope reflects only the precision of the method, although other sources of uncertainty we consider contribute negligibly to the overall error budget.", "date": "2018-01-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "852", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 128", "id_number": "CaltechAUTHORS:20180117-095337937", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180117-095337937", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Giacconi Fellowship" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51316.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51386.01" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "NSF", "grant_number": "AST-1614569" }, { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "NSF", "grant_number": "AST-1413269" }, { "agency": "NSF", "grant_number": "AST-1009882" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "Ministry of Education, Culture, Sports, Science and Technology (MEXT)", "grant_number": "2580098" }, { "agency": "Ministry of Education, Culture, Sports, Science and Technology (MEXT)", "grant_number": "16H01086" }, { "agency": "Ministry of Education, Culture, Sports, Science and Technology (MEXT)", "grant_number": "17H01101" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "local_group": { "items": [ { "id": "SPLASH" }, { "id": "COSMOS" }, { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" }, { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aa9f26", "primary_object": { "basename": "1711.02700.pdf", "url": "https://authors.library.caltech.edu/records/715v3-mn306/files/1711.02700.pdf" }, "related_objects": [ { "basename": "Gilbert_2018_ApJ_852_128.pdf", "url": "https://authors.library.caltech.edu/records/715v3-mn306/files/Gilbert_2018_ApJ_852_128.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Gilbert, Karoline M.; Tollerud, Erik J.; et el." }, { "id": "https://authors.library.caltech.edu/records/nj60g-75429", "eprint_id": 83592, "eprint_status": "archive", "datestamp": "2023-08-19 06:19:05", "lastmod": "2023-10-17 23:15:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carlin-J-L", "name": { "family": "Carlin", "given": "Jeffrey L." }, "orcid": "0000-0002-3936-9628" }, { "id": "Sand-D-J", "name": { "family": "Sand", "given": "David J." }, "orcid": "0000-0003-4102-380X" }, { "id": "Mu\u00f1oz-R-R", "name": { "family": "Mu\u00f1oz", "given": "Ricardo R." } }, { "id": "Spekkens-K", "name": { "family": "Spekkens", "given": "Kristine" }, "orcid": "0000-0002-0956-7949" }, { "id": "Willman-B", "name": { "family": "Willman", "given": "Beth" }, "orcid": "0000-0003-2892-9906" }, { "id": "Crnojevi\u0107-D", "name": { "family": "Crnojevi\u0107", "given": "Denija" }, "orcid": "0000-0002-1763-4128" }, { "id": "Forbes-D-A", "name": { "family": "Forbes", "given": "Duncan A." } }, { "id": "Hargis-J-R", "name": { "family": "Hargis", "given": "Jonathan" }, "orcid": "0000-0002-8722-9806" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Peter-A-H-G", "name": { "family": "Peter", "given": "Annika H. G." }, "orcid": "0000-0002-8040-6785" }, { "id": "Romanowsky-A-J", "name": { "family": "Romanowsky", "given": "Aaron J." }, "orcid": "0000-0003-2473-0369" }, { "id": "Strader-J", "name": { "family": "Strader", "given": "Jay" }, "orcid": "0000-0002-1468-9668" } ] }, "title": "Deep Subaru Hyper Suprime-Cam Observations of Milky Way Satellites Columba I and Triangulum II", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf \u2013 galaxies: individual (Columba I, Triangulum II) \u2013 galaxies: photometry \u2013 Galaxy: halo \u2013 Local Group", "note": "\u00a9 2017 The American Astronomical Society. \n\nReceived 2017 July 4; revised 2017 October 5; accepted 2017 October 17; published 2017 December 1. \n\nBased in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. \n\nWe thank the referee for a careful reading of the manuscript, and comments that helped us improve the paper. We thank Fumiaki Nakata and Rita Morris for assistance at the Subaru Telescope. J.L.C. and B.W. are partially supported by NSF Faculty Early Career Development (CAREER) award AST-1151462. D.J.S. acknowledges support from NSF grant AST-1412504. J.S. acknowledges support from NSF grant AST-1514763 and a Packard Fellowship. A.J.R. was supported by NSF grant AST-1616710 and as a Research Corporation for Science Advancement Cottrell Scholar. \n\nWe thank Edouard Bernard for kindly sharing the PS1 globular cluster fiducials, and Keith Bechtol and David Nidever for helpful discussions. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nThis research has made use of NASA's Astrophysics Data System, and Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013). This work has made use of the IAC-STAR Synthetic CMD computation code. IAC-STAR is supported and maintained by the computer division of the Instituto de Astrof\u00edsica de Canarias. \n\nSome of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. \n\nThe Pan-STARRS1 Surveys have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under grant AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), and the Los Alamos National Laboratory. \n\nFacility: Subaru (Hyper Suprime-Cam) - . \n\nSoftware: Astropy (Astropy Collaboration et al. 2013), IDL astronomy users library (Landsman 1993), iPython (Perez & Granger 2007), Matplotlib (Hunter 2007), NumPy (van der Walt et al. 2011), Topcat (Taylor 2005).\n\nPublished - Carlin_2017_AJ_154_267.pdf
Submitted - 1710.06444.pdf
", "abstract": "We present deep, wide-field Subaru Hyper Suprime-Cam photometry of two recently discovered satellites of the Milky Way (MW): Columba I (Col I) and Triangulum II (Tri II). The color\u2013magnitude diagrams of both objects point to exclusively old and metal-poor stellar populations. We re-derive structural parameters and luminosities of these satellites, and find M_(V,Col I) = -4.2 \u00b1 0.2 for Col I and M_(V,Tri II) = -1.2 \u00b1 0.4 for Tri II, with corresponding half-light radii of r_(h,Col I) = 117 \u00b1 17 pc and r_(h,Tri II) = 21 \u00b1 4 pc. The properties of both systems are consistent with observed scaling relations for MW dwarf galaxies. Based on archival data, we derive upper limits on the neutral gas content of these dwarfs, and find that they lack H I, as do the majority of observed satellites within the MW virial radius. Neither satellite shows evidence of tidal stripping in the form of extensions or distortions in matched-filter stellar density maps or surface-density profiles. However, the smaller Tri II system is relatively metal-rich for its luminosity (compared to other MW satellites), possibly because it has been tidally stripped. Through a suite of orbit simulations, we show that Tri II is approaching pericenter of its eccentric orbit, a stage at which tidal debris is unlikely to be seen. In addition, we find that Tri II may be on its first infall into the MW, which helps explain its unique properties among MW dwarfs. Further evidence that Tri II is likely an ultra-faint dwarf comes from its stellar mass function, which is similar to those of other MW dwarfs.", "date": "2017-12", "date_type": "published", "publication": "Astronomical Journal", "volume": "154", "number": "6", "publisher": "American Astronomical Society", "pagerange": "Art. No. 267", "id_number": "CaltechAUTHORS:20171130-095952338", "issn": "1538-3881", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171130-095952338", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1151462" }, { "agency": "NSF", "grant_number": "AST-1412504" }, { "agency": "NSF", "grant_number": "AST-1514763" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "NSF", "grant_number": "AST-1616710" }, { "agency": "Research Corporation" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "NASA", "grant_number": "NNX09AF08G" }, { "agency": "NASA", "grant_number": "NNX08AR22G" }, { "agency": "NSF", "grant_number": "AST-1238877" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-3881/aa94d0", "primary_object": { "basename": "1710.06444.pdf", "url": "https://authors.library.caltech.edu/records/nj60g-75429/files/1710.06444.pdf" }, "related_objects": [ { "basename": "Carlin_2017_AJ_154_267.pdf", "url": "https://authors.library.caltech.edu/records/nj60g-75429/files/Carlin_2017_AJ_154_267.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Carlin, Jeffrey L.; Sand, David J.; et el." }, { "id": "https://authors.library.caltech.edu/records/2yjmb-csa49", "eprint_id": 79116, "eprint_status": "archive", "datestamp": "2023-08-19 04:05:37", "lastmod": "2023-10-26 14:36:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Thygesen-A-O", "name": { "family": "Thygesen", "given": "Anders O." }, "orcid": "0000-0002-4912-1183" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Gallagher-A-J", "name": { "family": "Gallagher", "given": "Andrew J." }, "orcid": "0000-0003-3014-8981" }, { "id": "Ludwig-H-G", "name": { "family": "Ludwig", "given": "Hans-G." } }, { "id": "Caffau-E", "name": { "family": "Caffau", "given": "Elisabetta" } }, { "id": "Bonifacio-P", "name": { "family": "Bonifacio", "given": "Piercarlo" } }, { "id": "Sbordone-L", "name": { "family": "Sbordone", "given": "Luca" } } ] }, "title": "An Investigation of the Formation and Line Properties of MgH in 3D Hydrodynamical Model Stellar Atmospheres", "ispublished": "pub", "full_text_status": "public", "keywords": "hydrodynamics \u2013 line: formation \u2013 line: profiles \u2013 molecular processes \u2013 stars: atmospheres \u2013 techniques: spectroscopic", "note": "\u00a9 2017 The American Astronomical Society. \n\nReceived 2017 May 9; revised 2017 June 9; accepted 2017 June 12; published 2017 July 14. \n\nH.G.L. acknowledges financial support by the Sonderforschungsbereich SFB 881 \"The Milky Way System\" (subproject A4) of the German Research Foundation (DFG). A.J.G. acknowledges the support of the FONDATION MERAC, the matching fund granted by the Scientific Council of Observatoire de Paris, and the Collaborative Research Centre SFB 881 (Heidelberg University) of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). \n\nSoftware: CO^5BOLD (Freytag et al. 2012), Linfor3D (Steffen et al. 2015), Matplotlib (Hunter 2007), Fitprofile (Thygesen et al. 2016).\n\nPublished - Thygesen_2017_ApJ_843_144.pdf
Submitted - 1706.04218.pdf
", "abstract": "Studies of the isotopic composition of magnesium in cool stars have so far relied upon the use of 1D model atmospheres. Since the isotopic ratios derived are based on asymmetries of optical MgH lines, it is important to test the impact from other effects affecting line asymmetries, like stellar convection. Here, we present a theoretical investigation of the effects of including self-consistent modeling of convection. Using spectral syntheses based on 3D hydrodynamical CO^5BOLD models of dwarfs (4000 K \u227e T_(eff) \u227e 5160 K, 4.0 \u2264 log g \u2264 4.5, -3.0 \u2a7d [Fe/H] \u2a7d -1.0) and giants (T_(eff) ~ 4000 K, log g = 1.5, -3.0 \u2a7d [Fe/H] \u2a7d -1.0), we perform a detailed analysis comparing 3D and 1D syntheses. We describe the impact on the formation and behavior of MgH lines from using 3D models, and perform a qualitative assessment of the systematics introduced by the use of 1D syntheses. Using 3D model atmospheres significantly affect the strength of the MgH lines, especially in dwarfs, with 1D syntheses requiring an abundance correction of up to +0.69 dex, with the largest for our 5000 K models. The corrections are correlated with T_(eff) and are also affected by the metallicity. The shape of the strong ^(24) MgH component in the 3D syntheses is poorly reproduced in 1D. This results in 1D syntheses underestimating ^(25)Mg by up to ~5 percentage points and overestimating ^(24)Mg by a similar amount for dwarfs. This discrepancy increases with decreasing metallicity. ^(26)Mg is recovered relatively well, with the largest difference being ~2 percentage points. The use of 3D for giants has less impact, due to smaller differences in the atmospheric structure and a better reproduction of the line shape in 1D.", "date": "2017-07-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "843", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 144", "id_number": "CaltechAUTHORS:20170714-160235113", "issn": "1538-4357", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170714-160235113", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "SFB 881" }, { "agency": "Scientific Council of Observatoire de Paris" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aa79a0", "primary_object": { "basename": "1706.04218.pdf", "url": "https://authors.library.caltech.edu/records/2yjmb-csa49/files/1706.04218.pdf" }, "related_objects": [ { "basename": "Thygesen_2017_ApJ_843_144.pdf", "url": "https://authors.library.caltech.edu/records/2yjmb-csa49/files/Thygesen_2017_ApJ_843_144.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Thygesen, Anders O.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/7axft-j8a37", "eprint_id": 78509, "eprint_status": "archive", "datestamp": "2023-08-19 03:21:59", "lastmod": "2023-10-26 00:09:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spencer-M-E", "name": { "family": "Spencer", "given": "Meghin E." }, "orcid": "0000-0003-1240-1939" }, { "id": "Mateo-M", "name": { "family": "Mateo", "given": "Mario" } }, { "id": "Walker-M-G", "name": { "family": "Walker", "given": "Matthew G." }, "orcid": "0000-0003-2496-1925" }, { "id": "Olszewski-E-W", "name": { "family": "Olszewski", "given": "Edward W." } }, { "id": "McConnachie-A-W", "name": { "family": "McConnachie", "given": "Alan W." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Koch-A", "name": { "family": "Koch", "given": "Andreas" } } ] }, "title": "The Binary Fraction of Stars in Dwarf Galaxies: The Case of Leo II", "ispublished": "pub", "full_text_status": "public", "keywords": "binaries: general \u2013 galaxies: dwarf \u2013 galaxies: individual (Leo II) \u2013 galaxies: kinematics and dynamics", "note": "\u00a9 2017 The American Astronomical Society. \n\nReceived 2016 October 31; revised 2017 April 10; accepted 2017 April 11; published 2017 May 16. \n\nThe authors are very grateful to Josh Simon for allowing us to use his spectra to get velocities for the KG10 data set, and to Jan Kleyna for contributing to the KK07 data set. We thank Andy Szentgyorgyi and the Hectochelle team for their support over the past 12 years. We also thank the anonymous referee for helpful comments that improved this work. M.E.S. is supported by the National Science Foundation Graduate Research Fellowship under grant number DGE1256260. M.M. acknowledges support from NSF grant AST1312997. M.W. acknowledges support from NSF grants AST1313045 and AST1412999. E.O. acknowledges support from NSF grant AST1313006.\n\nPublished - Spencer_2017_AJ_153_254.pdf
", "abstract": "We combine precision radial velocity data from four different published works of the stars in the Leo II dwarf spheroidal galaxy. This yields a data set that spans 19 years, has 14 different epochs of observation, and contains 372 unique red giant branch stars, 196 of which have repeat observations. Using this multi-epoch data set, we constrain the binary fraction for Leo II. We generate a suite of Monte Carlo simulations that test different binary fractions using Bayesian analysis and determine that the binary fraction for Leo II ranges from 0.30^(+0.09)_(-0.10) to 0.34^(+0.11)_(-0.11), depending on the distributions of binary orbital parameters assumed. This value is smaller than what has been found for the solar neighborhood (~0.4\u20130.6) but falls within the wide range of values that have been inferred for other dwarf spheroidals (0.14\u20130.69). The distribution of orbital periods has the greatest impact on the binary fraction results. If the fraction we find in Leo II is present in low-mass ultra-faints, it can artificially inflate the velocity dispersion of those systems and cause them to appear more dark matter rich than in actuality. For a galaxy with an intrinsic dispersion of 1 km s^(\u22121) and an observational sample of 100 stars, the dispersion can be increased by a factor of 1.5\u20132 for Leo II-like binary fractions or by a factor of three for binary fractions on the higher end of what has been seen in other dwarf spheroidals.", "date": "2017-06", "date_type": "published", "publication": "Astronomical Journal", "volume": "153", "number": "6", "publisher": "American Astronomical Society", "pagerange": "Art. No. 254", "id_number": "CaltechAUTHORS:20170623-094913363", "issn": "1538-3881", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170623-094913363", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1256260" }, { "agency": "NSF", "grant_number": "AST-1312997" }, { "agency": "NSF", "grant_number": "AST-1313045" }, { "agency": "NSF", "grant_number": "AST-1412999" }, { "agency": "NSF", "grant_number": "AST-1313006" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-3881/aa6d51", "primary_object": { "basename": "Spencer_2017_AJ_153_254.pdf", "url": "https://authors.library.caltech.edu/records/7axft-j8a37/files/Spencer_2017_AJ_153_254.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Spencer, Meghin E.; Mateo, Mario; et el." }, { "id": "https://authors.library.caltech.edu/records/wk0fx-mdf75", "eprint_id": 71771, "eprint_status": "archive", "datestamp": "2023-08-19 02:47:41", "lastmod": "2023-10-23 17:03:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ma-Xiangcheng", "name": { "family": "Ma", "given": "Xiangcheng" }, "orcid": "0000-0001-8091-2349" }, { "id": "Hopkins-P-F", "name": { "family": "Hopkins", "given": "Philip F." }, "orcid": "0000-0003-3729-1684" }, { "id": "Wetzel-A-R", "name": { "family": "Wetzel", "given": "Andrew R." }, "orcid": "0000-0003-0603-8942" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Angl\u00e9s-Alc\u00e1zar-D", "name": { "family": "Angl\u00e9s-Alc\u00e1zar", "given": "Daniel" }, "orcid": "0000-0001-5769-4945" }, { "id": "Faucher-Gigu\u00e8re-C-A", "name": { "family": "Faucher-Gigu\u00e8re", "given": "Claude-Andr\u00e9" }, "orcid": "0000-0002-4900-6628" }, { "id": "Kere\u0161-D", "name": { "family": "Kere\u0161", "given": "Du\u0161an" }, "orcid": "0000-0002-1666-7067" }, { "id": "Quataert-E", "name": { "family": "Quataert", "given": "Eliot" }, "orcid": "0000-0001-9185-5044" } ] }, "title": "The Structure and Dynamical Evolution of the Stellar Disk of a Simulated Milky Way-Mass Galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances, galaxies: evolution, galaxies: formation, cosmology: theory", "note": "\u00a9 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 January 30. Received 2017 January 30; in original form 2016 August 14. Published: 01 February 2017. We thank David Nidever, Hans-Walter Rix, Charlie Conroy and Paul Torrey for useful discussions. We also acknowledge Oscar Agertz and Ivan Minchev for helpful comments after the first draft has appeared on arXiv, and the anonymous referee for a detailed report. The simulations used in this paper were run on XSEDE computational resources (allocations TG-AST120025, TG-AST130039 and TG-AST140023). The analysis was performed on the Caltech compute cluster 'Zwicky' (NSF MRI award #PHY-0960291). Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. ARW was supported by a Caltech-Carnegie Fellowship, in part through the Moore Center for Theoretical Cosmology and Physics at Caltech. DAA acknowledges support by a CIERA Postdoctoral Fellowship. C-AF-G was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G, and by STScI through grants HST-AR-14293.001-A and HST-GO-14268.022-A. DK was supported by NSF grant AST-1412153 and funds from the University of California, San Diego. EQ was supported by NASA ATP grant 12-APT12-0183, by a Simons Investigator award from the Simons Foundation, and by the David and Lucile Packard Foundation.\n\nPublished - stx273.pdf
Submitted - 1608.04133v1.pdf
", "abstract": "We study the structure, age and metallicity gradients, and dynamical evolution using a cosmological zoom-in simulation of a Milky Way-mass galaxy from the Feedback in Realistic Environments project. In the simulation, stars older than 6 Gyr were formed in a chaotic, bursty mode and have the largest vertical scaleheights (1.5\u20132.5 kpc) by z = 0, while stars younger than 6 Gyr were formed in a relatively calm, stable disc. The vertical scaleheight increases with stellar age at all radii, because (1) stars that formed earlier were thicker 'at birth', and (2) stars were kinematically heated to an even thicker distribution after formation. Stars of the same age are thicker in the outer disc than in the inner disc (flaring). These lead to positive vertical age gradients and negative radial age gradients. The radial metallicity gradient is negative at the mid-plane, flattens at larger disc height |Z|, and turns positive above |Z| \u223c 1.5\u2009kpc. The vertical metallicity gradient is negative at all radii, but is steeper at smaller radii. These trends broadly agree with observations in the Milky Way and can be naturally understood from the age gradients. The vertical stellar density profile can be well described by two components, with scaleheights 200\u2013500 pc and 1\u20131.5 kpc, respectively. The thick component is a mix of stars older than 4 Gyr, which formed through a combination of several mechanisms. Our results also demonstrate that it is possible to form a thin disc in cosmological simulations even with a strong stellar feedback.", "date": "2017-05", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "467", "number": "2", "publisher": "Royal Astronomical Society", "pagerange": "2430-2444", "id_number": "CaltechAUTHORS:20161107-114246249", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161107-114246249", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "TGA-ST120025" }, { "agency": "NSF", "grant_number": "TG-AST130039" }, { "agency": "NSF", "grant_number": "TG-AST140023" }, { "agency": "NSF", "grant_number": "PHY-0960291" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "NASA", "grant_number": "NNX14AH35G" }, { "agency": "NSF", "grant_number": "AST-1411920" }, { "agency": "NSF", "grant_number": "AST-1455342" }, { "agency": "Caltech-Carnegie Fellowship" }, { "agency": "Caltech Moore Center for Theoretical Cosmology and Physics" }, { "agency": "Northwestern University" }, { "agency": "NSF", "grant_number": "AST-1412836" }, { "agency": "NSF", "grant_number": "AST-1517491" }, { "agency": "NASA", "grant_number": "NNX15AB22G" }, { "agency": "NASA", "grant_number": "HST-AR-14293.001-A" }, { "agency": "NASA", "grant_number": "HST-GO-14268.022-A" }, { "agency": "NSF", "grant_number": "AST-1412153" }, { "agency": "University of California San Diego" }, { "agency": "NASA", "grant_number": "12-APT12-0183" }, { "agency": "Simons Foundation" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)" } ] }, "local_group": { "items": [ { "id": "Moore-Center-for-Theoretical-Cosmology-and-Physics" }, { "id": "TAPIR" }, { "id": "Astronomy-Department" } ] }, "doi": "10.1093/mnras/stx273", "primary_object": { "basename": "1608.04133v1.pdf", "url": "https://authors.library.caltech.edu/records/wk0fx-mdf75/files/1608.04133v1.pdf" }, "related_objects": [ { "basename": "stx273.pdf", "url": "https://authors.library.caltech.edu/records/wk0fx-mdf75/files/stx273.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Ma, Xiangcheng; Hopkins, Philip F.; et el." }, { "id": "https://authors.library.caltech.edu/records/506jv-naj24", "eprint_id": 75507, "eprint_status": "archive", "datestamp": "2023-08-19 02:30:52", "lastmod": "2023-10-25 15:06:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Thygesen-A-O", "name": { "family": "Thygesen", "given": "Anders O." }, "orcid": "0000-0002-4912-1183" }, { "id": "Duggan-G-E", "name": { "family": "Duggan", "given": "Gina E." }, "orcid": "0000-0002-9256-6735" } ] }, "title": "Triangulum II. Not Especially Dense After All", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: dwarf \u2013 Local Group", "note": "\u00a9 2017 American Astronomical Society. \n\nReceived 2017 January 7. Accepted 2017 March 8. Published 2017 March 29. \n\nWe thank D. Stern, S. Hemmati, and D. Masters for observing the TriIIc slitmask.\n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nFacility: Keck:II (DEIMOS).\n\nPublished - Kirby_2017_ApJ_838_83.pdf
Erratum - Kirby_2017_ApJ_839_135.pdf
", "abstract": "Among the Milky Way satellites discovered in the past three years, Triangulum II has presented the most difficulty in revealing its dynamical status. Kirby et al. identified it as the most dark-matter-dominated galaxy known, with a mass-to-light ratio within the half-light radius of 3600_(-2100)^(+3500)M_\u2609L_\u2609^(-1). On the other hand, Martin et al. measured an outer velocity dispersion that is 3.5 \u00b1 2.1 times larger than the central velocity dispersion, suggesting that the system might not be in equilibrium. From new multi-epoch Keck/DEIMOS measurements of 13 member stars in Triangulum II, we constrain the velocity dispersion to be \u03c3_v < 3.4 km s^(\u22121) (90% C.L.). Our previous measurement of \u03c3_v, based on six stars, was inflated by the presence of a binary star with variable radial velocity. We find no evidence that the velocity dispersion increases with radius. The stars display a wide range of metallicities, indicating that Triangulum II retained supernova ejecta and therefore possesses, or once possessed, a massive dark matter halo. However, the detection of a metallicity dispersion hinges on the membership of the two most metal-rich stars. The stellar mass is lower than galaxies of similar mean stellar metallicity, which might indicate that Triangulum II is either a star cluster or a tidally stripped dwarf galaxy. Detailed abundances of one star show heavily depressed neutron-capture abundances, similar to stars in most other ultra-faint dwarf galaxies but unlike stars in globular clusters.", "date": "2017-04-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "838", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 83", "id_number": "CaltechAUTHORS:20170329-095524041", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170329-095524041", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/aa6570", "primary_object": { "basename": "Kirby_2017_ApJ_838_83.pdf", "url": "https://authors.library.caltech.edu/records/506jv-naj24/files/Kirby_2017_ApJ_838_83.pdf" }, "related_objects": [ { "basename": "Kirby_2017_ApJ_839_135.pdf", "url": "https://authors.library.caltech.edu/records/506jv-naj24/files/Kirby_2017_ApJ_839_135.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Kirby, Evan N.; Cohen, Judith G.; et el." }, { "id": "https://authors.library.caltech.edu/records/09m3f-zem59", "eprint_id": 74266, "eprint_status": "archive", "datestamp": "2023-08-22 19:29:44", "lastmod": "2023-10-24 22:16:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Rizzi-L", "name": { "family": "Rizzi", "given": "Luca" }, "orcid": "0000-0003-0882-2327" }, { "id": "Held-E-V", "name": { "family": "Held", "given": "Enrico V." } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Cole-A-A", "name": { "family": "Cole", "given": "Andrew A." }, "orcid": "0000-0003-0303-3855" }, { "id": "Manning-E-M", "name": { "family": "Manning", "given": "Ellen M." } }, { "id": "Skillman-E-D", "name": { "family": "Skillman", "given": "Evan D." } }, { "id": "Weisz-D-R", "name": { "family": "Weisz", "given": "Daniel R." }, "orcid": "0000-0002-6442-6030" } ] }, "title": "Chemistry and Kinematics of the Late-Forming Dwarf Irregular Galaxies Leo A, Aquarius, and Sagittarius DIG", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: individual (Leo A, DDO 210, Sgr dIG); Local Group; stars: abundances", "note": "\u00a9 2016. The American Astronomical Society. \n\nReceived 2016 September 27; revised 2016 October 24; accepted 2016 October 26; published 2016 December 22. \n\nWe thank Alan McConnachie, Nobuo Arimoto, and Mike Irwin for kindly sharing their photometry catalog for Aquarius. We also thank Yazan Momany and his collaborators for sharing their photometry catalog of SagDIG. Deidre Hunter provided kind assistance with the LITTLE THINGS 21 cm images. We acknowledge support from the National Science Foundation through grant 1614081. \n\nFacility: Keck:II (DEIMOS) - . \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.\n\nPublished - Kirby_2017_ApJ_834_9.pdf
Accepted Version - 1610.08505.pdf
", "abstract": "We present Keck/DEIMOS spectroscopy of individual stars in the relatively isolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarf irregular galaxy. The three galaxies\u2014but especially Leo A and Aquarius\u2014share in common delayed star formation histories (SFHs) relative to many other isolated dwarf galaxies. The stars in all three galaxies are supported by dispersion. We found no evidence of stellar velocity structure, even for Aquarius, which has rotating H i gas. The velocity dispersions indicate that all three galaxies are dark-matter-dominated, with dark-to-baryonic mass ratios ranging from 4.4_(-0.8)^(+1.0) (SagDIG) to 9.6_(-1.8)^(+2.5) (Aquarius). Leo A and SagDIG have lower stellar metallicities than Aquarius, and they also have higher gas fractions, both of which would be expected if Aquarius were further along in its chemical evolution. The metallicity distribution of Leo A is inconsistent with a closed or leaky box model of chemical evolution, suggesting that the galaxy was pre-enriched or acquired external gas during star formation. The metallicities of stars increased steadily for all three galaxies, but possibly at different rates. The [\u03b1/Fe] ratios at a given [Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, which indicates more extended SFHs than Sculptor, consistent with photometrically derived SFHs. Overall, the bulk kinematic and chemical properties for the late-forming dwarf galaxies do not diverge significantly from those of less delayed dwarf galaxies, including dwarf spheroidal galaxies.", "date": "2017-01-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "834", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 9", "id_number": "CaltechAUTHORS:20170213-151130703", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170213-151130703", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1614081" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" } ] }, "doi": "10.3847/1538-4357/834/1/9", "primary_object": { "basename": "1610.08505.pdf", "url": "https://authors.library.caltech.edu/records/09m3f-zem59/files/1610.08505.pdf" }, "related_objects": [ { "basename": "Kirby_2017_ApJ_834_9.pdf", "url": "https://authors.library.caltech.edu/records/09m3f-zem59/files/Kirby_2017_ApJ_834_9.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Kirby, Evan N.; Rizzi, Luca; et el." }, { "id": "https://authors.library.caltech.edu/records/vv8d0-smy24", "eprint_id": 69983, "eprint_status": "archive", "datestamp": "2023-08-20 13:41:44", "lastmod": "2023-10-20 21:18:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carlin-J-L", "name": { "family": "Carlin", "given": "Jeffrey L." }, "orcid": "0000-0002-3936-9628" }, { "id": "Sand-D-J", "name": { "family": "Sand", "given": "David J." }, "orcid": "0000-0003-4102-380X" }, { "id": "Price-P-A", "name": { "family": "Price", "given": "Paul" } }, { "id": "Willman-B", "name": { "family": "Willman", "given": "Beth" }, "orcid": "0000-0003-2892-9906" }, { "id": "Karunakaran-A", "name": { "family": "Karunakaran", "given": "Ananthan" } }, { "id": "Spekkens-K", "name": { "family": "Spekkens", "given": "Kristine" }, "orcid": "0000-0002-0956-7949" }, { "id": "Bell-E-F", "name": { "family": "Bell", "given": "Eric F." } }, { "id": "Brodie-J-P", "name": { "family": "Brodie", "given": "Jean P." }, "orcid": "0000-0002-9658-8763" }, { "id": "Crnojevi\u0107-D", "name": { "family": "Crnojevi\u0107", "given": "Denija" } }, { "id": "Forbes-D-A", "name": { "family": "Forbes", "given": "Duncan A." } }, { "id": "Hargis-J-R", "name": { "family": "Hargis", "given": "Jonathan" }, "orcid": "0000-0002-8722-9806" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Lupton-R-H", "name": { "family": "Lupton", "given": "Robert" }, "orcid": "0000-0003-1666-0962" }, { "id": "Peter-A-H-G", "name": { "family": "Peter", "given": "Annika H. G." }, "orcid": "0000-0002-8040-6785" }, { "id": "Romanowsky-A-J", "name": { "family": "Romanowsky", "given": "Aaron J." }, "orcid": "0000-0003-2473-0369" }, { "id": "Strader-J", "name": { "family": "Strader", "given": "Jay" }, "orcid": "0000-0002-1468-9668" } ] }, "title": "First Results from the MADCASH Survey: A Faint Dwarf Galaxy Companion to the Low-mass Spiral Galaxy NGC 2403 at 3.2 Mpc", "ispublished": "pub", "full_text_status": "public", "keywords": "dark matter \u2013 galaxies: dwarf \u2013 galaxies: formation \u2013 galaxies: halos", "note": "\u00a9 2016 The American Astronomical Society. \n\nReceived 2016 July 5; revised 2016 August 6; accepted 2016 August 7; published 2016 August 25. \n\nBased in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.\n\nWe thank Fumiaki Nakata and Rita Morris for assistance at the Subaru Telescope, Mike Beasley for attempting to obtain a spectrum of the new dwarf, the referee for helpful comments, and Michael Wood-Vasey for conversations that helped improve our photometry. J.L.C. and B.W. acknowledge support by NSF Faculty Early Career Development (CAREER) award AST-1151462. D.J.S. acknowledges support from NSF grant AST-1412504. The work of D.J.S. was performed at the Aspen Center for Physics, which is supported by NSF grant PHY-1066293. J.P.B. and A.R. are supported by NSF grant AST-1211995. Some data presented here were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. The Pan-STARRS1 Surveys have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under grant AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), and the Los Alamos National Laboratory. \n\nFacilities: Subaru (Hyper Suprime-Cam), GALEX, GBT, HST (ACS).\n\nPublished - apjl_828_1_L5.pdf
Submitted - 1608.02591v1.pdf
", "abstract": "We report the discovery of the faintest known dwarf galaxy satellite of a Large Magellanic Cloud (LMC) stellar-mass host beyond the Local Group (LG), based on deep imaging with Subaru/Hyper Suprime-Cam. Magellanic Analog Dwarf Companions And Stellar Halos (MADCASH) J074238+652501-dw lies ~35 kpc in projection from NGC 2403, a dwarf spiral galaxy at D \u2248 3.2 Mpc. This new dwarf has M_g = -7.4 \u00b1 0.4 and a half-light radius of 168 \u00b1 70 pc, at the calculated distance of 3.39 \u00b1 0.41 Mpc. The color\u2013magnitude diagram reveals no evidence of young stellar populations, suggesting that MADCASH J074238+652501-dw is an old, metal-poor dwarf similar to low-luminosity dwarfs in the LG. The lack of either detected HI gas (M_(HI)/L_V < 0.69 M\u2299/L\u2299, based on Green Bank Telescope observations) or GALEX NUV/FUV flux enhancement is consistent with a lack of young stars. This is the first result from the MADCASH survey, which is conducting a census of the stellar substructure and faint satellites in the halos of Local Volume LMC analogs via resolved stellar populations. Models predict a total of ~4\u201310 satellites at least as massive as MADCASH J074238+652501-dw around a host with the mass of NGC 2403, with 2\u20133 within our field of view, slightly more than the one such satellite observed in our footprint.", "date": "2016-09-01", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "828", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. L5", "id_number": "CaltechAUTHORS:20160829-083636247", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160829-083636247", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1151462" }, { "agency": "NSF", "grant_number": "AST-1412504" }, { "agency": "NSF", "grant_number": "PHY-1066293" }, { "agency": "NSF", "grant_number": "AST-1211995" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "NASA", "grant_number": "NNX09AF08G" }, { "agency": "NASA", "grant_number": "NNX08AR22G" }, { "agency": "NSF", "grant_number": "AST-1238877" } ] }, "doi": "10.3847/2041-8205/828/1/L5", "primary_object": { "basename": "1608.02591v1.pdf", "url": "https://authors.library.caltech.edu/records/vv8d0-smy24/files/1608.02591v1.pdf" }, "related_objects": [ { "basename": "apjl_828_1_L5.pdf", "url": "https://authors.library.caltech.edu/records/vv8d0-smy24/files/apjl_828_1_L5.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Carlin, Jeffrey L.; Sand, David J.; et el." }, { "id": "https://authors.library.caltech.edu/records/ygqn7-nad91", "eprint_id": 68809, "eprint_status": "archive", "datestamp": "2023-08-22 17:58:19", "lastmod": "2023-10-20 15:45:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Guo-Yicheng", "name": { "family": "Guo", "given": "Yicheng" }, "orcid": "0000-0003-2775-2002" }, { "id": "Koo-David-C", "name": { "family": "Koo", "given": "David C." }, "orcid": "0000-0003-3385-6799" }, { "id": "Lu-Yu", "name": { "family": "Lu", "given": "Yu" }, "orcid": "0000-0003-2691-1622" }, { "id": "Forbes-J-C", "name": { "family": "Forbes", "given": "John C." } }, { "id": "Rafelski-M", "name": { "family": "Rafelski", "given": "Marc" }, "orcid": "0000-0002-9946-4731" }, { "id": "Trump-J-R", "name": { "family": "Trump", "given": "Jonathan R." } }, { "id": "Amor\u00edn-R", "name": { "family": "Amor\u00edn", "given": "Ricardo" } }, { "id": "Barro-G", "name": { "family": "Barro", "given": "Guillermo" }, "orcid": "0000-0001-6813-875X" }, { "id": "Dav\u00e9-R", "name": { "family": "Dav\u00e9", "given": "Romeel" } }, { "id": "Faber-S-M", "name": { "family": "Faber", "given": "S. M." }, "orcid": "0000-0003-4996-214X" }, { "id": "Hathi-N-P", "name": { "family": "Hathi", "given": "Nimish P." }, "orcid": "0000-0001-6145-5090" }, { "id": "Yesuf-Hassen", "name": { "family": "Yesuf", "given": "Hassen" } }, { "id": "Cooper-M-C", "name": { "family": "Cooper", "given": "Michael C." }, "orcid": "0000-0003-1371-6019" }, { "id": "Dekel-A", "name": { "family": "Dekel", "given": "Avishai" }, "orcid": "0000-0003-4174-0374" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Koekemoer-A-M", "name": { "family": "Koekemoer", "given": "Anton M." }, "orcid": "0000-0002-6610-2048" }, { "id": "P\u00e9rez-Gonz\u00e1lez-P-G", "name": { "family": "P\u00e9rez-Gonz\u00e1lez", "given": "Pablo G." }, "orcid": "0000-0003-4528-5639" }, { "id": "Lin-Lihwai", "name": { "family": "Lin", "given": "Lihwai" }, "orcid": "0000-0001-7218-7407" }, { "id": "Newman-J-A", "name": { "family": "Newman", "given": "Jeffery A." }, "orcid": "0000-0001-8684-2222" }, { "id": "Primack-J-R", "name": { "family": "Primack", "given": "Joel R." }, "orcid": "0000-0001-5091-5098" }, { "id": "Rosario-D-J", "name": { "family": "Rosario", "given": "David J." } }, { "id": "Willmer-C-N-A", "name": { "family": "Willmer", "given": "Christopher N. A." } }, { "id": "Yan-Renbin", "name": { "family": "Yan", "given": "Renbin" } } ] }, "title": "Stellar Mass--Gas-phase Metallicity Relation at 0.5 \u2264 z \u2264 0.7: A Power Law with Increasing Scatter toward the Low-mass Regime", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: evolution; galaxies: formation; galaxies: fundamental parameters; galaxies: ISM", "note": "\u00a9 2016 The American Astronomical Society. Received 2015 June 26; accepted 2016 March 14; published 2016 May 11. \n\nWe thank the anonymous referee for constructive comments\nthat improve this article. We thank Aldo Rodriguez-Puebla for useful discussions. Several authors from UCSC acknowledge support from NSF grant AST-0808133. Support for Program HST-GO-12060 and HST-AR-13891 was provided by NASA through a grant from the Space Telescope Science Institute,\nwhich is operated by the Association of Universities for\nResearch in Astronomy, Incorporated, under NASA contract\nNAS 5-26555. M.R. also acknowledges support from an\nappointment to the NASA Postdoctoral Program at Goddard\nSpace Flight Center. J.F. is supported by HST-AR-13909.\nJ.R.T. acknowledges support from NASA through Hubble\nFellowship grant #51330 awarded by the Space Telescope\nScience Institute. A.D. is supported by ISF grant 24/12, by the I-CORE Program of the PBC ISF grant 1829/12, and by NSF\ngrant AST-1405962. P.G.P.G. acknowledges support from\nSpanish MINECO grant AYA2012-31277.\nFacility: Keck (DEIMOS).\n\nPublished - astroj103.pdf
Submitted - 1603.04863v2.pdf
", "abstract": "We present the stellar mass (M_*)\u2013gas-phase metallicity relation (MZR) and its scatter at intermediate redshifts (0.5 \u2a7d z \u2a7d 0.7) for 1381 field galaxies collected from deep spectroscopic surveys. The star formation rate (SFR) and color at a given M_* of this magnitude-limited (R \u227e 24 AB) sample are representative of normal star-forming galaxies. For masses below 10^9 M_\u2609, our sample of 237 galaxies is ~10 times larger than those in previous studies beyond the local universe. This huge gain in sample size enables superior constraints on the MZR and its scatter in the low-mass regime. We find a power-law MZR at 10^8 M_\u2609 < M_* < 10^(11)M_\u2609: 12 + log(O/H)=(5.83 \u00b1 0.19)+(0.30 \u00b1 0.02)log(M_*/M_\u2609). At 10^9 M_\u2609 < M_* < 10^(10.5) M_\u2609, our MZR shows agreement with others measured at similar redshifts in the literature. Our power-law slope is, however, shallower than the extrapolation of the MZRs of others to masses below 10^9 M_\u2609. The SFR dependence of the MZR in our sample is weaker than that found for local galaxies (known as the fundamental metallicity relation). Compared to a variety of theoretical models, the slope of our MZR for low-mass galaxies agrees well with predictions incorporating supernova energy-driven winds. Being robust against currently uncertain metallicity calibrations, the scatter of the MZR serves as a powerful diagnostic of the stochastic history of gas accretion, gas recycling, and star formation of low-mass galaxies. Our major result is that the scatter of our MZR increases as M_* decreases. Our result implies that either the scatter of the baryonic accretion rate (\u03c3_\u1e40) or the scatter of the M_* M_(halo) relation (\u03c3_(SHMR)) increases as M_* decreases. Moreover, our measure of scatter at z = 0.7 appears consistent with that found for local galaxies. This lack of redshift evolution constrains models of galaxy evolution to have both \u03c3_\u1e40 and \u03c3_(SHMR) remain unchanged from z = 0.7 to z = 0.", "date": "2016-05-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "822", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 103", "id_number": "CaltechAUTHORS:20160701-104542973", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160701-104542973", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0808133" }, { "agency": "NASA", "grant_number": "HST-GO-12060" }, { "agency": "NASA", "grant_number": "HST-AR-13891" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NASA Postdoctoral Program" }, { "agency": "NASA", "grant_number": "HST-AR-13909" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51330" }, { "agency": "Israel Science Foundation", "grant_number": "24/12" }, { "agency": "Israel Science Foundation", "grant_number": "1829/12" }, { "agency": "NSF", "grant_number": "AST-1405962" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MINECO)", "grant_number": "AYA2012-31277" } ] }, "doi": "10.3847/0004-637X/822/2/103", "primary_object": { "basename": "1603.04863v2.pdf", "url": "https://authors.library.caltech.edu/records/ygqn7-nad91/files/1603.04863v2.pdf" }, "related_objects": [ { "basename": "astroj103.pdf", "url": "https://authors.library.caltech.edu/records/ygqn7-nad91/files/astroj103.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Guo, Yicheng; Koo, David C.; et el." }, { "id": "https://authors.library.caltech.edu/records/5ehhy-dyv76", "eprint_id": 66035, "eprint_status": "archive", "datestamp": "2023-08-22 17:35:03", "lastmod": "2023-10-18 17:04:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Zhang-Andrew-J", "name": { "family": "Zhang", "given": "Andrew J." } }, { "id": "Hong-Jerry", "name": { "family": "Hong", "given": "Jerry" } }, { "id": "Guo-Michelle", "name": { "family": "Guo", "given": "Michelle" } }, { "id": "Guo-Rachel", "name": { "family": "Guo", "given": "Rachel" } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Cunha-K", "name": { "family": "Cunha", "given": "Katia" } } ] }, "title": "Lithium-Rich Giants in Globular Clusters", "ispublished": "pub", "full_text_status": "public", "keywords": "globular clusters: general; stars: abundances; stars: chemically peculiar; stars: evolution", "note": "\u00a9 2016 The American Astronomical Society. Received 2015 October 5; accepted 2016 January 14; published 2016 March 8.\n\n\nThe data presented herein were obtained at the W. M. Keck Observatory,\nwhich is operated as a scientific partnership among the California Institute of\nTechnology, the University of California and the National Aeronautics and\nSpace Administration. The Observatory was made possible by the generous\nfinancial support of the W. M. Keck Foundation.\n\nThis manuscript is dedicated to the memory of Bob Kraft.\nWe are grateful to Bob for his mentorship and his inspirational discovery of a Li-rich red giant in M3.\nWe thank the colloquium audience at Steward Observatory\nfor helpful feedback. We also thank the anonymous referee for a detailed, thoughtful report that improved this article. AJZ, JH, MG, and RG carried out their work through UCSC's Science Internship Program for high school students. PG acknowledges support from NSF grants AST-1010039 and AST-1412648. We are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented\nherein would have been possible. \nFacility: Keck:II (DEIMOS).\n\nPublished - apj_819_2_135.pdf
Submitted - 1601.01315v2.pdf
", "abstract": "Although red giants deplete lithium on their surfaces, some giants are Li-rich. Intermediate-mass asymptotic giant branch (AGB) stars can generate Li through the Cameron\u2013Fowler conveyor, but the existence of Li-rich, low-mass red giant branch (RGB) stars is puzzling. Globular clusters are the best sites to examine this phenomenon because it is straightforward to determine membership in the cluster and to identify the evolutionary state of each star. In 72 hours of Keck/DEIMOS exposures in 25 clusters, we found four Li-rich RGB and two Li-rich AGB stars. There were 1696 RGB and 125 AGB stars with measurements or upper limits consistent with normal abundances of Li. Hence, the frequency of Li-richness in globular clusters is (0.2 \u00b1 0.1)% for the RGB, (1.6 \u00b1 1.1)% for the AGB, and (0.3 \u00b1 0.1)% for all giants. Because the Li-rich RGB stars are on the lower RGB, Li self-generation mechanisms proposed to occur at the luminosity function bump or He core flash cannot explain these four lower RGB stars. We propose the following origin for Li enrichment: (1) All luminous giants experience a brief phase of Li enrichment at the He core flash. (2) All post-RGB stars with binary companions on the lower RGB will engage in mass transfer. This scenario predicts that 0.1% of lower RGB stars will appear Li-rich due to mass transfer from a recently Li-enhanced companion. This frequency is at the lower end of our confidence interval.", "date": "2016-03-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "819", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 135", "id_number": "CaltechAUTHORS:20160408-153111518", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160408-153111518", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1412648" } ] }, "doi": "10.3847/0004-637X/819/2/135", "primary_object": { "basename": "apj_819_2_135.pdf", "url": "https://authors.library.caltech.edu/records/5ehhy-dyv76/files/apj_819_2_135.pdf" }, "related_objects": [ { "basename": "1601.01315v2.pdf", "url": "https://authors.library.caltech.edu/records/5ehhy-dyv76/files/1601.01315v2.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Kirby, Evan N.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/cyvd9-9ds07", "eprint_id": 62191, "eprint_status": "archive", "datestamp": "2023-08-20 09:08:31", "lastmod": "2023-10-25 16:56:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Triangulum II: Possibly a Very Dense Ultra-faint Dwarf Galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: dwarf \u2013 Local Group", "note": "\u00a9 2015 The American Astronomical Society. \n\nReceived 2015 October 12; accepted 2015 November 3; published 2015 November 16. \n\nWe thank Gina Duggan for obtaining LRIS images, Emily Cunningham for helpful statistics advice, and the anonymous referee for helpful feedback. P.G. acknowledges support from NSF grants AST-1010039 and AST-1412648. We are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nFacilities: Keck:I (LRIS) - , Keck:II (DEIMOS). - KECK II Telescope\n\nPublished - Kirby-ApJL-2015pdf.pdf
Submitted - 1510.03856v3.pdf
", "abstract": "Laevens et al. recently discovered Triangulum II (Tri II), a satellite of the Milky Way. Its Galactocentric distance is 36 kpc, and its luminosity is only 450 L_\u2299. Using Keck/DEIMOS, we measured the radial velocities of six member stars within 1'.2 of the center of Tri II, and we found a velocity dispersion of \u03c3_v = 5.1_(-1.4)^(+4.0) km s^(-1). We also measured the metallicities of three stars and found a range of 0.8 dex in [Fe/H]. The velocity and metallicity dispersions identify Tri II as a dark matter-dominated galaxy. The galaxy is moving very quickly toward the Galactic center v_(GSR) = -262 km s^(-1). Although it might be in the process of being tidally disrupted as it approaches pericenter, there is no strong evidence for disruption in our data set. The ellipticity is low, and the mean velocity, \u3008|v_(helio)\u3009 =-382.1 \u00b1 2.9 km s^(-1), rules out an association with the Triangulum\u2013Andromeda substructure or the Pan-Andromeda Archaeological Survey stellar stream. If Tri II is in dynamical equilibrium, then it would have a mass-to-light ratio of 3600_(-2100)^(+3500) M}_\u2299 L_\u2299^(-1), the highest of any non-disrupting galaxy (those for which dynamical mass estimates are reliable). The density within the 3D half-light radius would be 4.8_(-3.5)^(+8.1) M\u2299 pc^(-3), even higher than Segue 1. Hence, Tri II is an excellent candidate for the indirect detection of dark matter annihilation.", "date": "2015-11-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "814", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. L7", "id_number": "CaltechAUTHORS:20151118-093653068", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151118-093653068", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/2041-8205/814/1/L7", "primary_object": { "basename": "1510.03856v3.pdf", "url": "https://authors.library.caltech.edu/records/cyvd9-9ds07/files/1510.03856v3.pdf" }, "related_objects": [ { "basename": "Kirby-ApJL-2015pdf.pdf", "url": "https://authors.library.caltech.edu/records/cyvd9-9ds07/files/Kirby-ApJL-2015pdf.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Kirby, Evan N.; Cohen, Judith G.; et el." }, { "id": "https://authors.library.caltech.edu/records/zzd1q-z5060", "eprint_id": 58225, "eprint_status": "archive", "datestamp": "2023-08-20 08:04:20", "lastmod": "2023-10-23 19:10:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" } ] }, "title": "Spectroscopic Confirmation of the Dwarf Galaxies Hydra II and Pisces II and the Globular Cluster Laevens 1", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The American Astronomical Society. \n\nReceived 2015 June 2; accepted 2015 July 28; published 2015 August 28. \n\nWe thank D. Perley for obtaining LRIS images of Laevens 1, J.A. Newman for assistance with the DEIMOS wavelength solution, E. Tollerud for the spectrum of the radial velocity template star HD 38230, and M. de los Reyes for pointing out that tidal dwarf galaxies do not obey the LZR. We also thank B. Sesar and the Pan-STARRS team for information regarding star 399 in Laevens 1. The referee's helpful comments significantly improved this article. We are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nFacility: Keck:I (LRIS), Keck:II (DEIMOS).\n\nPublished - Kirby_2015.pdf
Submitted - 1506.01021v1.pdf
", "abstract": "We present Keck/DEIMOS spectroscopy of stars in the recently discovered Milky Way satellites Hydra II, Pisces II, and Laevens 1. We measured a velocity dispersion of 5.4^(+3.6)_(-2.4) km s^(\u22121) for Pisces II, but we did not resolve the velocity dispersions of Hydra II or Laevens 1. We marginally resolved the metallicity dispersions of Hydra II and Pisces II but not Laevens 1. Furthermore, Hydra II and Pisces II obey the luminosity\u2013metallicity relation for Milky Way dwarf galaxies (\u3008[Fe/H] \u3009 = -2.02 \u00b1 0.08 and -2.45 \u00b1 0.07, respectively), whereas Laevens 1 does not (\u3008[Fe/H]\u3009= -1.68 \u00b1 0.05). The kinematic and chemical properties suggest that Hydra II and Pisces II are dwarf galaxies, and Laevens 1 is a globular cluster. We determined that two of the previously observed blue stars near the center of Laevens 1 are not members of the cluster. A third blue star has ambiguous membership. Hydra II has a radial velocity \u3008\u03bd_(helio) \u3009 = 303.1 \u00b1 1.4 km s^(\u22121), similar to the leading arm of the Magellanic stream. The mass-to-light ratio for Pisces II is 370^(+310)_(-240) M\u2299/L\u2299. It is not among the most dark matter-dominated dwarf galaxies, but it is still worthy of inclusion in the search for gamma-rays from dark matter self-annihilation.", "date": "2015-09-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "810", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 56", "id_number": "CaltechAUTHORS:20150615-053227138", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150615-053227138", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1088/0004-637X/810/1/56", "primary_object": { "basename": "1506.01021v1.pdf", "url": "https://authors.library.caltech.edu/records/zzd1q-z5060/files/1506.01021v1.pdf" }, "related_objects": [ { "basename": "Kirby_2015.pdf", "url": "https://authors.library.caltech.edu/records/zzd1q-z5060/files/Kirby_2015.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Kirby, Evan N.; Simon, Joshua D.; et el." }, { "id": "https://authors.library.caltech.edu/records/95p4h-jc690", "eprint_id": 54268, "eprint_status": "archive", "datestamp": "2023-08-20 05:21:54", "lastmod": "2023-10-20 15:45:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guo-Michelle", "name": { "family": "Guo", "given": "Michelle" } }, { "id": "Zhang-Andrew-J", "name": { "family": "Zhang", "given": "Andrew J." } }, { "id": "Deng-Michelle", "name": { "family": "Deng", "given": "Michelle" } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Shetrone-M-D", "name": { "family": "Shetrone", "given": "Matthew D." } }, { "id": "Lee-Young-Sun", "name": { "family": "Lee", "given": "Young Sun" } }, { "id": "Rizzi-L", "name": { "family": "Rizzi", "given": "Luca" }, "orcid": "0000-0003-0882-2327" } ] }, "title": "Carbon in Red Giants in Globular Clusters and Dwarf Spheroidal Galaxies", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Astronomical Society. Received 2014 December 5; accepted 2015 January 27; published 2015 March 12. \nSubmitted on Jan. 27 2015.\nWe thank Vinicius Placco for kindly computing astra-\ntion corrections to carbon abundances. We also thank\nChris Sneden for constructive comments on the structure\nof this paper and the anonymous referee for an insightful\nreport. M.G., A.J.Z., and M.D. carried out their work\nthrough UCSC's Science Internship Program for highschool students. P.G. acknowledges support from NSF\ngrants AST-1010039 and AST-1412648.\nWe are grateful to the many people who have worked\nto make the Keck Telescope and its instruments a reality\nand to operate and maintain the Keck Observatory. The\nauthors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged\nto be guests. Without their generous hospitality, none of\nthe observations presented herein would have been possible.\n\nFacility: Keck:II (DEIMOS\n\nPublished - 0004-637X_801_2_125.pdf
Submitted - 1501.06908v1.pdf
", "abstract": "We present carbon abundances of red giants in Milky Way globular clusters and dwarf spheroidal galaxies (dSphs). Our sample includes measurements of carbon abundances for 154 giants in the clusters NGC 2419, M68, and M15 and 398 giants in the dSphs Sculptor, Fornax, Ursa Minor, and Draco. This sample doubles the number of dSph stars with measurements of [C/Fe]. The [C/Fe] ratio in the clusters decreases with increasing luminosity above log(L/L_\u2299)\u22431.6, which can be explained by deep mixing in evolved giants. The same decrease is observed in dSphs, but the initial [C/Fe] of the dSph giants is not uniform. Stars in dSphs at lower metallicities have larger [C/Fe] ratios. We hypothesize that [C/Fe] (corrected to the initial carbon abundance) declines with increasing [Fe/H] due to the metallicity dependence of the carbon yield of asymptotic giant branch stars and due to the increasing importance of Type Ia supernovae at higher metallicities. We also identified 11 very carbon-rich giants (8 previously known) in three dSphs. However, our selection biases preclude a detailed comparison to the carbon-enhanced fraction of the Milky Way stellar halo. Nonetheless, the stars with [C/Fe] < +1 in dSphs follow a different [C/Fe] track with [Fe/H] than the halo stars. Specifically, [C/Fe] in dSphs begins to decline at lower [Fe/H] than in the halo. The difference in the metallicity of the [C/Fe] \"knee\" adds to the evidence from [\u03b1/Fe] distributions that the progenitors of the halo had a shorter timescale for chemical enrichment than the surviving dSphs.", "date": "2015-03-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "801", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 125", "id_number": "CaltechAUTHORS:20150201-144307311", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150201-144307311", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1412648" }, { "agency": "University of California, Santa Cruz" } ] }, "doi": "10.1088/0004-637X/801/2/125", "primary_object": { "basename": "0004-637X_801_2_125.pdf", "url": "https://authors.library.caltech.edu/records/95p4h-jc690/files/0004-637X_801_2_125.pdf" }, "related_objects": [ { "basename": "1501.06908v1.pdf", "url": "https://authors.library.caltech.edu/records/95p4h-jc690/files/1501.06908v1.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Kirby, Evan N.; Guo, Michelle; et el." }, { "id": "https://authors.library.caltech.edu/records/f60ax-vjg85", "eprint_id": 52957, "eprint_status": "archive", "datestamp": "2023-08-22 14:27:13", "lastmod": "2023-10-18 21:48:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Vargas-L-C", "name": { "family": "Vargas", "given": "Luis C." }, "orcid": "0000-0001-7155-0040" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "[\u03b1/Fe] Abundances of Four Outer M31 Halo Stars", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: evolution; galaxies: individual (M31); Local Group", "note": "\u00a9 2014 American Astronomical Society. Received 2014 August 25; accepted 2014 November 6; published 2014 November 20.\n\nL.C.V. acknowledges useful conversations with Nikhil Padmanabhan during the analysis stage of this project. L.C.V. was supported by the NSF Graduate Research Fellowship (Grant DGE\u22121122492). M.G. and L.C.V. acknowledge support from NSF Grant AST\u22120908752, and P.G. acknowledges support from NSF grant AST\u22121010039. E.J.T. and K.G. were supported by NASA through Hubble Fellowship Grant Nos. 51316.01 and 51273.01, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.\nFacility: Keck:II (DEIMOS)\n\nPublished - 2041-8205_797_1_L2.pdf
Submitted - 1410.3475v1.pdf
", "abstract": "We present alpha element to iron abundance ratios, [\u03b1/Fe], for four stars in the outer stellar halo of the Andromeda Galaxy (M31). The stars were identified as high-likelihood field halo stars by Gilbert et al. and lie at projected distances between 70 and 140 kpc from M31's center. These are the first alpha abundances measured for a halo star in a galaxy beyond the Milky Way. The stars range in metallicity between [Fe/H] = \u20132.2 and [Fe/H] = \u20131.4. The sample's average [\u03b1/Fe] ratio is +0.20 \u00b1 0.20. The best-fit average value is elevated above solar, which is consistent with rapid chemical enrichment from Type II supernovae. The mean [\u03b1/Fe] ratio of our M31 outer halo sample agrees (within the uncertainties) with that of Milky Way inner/outer halo stars that have a comparable range of [Fe/H].", "date": "2014-12-10", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "797", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. L2", "id_number": "CaltechAUTHORS:20141217-104619921", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141217-104619921", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE\u22121122492" }, { "agency": "NSF", "grant_number": "AST\u22120908752" }, { "agency": "NSF", "grant_number": "AST\u22121010039" }, { "agency": "NASA", "grant_number": "51316.01" }, { "agency": "NASA", "grant_number": "51273.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/2041-8205/797/1/L2", "primary_object": { "basename": "1410.3475v1.pdf", "url": "https://authors.library.caltech.edu/records/f60ax-vjg85/files/1410.3475v1.pdf" }, "related_objects": [ { "basename": "2041-8205_797_1_L2.pdf", "url": "https://authors.library.caltech.edu/records/f60ax-vjg85/files/2041-8205_797_1_L2.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Vargas, Luis C.; Gilbert, Karoline M.; et el." }, { "id": "https://authors.library.caltech.edu/records/a0g5q-2n888", "eprint_id": 53077, "eprint_status": "archive", "datestamp": "2023-08-22 14:25:51", "lastmod": "2023-10-19 14:31:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Patterson-R-J", "name": { "family": "Patterson", "given": "Richard J." } }, { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Tanaka-Mikito", "name": { "family": "Tanaka", "given": "Mikito" } }, { "id": "Chiba-Masashi", "name": { "family": "Chiba", "given": "Masashi" }, "orcid": "0000-0002-9053-860X" } ] }, "title": "Global Properties of M31's Stellar Halo from the SPLASH Survey. II. Metallicity Profile", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: groups: individual (M31); galaxies: halos; stars: kinematics and dynamics; techniques: spectroscopic", "note": "\u00a9 2014 American Astronomical Society. \n\nReceived 2014 April 30; accepted 2014 September 7; published 2014 November 10. \n\nSupport for this work was provided by NASA through Hubble\nFellowship grants 51273.01, and 51316.01 awarded to K.M.G.\nand E.J.T. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. P.G., J.S.B., S.R.M., and R.L.B. acknowledge support from collaborative NSF grants AST-1010039, AST-1009973, AST-1009882, and AST-0607726. This project was also supported by NSF grants AST03-07842, AST03-07851, AST06-07726, AST08-07945, and AST10-09882, NASA grant ST-GO-12105.03 through STScI, NASA/JPL contract 1228235, the David and Lucile Packard Foundation, and the F. H. Levinson Fund of the Peninsula Community Foundation (S.R.M., R.J.P., and R.L.B.). E.N.K acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973. E.J.T. acknowledges support from a Graduate Assistance in Areas of National Need (GAANN) fellowship. R.L.B. acknowledges receipt of the Mark C. Pirrung Family Graduate Fellowship from the Jefferson Scholars Foundation and a Fellowship Enhancement for Outstanding Doctoral Candidates from the Office of the Vice President of Research at the University of Virginia. M.T. acknowledges support from Grant-in-Aid for Scientific Research (25800098) of the Ministry of Education, Culture, Sports, Science, and Technology of Japan. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - 0004-637X_796_2_76.pdf
Accepted Version - 1409.3843.pdf
", "abstract": "We present the metallicity distribution of red giant branch (RGB) stars in M31's stellar halo, derived from photometric metallicity estimates for over 1500 spectroscopically confirmed RGB halo stars. The stellar sample comes from 38 halo fields observed with the Keck/DEIMOS spectrograph, ranging from 9 to 175 kpc in projected distance from M31's center, and includes 52 confirmed M31 halo stars beyond 100 kpc. While a wide range of metallicities is seen throughout the halo, the metal-rich peak of the metallicity distribution function becomes significantly less prominent with increasing radius. The metallicity profile of M31's stellar halo shows a continuous gradient from 9 to ~100 kpc, with a magnitude of ~ \u2013 0.01 dex kpc\u20131. The stellar velocity distributions in each field are used to identify stars that are likely associated with tidal debris features. The removal of tidal debris features does not significantly alter the metallicity gradient in M31's halo: a gradient is maintained in fields spanning 10-90 kpc. We analyze the halo metallicity profile, as well as the relative metallicities of stars associated with tidal debris features and the underlying halo population, in the context of current simulations of stellar halo formation. We argue that the large-scale gradient in M31's halo implies M31 accreted at least one relatively massive progenitor in the past, while the field to field variation seen in the metallicity profile indicates that multiple smaller progenitors are likely to have contributed substantially to M31's outer halo.", "date": "2014-12-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "796", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 76", "id_number": "CaltechAUTHORS:20141222-094115048", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141222-094115048", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "51273.01" }, { "agency": "NASA", "grant_number": "51316.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST-1009882" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NSF", "grant_number": "AST03-07842" }, { "agency": "NSF", "grant_number": "AST03-07851" }, { "agency": "NSF", "grant_number": "AST06-07726" }, { "agency": "NSF", "grant_number": "AST08-07945" }, { "agency": "NSF", "grant_number": "AST10-09882" }, { "agency": "NASA", "grant_number": "ST-GO-12105.03" }, { "agency": "NASA/JPL", "grant_number": "1228235" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "F. H. Levinson Fund of the Peninsula Community Foundation" }, { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "Graduate Assistance in Areas of National Need (GAANN) fellowship" }, { "agency": "Jefferson Scholars Foundation" }, { "agency": "University of Virginia" }, { "agency": "Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan", "grant_number": "25800098" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "local_group": { "items": [ { "id": "SPLASH" } ] }, "doi": "10.1088/0004-637X/796/2/76", "primary_object": { "basename": "0004-637X_796_2_76.pdf", "url": "https://authors.library.caltech.edu/records/a0g5q-2n888/files/0004-637X_796_2_76.pdf" }, "related_objects": [ { "basename": "1409.3843.pdf", "url": "https://authors.library.caltech.edu/records/a0g5q-2n888/files/1409.3843.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Gilbert, Karoline M.; Kalirai, Jason S.; et el." }, { "id": "https://authors.library.caltech.edu/records/42rt0-crc80", "eprint_id": 95400, "eprint_status": "archive", "datestamp": "2023-08-20 03:19:28", "lastmod": "2023-10-20 20:12:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Garrison-Kimmel-S", "name": { "family": "Garrison-Kimmel", "given": "Shea" }, "orcid": "0000-0002-4655-8128" }, { "id": "Boylan-Kolchin-M", "name": { "family": "Boylan-Kolchin", "given": "Michael" }, "orcid": "0000-0002-9604-343X" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "Too big to fail in the Local Group", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: haloes, Local Group, cosmology: theory, dark matter", "note": "\u00a9 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. \n\nAccepted 2014 July 18. Received 2014 July 12; in original form 2014 April 21. \n\nWe thank Manoj Kaplinghat, Anna Nierenberg, Mike Cooper, Erik Tollerud, Arianna Di Cintio, Shunsaku Horiuchi, and Jose O\u00f1orbe for helpful discussions, and the anonymous referee for many helpful comments. \n\nSupport for this work was provided by NASA through a Hubble Space Telescope theory grant (programme AR-12836) from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. This work was also supported by a matching equipment grant from UC-HiPACC, a multicampus research programme funded by the University of California Office of Research. \n\nWe also acknowledge the computational support of the NASA Advanced Supercomputing Division and the NASA Center for Climate Simulation, upon whose Pleiades and Discover systems the ELVIS simulations were run, and the Greenplanet cluster at UCI, upon which much of the secondary analysis was performed.\n\nPublished - stu1477.pdf
Submitted - 1404.5313.pdf
", "abstract": "We compare the dynamical masses of dwarf galaxies in the Local Group (LG) to those of haloes in the ELVIS (Exploring the Local Volume in Simulations) suite of \u039b cold dark matter simulations. We enumerate unaccounted-for, dense haloes (V_(ma)x \u2273 25\u2009km\u2009s^(\u22121)) that became massive enough to have formed stars in the presence of an ionizing background (V_(peak) > 30\u2009km\u2009s^(\u22121)). Within 300\u2009kpc of the Milky Way, the number of these objects ranges from 2 to 25 over our full sample. Moreover, this 'too big to fail' count grows when extended to the outer regions of the LG: there are 12\u201340 unaccounted-for massive haloes in the outskirts of the LG, a region that should be largely unaffected by any environmental processes. According to models that reproduce the LG stellar mass function, all of these missing massive systems should have M_\u2605 > 10^6\u2009M_\u2299. We find, unexpectedly, that there is no obvious trend in the M_\u2605\u2212V_(max) relation for LG field galaxies with stellar masses in the range of \u223c 10^5 \u2212 10^8\u2009M_\u2299. Solutions to the too big to fail problem that rely on ram pressure stripping, tidal effects, or statistical flukes appear less likely in the face of these results.", "date": "2014-10-11", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "444", "number": "1", "publisher": "Royal Astronomical Society", "pagerange": "222-236", "id_number": "CaltechAUTHORS:20190510-120907607", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120907607", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "AR-12836" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "University of California" } ] }, "doi": "10.1093/mnras/stu1477", "primary_object": { "basename": "1404.5313.pdf", "url": "https://authors.library.caltech.edu/records/42rt0-crc80/files/1404.5313.pdf" }, "related_objects": [ { "basename": "stu1477.pdf", "url": "https://authors.library.caltech.edu/records/42rt0-crc80/files/stu1477.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Garrison-Kimmel, Shea; Boylan-Kolchin, Michael; et el." }, { "id": "https://authors.library.caltech.edu/records/h6ejb-y9z34", "eprint_id": 95491, "eprint_status": "archive", "datestamp": "2023-08-20 01:00:35", "lastmod": "2023-10-20 20:17:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roederer-I-U", "name": { "family": "Roederer", "given": "Ian U." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "Detailed abundance analysis of the brightest star in Segue 2, the least massive galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "nuclear reactions, nucleosynthesis, abundances \u2013 stars: abundances \u2013 stars: individual: SDSS J021933.13+200830.2 \u2013 galaxies: individual: Segue 2", "note": "\u00a9 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. \n\nAccepted 2014 March 7. Received 2014 March 7; in original form 2014 January 22. Published: 09 April 2014. \n\nThis paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. \n\nIUR thanks J. Sobeck and C. Sneden for their expert assistance with\u2009MOOG. We thank the referee for providing helpful suggestions on the manuscript. This research has made use of NASA's Astrophysics Data System Bibliographic Services, the arXiv preprint server operated by Cornell University, the SIMBAD and VizieR data bases hosted by the Strasbourg Astronomical Data Center, and the Atomic Spectra Database (Kramida et al. 2013) hosted by the National Institute of Standards and Technology.\u2009IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. ENK acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973.\n\nPublished - stu491.pdf
Accepted Version - 1403.2733.pdf
Supplemental Material - stu491_Supplementary_Data.zip
", "abstract": "We present the first high-resolution spectroscopic observations of one red giant star in the ultra-faint dwarf galaxy Segue 2, which has the lowest total mass (including dark matter) estimated for any known galaxy. These observations were made using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the Magellan II Telescope at Las Campanas Observatory. We perform a standard abundance analysis of this star, SDSS J021933.13+200830.2, and present abundances of 21 species of 18 elements as well as upper limits for 25 additional species. We derive [Fe/H] = \u22122.9, in excellent agreement with previous estimates from medium-resolution spectroscopy. Our main result is that this star bears the chemical signatures commonly found in field stars of similar metallicity. The heavy elements produced by neutron-capture reactions are present, but they are deficient at levels characteristic of stars in other ultra-faint dwarf galaxies and a few luminous dwarf galaxies. The otherwise normal abundance patterns suggest that the gas from which this star formed was enriched by metals from multiple Type II supernovae reflecting a relatively well-sampled IMF. This adds to the growing body of evidence indicating that Segue 2 may have been substantially more massive in the past.", "date": "2014-05-21", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "440", "number": "3", "publisher": "Royal Astronomical Society", "pagerange": "2665-2675", "id_number": "CaltechAUTHORS:20190514-120114668", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190514-120114668", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California" }, { "agency": "NSF", "grant_number": "AST-1009973" } ] }, "doi": "10.1093/mnras/stu491", "primary_object": { "basename": "1403.2733.pdf", "url": "https://authors.library.caltech.edu/records/h6ejb-y9z34/files/1403.2733.pdf" }, "related_objects": [ { "basename": "stu491.pdf", "url": "https://authors.library.caltech.edu/records/h6ejb-y9z34/files/stu491.pdf" }, { "basename": "stu491_Supplementary_Data.zip", "url": "https://authors.library.caltech.edu/records/h6ejb-y9z34/files/stu491_Supplementary_Data.zip" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Roederer, Ian U. and Kirby, Evan N." }, { "id": "https://authors.library.caltech.edu/records/wpzpy-6t375", "eprint_id": 95401, "eprint_status": "archive", "datestamp": "2023-08-22 12:40:23", "lastmod": "2023-10-20 20:12:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Frebel-A", "name": { "family": "Frebel", "given": "Anna" }, "orcid": "0000-0002-2139-7145" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "Segue 1: An Unevolved Fossil Galaxy from the Early Universe", "ispublished": "pub", "full_text_status": "public", "keywords": "early universe; galaxies: dwarf; Galaxy: halo; Local Group; stars: abundances; stars: Population II", "note": "\u00a9 2014. The American Astronomical Society. \n\nReceived 2013 December 14; accepted 2014 March 13; published 2014 April 16. \n\nWe thank Andrew McWilliam for providing the Arcturus spectrum. A.F. is supported by NSF CAREER grant AST-1255160. J.D.S. is supported by NSF grant AST-1108811. E.N.K. acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research. This work made use of NASA's Astrophysics Data System Bibliographic Services. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nFacilities: Magellan:Clay (MIKE) - Magellan II Landon Clay Telescope, Keck:I (HIRES) - KECK I Telescope\n\nPublished - Frebel_2014_ApJ_786_74.pdf
Accepted Version - 1403.6116.pdf
", "abstract": "We present Magellan/MIKE and Keck/HIRES high-resolution spectra of six red giant stars in the dwarf galaxy Segue 1. Including one additional Segue 1 star observed by Norris et al., high-resolution spectra have now been obtained for every red giant in Segue 1. Remarkably, three of these seven stars have metallicities below [Fe/H] = \u20133.5, suggesting that Segue 1 is the least chemically evolved galaxy known. We confirm previous medium-resolution analyses demonstrating that Segue 1 stars span a metallicity range of more than 2 dex, from [Fe/H] = \u20131.4 to [Fe/H] = \u20133.8. All of the Segue 1 stars are \u03b1-enhanced, with [\u03b1/Fe] ~ 0.5. High \u03b1-element abundances are typical for metal-poor stars, but in every previously studied galaxy [\u03b1/Fe] declines for more metal-rich stars, which is typically interpreted as iron enrichment from supernova Ia. The absence of this signature in Segue 1 indicates that it was enriched exclusively by massive stars. Other light element abundance ratios in Segue 1, including carbon enhancement in the three most metal-poor stars, closely resemble those of metal-poor halo stars. Finally, we classify the most metal-rich star as a CH star given its large overabundances of carbon and s-process elements. The other six stars show remarkably low neutron-capture element abundances of [Sr/H] < \u20134.9 and [Ba/H] < \u20134.2, which are comparable to the lowest levels ever detected in halo stars. This suggests minimal neutron-capture enrichment, perhaps limited to a single r-process or weak s-process synthesizing event. Altogether, the chemical abundances of Segue 1 indicate no substantial chemical evolution, supporting the idea that it may be a surviving first galaxy that experienced only one burst of star formation.", "date": "2014-05-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "786", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 74", "id_number": "CaltechAUTHORS:20190510-120907697", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120907697", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1255160" }, { "agency": "NSF", "grant_number": "AST-1108811" }, { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California" } ] }, "doi": "10.1088/0004-637x/786/1/74", "primary_object": { "basename": "1403.6116.pdf", "url": "https://authors.library.caltech.edu/records/wpzpy-6t375/files/1403.6116.pdf" }, "related_objects": [ { "basename": "Frebel_2014_ApJ_786_74.pdf", "url": "https://authors.library.caltech.edu/records/wpzpy-6t375/files/Frebel_2014_ApJ_786_74.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Frebel, Anna; Simon, Joshua D.; et el." }, { "id": "https://authors.library.caltech.edu/records/xp2xm-6j918", "eprint_id": 45194, "eprint_status": "archive", "datestamp": "2023-08-22 12:00:17", "lastmod": "2023-10-26 17:51:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Boylan-Kolchin-M", "name": { "family": "Boylan-Kolchin", "given": "Michael" }, "orcid": "0000-0002-9604-343X" }, { "id": "Kaplinghat-M", "name": { "family": "Kaplinghat", "given": "Manoj" } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" } ] }, "title": "The dynamics of isolated Local Group galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: kinematics and dynamics; Local Group", "note": "\u00a9 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.\n\nAccepted 2014 January 6; Received 2013 December 20; in original form 2013 October 31.\n\nWe are grateful to the many people who have worked to make the Keck Telescopes and their instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests.Without their generous hospitality, none of the observations presented herein would have been possible.\nWe thank Josh Simon and Marla Geha for providing their\nDEIMOS radial velocity template spectra. We also thank Alan\nMcConnachie and Mike Irwin for sharing their photometric and\nastrometric catalogue for Cetus. ENK acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973. JGC thanks NSF grant AST-0908139 for partial support.\n\nPublished - MNRAS-2014-Kirby-1015-27.pdf
Submitted - 1401.1208v2.pdf
Supplemental Material - table2.txt
", "abstract": "We measured velocities of 862 individual red giant stars in seven isolated dwarf galaxies in the Local Group: NGC 6822, IC 1613, VV 124 (UGC 4879), the Pegasus dwarf irregular galaxy (DDO 216), Leo A, Cetus and Aquarius (DDO 210). We also computed velocity dispersions, taking into account the measurement uncertainties on individual stars. None of the isolated galaxies is denser than the densest Local Group satellite galaxy. Furthermore, the isolated dwarf galaxies have no obvious distinction in the velocity dispersion\u2013half-light radius plane from the satellite galaxies of the Milky Way and M31. The similarity of the isolated and satellite galaxies' dynamics and structural parameters imposes limitations on environmental solutions to the 'too big to fail' problem, wherein there are fewer dense dwarf satellite galaxies than would be expected from cold dark matter simulations. This data set also has many other applications for dwarf galaxy evolution, including the transformation of dwarf irregular into dwarf spheroidal galaxies. We intend to explore these issues in future work.", "date": "2014-03-21", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "439", "number": "1", "publisher": "Royal Astronomical Society", "pagerange": "1015-1027", "id_number": "CaltechAUTHORS:20140424-141430731", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140424-141430731", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST-0908139" } ] }, "doi": "10.1093/mnras/stu025", "primary_object": { "basename": "MNRAS-2014-Kirby-1015-27.pdf", "url": "https://authors.library.caltech.edu/records/xp2xm-6j918/files/MNRAS-2014-Kirby-1015-27.pdf" }, "related_objects": [ { "basename": "table2.txt", "url": "https://authors.library.caltech.edu/records/xp2xm-6j918/files/table2.txt" }, { "basename": "1401.1208v2.pdf", "url": "https://authors.library.caltech.edu/records/xp2xm-6j918/files/1401.1208v2.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Kirby, Evan N.; Bullock, James S.; et el." }, { "id": "https://authors.library.caltech.edu/records/dx8p3-k2z24", "eprint_id": 43445, "eprint_status": "archive", "datestamp": "2023-08-22 11:09:11", "lastmod": "2023-10-25 23:33:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Cheng-Lucy", "name": { "family": "Cheng", "given": "Lucy" } }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Gallazzi-A", "name": { "family": "Gallazzi", "given": "Anna" } } ] }, "title": "The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: fundamental parameters; galaxies: irregular; Local Group", "note": "\u00a9 2013 American Astronomical Society. Received 2013 August 15; accepted 2013 October 1; published 2013 November 27. \n\nThe data presented herein were obtained at the W. M. Keck Observatory,\nwhich is operated as a scientific partnership among the California Institute of\nTechnology, the University of California and the National Aeronautics and\nSpace Administration. The Observatory was made possible by the generous\nfinancial support of the W. M. Keck Foundation.\n\nWe are grateful to the many people who have worked to make the Keck Telescopes and their instruments a reality and to\noperate and maintain the Keck Observatory. The authors wish\nto extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. We extend a special note of gratitude to Keck support astronomers Luca Rizzi, Greg Wirth, and Marc Kassis.\nWe thank the anonymous referee for reviewing our manuscript. We also thank Yuichi Matsuda and Brenda Frye\nfor obtaining the Subaru images of Aquarius presented in\nSection 2.2.5, Andrew Cole and Mike Irwin for sharing the\nINTWide Field Survey photometric catalog of Leo A, Edouard\nBernard for sharing his photometric catalog of IC 1613, and Josh Simon and Marla Geha for sharing their DEIMOS spectroscopy of Leo T and other faint galaxies. E.N.K. thanks Evan Skillman, Leslie Hunt, Laura Magrini, and Jose O\u00f1orbe for helpful conversations. We thank Edouard Bernard for a careful reading of the manuscript and helpful comments. We also thank Namrata Anand for early contributions to the coaddition of DEIMOS spectra. E.N.K. acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program\nfunded by the University of California Office of Research, and partial support from NSF grant AST-1009973. J.G.C. thanks NSF grant AST-0908139 for partial support. P.G. acknowledges support from NSF grant AST-10-10039. He thanks the staff of the Aspen Center for Physics for their generous hospitality during his visit. L.C. was supported by UCSC's Science Internship Program (SIP). A.G. acknowledges support from the EU FP7/2007-2013 under grant agreement No. 267251 AstroFIt. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is http://www.sdss.org/. IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy,\nInc., under cooperative agreement with the National Science\nFoundation.\nFacility: Keck:II (DEIMOS)\n\nPublished - 0004-637X_779_2_102.pdf
Submitted - 1310.0814v2.pdf
", "abstract": "We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z_* \u221d M_*^(0.30\u00b10.02). The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M_* = 10^(12) M_\u2609. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping.", "date": "2013-12-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "779", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 102", "id_number": "CaltechAUTHORS:20140121-091543595", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140121-091543595", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NSF", "grant_number": "AST-10-10039" }, { "agency": "University of California, Santa Cruz" }, { "agency": "European Research Council (ERC)", "grant_number": "267251" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NASA" }, { "agency": "Japanese Monbukagakusho" }, { "agency": "Max Planck Society" }, { "agency": "Higher Education Funding Council for England" } ] }, "doi": "10.1088/0004-637X/779/2/102", "primary_object": { "basename": "0004-637X_779_2_102.pdf", "url": "https://authors.library.caltech.edu/records/dx8p3-k2z24/files/0004-637X_779_2_102.pdf" }, "related_objects": [ { "basename": "1310.0814v2.pdf", "url": "https://authors.library.caltech.edu/records/dx8p3-k2z24/files/1310.0814v2.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Kirby, Evan N.; Cohen, Judith G.; et el." }, { "id": "https://authors.library.caltech.edu/records/3b1vz-k3234", "eprint_id": 43154, "eprint_status": "archive", "datestamp": "2023-08-22 10:54:45", "lastmod": "2023-10-25 23:19:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Christlieb-N", "name": { "family": "Christlieb", "given": "Norbert" }, "orcid": "0000-0002-4043-2727" }, { "id": "Thompson-I", "name": { "family": "Thompson", "given": "Ian" } }, { "id": "McWilliam-A", "name": { "family": "McWilliam", "given": "Andrew" } }, { "id": "Shectman-S", "name": { "family": "Shectman", "given": "Stephen" } }, { "id": "Reimers-D", "name": { "family": "Reimers", "given": "Dieter" } }, { "id": "Wisotzki-L", "name": { "family": "Wisotzki", "given": "Lutz" } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" } ] }, "title": "Normal and Outlying Populations of the Milky Way Stellar Halo at [Fe/H] < \u20132", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxy: abundances; Galaxy: formation; Galaxy: halo", "note": "\u00a9 2013 American Astronomical Society. Received 2013 June 8; accepted 2013 September 23; published 2013 November 1. \n\nBased in part on observations obtained in part at the W. M. Keck\nObservatory, which is operated jointly by the California Institute of\nTechnology, the University of California, and the National Aeronautics and\nSpace Administration.\n\nWe are very grateful to the Palomar, Las Campanas, and Keck\ntime allocation committees for their long-term support of this campaign during the initial phase of moderate resolution spectroscopy which began in 2000 and ended in 2006 as well as the subsequent high resolution spectroscopy. J. Cohen acknowledges partial support from NSF grants AST-0507219 and AST-0908139. I. Thompson acknowledges partial support from NSF AST-0507325. E.N.K. acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973. This work was partially supported by Sonderforschungsbereich SFB 881 \"The Milky Way System\" (subproject A4) of the German Research Foundation (DFG). We are grateful to the many people who have worked to make the Keck Telescopes and their instruments, and the Magellan Telescopes and their\ninstruments, a reality and to operate and maintain these observatories. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible.\n\nPublished - 0004-637X_778_1_56.pdf
Submitted - 1310.1527v3.pdf
", "abstract": "From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H] < \u20133.0 dex. We identify a heretofore unidentified group: Ca-deficient stars with sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances; the Ca-deficient group comprises ~10% of the sample, excluding Carbon stars. Our radial velocity distribution shows that the carbon-enhanced stars with no s-process enhancements, CEMP-no, and which do not show C2 bands are not preferentially binary systems. Ignoring Carbon stars, approximately 15% of our sample are strong (\u22655\u03c3) outliers in one or more elements between Mg and Ni; this rises to ~19% if very strong (\u226510\u03c3) outliers for Sr and Ba are included. Examples include: HE0305\u20130554 with the lowest [Ba/H] known; HE1012\u20131540 and HE2323\u20130256, two (non-velocity variable) C-rich stars with very strong [Mg,Al/Fe] enhancements; and HE1226\u20131149, an extremely r-process rich star.", "date": "2013-11-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "778", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 56", "id_number": "CaltechAUTHORS:20131224-070301937", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131224-070301937", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0507219" }, { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NSF", "grant_number": "AST-0507325" }, { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California Office of Research" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "SFB 881" } ] }, "doi": "10.1088/0004-637X/778/1/56", "primary_object": { "basename": "1310.1527v3.pdf", "url": "https://authors.library.caltech.edu/records/3b1vz-k3234/files/1310.1527v3.pdf" }, "related_objects": [ { "basename": "0004-637X_778_1_56.pdf", "url": "https://authors.library.caltech.edu/records/3b1vz-k3234/files/0004-637X_778_1_56.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Cohen, Judith G.; Christlieb, Norbert; et el." }, { "id": "https://authors.library.caltech.edu/records/81ajc-1se80", "eprint_id": 41913, "eprint_status": "archive", "datestamp": "2023-08-22 10:12:36", "lastmod": "2023-10-25 14:54:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Newman-J-A", "name": { "family": "Newman", "given": "Jeffrey A." }, "orcid": "0000-0001-8684-2222" }, { "id": "Kassin-S-A", "name": { "family": "Kassin", "given": "Susan A." } }, { "id": "Noeske-K-G", "name": { "family": "Noeske", "given": "K. G." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Lotz-J-M", "name": { "family": "Lotz", "given": "Jennifer M." }, "orcid": "0000-0003-3130-5643" } ] }, "title": "The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts", "ispublished": "pub", "full_text_status": "public", "keywords": "cosmology: observations; galaxies: distances and redshifts; galaxies: evolution; galaxies: fundamental parameters; galaxies: high-redshift; galaxies: statistics; large-scale structure of universe; methods: data analysis; surveys", "note": "\u00a9 2013 The American Astronomical Society.\n\nReceived 2012 March 14; accepted 2013 May 31; published 2013 August 29.\n\nThanks are due to the many institutions and individuals who have made the DEEP2 survey possible. First thanks go\nto the W. M. Keck Foundation, the University of California, and NASA for providing funds to construct and operate the\nKeck telescopes. Second, we wish to thank the technical teams in the UCO/Lick Shops and at Keck Observatory for their\nrole in building and commissioning the DEIMOS spectrograph and for their superb support during many observing runs.\nFunds for the spectrograph were provided by instrumentation grant ARI 92-14621 from the National Science Foundation and\ninstrument funds from the California Association for Research in Astronomy (Keck Observatory) and from the University of\nCalifornia/Lick Observatory. The DEIMOS data-reduction pipeline is based in part on code from the Princeton Sloan Digital Sky Survey spectrograph\npipeline, and we thank Scott Burles and David Schlegel for their help in adapting this software for DEIMOS. Particularly\nvital components were the SDSS code developed for slitlet extractions, B-spline sky subtraction, and redshift determination.\nPatrik Jonsson's study of fringing in the LRIS spectrograph led to the basic understanding of fringing needed to establish image stability\nspecifications for DEIMOS. The ATV image display tool created by Aaron Barth, SPLOT created by David Schlegel,\nthe IDL Astronomy User's Library supported by the Goddard Space Flight Center, and the idlutils package were all instrumental\nin this work. The submit_prepare perl script by Marshall Perrin was of great assistance in the submission of this paper.\nWe benefitted greatly from advice and input from Jeremy Mould, Charles Steidel, Mark Metzger, Richard Ellis, Chris\nConselice, Harlan Epps, Edward Groth, Garth Illingworth, Richard Kron, Alex Szalay, Roc Cutri, Charles Beichman, Peter\nEisenhardt, Giovanni Fazio, and Kevin Bundy in conceiving, designing, and executing the survey. We wish to thank the anonymous\nreferee for their detailed reading and helpful comments on this paper, and for helping to raise awareness of our unconscious\nboreal-centrism. We also wish to thank the entire DEEP1 team for their pioneering efforts which helped greatly in designing\nDEEP2. The DEEP2 survey was initiated under the auspices of the NSF Center for Particle Astrophysics. Major grant support\nwas provided by National Science Foundation grants AST 95-29098, 00-711098, 05-07483, and 08-08133 to UCSC, AST\n00-71048, 05-07428, and 08-07630 to UCB, and 08-06732 to the University of Pittsburgh. Computing hardware used to\nanalyze DEEP2 data was provided by Sun Microsystems. The HST ACS imaging mosaic in EGS was constructed by Anton\nKoekemoer and Jennifer Lotz and was funded by grant HST-AR-01947 from NASA. NASA imaging of the original Groth Strip\nwas planned and executed by Ed Groth and Jason Rhodes with support from NAS5-1661 and NAG5-6279 to the WFPC1 IDT.\nSupport for this work was provided by NASA through Hubble Fellowship grants 51256.01 and 51269.01 awarded to E.N.K.\nand M.C.C., respectively, by the Space Telescope Science Institute, which is operated by the Association of Universities for\nResearch in Astronomy, Inc., for NASA, under contract NAS 5-26555. Sandra Faber thank CARA for a generous research grant\nand the Miller Institute at UC Berkeley for a Visiting Miller Professorship, during which much of this paper was written.\nJeffrey Newman and Alison Coil acknowledge support from Hubble Fellowships during their DEEP2 work, and Michael Cooper acknowledges support from both Hubble and Spitzer Fellowships. Marc Davis acknowledges support from the entire DEEP2 team who filled in while he was recovering from a stroke.\nFinally, we recognize and acknowledge the highly significant cultural role and reverence that the summit of Mauna Kea\nhas always had within the indigenous Hawaiian community; it has been a privilege to be given the opportunity to conduct\nobservations from this mountain.\n\nPublished - 0067-0049_208_1_5.pdf
Submitted - 1203.3192v3.pdf
", "abstract": "We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude M_B = \u221220 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg^2 divided into four separate fields observed to a limiting apparent magnitude of R_(AB) = 24.1. Objects with z \u227e0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z ~ 1.45, where the [O\u2009ii] 3727\u2009\u00c5 doublet lies in the infrared. The DEIMOS 1200 line mm^(\u22121) grating used for the survey delivers high spectral resolution (R ~ 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other artifacts that in some cases remain after data reduction. Redshift errors and catastrophic failure rates are assessed through more than 2000 objects with duplicate observations. Sky subtraction is essentially photon-limited even under bright OH sky lines; we describe the strategies that permitted this, based on high image stability, accurate wavelength solutions, and powerful B-spline modeling methods. We also investigate the impact of targets that appear to be single objects in ground-based targeting imaging but prove to be composite in Hubble Space Telescope data; they constitute several percent of targets at z ~ 1, approaching ~5%\u201310% at z > 1.5. Summary data are given that demonstrate the superiority of DEEP2 over other deep high-precision redshift surveys at z ~ 1 in terms of redshift accuracy, sample number density, and amount of spectral information. We also provide an overview of the scientific highlights of the DEEP2 survey thus far.", "date": "2013-09", "date_type": "published", "publication": "Astrophysical Journal Supplement Series", "volume": "208", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 5", "id_number": "CaltechAUTHORS:20131015-090200542", "issn": "0067-0049", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131015-090200542", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "W. M. Keck Foundation" }, { "agency": "University of California" }, { "agency": "NASA" }, { "agency": "NSF", "grant_number": "ARI 92-14621" }, { "agency": "Lick Observatory" }, { "agency": "NSF", "grant_number": "AST 95-29098" }, { "agency": "NSF", "grant_number": "AST 00-711098" }, { "agency": "NSF", "grant_number": "AST 05-07483" }, { "agency": "NSF", "grant_number": "AST 08-08133" }, { "agency": "NSF", "grant_number": "AST 00-71048" }, { "agency": "NSF", "grant_number": "AST 05-07428" }, { "agency": "NSF", "grant_number": "AST 08-07630" }, { "agency": "NSF", "grant_number": "AST 08-06732" }, { "agency": "NASA", "grant_number": "HST-AR-01947" }, { "agency": "NASA", "grant_number": "NAS5-1661" }, { "agency": "NASA", "grant_number": "NAG5-6279" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51269.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "CARA" }, { "agency": "Miller Institute for Basic Research in Science" }, { "agency": "NASA Spitzer Fellowship" } ] }, "doi": "10.1088/0067-0049/208/1/5", "primary_object": { "basename": "0067-0049_208_1_5.pdf", "url": "https://authors.library.caltech.edu/records/81ajc-1se80/files/0067-0049_208_1_5.pdf" }, "related_objects": [ { "basename": "1203.3192v3.pdf", "url": "https://authors.library.caltech.edu/records/81ajc-1se80/files/1203.3192v3.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Newman, Jeffrey A.; Kassin, Susan A.; et el." }, { "id": "https://authors.library.caltech.edu/records/zm0bb-maw06", "eprint_id": 39534, "eprint_status": "archive", "datestamp": "2023-08-22 09:36:48", "lastmod": "2023-10-24 16:54:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Boylan-Kolchin-M", "name": { "family": "Boylan-Kolchin", "given": "Michael" }, "orcid": "0000-0002-9604-343X" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Kaplinghat-M", "name": { "family": "Kaplinghat", "given": "Manoj" } } ] }, "title": "Segue 2: The Least Massive Galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: individual (Segue 2); galaxies: kinematics and dynamics; Local Group", "note": "\u00a9 2013 American Astronomical Society. Received 2013 March 11; accepted 2013 April 21; published 2013 May 20. \n\nThe data presented herein were obtained at the W. M. Keck Observatory,\nwhich is operated as a scientific partnership among the California Institute of\nTechnology, the University of California and the National Aeronautics and\nSpace Administration. The Observatory was made possible by the generous\nfinancial support of the W. M. Keck Foundation.\n\n\nWe are grateful to the many people who have worked to make the Keck telescope and its instruments a reality and to operate\nand maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible.\nWe thank the anonymous referee for a courteous report\non our article and Josh Simon for a helpful discussion.\nWe are also grateful to Shunsaku Horiuchi for confirming that Segue 2 shows no signal in sky maps from the Fermi\nGamma-ray Space Telescope. E.N.K. and M.B.K. acknowledge\nsupport from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973. J.G.C. thanks NSF grant AST-0908139 for partial support.\nFacility: Keck:II (DEIMOS)\n\nPublished - 0004-637X_770_1_16.pdf
Submitted - 1304.6080v3.pdf
", "abstract": "Segue 2, discovered by Belokurov et al., is a galaxy with a luminosity of only 900 L_\u2609. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2\u2014a threefold increase in spectroscopic sample size. The velocity dispersion is too small to be measured with our data. The upper limit with 90% (95%) confidence is \u03c3_v < 2.2 (2.6) km s^(\u20131), the most stringent limit for any galaxy. The corresponding limit on the mass within the three-dimensional half-light radius (46 pc) is M_(1/2) < 1.5 (2.1) \u00d7 10^5 M_\u2609. Segue 2 is the least massive galaxy known. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in [Fe/H] (from \u20132.85 to \u20131.33) among the member stars. The stars' [\u03b1/Fe] ratios decline with increasing [Fe/H], indicating that Segue 2 retained Type Ia supernova ejecta despite its presently small mass and that star formation lasted for at least 100 Myr. The mean metallicity, \u3008[Fe/H]\u3009 = -2.22 \u00b1 0.13 (about the same as the Ursa Minor galaxy, 330 times more luminous than Segue 2), is higher than expected from the luminosity-metallicity relation defined by more luminous dwarf galaxy satellites of the Milky Way. Segue 2 may be the barest remnant of a tidally stripped, Ursa Minor-sized galaxy. If so, it is the best example of an ultra-faint dwarf galaxy that came to be ultra-faint through tidal stripping. Alternatively, Segue 2 could have been born in a very low mass dark matter subhalo (v_(max) < 10 km s^(\u20131)), below the atomic hydrogen cooling limit.", "date": "2013-06-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "770", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 16", "id_number": "CaltechAUTHORS:20130723-132136704", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130723-132136704", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST-0908139" } ] }, "doi": "10.1088/0004-637X/770/1/16", "primary_object": { "basename": "0004-637X_770_1_16.pdf", "url": "https://authors.library.caltech.edu/records/zm0bb-maw06/files/0004-637X_770_1_16.pdf" }, "related_objects": [ { "basename": "1304.6080v3.pdf", "url": "https://authors.library.caltech.edu/records/zm0bb-maw06/files/1304.6080v3.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Kirby, Evan N.; Boylan-Kolchin, Michael; et el." }, { "id": "https://authors.library.caltech.edu/records/841sb-v1m48", "eprint_id": 38750, "eprint_status": "archive", "datestamp": "2023-08-22 09:17:40", "lastmod": "2023-10-23 23:26:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yang-Lei", "name": { "family": "Yang", "given": "Lei" } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Peng-Eric-W", "name": { "family": "Peng", "given": "Eric W." } }, { "id": "Cheng-Lucy", "name": { "family": "Cheng", "given": "Lucy" } } ] }, "title": "Measuring Detailed Chemical Abundances from Co-added Medium-resolution Spectra. I. Tests Using Milky Way Dwarf Spheroidal Galaxies and Globular Clusters", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: evolution; galaxies: stellar content; Local Group", "note": "\u00a9 2013 American Astronomical Society. \n\nReceived 2012 July 7; accepted 2013 March 3; published 2013 April 8. \n\nData herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nL.Y. and E.W.P. gratefully acknowledge partial support from the Peking University Hundred Talent Fund (985) and grants 10873001 and 11173003 from the . L.Y. also acknowledges support from the LAMOST-PLUS collaboration, a partnership funded by NSF grant AST-09-37523, and NSFC grants 10973015 and 11061120454. Support for this work was also provided by NASA through Hubble Fellowship grant 51256.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. \n\nP.G. acknowledges support from NSF grant AST-10-10039. He thanks the staff of the Kavli Institute for Astronomy and Astrophysics at Peking University for their generous hospitality during his collaborative visits. L.C. was supported by UCSC's Science Internship Program (SIP). \n\nFacility: Keck:II (DEIMOS)\n\nPublished - 0004-637X_768_1_4.pdf
Submitted - 1303.1222.pdf
", "abstract": "The ability to measure metallicities and \u03b1-element abundances in individual red giant branch (RGB) stars using medium-resolution spectra (R \u2248 6000) is a valuable tool for deciphering the nature of Milky Way dwarf satellites and the history of the Galactic halo. Extending such studies to more distant systems like Andromeda is beyond the ability of the current generation of telescopes, but by co-adding the spectra of similar stars, we can attain the necessary signal-to-noise ratio (S/N) to make detailed abundance measurements. In this paper, we present a method to determine metallicities and \u03b1-element abundances using the co-addition of medium-resolution spectra. We test the method of spectral co-addition using high-S/N spectra of more than 1300 RGB stars from Milky Way globular clusters and dwarf spheroidal galaxies obtained with the Keck II telescope/DEIMOS spectrograph. We group similar stars using photometric criteria and compare the weighted ensemble average abundances ([Fe/H], [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]) of individual stars in each group with the measurements made on the corresponding co-added spectrum. We find a high level of agreement between the two methods, which permits us to apply this co-added spectra technique to more distant RGB stars, like stars in the M31 satellite galaxies. This paper outlines our spectral co-addition and abundance measurement methodology and describes the potential biases in making these measurements.", "date": "2013-05-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "768", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 4", "id_number": "CaltechAUTHORS:20130603-094307697", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130603-094307697", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Peking University Hundred Talent Fund (985)" }, { "agency": "National Natural Science Foundation of China (NSFC)", "grant_number": "10873001" }, { "agency": "National Natural Science Foundation of China (NSFC)", "grant_number": "11173003" }, { "agency": "LAMOST-PLUS collaboration" }, { "agency": "NSF", "grant_number": "AST-09-37523" }, { "agency": "National Natural Science Foundation of China (NSFC)", "grant_number": "10973015" }, { "agency": "National Natural Science Foundation of China (NSFC)", "grant_number": "11061120454" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-10-10039" }, { "agency": "University of California, Santa Cruz" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/0004-637X/768/1/4", "primary_object": { "basename": "0004-637X_768_1_4.pdf", "url": "https://authors.library.caltech.edu/records/841sb-v1m48/files/0004-637X_768_1_4.pdf" }, "related_objects": [ { "basename": "1303.1222.pdf", "url": "https://authors.library.caltech.edu/records/841sb-v1m48/files/1303.1222.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Yang, Lei; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/1gcdt-w5g60", "eprint_id": 95484, "eprint_status": "archive", "datestamp": "2023-08-19 19:36:29", "lastmod": "2023-10-20 20:16:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Vargas-L-C", "name": { "family": "Vargas", "given": "Luis C." }, "orcid": "0000-0001-7155-0040" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } } ] }, "title": "The Distribution of Alpha Elements in Ultra-Faint Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: dwarf \u2013 galaxies: evolution \u2013 Local Group", "note": "\u00a9 2013 The American Astronomical Society. \n\nReceived 2012 December 11; accepted 2013 March 1; published 2013 April 4. \n\nThe authors would like to thank Ana Bonaca and the anonymous referee for helpful comments on the manuscript. L.C.V. is supported by an NSF Graduate Research Fellowship. M.G. acknowledges support from NSF grant AST-0908752 and the Alfred P. Sloan Foundation. E.N.K. acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research program funded by the University of California Office of Research, and partial support from NSF grant AST-1009973. \n\nWe wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - Vargas_2013_ApJ_767_134.pdf
Submitted - 1302.6594.pdf
", "abstract": "The Milky Way ultra-faint dwarf (UFD) galaxies contain some of the oldest, most metal-poor stars in the universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], and mean [\u03b1/Fe] abundance ratios for 61 individual red giant branch stars across eight UFDs. This is the largest sample of alpha abundances published to date in galaxies with absolute magnitudes M_V > \u20138, including the first measurements for Segue 1, Canes Venatici II, Ursa Major I, and Leo T. Abundances were determined via medium-resolution Keck/DEIMOS spectroscopy and spectral synthesis. The sample spans the metallicity range \u20133.4 <[Fe/H] < \u20131.1. With the possible exception of Segue 1 and Ursa Major II, the individual UFDs show on average lower [\u03b1/Fe] at higher metallicities, consistent with enrichment from Type Ia supernovae. Thus, even the faintest galaxies have undergone at least a limited level of chemical self-enrichment. Together with recent photometric studies, this suggests that star formation in the UFDs was not a single burst, but instead lasted at least as much as the minimum time delay of the onset of Type Ia supernovae (~100 Myr) and less than ~2 Gyr. We further show that the combined population of UFDs has an [\u03b1/Fe] abundance pattern that is inconsistent with a flat, Galactic halo-like alpha abundance trend, and is also qualitatively different from that of the more luminous CVn I dSph, which does show a hint of a plateau at very low [Fe/H].", "date": "2013-04-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "767", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 134", "id_number": "CaltechAUTHORS:20190514-105618815", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190514-105618815", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NSF", "grant_number": "AST-0908752" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Southern California Center for Galaxy Evolution" }, { "agency": "University of California" }, { "agency": "NSF", "grant_number": "AST-1009973" } ] }, "doi": "10.1088/0004-637x/767/2/134", "primary_object": { "basename": "1302.6594.pdf", "url": "https://authors.library.caltech.edu/records/1gcdt-w5g60/files/1302.6594.pdf" }, "related_objects": [ { "basename": "Vargas_2013_ApJ_767_134.pdf", "url": "https://authors.library.caltech.edu/records/1gcdt-w5g60/files/Vargas_2013_ApJ_767_134.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Vargas, Luis C.; Geha, Marla; et el." }, { "id": "https://authors.library.caltech.edu/records/yyzgq-1b756", "eprint_id": 37726, "eprint_status": "archive", "datestamp": "2023-08-22 08:52:19", "lastmod": "2023-10-23 17:59:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Howley-K-M", "name": { "family": "Howley", "given": "K. M." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "P." }, "orcid": "0000-0001-8867-4234" }, { "id": "van-der-Marel-R-P", "name": { "family": "van der Marel", "given": "R." }, "orcid": "0000-0001-7827-7825" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "M." }, "orcid": "0000-0002-7007-9725" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "J." }, "orcid": "0000-0001-9690-4159" }, { "id": "Yniguez-B", "name": { "family": "Yniguez", "given": "B." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cuillandre-J-C", "name": { "family": "Cuillandre", "given": "J.-C." } }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "K." }, "orcid": "0000-0003-0394-8377" } ] }, "title": "Internal Stellar Kinematics of M32 from the SPLASH Survey: Dark Halo Constraints", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: individual (M32, NGC 221); galaxies: kinematics and dynamics; Local Group; techniques: radial velocities; techniques: spectroscopic", "note": "\u00a9 2013 American Astronomical Society. Received 2012 February 10; accepted 2012 November 19; published 2013 February 15. \n\nData herein were obtained at the W. M. Keck Observatory, which is operated\nas a scientific partnership among the California Institute of Technology, the\nUniversity of California, and NASA. The Observatory was made possible by\nthe generous financial support of the W. M. Keck Foundation.\nK.M.H. was supported in part by the Lawrence Scholars Program at Lawrence Livermore National Laboratory\n(LLNL-JRNL-496754). E.K. and K.G. were supported through\nHubble Fellowship grants 51256.01 and 51273.01, respectively, from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. P.G., K.M.H., and B.Y. acknowledge support from NSF grants AST-0607852 and AST-1010039. J.S.K.'s research is supported in part by a grant from the STScI Director's Discretionary Research Fund. K.M.H. thanks STScI and Yale University for their hospitality during her visits to carry out some of this work.\nThe authors wish to recognize and acknowledge the very\nsignificant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\nFacility: Keck:II (DEIMOS)\n\nPublished - 0004-637X_765_1_65.pdf
", "abstract": "As part of the SPLASH survey of the Andromeda (M31) system, we have obtained Keck/DEIMOS spectra of the compact elliptical (cE) satellite M32. This is the first resolved-star kinematical study of any cE galaxy. In contrast to most previous kinematical studies that extended out to r\u227e30\" ~ 1 r^(eff) I ~ 100 pc, we measure the rotation curve and velocity dispersion profile out to r ~ 250\" and higher order Gauss-Hermite moments out to r ~ 70\". We achieve this by combining integrated-light spectroscopy at small radii (where crowding/blending are severe) with resolved stellar spectroscopy at larger radii, using spatial and kinematical information to account statistically for M31 contamination. The rotation curve and velocity dispersion profile extend well beyond the radius (r ~ 150\") where the isophotes are distorted. Unlike NGC 205, another close dwarf companion of M31, M32's kinematics appear regular and symmetric and do not show obvious sharp gradients across the region of isophotal elongation and twists. We interpret M31's kinematics using three-integral axisymmetric dynamical equilibrium models constructed using Schwarzschild's orbit superposition technique. Models with a constant mass-to-light ratio can fit the data remarkably well. However, since such a model requires an increasing tangential anisotropy with radius, invoking the presence of an extended dark halo may be more plausible. Such an extended dark halo is definitely required to bind a half-dozen fast-moving stars observed at the largest radii, but these stars may not be an equilibrium component of M32.", "date": "2013-03-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "765", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 65", "id_number": "CaltechAUTHORS:20130402-133929316", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130402-133929316", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Lawrence Livermore National Laboratory", "grant_number": "LLNL-JRNL-496754" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51273.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "Space Telescope Science Institute" } ] }, "doi": "10.1088/0004-637X/765/1/65", "primary_object": { "basename": "0004-637X_765_1_65.pdf", "url": "https://authors.library.caltech.edu/records/yyzgq-1b756/files/0004-637X_765_1_65.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Howley, K. M.; Guhathakurta, P.; et el." }, { "id": "https://authors.library.caltech.edu/records/qp1rv-t8j12", "eprint_id": 34682, "eprint_status": "archive", "datestamp": "2023-08-19 13:35:50", "lastmod": "2023-10-19 21:22:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" } ] }, "title": "Detailed Abundances of Two Very Metal-Poor Stars in Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances \u2013 galaxies: dwarf \u2013 galaxies: evolution \u2013 Local Group", "note": "\u00a9 2012 The American Astronomical Society. \n\nReceived 2011 May 18; accepted 2012 September 17; published 2012 November 8. \n\nData herein were obtained at theW. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nWe thank the referee for a careful report that greatly improved the quality of our study. We also thank K. Lind for providing a customized table of NLTE corrections for sodium. Support for this work was provided by NASA through Hubble Fellowship grant 51256.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. J.G.C. thanks NSF grant AST-0908139 for partial support. \n\nWe are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. \n\nFacility: Keck:I (HIRES) - KECK I Telescope.\n\nPublished - Kirby_2012_AJ_144_168.pdf
Accepted Version - 1209.3778v1.pdf
", "abstract": "The most metal-poor stars in dwarf spheroidal galaxies (dSphs) can show the nucleosynthetic patterns of one or a few supernovae (SNe). These SNe could have zero metallicity, making metal-poor dSph stars the closest surviving links to Population III stars. Metal-poor dSph stars also help to reveal the formation mechanism of the Milky Way (MW) halo. We present the detailed abundances from Keck/HIRES spectroscopy for two very metal-poor stars in two MW dSphs. One star, in the Sculptor dSph, has [Fe I/H] = -2.40. The other star, in the Ursa Minor dSph, has [Fe I/H] = -3.16. Both stars fall in the previously discovered low-metallicity, high-[\u03b1/Fe] plateau. Most abundance ratios of very metal-poor stars in these two dSphs are largely consistent with very metal-poor halo stars. However, the abundances of Na and some r-process elements lie at the lower end of the envelope defined by inner halo stars of similar metallicity. We propose that the metallicity dependence of SN yields is the cause. The earliest SNe in low-mass dSphs have less gas to pollute than the earliest SNe in massive halo progenitors. As a result, dSph stars at \u20133 < [Fe/H] < \u20132 sample SNe with [Fe/H] Lt \u20133, whereas halo stars in the same metallicity range sample SNe with [Fe/H] ~ \u20133. Consequently, enhancements in [Na/Fe] and [r/Fe] were deferred to higher metallicity in dSphs than in the progenitors of the inner halo.", "date": "2012-12", "date_type": "published", "publication": "Astronomical Journal", "volume": "144", "number": "6", "publisher": "American Astronomical Society", "pagerange": "Art. No. 168", "id_number": "CaltechAUTHORS:20121004-112928567", "issn": "0004-6256", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121004-112928567", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/0004-6256/144/6/168", "primary_object": { "basename": "1209.3778v1.pdf", "url": "https://authors.library.caltech.edu/records/qp1rv-t8j12/files/1209.3778v1.pdf" }, "related_objects": [ { "basename": "Kirby_2012_AJ_144_168.pdf", "url": "https://authors.library.caltech.edu/records/qp1rv-t8j12/files/Kirby_2012_AJ_144_168.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Kirby, Evan N. and Cohen, Judith G." }, { "id": "https://authors.library.caltech.edu/records/czytw-cqv42", "eprint_id": 36047, "eprint_status": "archive", "datestamp": "2023-08-22 07:46:16", "lastmod": "2023-10-20 22:11:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James" }, "orcid": "0000-0003-4298-5082" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Ostheimer-J-C", "name": { "family": "Ostheimer", "given": "James C." } }, { "id": "Patterson-R-J", "name": { "family": "Patterson", "given": "Richard J." } }, { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Tanaka-Mikito", "name": { "family": "Tanaka", "given": "Mikito" } }, { "id": "Chiba-Masashi", "name": { "family": "Chiba", "given": "Masashi" }, "orcid": "0000-0002-9053-860X" } ] }, "title": "Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: halos; galaxies: individual (M31); galaxies: structure", "note": "\u00a9 2012 American Astronomical Society. \n\nReceived 2012 April 21; accepted 2012 September 25; published 2012 November 6. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nWe thank Teresa Krause of Castilleja School, a participant in the Science Internship Program (SIP) at UCSC, for her work on the separation of M31 RGB and MW dwarf star samples.\nSupport for this work was provided by NASA through Hubble Fellowship grants 51273.01 and 51256.01 awarded to K.M.G. and E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. P.G., J.S.B., and S.R.M. acknowledge support from collaborative NSF grants AST-1010039, AST-1009973, AST-1009882, and AST-0607726. This project was also supported by NSF grants AST03-07842, AST03-07851, AST06-07726, AST08-07945, and AST10-09882, NASA grant HST-GO-12105.03 through STScI, NASA/JPL contract 1228235, the David and Lucile Packard Foundation, and the F. H. Levinson Fund of the Peninsula Community Foundation (S.R.M., R.J.P., and R.L.B.). E.J.T. acknowledges support from a Graduate Assistance in Areas of National Need (GAANN) fellowship. R.L.B. acknowledges receipt of the Mark C. Pirrung Family Graduate Fellowship from the Jefferson Scholars Foundation and a Fellowship Enhancement for Outstanding Doctoral Candidates from the Office of the Vice President of Research at the University of Virginia. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - 0004-637X_760_1_76.pdf
Accepted Version - 1210.3362.pdf
", "abstract": "We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index \u20132.2 \u00b1 0.2 and extends to a projected distance of at least ~175 kpc (~2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects.", "date": "2012-11-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "760", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 76", "id_number": "CaltechAUTHORS:20121219-104906863", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121219-104906863", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "51273.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST-1009882" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NSF", "grant_number": "AST03-07842" }, { "agency": "NSF", "grant_number": "AST03-07851" }, { "agency": "NSF", "grant_number": "AST06-07726" }, { "agency": "NSF", "grant_number": "AST08-07945" }, { "agency": "NSF", "grant_number": "AST10-09882" }, { "agency": "NASA", "grant_number": "HST-GO-12105.03" }, { "agency": "NASA/JPL", "grant_number": "1228235" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "Peninsula Community Foundation" }, { "agency": "Graduate Assistance in Areas of National Need (GAANN) fellowship" }, { "agency": "NSF", "grant_number": "AST-0071048" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/0004-637X/760/1/76", "primary_object": { "basename": "0004-637X_760_1_76.pdf", "url": "https://authors.library.caltech.edu/records/czytw-cqv42/files/0004-637X_760_1_76.pdf" }, "related_objects": [ { "basename": "1210.3362.pdf", "url": "https://authors.library.caltech.edu/records/czytw-cqv42/files/1210.3362.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Gilbert, Karoline M.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/5y7xp-zy187", "eprint_id": 36049, "eprint_status": "archive", "datestamp": "2023-08-22 07:46:24", "lastmod": "2023-10-23 19:30:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "The Bizarre Chemical Inventory of NGC 2419, An Extreme Outer Halo Globular Cluster", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxy: formation; Galaxy: halo; globular clusters: individual (NGC 2419)", "note": "\u00a9 2012 American Astronomical Society. Received 2012 July 24; accepted 2012 September 12; published 2012 November 6. \nBased in part on observations obtained at the W. M. Keck Observatory,\nwhich is operated jointly by the California Institute of Technology, the\nUniversity of California, and the National Aeronautics and Space\nAdministration.\n\nWe are grateful to the many people who have worked to\nmake the Keck Telescope and its instruments a reality and\nto operate and maintain the Keck Observatory. The authors\nwish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. We thank S. Woosley for a helpful conversation on the nucleosynthetic origin of potassium. J.G.C. thanks NSF Grant AST-0908139 for partial support. Work by E.N.K. was supported by NASA through Hubble Fellowship Grant HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for\nNASA, under contract NAS 5-26555.\n\nPublished - 0004-637X_760_1_86.pdf
Submitted - 1209.2705v1.pdf
Erratum - 0004-637X_793_1_69.pdf
", "abstract": "We present new Keck/HIRES observations of six red giants in the globular cluster (GC) NGC 2419. Although the cluster is among the most distant and most luminous in the Milky Way, it was considered chemically ordinary until very recently. Our previous work showed that the near-infrared Ca II triplet line strength varied more than expected for a chemically homogeneous cluster, and that at least one star had unusual abundances of Mg and K. Here, we confirm that NGC 2419 harbors a population of stars, comprising about one-third of its mass, that is depleted in Mg by a factor of eight and enhanced in K by a factor of six with respect to the Mg-normal population. Although the majority, Mg-normal population appears to have a chemical abundance pattern indistinguishable from ordinary, inner-halo GCs, the Mg-poor population exhibits dispersions of several elements. The abundances of K and Sc are strongly anti-correlated with Mg, and some other elements (Si and Ca among others) are weakly anti-correlated with Mg. These abundance patterns suggest that the different populations of NGC 2419 sample the ejecta of diverse supernovae in addition to asymptotic giant branch ejecta. However, the abundances of Fe-peak elements except Sc show no star-to-star variation. We find no nucleosynthetic source that satisfactorily explains all of the abundance variations in this cluster. Because NGC 2419 appears like no other GC, we reiterate our previous suggestion that it is not a GC at all, but rather the core of an accreted dwarf galaxy.", "date": "2012-11-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "760", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 86", "id_number": "CaltechAUTHORS:20121219-112340754", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121219-112340754", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/0004-637X/760/1/86", "primary_object": { "basename": "0004-637X_760_1_86.pdf", "url": "https://authors.library.caltech.edu/records/5y7xp-zy187/files/0004-637X_760_1_86.pdf" }, "related_objects": [ { "basename": "0004-637X_793_1_69.pdf", "url": "https://authors.library.caltech.edu/records/5y7xp-zy187/files/0004-637X_793_1_69.pdf" }, { "basename": "1209.2705v1.pdf", "url": "https://authors.library.caltech.edu/records/5y7xp-zy187/files/1209.2705v1.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Cohen, Judith G. and Kirby, Evan N." }, { "id": "https://authors.library.caltech.edu/records/8b4ns-0wb70", "eprint_id": 34600, "eprint_status": "archive", "datestamp": "2023-08-22 06:48:40", "lastmod": "2023-10-19 21:19:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Makarov-D", "name": { "family": "Makarov", "given": "Dmitry" } }, { "id": "Makarova-L", "name": { "family": "Makarova", "given": "Lidia" } }, { "id": "Sharina-M", "name": { "family": "Sharina", "given": "Margarita" } }, { "id": "Uklein-R", "name": { "family": "Uklein", "given": "Roman" } }, { "id": "Tikhonov-A", "name": { "family": "Tikhnov", "given": "Anton" } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Terekhova-N", "name": { "family": "Terekhova", "given": "Natalya" } } ] }, "title": "A unique isolated dwarf spheroidal galaxy at D\u2009=\u20091.9\u2009Mpc", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: distances and redshifts; galaxies: dwarf; galaxies: individual: KKR\u200925; galaxies: stellar content", "note": "\u00a9 2012 The Authors. Monthly Notices of the Royal Astronomical Society \u00a9 2012 RAS. Accepted 2012 June 23. Received 2012 June 11; in original form 2012 April 9.\n\nWe are thankful to Dr S. Pustilnik for very useful discussions of our work. We acknowledge the usage of the HyperLEDA data base (http://leda.univ-lyon1.fr). STSDAS is a product of the Space Telescope Science Institute, which is operated by AURA for NASA. The work was supported by the Russian Foundation for Basic Research (RFBR) grant 11-02-00639, Russian\u2013Ukrainian RFBR grant 11-02-90449 and the programme no. 17 'Active processes in galactic\nand extragalactic objects' of the Department of Physical Sciences of the Russian Academy of Sciences. We acknowledge the support of the Ministry of Education and Science of the Russian Federation, contract 14.740.11.0901.\n\nPublished - mnr21581.pdf
", "abstract": "We present a photometric and spectroscopic study of the unique isolated nearby dwarf spheroidal (dSph) galaxy KKR\u200925. The galaxy was resolved into stars with Hubble Space Telescope/Wide Field Planetary Camera 2 including old red giant branch and red clump. We have constructed a model of the resolved stellar populations and measured the star formation rate and metallicity as a function of time. The main star formation activity period occurred about 12.6\u201313.7 Gyr ago. These stars are mostly metal poor, with a mean metallicity [Fe/H] \u223c \u22121 to \u22121.6 dex. About 60\u2009per cent of the total stellar mass was formed during this event. There are indications of intermediate-age star formation in KKR\u200925 between 1 and 4 Gyr with no significant signs of metal enrichment for these stars. Long-slit spectroscopy was carried out using the Russian 6-m telescope of the integrated starlight and bright individual objects in the galaxy. We have discovered a planetary nebula (PN) in KKR\u200925. This is the first known PN in a dSph galaxy outside the Local Group. We have measured its oxygen abundance 12 + log\u2009(O/H) = 7.60 \u00b1 0.07 dex and a radial velocity V_h = \u221279 km\u2009s^(\u22121). We have analysed the stellar density distribution in the galaxy body. The galaxy has an exponential surface brightness profile with a central light depression. We discuss the evolutionary status of KKR\u200925, which belongs to a rare class of very isolated dwarf galaxies with spheroidal morphology.", "date": "2012-09-01", "date_type": "published", "publication": "Monthly Notices of the Royal Astronomical Society", "volume": "425", "number": "1", "publisher": "Royal Astronomical Society", "pagerange": "709-719", "id_number": "CaltechAUTHORS:20121001-141730015", "issn": "0035-8711", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121001-141730015", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1111/j.1365-2966.2012.21581.x", "primary_object": { "basename": "mnr21581.pdf", "url": "https://authors.library.caltech.edu/records/8b4ns-0wb70/files/mnr21581.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Makarov, Dmitry; Makarova, Lidia; et el." }, { "id": "https://authors.library.caltech.edu/records/zzbg1-te088", "eprint_id": 31938, "eprint_status": "archive", "datestamp": "2023-09-14 19:26:49", "lastmod": "2023-10-23 20:50:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sesar-B", "name": { "family": "Sesar", "given": "Branimir" }, "orcid": "0000-0002-0834-3978" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Levitan-D", "name": { "family": "Levitan", "given": "David" } }, { "id": "Grillmair-C-J", "name": { "family": "Grillmair", "given": "Carl J." }, "orcid": "0000-0003-4072-169X" }, { "id": "Juri\u0107-M", "name": { "family": "Juri\u0107", "given": "Mario" } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Laher-R-R", "name": { "family": "Laher", "given": "Russ R." }, "orcid": "0000-0003-2451-5482" }, { "id": "Ofek-E-O", "name": { "family": "Ofek", "given": "Eran O." }, "orcid": "0000-0002-6786-8774" }, { "id": "Surace-J-A", "name": { "family": "Surace", "given": "Jason A." }, "orcid": "0000-0001-7291-0087" }, { "id": "Kulkarni-S-R", "name": { "family": "Kulkarni", "given": "Shrinivas R." }, "orcid": "0000-0001-5390-8563" }, { "id": "Prince-T-A", "name": { "family": "Prince", "given": "Thomas A." }, "orcid": "0000-0002-8850-3627" } ] }, "title": "Two Distant Halo Velocity Groups Discovered by the Palomar Transient Factory", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxy: halo \u2013 Galaxy: kinematics and dynamics \u2013 Galaxy: structure \u2013 stars: variables: RR Lyrae", "note": "\u00a9 2012 The American Astronomical Society.\nReceived 2012 March 7; accepted 2012 June 26; published 2012 August 2.\n\nJ.G.C. and B.S. thank NSF grant AST-0908139 to J.G.C for partial support, as do\nS.R.K (to NSF grant AST-1009987), and C.J.G (for a NASA grant). Support for this work\nwas provided by NASA through Hubble Fellowship grant 51256.01 awarded to E.N.K by the\nSpace Telescope Science Institute, which is operated by the Association of Universities for\nResearch in Astronomy, Inc., for NASA, under contract NAS 5-26555.\nWe thank the referee for a thorough review and suggestions which led to an improved\nmanuscript. B.S. would like to thank \u0179. Ivezi\u0107, B. Willman, and K. Vivas for useful discussions.\nWe thank I. Arcavi, A. Gal-Yam, P. Groot, A. Horesh, and D. Perley for observing at\nKeck and Palomar. We thank the staff at the Palomar Hale telescope for help and support\nwith observations. We are grateful to the many people who have worked to make the Keck\nTelescope and its instruments a reality and to operate and maintain the Keck Observatory.\nThe authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred\nmountain we are privileged to be guests. Without their generous hospitality, none of the\nobservations presented herein would have been possible.\nThis article is based on observations obtained with the Samuel Oschin Telescope as part\nof the Palomar Transient Factory project, a scientific collaboration between the California\nInstitute of Technology, Columbia University, Las Cumbres Observatory, the Lawrence\nBerkeley National Laboratory, the National Energy Research Scientific Computing Center,\nthe University of Oxford, and the Weizmann Institute of Science.\n\nPublished - 0004-637X_755_2_134.pdf
Submitted - 1206.0269v1.pdf
", "abstract": "We report the discovery of two new halo velocity groups (Cancer groups A and B) traced by 8 distant RR Lyrae stars and observed by the Palomar Transient Factory (PTF) survey at R.A.~129\u00b0, Dec~20\u00b0 (l~205\u00b0, b~32\u00b0). Located at 92 kpc from the Galactic center (86 kpc from the Sun), these are some of the most distant substructures in the Galactic halo known to date. Follow-up spectroscopic observations with the Palomar Observatory 5.1-m Hale telescope and W. M. Keck Observatory 10-m Keck I telescope indicate that the two groups are moving away from the Galaxy at v_(gsr) = 78.0+-5.6 km s^(-1) (Cancer group A) and v_(gsr) = 16.3+-7.1 km s^(-1) (Cancer group B). The groups have velocity dispersions of \u03c3_(v_)gsr))=12.4+-5.0 km s^(-1) and \u03c3 _(v_(gsr))=14.9+-6.2 km s^(-1), and are spatially extended (about several kpc) making it very unlikely that they are bound systems, and are more likely to be debris of tidally disrupted dwarf galaxies or globular clusters. Both groups are metal-poor (median metallicities of [Fe/H]^A = -1.6 dex and [Fe/H]^B =-2.1 dex), and have a somewhat uncertain (due to small sample size) metallicity dispersion of ~0.4 dex, suggesting dwarf galaxies as progenitors. Two additional RR Lyrae stars with velocities consistent with those of the Cancer groups have been observed ~25 \u00b0 east, suggesting possible extension of the groups in that direction.", "date": "2012-08-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "755", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 134", "id_number": "CaltechAUTHORS:20120618-134946055", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120618-134946055", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NSF", "grant_number": "AST-1009987" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "local_group": { "items": [ { "id": "Space-Radiation-Laboratory" }, { "id": "Palomar-Transient-Factory" }, { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" }, { "id": "Division-of-Geological-and-Planetary-Sciences" } ] }, "doi": "10.1088/0004-637X/755/2/134", "primary_object": { "basename": "0004-637X_755_2_134.pdf", "url": "https://authors.library.caltech.edu/records/zzbg1-te088/files/0004-637X_755_2_134.pdf" }, "related_objects": [ { "basename": "1206.0269v1.pdf", "url": "https://authors.library.caltech.edu/records/zzbg1-te088/files/1206.0269v1.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Sesar, Branimir; Cohen, Judith G.; et el." }, { "id": "https://authors.library.caltech.edu/records/qmg1e-0ax22", "eprint_id": 32655, "eprint_status": "archive", "datestamp": "2023-08-22 06:09:55", "lastmod": "2023-10-18 14:38:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Brown-T-M", "name": { "family": "Brown", "given": "Thomas M." }, "orcid": "0000-0002-1793-9968" }, { "id": "Tumlinson-J", "name": { "family": "Tumlinson", "given": "Jason" }, "orcid": "0000-0002-7982-412X" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "VandenBerg-D-A", "name": { "family": "VandenBerg", "given": "Don A." } }, { "id": "Mu\u00f1oz-R-R", "name": { "family": "Mu\u00f1oz", "given": "Ricardo R." } }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Avila-R-J", "name": { "family": "Avila", "given": "Roberto J." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Renzini-A", "name": { "family": "Renzini", "given": "Alvio" }, "orcid": "0000-0002-7093-7355" }, { "id": "Ferguson-H-C", "name": { "family": "Ferguson", "given": "Henry C." }, "orcid": "0000-0001-7113-2738" } ] }, "title": "The Primeval Populations of the Ultra-faint Dwarf Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: evolution; galaxies: formation; galaxies: photometry; galaxies: stellar content; Local Group", "note": "\u00a9 2012 The American Astronomical Society. \n\nReceived 2012 April 20; accepted 2012 June 4; published 2012 June 15. \n\nSupport for GO-12549 was provided by NASA through a grant from STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555. E. N. K. acknowledges support by NASA through Hubble Fellowship grant 51256.01 from STScI. A. R. acknowledges support from ASI via grant I/009/10/0. R. R. M. acknowledges support from the GEMINI-CONICYT Fund, allocated to the project No. 32080010. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555.\n\nPublished - Brown2012p18934Astrophys_J_Lett.pdf
Accepted Version - 1206.0941.pdf
", "abstract": "We present new constraints on the star formation histories of the ultra-faint dwarf (UFD) galaxies, using deep\nphotometry obtained with the Hubble Space Telescope (HST). A galaxy class recently discovered in the Sloan\nDigital Sky Survey, the UFDs appear to be an extension of the classical dwarf spheroidals to low luminosities,\noffering a new front in efforts to understand the missing satellite problem. They are the least luminous, most dark-matter-dominated, and least chemically evolved galaxies known. Our HST survey of six UFDs seeks to determine if these galaxies are true fossils from the early universe. We present here the preliminary analysis of three UFD galaxies: Hercules, Leo IV, and Ursa Major I. Classical dwarf spheroidals of the Local Group exhibit extended star\nformation histories, but these three Milky Way satellites are at least as old as the ancient globular cluster M92, with no evidence for intermediate-age populations. Their ages also appear to be synchronized to within \u223c1 Gyr of each\nother, as might be expected if their star formation was truncated by a global event, such as reionization.", "date": "2012-07-01", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "753", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. L21", "id_number": "CaltechAUTHORS:20120723-151504481", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120723-151504481", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "HF-51256.01" }, { "agency": "Agenzia Spaziale Italiana (ASI)", "grant_number": "I/009/10/0" }, { "agency": "Comisi\u00f3n Nacional de Investigaci\u00f3n Cient\u00edfica y Tecnol\u00f3gica (CONICYT)", "grant_number": "N32080010" }, { "agency": "Istituto Nazionale di Astrofisica (INAF)" } ] }, "doi": "10.1088/2041-8205/753/1/L21", "primary_object": { "basename": "1206.0941.pdf", "url": "https://authors.library.caltech.edu/records/qmg1e-0ax22/files/1206.0941.pdf" }, "related_objects": [ { "basename": "Brown2012p18934Astrophys_J_Lett.pdf", "url": "https://authors.library.caltech.edu/records/qmg1e-0ax22/files/Brown2012p18934Astrophys_J_Lett.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Brown, Thomas M.; Tumlinson, Jason; et el." }, { "id": "https://authors.library.caltech.edu/records/v6g9c-12v57", "eprint_id": 32478, "eprint_status": "archive", "datestamp": "2023-08-22 05:54:48", "lastmod": "2023-10-18 14:27:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Yniguez-B", "name": { "family": "Yniguez", "given": "Basilio" } }, { "id": "Patterson-R-J", "name": { "family": "Patterson", "given": "Richard J." } }, { "id": "Ostheimer-J-C", "name": { "family": "Ostheimer", "given": "James C." } }, { "id": "Cooke-J", "name": { "family": "Cooke", "given": "Jeff" }, "orcid": "0000-0001-5703-2108" }, { "id": "Dorman-C-E", "name": { "family": "Dorman", "given": "Claire E." } }, { "id": "Choudhury-A", "name": { "family": "Choudhury", "given": "Abrar" } }, { "id": "Cooper-M-C", "name": { "family": "Cooper", "given": "Michael C." }, "orcid": "0000-0003-1371-6019" } ] }, "title": "The SPLASH Survey: Spectroscopy of 15 M31 Dwarf Spheroidal Satellite Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "dark matter; galaxies: dwarf; galaxies: fundamental parameters; galaxies: individual (And I, And III, And V, And VII, And IX, And X, And XI, And XII, And XIII, And XIV, And XV, And XVI, And XVIII, And XXI, And XXII); galaxies: kinematics and dynamics; Local Group", "note": "\u00a9 2012 American Astronomical Society. \n\nReceived 2011 December 6; accepted 2012 April 2; published 2012 May 24. \n\nWe wish to acknowledge Nhung Ho, Greg Martinez, and Ricardo Munoz for helpful discussions, as well as Stacy McGaugh, Mark Fardal, Alan McConnachie, and the anonymous referee for helpful suggestions regarding the manuscript. E.J.T. acknowledges support from a Graduate Assistance in Areas of National Need (GAANN) Fellowship and a Fletcher Jones Fellowship. R.L.B. acknowledges receipt of the Mark C. Pirrung Family Graduate Fellowship from the Jefferson Scholars Foundation and a Fellowship Enhancement for Outstanding Doctoral Candidates from the Office of the Vice President of Research at the University of Virginia. M.G. acknowledges support from NSF grant AST-0908752 and the Alfred P. Sloan Foundation. P.G., J.S.B., and S.R.M. acknowledge support from collaborative NSF grants AST-1010039, AST-1009973, AST-1009882, and AST-0607726. A.C. thanks the UC Santa Cruz Science Internship Program for support. Additional support for this work was provided by NASA through Hubble Fellowship grants 51256.01 and 51273.01 awarded to E.N.K. and K.M.G. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The spec2d pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048. This work made extensive use of code developed for the Astropysics18 and Pymodelfit (Tollerud 2011)19 open-source projects. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Some slitmasks were designed based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona University System; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. \n\nFacilities: Keck:II (DEIMOS),Mayall (Mosaic), LBT (LBC). \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.\n\nPublished - Tollerud2012p18834Astrophys_J.pdf
Accepted Version - 1112.1067.pdf
", "abstract": "We present a resolved star spectroscopic survey of 15 dwarf spheroidal (dSph) satellites of the Andromeda galaxy (M31). We filter foreground contamination from Milky Way (MW) stars, noting that MW substructure is evident in this contaminant sample. We also filter M31 halo field giant stars and identify the remainder as probable dSph members. We then use these members to determine the kinematical properties of the dSphs. For the first time, we confirm that And XVIII, XXI, and XXII show kinematics consistent with bound, dark-matter-dominated galaxies. From the velocity dispersions for the full sample of dSphs we determine masses, which we combine with the size and luminosity of the galaxies to produce mass-size-luminosity scaling relations. With these scalings we determine that the M31 dSphs are fully consistent with the MW dSphs, suggesting that the well-studied MW satellite population provides a fair sample for broader conclusions. We also estimate dark matter halo masses of the satellites and find that there is no sign that the luminosity of these galaxies depends on their dark halo mass, a result consistent with what is seen for MW dwarfs. Two of the M31 dSphs (And XV, XVI) have estimated maximum circular velocities smaller than 12 km s^(\u20131) (to 1\u03c3), which likely places them within the lowest-mass dark matter halos known to host stars (along with Bo\u00f6tes I of the MW). Finally, we use the systemic velocities of the M31 satellites to estimate the mass of the M31 halo, obtaining a virial mass consistent with previous results.", "date": "2012-06-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "752", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 45", "id_number": "CaltechAUTHORS:20120716-133219730", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120716-133219730", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Fletcher Jones Fellowship" }, { "agency": "Jefferson Scholars Foundation" }, { "agency": "University of Virginia" }, { "agency": "NSF", "grant_number": "AST-0908752" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "NSF", "grant_number": "AST-1010039" }, { "agency": "NSF", "grant_number": "AST-1009973" }, { "agency": "NSF", "grant_number": "AST- 1009882" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "University of California, Santa Cruz" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51273.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/0004-637X/752/1/45", "primary_object": { "basename": "1112.1067.pdf", "url": "https://authors.library.caltech.edu/records/v6g9c-12v57/files/1112.1067.pdf" }, "related_objects": [ { "basename": "Tollerud2012p18834Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/v6g9c-12v57/files/Tollerud2012p18834Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Tollerud, Erik J.; Beaton, Rachael L.; et el." }, { "id": "https://authors.library.caltech.edu/records/ht6vn-x5a60", "eprint_id": 30031, "eprint_status": "archive", "datestamp": "2023-08-19 10:59:48", "lastmod": "2023-10-23 15:41:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Bellazzini-M", "name": { "family": "Bellazzini", "given": "Michele" }, "orcid": "0000-0001-8200-810X" } ] }, "title": "The Dynamics and Metallicity Distribution of the Distant Dwarf Galaxy VV124", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: individual (VV124) \u2014 galaxies: dwarf \u2014 Local Group \u2014 galaxies: kinematics\nand dynamics \u2014 galaxies: abundances", "note": "\u00a9 2012 The American Astronomical Society. Received 2011 December 14; accepted 2012 March 19; published 2012 May 3. The data presented herein were obtained at the W. M. Keck\nObservatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial\nsupport of the W. M. Keck Foundation. We are grateful to the many people who have worked\nto make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian\nancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible.\nWe thank Marla Geha for providing radial velocity template spectra observed with DEIMOS and for her\ngenerous assistance in measuring radial velocities. We also thank the referee for a detailed report that greatly improved this manuscript. Support for this work was provided by NASA through Hubble Fellowship grant 51256.01 awarded to ENK by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. JGC thanks NSF grant AST-0908139 for partial support. Facility: Keck:II (DEIMOS)\n\nPublished - 0004-637X_751_1_46.pdf
Accepted Version - 1203.4561
Erratum - 0004-637X_768_1_96.pdf
", "abstract": "VV124 (UGC 4879) is an isolated, dwarf irregular/dwarf spheroidal (dIrr/dSph) transition-type\ngalaxy at a distance of 1.36 Mpc. Previous low-resolution spectroscopy yielded inconsistent radial\nvelocities for different components of the galaxy, and photometry hinted at the presence of a stellar\ndisk. In order to quantify the stellar dynamics, we observed individual red giants in VV124 with the Keck/DEIMOS spectrograph. We validated members based on their positions in the color-magnitude\ndiagram, radial velocities, and spectral features. Our sample contains 67 members. The average\nradial velocity is = \u221229.1 \u00b1 1.3 km s^(\u22121), in agreement with the previous radio measurements\nof H I gas. The velocity distribution is Gaussian, indicating that VV124 is supported primarily by\nvelocity dispersion inside a radius of 1.5 kpc. Outside that radius, our measurements provide only an\nupper limit of 8.6 km s^(\u22121) on any rotation in the photometric disk-like feature. The velocity dispersion\nis \u03c3_v = 9.4\u00b1 1.0 km s^(\u22121), from which we inferred a mass of M_(1/2) = (2.1 \u00b1 0.2)\u00d7 10^7 M_\u2299 and a mass-to-\nlight ratio of (M/L_V)_(1/2) = 5.2 \u00b1 1.1 M_\u2299/L_\u2299, both measured within the half-light radius. Thus,\nVV124 contains dark matter. We also measured the metallicity distribution from neutral iron lines.\nThe average metallicity, <[Fe/H]> = \u22121.14 \u00b1 0.06, is consistent with the mass-metallicity relation\ndefined by dwarf spheroidal galaxies. The dynamics and metallicity distribution of VV124 appear\nsimilar to dSphs of similar stellar mass.", "date": "2012-05-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "751", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 46", "id_number": "CaltechAUTHORS:20120409-082635030", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120409-082635030", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-0908139" } ] }, "doi": "10.1088/0004-637X/751/1/46", "primary_object": { "basename": "0004-637X_768_1_96.pdf", "url": "https://authors.library.caltech.edu/records/ht6vn-x5a60/files/0004-637X_768_1_96.pdf" }, "related_objects": [ { "basename": "1203.4561", "url": "https://authors.library.caltech.edu/records/ht6vn-x5a60/files/1203.4561" }, { "basename": "0004-637X_751_1_46.pdf", "url": "https://authors.library.caltech.edu/records/ht6vn-x5a60/files/0004-637X_751_1_46.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Kirby, Evan N.; Cohen, Judith G.; et el." }, { "id": "https://authors.library.caltech.edu/records/1v3ez-zcd57", "eprint_id": 28905, "eprint_status": "archive", "datestamp": "2023-08-19 10:15:15", "lastmod": "2023-10-24 18:13:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Muirhead-P-S", "name": { "family": "Muirhead", "given": "Philip S." }, "orcid": "0000-0002-0638-8822" }, { "id": "Johnson-J-A", "name": { "family": "Johnson", "given": "John Asher" }, "orcid": "0000-0001-9808-7172" }, { "id": "Morton-T-D", "name": { "family": "Morton", "given": "Timothy D." }, "orcid": "0000-0002-8537-5711" }, { "id": "Pineda-J-S", "name": { "family": "Pineda", "given": "J. Sebastian" }, "orcid": "0000-0002-4489-0135" }, { "id": "Bottom-M", "name": { "family": "Bottom", "given": "Michael" }, "orcid": "0000-0003-1341-5531" }, { "id": "Crepp-J-R", "name": { "family": "Crepp", "given": "Justin R." }, "orcid": "0000-0003-0800-0593" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Howard-A-W", "name": { "family": "Howard", "given": "Andrew W." }, "orcid": "0000-0001-8638-0320" }, { "id": "Levitan-D-B", "name": { "family": "Levitan", "given": "David" } }, { "id": "D\u00edaz-Santos-T", "name": { "family": "D\u00edaz-Santos", "given": "Tanio" }, "orcid": "0000-0003-0699-6083" }, { "id": "Armus-L", "name": { "family": "Armus", "given": "Lee" }, "orcid": "0000-0003-3498-2973" } ] }, "title": "Characterizing the Cool KOIs. III. KOI-961: A Small Star with Large Proper Motion and Three Small Planets", "ispublished": "pub", "full_text_status": "public", "keywords": "Stars: individual (Barnard's Star, KOI 961) \u2014 Stars: low-mass \u2014 Stars: funda-\nmental parameters \u2014 Stars: late-type \u2014 Planetary Systems", "note": "We would like to thank Peter Dawson, who provided\nthe multi-wavelength spectrum of Barnard's Star. We\nwould like to thank Sarah Ballard and Michael Line for\nthe thoughtful discussions concerning the paper. We\nwould like to thank Bruce Gary of Hereford Arizona Observatory for taking the B,V and RC photometric measurements of KOI 961.\nThis work includes observations taken at the Palomar\nObervatory 200-inch Hale Telescope granted by Cornell\nUniversity. The TripleSpec spectrograph was built at\nCornell and delivered to Palomar as part of the Cornell-\nCaltech-Palomar arrangement. This work includes observations taken at the W. M. Keck Observatory and\nPalomar Observatory granted by the California Institute\nof Technology. Some of the Palomar 200-inch Telescope\ntime was provided by NASA/JPL. We thank Melodie\nKao, Matthew Giguere and Ming Zhao for assisting with\nthe Keck observations.\nJ.A.C, K.R.C., D.C.F. and E.N.K. acknowledge support for this work from the Hubble Fellowship Pro-\ngram, provided by NASA through Hubble Fellowship grants HF-51267.01-A, HST-HF-51253.01-A, HF-\n51272.01-A and HST-HF-51256.01-A, awarded by the\nSpace Telescope Science Institute, which is operated by the AURA, Inc., for NASA, under contract NAS 5-26555.\nK.G.S., J.P. and L.H. acknowledge support through the Vanderbilt Initiative in Data-intensive Astrophysics and NSF grants AST-0849736 and AST-1009810.\nThis paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the\nNASA Science Mission directorate. Some of the data \npresented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute\n(MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA\ncontract NAS5-26555. Support for MAST for non-HST\ndata is provided by the NASA Office of Space Science via\ngrant NNX09AF08G and by other grants and contracts.\nThe United Kingdom Infrared Telescope (UKIRT) is\noperated by the Joint Astronomy Centre on behalf of the\nScience and Technology Facilities Council of the U.K.\nThe Digitized Sky Surveys were produced at the Space\nTelescope Science Institute under U.S. Government grant\nNAG W-2166. The images of these surveys are based on\nphotographic data obtained using the Oschin Schmidt\nTelescope on Palomar Mountain and the UK Schmidt\nTelescope. The plates were processed into the present\ncompressed digital form with the permission of these institutions.\nThe National Geographic Society - Palomar Observatory Sky Atlas (POSS-I) was made by the California\nInstitute of Technology with grants from the National\nGeographic Society. The Second Palomar Observatory\nSky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Geographic Society, the\nSloan Foundation, the Samuel Oschin Foundation, and\nthe Eastman Kodak Corporation. The Oschin Schmidt\nTelescope is operated by the California Institute of Technology and Palomar Observatory.\n\nPublished - 0004-637X_747_2_144.pdf
", "abstract": "We present the characterization of the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets, originally discovered by the Kepler Mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. By comparing colors, optical and near-infrared spectra, we find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion and no quiescent H-alpha emission--all of which is consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 \u00b1 0.05 M_\u2299), radius (0.17 \u00b1 0.04 R_\u2299) and luminosity (2.40 x 10^(-3.0 \u00b1 0.3) L_\u2299). We calculate KOI 961's distance (38.7 \u00b1 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet-candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 Re_\u2295, with KOI 961.03 being Mars-sized (Rp = 0.57 \u00b1 0.18 R_\u2295), and they represent some of the smallest exoplanets detected to date.", "date": "2012-03-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "747", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. no. 144", "id_number": "CaltechAUTHORS:20120123-084606565", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120123-084606565", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "HF-51267.01-A" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-51253.01-A" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-51272.01-A" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-51256.01-A" }, { "agency": "Vanderbilt Initiative in Data-intensive Astrophysics" }, { "agency": "NSF", "grant_number": "AST-0849736" }, { "agency": "NSF", "grant_number": "AST-1009810" } ] }, "local_group": { "items": [ { "id": "Space-Radiation-Laboratory" }, { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" } ] }, "doi": "10.1088/0004-637X/747/2/144", "primary_object": { "basename": "0004-637X_747_2_144.pdf", "url": "https://authors.library.caltech.edu/records/1v3ez-zcd57/files/0004-637X_747_2_144.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Muirhead, Philip S.; Johnson, John Asher; et el." }, { "id": "https://authors.library.caltech.edu/records/2grgd-jy132", "eprint_id": 29093, "eprint_status": "archive", "datestamp": "2023-08-22 04:26:32", "lastmod": "2023-10-23 16:13:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bradford-J-D", "name": { "family": "Bradford", "given": "J. D." } }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "M." }, "orcid": "0000-0002-7007-9725" }, { "id": "Mu\u00f1oz-R-R", "name": { "family": "Mu\u00f1oz", "given": "R. R." } }, { "id": "Santana-F-A", "name": { "family": "Santana", "given": "F. A." }, "orcid": "0000-0002-4023-7649" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "J. D." } }, { "id": "C\u00f4t\u00e9-P", "name": { "family": "C\u00f4t\u00e9", "given": "P." }, "orcid": "0000-0003-1184-8114" }, { "id": "Stetson-P-B", "name": { "family": "Stetson", "given": "P. B." }, "orcid": "0000-0001-6074-6830" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E." }, "orcid": "0000-0001-6196-5162" }, { "id": "Djorgovski-S-G", "name": { "family": "Djorgovski", "given": "S. G." }, "orcid": "0000-0002-0603-3087" } ] }, "title": "Structure and Dynamics of the Globular Cluster Palomar 13", "ispublished": "pub", "full_text_status": "public", "keywords": "dark matter; galaxies: kinematics and dynamics; globular clusters: individual (Palomar 13)", "note": "\u00a9 2011 The American Astronomical Society. Received 2011 August 19; accepted 2011 October 7; published 2011 December 2. \nThe data presented herein were obtained at the W. M. Keck Observatory,\nwhich is operated as a scientific partnership among the California Institute of\nTechnology, the University of California, and the National Aeronautics and\nSpace Administration. The Observatory was made possible by the generous\nfinancial support of the W. M. Keck Foundation.\n\nJ.D.B. acknowledges support from the CT Space Grant.\nM.G. acknowledges support from NSF grant AST-0908752 and\nthe Alfred P. Sloan Foundation. R.R.M. acknowledges support\nfrom the GEMINI-CONICYT Fund, allocated to the project\nN32080010 and from CONICYT through projects FONDAP\nN15010003 and BASAL PFB-06. Support for this work was\nprovided by NASA through Hubble Fellowship grant 51256.01\nawarded to E.N.K. by the Space Telescope Science Institute,\nwhich is operated by the Association of Universities for\nResearch in Astronomy, Inc., for NASA, under contract\nNAS 5-26555. S.G.D. acknowledges a partial support from the\nNSF grant AST-0909182. We thank Andreas K\u00fcpper and Luis\nVargas for useful conversation.\n\nPublished - Bradford2011p16931Astrophys_J.pdf
Erratum - 0004-637X_778_1_85.pdf
", "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.", "date": "2011-12-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "743", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 167", "id_number": "CaltechAUTHORS:20120202-110752104", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120202-110752104", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Connecticut Space Grant Consortium" }, { "agency": "NSF", "grant_number": "AST-0908752" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Comisi\u00f3n Nacional de Investigaci\u00f3n Cient\u00edfica y Tecnol\u00f3gica (CONICYT)", "grant_number": "N32080010" }, { "agency": "Fondo de Financiamiento de Centros de Investigaci\u00f3n en \u00c1reas Prioritarias (FONDAP)", "grant_number": "N15010003" }, { "agency": "Basal-CATA", "grant_number": "PFB-06/2007" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA", "grant_number": "NAS-5-26555" }, { "agency": "NSF", "grant_number": "AST-0909182" } ] }, "doi": "10.1088/0004-637X/743/2/167", "primary_object": { "basename": "0004-637X_778_1_85.pdf", "url": "https://authors.library.caltech.edu/records/2grgd-jy132/files/0004-637X_778_1_85.pdf" }, "related_objects": [ { "basename": "Bradford2011p16931Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/2grgd-jy132/files/Bradford2011p16931Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Bradford, J. D.; Geha, M.; et el." }, { "id": "https://authors.library.caltech.edu/records/yxa2x-rb683", "eprint_id": 28422, "eprint_status": "archive", "datestamp": "2023-08-22 04:19:22", "lastmod": "2023-10-24 17:53:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Martin-C-L", "name": { "family": "Martin", "given": "Crystal L." } }, { "id": "Finlator-K", "name": { "family": "Finlator", "given": "Kristian" } } ] }, "title": "Metals Removed by Outflows from Milky Way Dwarf Spheroidal Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: evolution; intergalactic medium; Local Group", "note": "\u00a9 2011 American Astronomical Society.\n\nReceived 2011 September 26; accepted 2011 October 25; published 2011 November 8.\nThe data presented herein were obtained at the W.M. Keck Observatory,\nwhich is operated as a scientific partnership among the California Institute of\nTechnology, the University of California, and the National Aeronautics and\nSpace Administration. The Observatory was made possible by the generous\nfinancial support of the W. M. Keck Foundation.\n\nWe thank J. Cohen and the anonymous referee for careful,\nconstructive criticism that improved this Letter. Support for this work was provided by NASA through Hubble Fellowship grants 51256.01 awarded to E.N.K. and 51254.01 awarded to K.F. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. Support to C.L.M. was provided through NSF Grant AST-080816.\nFacility: Keck:II (DEIMOS)\n\nPublished - Kirby2011p16473Astrophys_J_Lett.pdf
Submitted - 1110.5624v2.pdf
", "abstract": "The stars in the dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are significantly more metal-poor than would be expected from a closed box model of chemical evolution. Gas outflows likely carried away most of the metals produced by the dSphs. Based on previous Keck/DEIMOS observations and models, we calculate the mass in Mg, Si, Ca, and Fe expelled from each of eight dSphs. Essentially, these masses are the differences between the observed amount of metals present in the dSphs' stars today and the inferred amount of metals produced by supernovae. We conclude that the dSphs lost 96% to >99% of the metals their stars manufactured. We apply the observed mass function of Milky Way dSphs to the ejected mass function to determine that a single large dSph, like Fornax, lost more metals over 10 Gyr than all smaller dSphs combined. Therefore, small galaxies like dSphs are not significant contributors to the metal content of the intergalactic medium. Finally, we compare our ejected mass function to previous X-ray measurements of the metal content of the winds from the post-starburst dwarf irregular galaxy NGC 1569. Remarkably, the most recent starburst in that galaxy falls exactly on the ejected-mass-stellar-mass relation defined by the Milky Way dSphs.", "date": "2011-12-01", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "742", "number": "2", "publisher": "American Astronomical Society", "pagerange": "L25", "id_number": "CaltechAUTHORS:20111212-121257181", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111212-121257181", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51254.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NSF", "grant_number": "AST-080816" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/2041-8205/742/2/L25", "primary_object": { "basename": "1110.5624v2.pdf", "url": "https://authors.library.caltech.edu/records/yxa2x-rb683/files/1110.5624v2.pdf" }, "related_objects": [ { "basename": "Kirby2011p16473Astrophys_J_Lett.pdf", "url": "https://authors.library.caltech.edu/records/yxa2x-rb683/files/Kirby2011p16473Astrophys_J_Lett.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Kirby, Evan N.; Martin, Crystal L.; et el." }, { "id": "https://authors.library.caltech.edu/records/k0z2e-qtd26", "eprint_id": 28309, "eprint_status": "archive", "datestamp": "2023-08-22 03:58:23", "lastmod": "2023-10-24 17:48:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Huang-Wenjin", "name": { "family": "Huang", "given": "Wenjin" } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "The Peculiar Chemical Inventory of NGC 2419: an Extreme Outer Halo \"Globular Cluster\"", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxy: formation; Galaxy: halo; globular clusters: individual (NGC 2419)", "note": "\u00a9 2011 The American Astronomical Society. Received 2011 March 4; accepted 2011 July 12; published 2011 September 29. \nBased in part on observations obtained at the W. M. Keck Observatory,\nwhich is operated jointly by the California Institute of Technology, the\nUniversity of California, and the National Aeronautics and Space\nAdministration.\nWe are grateful to the many people who have worked to\nmake the Keck Telescope and its instruments a reality and to\noperate and maintain the Keck Observatory. The authors extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. We thank Alex Heger and Ken Nomoto for helpful conversations. J.G.C. and W.H. thank NSF grants AST-0507219 and AST-0908139 for partial support. Work by E.N.K. was supported by NASA through Hubble Fellowship grand HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.\n\nPublished - Cohen2011p16390Astrophys_J.pdf
", "abstract": "NGC 2419 is a massive outer halo Galactic globular cluster (GC) whose stars have previously been shown to have\nsomewhat peculiar abundance patterns. We have observed seven luminous giants that are members of NGC 2419\nwith Keck/HIRES at reasonable signal-to-noise ratio. One of these giants is very peculiar, with an extremely low\n[Mg/Fe] and high [K/Fe] but normal abundances of most other elements. The abundance pattern does not match\nthe nucleosynthetic yields of any supernova model. The other six stars show abundance ratios typical of inner halo\nGalactic GCs, represented here by a sample of giants in the nearby GC M30. Although our measurements show\nthat NGC 2419 is unusual in some respects, its bulk properties do not provide compelling evidence for a difference between inner and outer halo GCs.", "date": "2011-10-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "740", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 60", "id_number": "CaltechAUTHORS:20111206-090232829", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111206-090232829", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0507219" }, { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/0004-637X/740/2/60", "primary_object": { "basename": "Cohen2011p16390Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/k0z2e-qtd26/files/Cohen2011p16390Astrophys_J.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Cohen, Judith G.; Huang, Wenjin; et el." }, { "id": "https://authors.library.caltech.edu/records/78vyq-we729", "eprint_id": 27670, "eprint_status": "archive", "datestamp": "2023-08-22 03:48:09", "lastmod": "2023-10-24 17:19:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Willman-B", "name": { "family": "Willman", "given": "Beth" }, "orcid": "0000-0003-2892-9906" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Strader-J", "name": { "family": "Strader", "given": "Jay" }, "orcid": "0000-0002-1468-9668" }, { "id": "Strigari-L-E", "name": { "family": "Strigari", "given": "Louis E." } }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan" }, "orcid": "0000-0001-6196-5162" }, { "id": "Ho-Nhung", "name": { "family": "Ho", "given": "Nhung" } }, { "id": "Warres-A", "name": { "family": "Warres", "given": "Alex" } } ] }, "title": "Willman 1\u2014A Probable Dwarf Galaxy with an Irregular Kinematic Distribution", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: individual (Willman 1); galaxies: kinematics and dynamics; galaxies: star clusters: general", "note": "\u00a9 2011 American Astronomical Society. Received 2010 July 21; accepted 2011 July 30; published 2011 September 14. B.W. acknowledges support from NSF AST-0908193 and thanks Ewa Lokas, Anil Seth, Joe Wolf, and Gail Gutowkski for interesting and helpful conversations during the preparation\nof this paper. We also thank the anonymous referee for\nproviding thoughtful suggestions that resulted in substantial improvement of this manuscript. M.G. acknowledges support from NSF AST-9008752. E.N.K., J. Strader, and L.E.S. acknowledge support provided by NASA through Hubble Fellowship grants HST-HF-01233.01, HST-HF-51237.01, and HST-HF-01225.01, respectively, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. We thank David W. Hogg and Morad Masjedi for obtaining the Wil 1 observations at KPNO in 2005. Some of the data presented herein were obtained at the W. M. Keck Observatory,\nwhich is operated as a scientific partnership among the\nCalifornia Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This research has also made use of NASA's Astrophysics Data System Bibliographic Services.\n\nPublished - Willman2011p16183Astron_J.pdf
", "abstract": "We investigate the kinematic properties and stellar population of the Galactic satellite Willman 1 (Wil 1) by combining Keck/DEIMOS spectroscopy with Kitt Peak National Observatory mosaic camera imaging. Wil 1, also known as SDSS J1049+5103, is a nearby, ultra-low luminosity Milky Way companion. This object lies in a region of size-luminosity space (M_V ~ \u20132 mag, d ~ 38 kpc, r_(half) ~ 20 pc) also occupied by the Galactic satellites Bo\u00f6tes II and Segue 1 and 2, but no other known old stellar system. We use kinematic and color-magnitude criteria to identify 45 stars as possible members of Wil 1. With a systemic velocity of v_(helio) = \u201312.8 \u00b1 1.0 km s^(\u20131), Wil 1 stars have velocities similar to those of foreground Milky Way stars. Informed by Monte Carlo simulations, we identify 5 of the 45 candidate member stars as likely foreground contaminants, with a small number possibly remaining at faint apparent magnitudes. These contaminants could have mimicked a large velocity dispersion and abundance spread in previous work. The significant spread in the [Fe/H] of the highly likely Wil 1 red giant branch members ([Fe/H] = \u20131.73 \u00b1 0.12 and \u20132.65 \u00b1 0.12) supports the scenario that Wil 1 is an ultra-low luminosity dwarf galaxy, or the remnants thereof, rather than a star cluster. However, Wil 1's innermost stars move with radial velocities offset by 8 km s^(\u20131) from its outer stars and have a velocity dispersion consistent with 0 km s^(\u20131), suggesting that Wil 1 may not be in dynamical equilibrium. The combination of the foreground contamination and unusual kinematic distribution make it difficult to robustly determine the dark matter mass of Wil 1. As a result, X-ray or gamma-ray observations of Wil 1 that attempt to constrain models of particle dark matter using an equilibrium mass model are strongly affected by the systematics in the observations presented here. We conclude that, despite the unusual features in the Wil 1 kinematic distribution, evidence indicates that this object is, or at least once was, a dwarf galaxy.", "date": "2011-10", "date_type": "published", "publication": "Astronomical Journal", "volume": "142", "number": "4", "publisher": "American Astronomical Society", "pagerange": "Art. No. 128", "id_number": "CaltechAUTHORS:20111108-103559221", "issn": "0004-6256", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111108-103559221", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0908193" }, { "agency": "NSF", "grant_number": "AST-9008752" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-51237.01" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01225.01" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/0004-6256/142/4/128", "primary_object": { "basename": "Willman2011p16183Astron_J.pdf", "url": "https://authors.library.caltech.edu/records/78vyq-we729/files/Willman2011p16183Astron_J.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Willman, Beth; Geha, Marla; et el." }, { "id": "https://authors.library.caltech.edu/records/cnn04-84084", "eprint_id": 23843, "eprint_status": "archive", "datestamp": "2023-08-22 02:45:11", "lastmod": "2023-10-23 20:04:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Minor-Q-E", "name": { "family": "Minor", "given": "Quinn E." } }, { "id": "Martinez-G-D", "name": { "family": "Martinez", "given": "Gregory D." }, "orcid": "0000-0002-7476-2521" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Bullock-J-S", "name": { "family": "Bullock", "given": "James S." }, "orcid": "0000-0003-4298-5082" }, { "id": "Kaplinghat-M", "name": { "family": "Kaplinghat", "given": "Manoj" } }, { "id": "Strigari-L-E", "name": { "family": "Strigari", "given": "Louis E." } }, { "id": "Willman-B", "name": { "family": "Willman", "given": "Beth" }, "orcid": "0000-0003-2892-9906" }, { "id": "Choi-Philip-I", "name": { "family": "Choi", "given": "Philip I." } }, { "id": "Tollerud-E-J", "name": { "family": "Tollerud", "given": "Erik J." }, "orcid": "0000-0002-9599-310X" }, { "id": "Wolf-J", "name": { "family": "Wolf", "given": "Joe" } } ] }, "title": "A Complete Spectroscopic Survey of the Milky Way Satellite Segue 1: The Darkest Galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "dark matter; galaxies: dwarf; galaxies: individual (Segue 1); galaxies: kinematics and dynamics; Local Group", "note": "\u00a9 2011 The American Astronomical Society. \n\nReceived 2010 July 26; accepted 2011 March 10; published 2011 May 3. \n\nThe data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nJ.D.S. gratefully acknowledges the support of a Vera Rubin Fellowship provided by the Carnegie Institution of Washington. M.G. acknowledges support from NSF grant AST-0908752. Work at UCI was supported by NSF grant PHY-0855462 and NASA grant NNX09AD09G. Support for this work was also provided by NASA through Hubble Fellowship grant HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. B.W. acknowledges support from NSF grant AST-0908193. This paper benefitted from the workshop \"Shedding Light on the Nature of Dark Matter\" held by the Keck Institute of Space Studies. We appreciate the contributions of the referee, who helped us clarify the paper. We thank Vasily Belokurov, Michael Cooper, Gerry Gilmore, Juna Kollmeier, Mark Krumholz, David Law, and George Preston for helpful conversations, and Matt Walker for providing his EM code.We also thank Alan McConnachie and Pat C\u00f4t\u00e9 for sharing a draft of their work on binary stars prior to publication. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST-0071048. This research has also made use of NASA's Astrophysics Data System Bibliographic Services. \n\nFacilities: Keck:II (DEIMOS)\n\nPublished - Simon2011p13971Astrophys_J.pdf
Submitted - 1007.4198.pdf
", "abstract": "We present the results of a comprehensive Keck/DEIMOS spectroscopic survey of the ultra-faint Milky Way satellite galaxy Segue 1. We have obtained velocity measurements for 98.2% of the stars within 67 pc (10', or 2.3 half-light radii) of the center of Segue 1 that have colors and magnitudes consistent with membership, down to a magnitude limit of r = 21.7. Based on photometric, kinematic, and metallicity information, we identify 71 stars as probable Segue 1 members, including some as far out as 87 pc. After correcting for the influence of binary stars using repeated velocity measurements, we determine a velocity dispersion of 3.7^(+1.4) \u2013 1.1 km s^(\u20131). The mass within the half-light radius is 5.8^(+8.2) _(\u2013 3.1) \u00d7 10^5 M _\u2299. The stellar kinematics of Segue 1 require very high mass-to-light ratios unless the system is far from dynamical equilibrium, even if the period distribution of unresolved binary stars is skewed toward implausibly short periods. With a total luminosity less than that of a single bright red giant and a V-band mass-to-light ratio of 3400 M _\u2299/L_\u2299, Segue 1 is the darkest galaxy currently known. We critically re-examine recent claims that Segue 1 is a tidally disrupting star cluster and that kinematic samples are contaminated by the Sagittarius stream. The extremely low metallicities ([Fe/H] < \u20133) of two Segue 1 stars and the large metallicity spread among the members demonstrate conclusively that Segue 1 is a dwarf galaxy, and we find no evidence in favor of tidal effects. We also show that contamination by the Sagittarius stream has been overestimated. Segue 1 has the highest estimated dark matter density of any known galaxy and will therefore be a prime testing ground for dark matter physics and galaxy formation on small scales.", "date": "2011-05-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "733", "number": "1", "publisher": "American Astronomical Society", "pagerange": "Art. No. 46", "id_number": "CaltechAUTHORS:20110531-141523338", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110531-141523338", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Carnegie Institute of Washington" }, { "agency": "NSF", "grant_number": "AST-0908752" }, { "agency": "NSF", "grant_number": "PHY-0855462" }, { "agency": "NASA", "grant_number": "NNX09AD09G" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NASA", "grant_number": "NAS-5-26555" }, { "agency": "NSF", "grant_number": "AST-0908193" }, { "agency": "NSF", "grant_number": "AST-0071048" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/0004-637X/733/1/46", "primary_object": { "basename": "1007.4198.pdf", "url": "https://authors.library.caltech.edu/records/cnn04-84084/files/1007.4198.pdf" }, "related_objects": [ { "basename": "Simon2011p13971Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/cnn04-84084/files/Simon2011p13971Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Simon, Joshua D.; Geha, Marla; et el." }, { "id": "https://authors.library.caltech.edu/records/gb6c0-by709", "eprint_id": 23985, "eprint_status": "archive", "datestamp": "2023-08-19 06:21:16", "lastmod": "2023-10-23 20:13:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "Grids of ATLAS9 Model Atmospheres and MOOG Synthetic Spectra", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 The Astronomical Society of the Pacific. \n\nReceived 2011 February 14; accepted 2011 March 5; published 2011 April 5. \n\nThe author thanks Joel Primack for sharing his time on the Pleiades Astrophysics Computing Cluster at the University of California, Santa Cruz, supported by a grant from the National Science Foundation Major Research Instrumentation program; Judy Cohen for sharing a list of helpful references; Fran\u00e7ois Ochsenbein for his help in preparing the data for online access via VizieR; F. Castelli for her helpful comments; and R. Kurucz, the referee, whose suggestions improved this article. Support for this work was provided by NASA through Hubble Fellowship grant 51256.01 awarded to E. N. K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France.\n\nPublished - Kirby2011p14070Publ_Astron_Soc_Pac.pdf
Submitted - 1103.1385.pdf
", "abstract": "A grid of ATLAS9 model atmospheres has been computed, spanning 3500 K \u2264 T_(eff) \u2264 8000 K, 0.0 \u2264 log g \u2264 5.0, -4.0 \u2264 [M/H] \u2264 0.0, and -0.8 \u2264 [\u03b1/Fe] \u2264 +1.2. These parameters are appropriate for old stars in the red giant branch, subgiant branch, and the lower main sequence. The main difference from a previous similar grid is the range of [\u03b1/Fe] values. A grid of synthetic spectra, calculated from the model atmospheres, is also presented. The fluxes are computed every 0.02 \u00c5 from 6300 \u00c5 to 9100 \u00c5. The microturbulent velocity is given by a relation to the surface gravity. This relation is appropriate for red giants, but not for subgiants or dwarfs. Therefore, caution is urged for the synthetic spectra with log g > 3.5 or for any star that is not a red giant. Both the model atmosphere and synthetic spectrum grids are available online through VizieR. Applications of these grids include abundance analysis for large samples of stellar spectra and constructing composite spectra for stellar populations.", "date": "2011-05", "date_type": "published", "publication": "Publications of the Astronomical Society of the Pacific", "volume": "123", "number": "903", "publisher": "Astronomical Society of the Pacific", "pagerange": "531-535", "id_number": "CaltechAUTHORS:20110613-100240345", "issn": "0004-6280", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110613-100240345", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1086/660019", "primary_object": { "basename": "Kirby2011p14070Publ_Astron_Soc_Pac.pdf", "url": "https://authors.library.caltech.edu/records/gb6c0-by709/files/Kirby2011p14070Publ_Astron_Soc_Pac.pdf" }, "related_objects": [ { "basename": "1103.1385.pdf", "url": "https://authors.library.caltech.edu/records/gb6c0-by709/files/1103.1385.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Kirby, Evan N." }, { "id": "https://authors.library.caltech.edu/records/zy6d9-qmj14", "eprint_id": 22805, "eprint_status": "archive", "datestamp": "2023-08-22 02:02:37", "lastmod": "2023-10-23 16:11:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Lanfranchi-G-A", "name": { "family": "Lanfranchi", "given": "Gustavo A." } }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Multi-element Abundance Measurements from Medium-resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: evolution; Local Group", "note": "\u00a9 2011 American Astronomical Society. \n\nReceived 2010 May 12; accepted 2010 November 7; published 2011 January 5. \n\nWe thank the anonymous referee for helpful advice that improved this manuscript. We also thank Bob Kraft for helpful comments and Julianne Dalcanton for the suggestion that gas may become available for SF in ways other than the infall of external gas. We also recognize the work of Marla Geha, Steve Majewski, Connie Rockosi, Michael Siegel, Chris Sneden, Tony Sohn, and Peter Stetson in making the data catalog used in this article possible. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF-51256.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. G.A.L. acknowledges financial support from the Brazilian agency FAPESP (proj. 06/57824-1). NSF grant AST-0908139, awarded to J.G.C., provided partial support for this project. P.G. acknowledges NSF grants AST-0307966, AST-0607852, and AST-0507483. \n\nThe authors recognize and acknowledge the very significant\ncultural role and reverence that the summit of Mauna Kea has\nalways had within the indigenous Hawaiian community.We are\nmost fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - Kirby2011p12849Astrophys_J.pdf
Accepted Version - 1011.4937.pdf
Erratum - Kirby2012p18282Astrophys_J.pdf
", "abstract": "We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of\nthe Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the\npublished catalog of abundance measurements from the previous paper in this series. The measurements are based\non spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box,\nPre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail,\na Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of\nsome galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit\neffective yields of the less luminous half of our galaxy sample do not exceed 0.02Z_\u2299, indicating that gas outflow\nis important in the chemical evolution of the less luminous galaxies. We surmise that the ratio of the importance\nof gas infall to gas outflow increases with galaxy luminosity. Strong correlations of average [Fe/H] and metallicity spread with luminosity support this hypothesis.", "date": "2011-02-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "727", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 78", "id_number": "CaltechAUTHORS:20110310-100115284", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110310-100115284", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-51256.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)", "grant_number": "06/57824-1" }, { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NSF", "grant_number": "AST-0307966" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0507483" } ] }, "doi": "10.1088/0004-637X/727/2/78", "primary_object": { "basename": "Kirby2011p12849Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/zy6d9-qmj14/files/Kirby2011p12849Astrophys_J.pdf" }, "related_objects": [ { "basename": "Kirby2012p18282Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/zy6d9-qmj14/files/Kirby2012p18282Astrophys_J.pdf" }, { "basename": "1011.4937.pdf", "url": "https://authors.library.caltech.edu/records/zy6d9-qmj14/files/1011.4937.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Kirby, Evan N.; Lanfranchi, Gustavo A.; et el." }, { "id": "https://authors.library.caltech.edu/records/ys5dk-bts29", "eprint_id": 22806, "eprint_status": "archive", "datestamp": "2023-08-22 02:02:44", "lastmod": "2023-10-23 17:13:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Smith-G-H", "name": { "family": "Smith", "given": "Graeme H." } }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Sohn-Sangmo-Tony", "name": { "family": "Sohn", "given": "Sangmo Tony" } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" } ] }, "title": "Multi-element Abundance Measurements from Medium-resolution Spectra. IV. Alpha Element Distributions in Milky Way Satellite Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: evolution; Local Group", "note": "\u00a9 2011 American Astronomical Society. \n\nReceived 2010 September 15; accepted 2010 November 16; published 2011 January 5. \n\nWe thank John Johnson, Hai Fu, Julianne Dalcanton, Chris Sneden, and Bob Kraft for insightful discussions. Support for this work was provided by NASA through Hubble Fellowship grant 51256.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. S.R.M. acknowledges support from NSF grants AST-0307851 and AST-0807945, and from the SIM Lite key project \"Taking Measure of the Milky Way\" under NASA/JPL contract 1228235. P.G. acknowledges NSF grants AST-0507483, AST-0607852, and AST-0808133. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - Kirby2011p12852Astrophys_J.pdf
Accepted Version - 1011.5221.pdf
", "abstract": "We derive the star formation histories of eight dwarf spheroidal (dSph) Milky Way satellite galaxies from their\nalpha element abundance patterns. Nearly 3000 stars from our previously published catalog comprise our data\nset. The average [\u03b1/Fe] ratios for all dSphs follow roughly the same path with increasing [Fe/H]. We do not\nobserve the predicted knees in the [\u03b1/Fe] versus [Fe/H] diagram, corresponding to the metallicity at which Type Ia\nsupernovae begin to explode. Instead, we find that Type Ia supernova ejecta contribute to the abundances of all but\nthe most metal-poor ([Fe/H] < \u22122.5) stars.We have also developed a chemical evolution model that tracks the star\nformation rate, Types II and Ia supernova explosions, and supernova feedback. Without metal enhancement in the\nsupernova blowout, massive amounts of gas loss define the history of all dSphs except Fornax, the most luminous in\nour sample. All six of the best-fit model parameters correlate with dSph luminosity but not with velocity dispersion, half-light radius, or Galactocentric distance.", "date": "2011-02-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "727", "number": "2", "publisher": "American Astronomical Society", "pagerange": "Art. No. 79", "id_number": "CaltechAUTHORS:20110310-100115617", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110310-100115617", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "51256.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-0307851" }, { "agency": "NSF", "grant_number": "AST-0807945" }, { "agency": "NASA/JPL", "grant_number": "1228235" }, { "agency": "NSF", "grant_number": "AST-0507483" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0808133" } ] }, "doi": "10.1088/0004-637X/727/2/79", "primary_object": { "basename": "1011.5221.pdf", "url": "https://authors.library.caltech.edu/records/ys5dk-bts29/files/1011.5221.pdf" }, "related_objects": [ { "basename": "Kirby2011p12852Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/ys5dk-bts29/files/Kirby2011p12852Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Kirby, Evan N.; Cohen, Judith G.; et el." }, { "id": "https://authors.library.caltech.edu/records/gqc69-dfg55", "eprint_id": 21512, "eprint_status": "archive", "datestamp": "2023-08-22 01:33:34", "lastmod": "2023-10-21 00:05:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" } ] }, "title": "NGC 2419-Another Remnant of Accretion by the Milky Way", "ispublished": "pub", "full_text_status": "public", "keywords": "Galaxy: formation; Galaxy: halo; globular clusters: individual (NGC 2419)", "note": "\u00a9 2010 American Astronomical Society. \n\nReceived 2010 June 4; accepted 2010 September 29; published 2010 November 17. \n\nBased in part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. \n\nWe are grateful to the many people who have worked to make\nthe Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. We thank the anonymous referee for helpful suggestions. J.G.C. thanks NSF grant AST-0908139 for partial support. Work by E.N.K. was supported by NASA through Hubble Fellowship grand HST-HF-01233.01 awarded to ENK by the Space Telescope Science institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from the NSF grant AST-0071048.\n\nPublished - Cohen2010p12231Astrophys_J.pdf
Accepted Version - 1010.0031.pdf
", "abstract": "We isolate a sample of 43 upper red giant branch stars in the extreme outer halo Galactic globular cluster (GC) NGC 2419 from two Keck/DEIMOS slitmasks. The probability that there is more than one contaminating halo field star in this sample is extremely low. Analysis of moderate-resolution spectra of these cluster members, as well as of our Keck/HIRES high-resolution spectra of a subsample of them, demonstrates that there is a small but real spread in Ca abundance of ~0.2 dex within this massive metal-poor GC. This provides additional support to earlier suggestions that NGC 2419 is the remnant of a dwarf galaxy accreted long ago by the Milky Way.", "date": "2010-12-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "725", "number": "1", "publisher": "American Astronomical Society", "pagerange": "288-295", "id_number": "CaltechAUTHORS:20101223-095343420", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101223-095343420", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0908139" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NSF", "grant_number": "AST-0071048" } ] }, "doi": "10.1088/0004-637X/725/1/288", "primary_object": { "basename": "1010.0031.pdf", "url": "https://authors.library.caltech.edu/records/gqc69-dfg55/files/1010.0031.pdf" }, "related_objects": [ { "basename": "Cohen2010p12231Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/gqc69-dfg55/files/Cohen2010p12231Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Cohen, Judith G.; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/yjs02-k1a46", "eprint_id": 22803, "eprint_status": "archive", "datestamp": "2023-08-22 01:30:19", "lastmod": "2023-10-23 17:13:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "id": "Rockosi-C-M", "name": { "family": "Rockosi", "given": "Constance M." } }, { "id": "Sneden-C", "name": { "family": "Sneden", "given": "Christopher" }, "orcid": "0000-0002-3456-5929" }, { "id": "Cohen-J-G", "name": { "family": "Cohen", "given": "Judith G." }, "orcid": "0000-0002-8039-4673" }, { "id": "Sohn-Sangmo-Tony", "name": { "family": "Sohn", "given": "Sangmo Tony" } }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Siegel-M", "name": { "family": "Siegel", "given": "Michael" } } ] }, "title": "Multi-element Abundance Measurements from Medium-resolution Spectra. II. Catalog of Stars in Milky Way Dwarf Satellite Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; Galaxy: evolution; Local Group", "note": "\u00a9 2010 American Astronomical Society. \n\nReceived 2010 March 7; accepted 2010 October 26; published 2010 November 30. \n\nData herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nThe authors thank the referee, Piercarlo Bonifacio, for his thoughtful suggestions, which improved this manuscript. We gratefully acknowledge Sandra Faber, Ricardo Schiavon, and Michael Cooper of the DEEP2 team for acquiring Keck/DEIMOS spectroscopy of bright Milky Way halo field stars during nights of poor transparency. \n\nWe also thank Peter Stetson for providing additional globular cluster photometry and Bob Kraft for helpful discussions and for providing some of the globular cluster spectroscopy for this work. The generation of synthetic spectra made use of the University of California Santa Cruz Pleiades supercomputer and the Yale High Performance Computing cluster Bulldog. We thank Joel Primack for sharing his allocation of Pleiades supercomputer time and Mario Juri\u0107 for a helpful discussion on the mass of the components of the Milky Way. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. P.G. acknowledges NSF grants AST-0307966, AST-0607852, and AST-0507483. MG acknowledges support from NSF grant AST-0908752. C.S. acknowledges NSF grant AST-0909978. J.G.C. acknowledges NSF grant AST-090109. M.H.S. was supported at PSU by NASA contractNAS5-00136. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. \n\nFacility: Keck:II (DEIMOS)\n\nPublished - Kirby2010p12845Astrophys_J_Suppl_S.pdf
Accepted Version - 1011.4516.pdf
", "abstract": "We present a catalog of Fe, Mg, Si, Ca, and Ti abundances for 2961 stars in eight dwarf satellite galaxies of the Milky Way (MW): Sculptor, Fornax, Leo I, Sextans, Leo II, Canes Venatici I, Ursa Minor, and Draco. For the purposes of\nvalidating our measurements, we also observed 445 red giants in MW globular clusters and 21 field red giants in the MW halo. Themeasurements are based on Keck/DEIMOS medium-resolution spectroscopy (MRS) combined with\nspectral synthesis. We estimate uncertainties in [Fe/H] by quantifying the dispersion of [Fe/H] measurements in a\nsample of stars inmonometallic globular clusters (GCs).We estimate uncertainties in Mg, Si, Ca, and Ti abundances\nby comparing to high-resolution spectroscopic abundances of the same stars. For this purpose, a sample of 132\nstars with published high-resolution spectroscopy in GCs, the MW halo field, and dwarf galaxies has been observed\nwith MRS. The standard deviations of the differences in [Fe/H] and ([\u03b1/Fe]) (the average of [Mg/Fe], [Si/Fe],\n[Ca/Fe], and [Ti/Fe]) between the two samples is 0.15 and 0.16, respectively. This catalog represents the largest\nsample of multi-element abundances in dwarf galaxies to date. The next papers in this series draw conclusions on\nthe chemical evolution, gas dynamics, and star formation histories from the catalog presented here. The wide range\nof dwarf galaxy luminosity reveals the dependence of dwarf galaxy chemical evolution on galaxy stellar mass.", "date": "2010-12", "date_type": "published", "publication": "Astrophysical Journal Supplement Series", "volume": "191", "number": "2", "publisher": "American Astronomical Society", "pagerange": "352-375", "id_number": "CaltechAUTHORS:20110310-100114131", "issn": "0067-0049", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110310-100114131", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "Space Telescope Science Institute" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "NSF", "grant_number": "AST-0307966" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0507483" }, { "agency": "NSF", "grant_number": "AST-0908752" }, { "agency": "NSF", "grant_number": "AST-0909978" }, { "agency": "NSF", "grant_number": "AST-090109" }, { "agency": "NASA", "grant_number": "NAS5-00136" }, { "agency": "Canadian Space Agency (CSA)" } ] }, "doi": "10.1088/0067-0049/191/2/352", "primary_object": { "basename": "1011.4516.pdf", "url": "https://authors.library.caltech.edu/records/yjs02-k1a46/files/1011.4516.pdf" }, "related_objects": [ { "basename": "Kirby2010p12845Astrophys_J_Suppl_S.pdf", "url": "https://authors.library.caltech.edu/records/yjs02-k1a46/files/Kirby2010p12845Astrophys_J_Suppl_S.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Kirby, Evan N.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/49qfk-7qy02", "eprint_id": 18714, "eprint_status": "archive", "datestamp": "2023-08-22 00:06:00", "lastmod": "2023-10-20 16:41:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Frebel-A", "name": { "family": "Frebel", "given": "Anna" }, "orcid": "0000-0002-2139-7145" }, { "id": "McWilliam-A", "name": { "family": "McWilliam", "given": "Andrew" } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Thompson-I-B", "name": { "family": "Thompson", "given": "Ian B." } } ] }, "title": "High-resolution Spectroscopy of Extremely Metal-poor Stars in the Least Evolved Galaxies: Leo IV", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: individual (Leo IV); Local Group; stars: abundances", "note": "\u00a9 2010 American Astronomical Society. \n\nReceived 2010 January 18; accepted 2010 April 16; published 2010 May 19. \nThis paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. \n\nWe thank Dan Kelson for assistance with the data reduction, Steve Shectman for observing suggestions, Alexander Heger for extensive help with comparisons to theoretical SN models, and the referee for a helpful report. J.D.S gratefully acknowledges the support of a Vera Rubin Fellowship provided by the Carnegie Institution of Washington, and A.F. that of a Clay Fellowship administered by the Smithsonian Astrophysical Observatory. \n\nThis work was also supported by NASA through Hubble Fellowship grant HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. This research made use of NASA's Astrophysics Data System Bibliographic Services. \n\nFacilities: Magellan:Clay (MIKE)\n\nPublished - Simon2010p10348Astrophys_J.pdf
Accepted Version - 1001.3137.pdf
", "abstract": "We present high-resolution Magellan/MIKE spectroscopy of the brightest star in the ultra-faint dwarf galaxy Leo IV. We measure an iron abundance of [Fe/H] = \u20133.2, adding to the rapidly growing sample of extremely metal-poor (EMP) stars being identified in Milky Way satellite galaxies. The star is enhanced in the \u03b1 elements Mg, Ca, and Ti by ~0.3 dex, very similar to the typical Milky Way halo abundance pattern. All of the light and iron-peak elements follow the trends established by EMP halo stars, but the neutron-capture elements Ba and Sr are significantly underabundant. These results are quite similar to those found for stars in the ultra-faint dwarfs Ursa Major II, Coma Berenices, Bo\u00f6tes I, and Hercules, suggesting that the chemical evolution of the lowest-luminosity galaxies may be universal. The abundance pattern we observe is consistent with predictions for nucleosynthesis from a Population III supernova explosion. The extremely low metallicity of this star also supports the idea that a significant fraction (\u227310%) of the stars in the faintest dwarfs have metallicities below [Fe/H] = \u20133.0.", "date": "2010-06-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "716", "number": "1", "publisher": "American Astronomical Society", "pagerange": "446-452", "id_number": "CaltechAUTHORS:20100616-152157779", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100616-152157779", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Carnegie Mellon Institute of Washington" }, { "agency": "Smithsonian Astrophysical Observatory" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/0004-637X/716/1/446", "primary_object": { "basename": "1001.3137.pdf", "url": "https://authors.library.caltech.edu/records/49qfk-7qy02/files/1001.3137.pdf" }, "related_objects": [ { "basename": "Simon2010p10348Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/49qfk-7qy02/files/Simon2010p10348Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Simon, Joshua D.; Frebel, Anna; et el." }, { "id": "https://authors.library.caltech.edu/records/ez0cb-hs087", "eprint_id": 17767, "eprint_status": "archive", "datestamp": "2023-08-21 23:34:32", "lastmod": "2023-10-20 00:13:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Ostheimer-J-C", "name": { "family": "Ostheimer", "given": "James C." } }, { "id": "Patterson-R-J", "name": { "family": "Patterson", "given": "Richard J." } }, { "id": "Wolf-J", "name": { "family": "Wolf", "given": "Joe" } } ] }, "title": "The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV Dwarf Spheroidal Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "dark matter; galaxies: abundances; galaxies: dwarf; galaxies: individual (And I, And I, And I, And I, And I, And II, And II, And II, And II, And II, And III, And III, And III, And III, And III, And VII, And VII, And VII, And VII, And VII, And X, And X, And X, And X, And X, And XIV, And XIV, And XIV, And XIV, And XIV); techniques: photometric; techniques: spectroscopic", "note": "\u00a9 2010 The American Astronomical Society. \n\nIssue 2 (2010 March 10); received 2009 November 11, accepted for publication 2010 January 21; published 2010 February 17. \n\nWe thank Eva Grebel, Steve Vogt, and Dan Zucker for their valuable contribution to the And VII and X observations. J.S.K.'s research is supported in part by a grant from the STScI Director's Discretionary Research Fund, and was supported by NASA through Hubble Fellowship grant HF-01185.01-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. This project was also supported by NSF grants AST-0307966, AST-0507483, AST-0607852, and AST-0808133 and NASA/STScI grant GO-10265.02 (J.S.K., P.G., K.M.G., and E.N.K.), an NSF Graduate Fellowship (K.M.G.), a Hubble Fellowship grant (HST-HF-01233.01) awarded by STScI (E.N.K.), and\nNSF grants AST-0307842, AST-0307851, and AST-0607726, NASA/JPL contract 1228235, the David and Lucile Packard Foundation, and The F. H. Levinson Fund of the Peninsula Community Foundation (S.R.M., R.J.P., and R.L.B.).\n\nPublished - Kalirai2010p7266Astrophys_J.pdf
Accepted Version - 0911.1998.pdf
", "abstract": "We present new Keck/DEIMOS spectroscopic observations of hundreds of individual stars along the sightline to the first three of the Andromeda (M31) dwarf spheroidal (dSph) galaxies to be discovered, And I, II, and III, and combine them with recent spectroscopic studies by our team of three additional M31 dSphs, And VII, X, and XIV, as a part of the SPLASH Survey (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo). Member stars of each dSph are isolated from foreground Milky Way dwarf stars and M31 field contamination using a variety of photometric and spectroscopic diagnostics. Our final spectroscopic sample of member stars in each dSph, for which we measure accurate radial velocities with a median uncertainty (random plus systematic errors) of 4-5 km s^(\u20131), includes 80 red giants in And I, 95 in And II, 43 in And III, 18 in And VII, 22 in And X, and 38 in And XIV. The sample of confirmed members in the six dSphs is used to derive each system's mean radial velocity, intrinsic central velocity dispersion, mean abundance, abundance spread, and dynamical mass. This combined data set presents us with a unique opportunity to perform the first systematic comparison of the global properties (e.g., metallicities, sizes, and dark matter masses) of one-third of Andromeda's total known dSph population with Milky Way counterparts of the same luminosity. Our overall comparisons indicate that the family of dSphs in these two hosts have both similarities and differences. For example, we find that the luminosity-metallicity relation is very similar between L ~ 10^5 and 10^7 L_\u2609, suggesting that the chemical evolution histories of each group of dSphs are similar. The lowest luminosity M31 dSphs appear to deviate from the relation, possibly suggesting tidal stripping. Previous observations have noted that the sizes of M31's brightest dSphs are systematically larger than Milky Way satellites of similar luminosity. At lower luminosities between L = 10^4 and 10^6 L_\u2609, we find that the sizes of dSphs in the two hosts significantly overlap and that four of the faintest M31 dSphs are smaller than Milky Way counterparts. The first dynamical mass measurements of six M31 dSphs over a large range in luminosity indicate similar mass-to-light ratios compared to Milky Way dSphs among the brighter satellites, and smaller mass-to-light ratios among the fainter satellites. Combined with their similar or larger sizes at these luminosities, these results hint that the M31 dSphs are systematically less dense than Milky Way dSphs. The implications of these similarities and differences for general understanding of galaxy formation and evolution are summarized.", "date": "2010-03-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "711", "number": "2", "publisher": "American Astronomical Society", "pagerange": "671-692", "id_number": "CaltechAUTHORS:20100317-113720269", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100317-113720269", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Space Telescope Science Institute" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-01185.01-A" }, { "agency": "NSF", "grant_number": "AST-0307966" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0808133" }, { "agency": "NASA", "grant_number": "GO-10265.02" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NSF", "grant_number": "AST-0307842" }, { "agency": "NSF", "grant_number": "AST-0307851" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NASA/JPL", "grant_number": "1228235" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "Peninsula Community Foundation" } ] }, "local_group": { "items": [ { "id": "SPLASH" }, { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" } ] }, "doi": "10.1088/0004-637X/711/2/671", "primary_object": { "basename": "0911.1998.pdf", "url": "https://authors.library.caltech.edu/records/ez0cb-hs087/files/0911.1998.pdf" }, "related_objects": [ { "basename": "Kalirai2010p7266Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/ez0cb-hs087/files/Kalirai2010p7266Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Kalirai, Jason S.; Beaton, Rachael L.; et el." }, { "id": "https://authors.library.caltech.edu/records/kt4b8-bsp78", "eprint_id": 17740, "eprint_status": "archive", "datestamp": "2023-08-19 01:55:38", "lastmod": "2023-10-20 00:11:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Frebel-A", "name": { "family": "Frebel", "given": "Anna" }, "orcid": "0000-0002-2139-7145" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } } ] }, "title": "Linking dwarf galaxies to halo building blocks with the most metal-poor star in Sculptor", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2010 Macmillan Publishers Limited. \n\nReceived 4 September; accepted 22 December 2009. \n\nOur data was gathered using the 6.5-m Magellan telescopes located at Las Campanas Observatory, Chile. We thank L. Hernquist for discussions on galaxy formation. A.F. acknowledges support through a Clay Fellowship administered by the Smithsonian Astrophysical Observatory. Support for this work was provided by NASA through a Hubble fellowship grant awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA (to E.N.K., who is a Hubble Fellow). J.D.S. acknowledges the support of a Vera Rubin Fellowship provided by the Carnegie Institution of Washington. \n\nAuthor Contributions A.F. took the high-resolution observations, and led the analysis; E.N.K. provided the target; J.D.S. contributed to the analysis. All authors contributed to the writing of the paper. \n\nThe authors declare no competing financial interests.", "abstract": "Current cosmological models indicate that the Milky Way's stellar halo was assembled from many smaller systems. On the basis of the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. The discovery of an extremely iron-poor star (S1020549) in the Sculptor dwarf galaxy based on a medium-resolution spectrum cast some doubt on this conclusion. Verification of the iron-deficiency, however, and measurements of additional elements, such as the \u03b1-element Mg, are necessary to demonstrate that the same type of stars produced the metals found in dwarf galaxies and the Galactic halo. Only then can dwarf galaxy stars be conclusively linked to early stellar halo assembly. Here we report high-resolution spectroscopic abundances for 11 elements in S1020549, confirming its iron abundance of less than 1/4,000th that of the Sun, and showing that the overall abundance pattern follows that seen in low-metallicity halo stars, including the \u03b1-elements. Such chemical similarity indicates that the systems destroyed to form the halo billions of years ago were not fundamentally different from the progenitors of present-day dwarfs, and suggests that the early chemical enrichment of all galaxies may be nearly identical.", "date": "2010-03-04", "date_type": "published", "publication": "Nature", "volume": "464", "number": "7285", "publisher": "Nature Publishing Group", "pagerange": "72-75", "id_number": "CaltechAUTHORS:20100315-154957943", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100315-154957943", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Space Telescope Science Institute" }, { "agency": "Carnegie Institution of Washington" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1038/nature08772", "resource_type": "article", "pub_year": "2010", "author_list": "Frebel, Anna; Kirby, Evan N.; et el." }, { "id": "https://authors.library.caltech.edu/records/6x5vn-hr126", "eprint_id": 95410, "eprint_status": "archive", "datestamp": "2023-08-21 23:33:47", "lastmod": "2023-10-20 20:12:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Geha-M-C", "name": { "family": "Geha", "given": "M." }, "orcid": "0000-0002-7007-9725" }, { "id": "van-der-Marel-R-P", "name": { "family": "van der Marel", "given": "R. P." }, "orcid": "0000-0001-7827-7825" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "P." }, "orcid": "0000-0001-8867-4234" }, { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "K. M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "J." }, "orcid": "0000-0001-9690-4159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E. N." }, "orcid": "0000-0001-6196-5162" } ] }, "title": "Local Group Dwarf Elliptical Galaxies: II. Stellar Kinematics to Large Radii in NGC 147 and NGC 185", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: individual (NGC 147 NGC 185); galaxies: kinematics and dynamics", "note": "\u00a9 2010. The American Astronomical Society. \n\nReceived 2009 July 30; accepted 2010 January 6; published 2010 February 10. \n\nWe thank S. Demers and P. Battinelli for kindly providing their photometric catalogs before publication. We also kindly thank Michael Rich for sharing Keck observing time with part of this project. Support for this work was provided in part by NASA through Hubble Fellowship grant HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS 5-26555.\n\nPublished - Geha_2010_ApJ_711_361.pdf
Accepted Version - 0911.3654.pdf
", "abstract": "We present kinematic and metallicity profiles for the M 31 dwarf elliptical (dE) satellite galaxies NGC 147 and NGC 185. The profiles represent the most extensive spectroscopic radial coverage for any dE galaxy, extending to a projected distance of 8 half-light radii (8r_(eff) ~ 14'). We achieve this coverage via Keck/DEIMOS multislit spectroscopic observations of 520 and 442 member red giant branch stars in NGC 147 and NGC 185, respectively. In contrast to previous studies, we find that both dEs have significant internal rotation. We measure a maximum rotational velocity of 17 \u00b1 2 km s^(\u20131) for NGC 147 and 15 \u00b1 5 km s^(\u20131) for NGC 185. While both rotation profiles suggest a flattening in the outer regions, there is no indication that we have reached the radius of maximum rotation velocity. The velocity dispersions decrease gently with radius with average dispersions of 16 \u00b1 1 km s^(\u20131) and 24 \u00b1 1 km s^(\u20131) for NGC 147 and NGC 185, respectively. The average metallicities for NGC 147 and NGC 185 are [Fe/H] = \u20131.1 \u00b1 0.1 and [Fe/H] = \u20131.3 \u00b1 0.1, respectively; both dEs have internal metallicity dispersions of 0.5 dex, but show no evidence for a radial metallicity gradient. We construct two-integral axisymmetric dynamical models and find that the observed kinematical profiles cannot be explained without modest amounts of non-baryonic dark matter. We measure central mass-to-light ratios of M/L_V = 4.2 \u00b1 0.6 and M/LV = 4.6 \u00b1 0.6 for NGC 147 and NGC 185, respectively. Both dE galaxies are consistent with being primarily flattened by their rotational motions, although some anisotropic velocity dispersion is needed to fully explain their observed shapes. The velocity profiles of all three Local Group dEs (NGC 147, NGC 185, and NGC 205) suggest that rotation is more prevalent in the dE galaxy class than previously assumed, but often manifests only at several times the effective radius. Since all dEs outside the Local Group have been probed to only inside the effective radius, this opens the door for formation mechanisms in which dEs are transformed or stripped versions of gas-rich rotating progenitor galaxies.", "date": "2010-03-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "711", "number": "1", "publisher": "American Astronomical Society", "pagerange": "361-373", "id_number": "CaltechAUTHORS:20190510-120908598", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120908598", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Hubble Fellowship", "grant_number": "HST-HF-01233.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/0004-637x/711/1/361", "primary_object": { "basename": "0911.3654.pdf", "url": "https://authors.library.caltech.edu/records/6x5vn-hr126/files/0911.3654.pdf" }, "related_objects": [ { "basename": "Geha_2010_ApJ_711_361.pdf", "url": "https://authors.library.caltech.edu/records/6x5vn-hr126/files/Geha_2010_ApJ_711_361.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Geha, M.; van der Marel, R. P.; et el." }, { "id": "https://authors.library.caltech.edu/records/2bgw0-pt755", "eprint_id": 16661, "eprint_status": "archive", "datestamp": "2023-08-21 22:41:23", "lastmod": "2023-10-19 22:27:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gilbert-K-M", "name": { "family": "Gilbert", "given": "Karoline M." }, "orcid": "0000-0003-0394-8377" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kollipara-P", "name": { "family": "Kollipara", "given": "Priya" } }, { "id": "Beaton-R-L", "name": { "family": "Beaton", "given": "Rachael L." }, "orcid": "0000-0002-1691-8217" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" }, { "id": "Kalirai-J-S", "name": { "family": "Kalirai", "given": "Jason S." }, "orcid": "0000-0001-9690-4159" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Majewski-S-R", "name": { "family": "Majewski", "given": "Steven R." }, "orcid": "0000-0003-2025-3147" }, { "id": "Patterson-R-J", "name": { "family": "Patterson", "given": "Richard J." } } ] }, "title": "The Splash Survey: A Spectroscopic Portrait of Andromeda's Giant Southern Stream", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: halos; galaxies: individual (M31); stars: kinematics; techniques: spectroscopic", "note": "\u00a9 2009 The American Astronomical Society. \n\nReceived 2008 December 15; accepted 2009 September 23; published 2009 October 20. \n\nThe authors thank Mark Fardal for many useful discussions. This project was supported by NSF grants AST-0307966, AST-0507483, and AST-0607852 (K.M.G., P.G., J.S.K., P.K., and E.N.K.), NSF Graduate Student Research Fellowships (K.M.G., P.K., and E.N.K.), and NSF grants AST-0307842, AST-0307851, and AST-0607726, NASA/JPL contract 1228235, the David and Lucile Packard Foundation, and The F. H. Levinson Fund of the Peninsula Community Foundation (S.R.M., R.J.P., and R.L.B.). J.S.K. was supported by NASA through Hubble Fellowship grant HF-01185.01-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.\n\nPublished - Gilbert2009p6292Astrophys_J.pdf
Accepted Version - 0909.4540.pdf
", "abstract": "The giant southern stream (GSS) is the most prominent tidal debris feature in M31's stellar halo and covers a significant fraction of its southern quadrant. The GSS is a complex structure composed of a relatively metal-rich, high-surface-brightness \"core\" and a lower metallicity, lower-surface-brightness \"envelope.\" We present spectroscopy of red giant stars in six fields in the vicinity of M31's GSS (including four new fields and improved spectroscopic reductions for two previously published fields) and one field on stream C, an arc-like feature seen in star-count maps on M31's southeast minor axis at R ~ 60 kpc. These data are part of our ongoing Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey of M31 using the DEIMOS instrument on the Keck II 10 m telescope. Several GSS-related findings and measurements are presented here. We present the innermost kinematical detection of the GSS core to date (R = 17 kpc). This field also contains the inner continuation of a second kinematically cold component that was originally seen in a GSS core field at R ~ 21 kpc. The velocity gradients of the GSS and the second component in the combined data set are parallel over a range of \u0394R = 7 kpc, suggesting that this may represent a bifurcation in the line-of-sight velocities of GSS stars. We present the first kinematical detection of substructure in the GSS envelope (S quadrant, R ~ 58 kpc). Using kinematically identified samples, we show that the envelope debris has a ~0.7 dex lower mean photometric metallicity and possibly higher intrinsic velocity dispersion than the GSS core. The GSS is also identified in the field of the M31 dwarf spheroidal satellite And I; the GSS in this field has a metallicity distribution identical to that of the GSS core. We confirm the previous finding of two kinematically cold components in stream C, and measure intrinsic velocity dispersions of ~10 and ~4 km s^(\u20131). This compilation of the kinematical (mean velocity, intrinsic velocity dispersion) and chemical properties of stars in the GSS core and envelope, coupled with published surface-brightness measurements and wide-area star-count maps, will improve constraints on the orbit and internal structure of the dwarf satellite progenitor.", "date": "2009-11-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "705", "number": "2", "publisher": "American Astronomical Society", "pagerange": "1275-1297", "id_number": "CaltechAUTHORS:20091111-093926622", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091111-093926622", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0307966" }, { "agency": "NSF", "grant_number": "AST-0507483" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0307842" }, { "agency": "NSF", "grant_number": "AST-0307851" }, { "agency": "NSF", "grant_number": "AST-0607726" }, { "agency": "NASA/JPL", "grant_number": "1228235" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "Peninsula Community Foundation" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-01185.01-A" }, { "agency": "NASA", "grant_number": "NAS5-26555" }, { "agency": "Space Telescope Science Institute" } ] }, "local_group": { "items": [ { "id": "SPLASH" }, { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" } ] }, "doi": "10.1088/0004-637X/705/2/1275", "primary_object": { "basename": "0909.4540.pdf", "url": "https://authors.library.caltech.edu/records/2bgw0-pt755/files/0909.4540.pdf" }, "related_objects": [ { "basename": "Gilbert2009p6292Astrophys_J.pdf", "url": "https://authors.library.caltech.edu/records/2bgw0-pt755/files/Gilbert2009p6292Astrophys_J.pdf" } ], "resource_type": "article", "pub_year": "2009", "author_list": "Gilbert, Karoline M.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/ry0vg-9ba22", "eprint_id": 95408, "eprint_status": "archive", "datestamp": "2023-08-21 22:40:11", "lastmod": "2023-10-20 20:12:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Bolte-M", "name": { "family": "Bolte", "given": "Michael" } }, { "id": "Sneden-C", "name": { "family": "Sneden", "given": "Christopher" }, "orcid": "0000-0002-3456-5929" }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla C." }, "orcid": "0000-0002-7007-9725" } ] }, "title": "Multi-Element Abundance Measurements from Medium-Resolution Spectra. I. The Sculptor Dwarf Spheroidal Galaxy", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf; galaxies: individual (Sculptor dwarf); Galaxy: evolution; Local Group", "note": "\u00a9 2009. The American Astronomical Society. \n\nReceived 2009 March 3; accepted 2009 September 17; published 2009 October 9. \n\nWe thank Kyle Westfall for providing the photometric catalog, Gustavo Lanfranchi and Francesca Matteucci for providing their chemical evolution model, David Lai for thoughtful conversations, and the anonymous referee for helpful comments that improved this manuscript. The generation of synthetic spectra made use of the Yale High Performance Computing cluster Bulldog. E.N.K. is grateful for the support of a UC Santa Cruz Chancellor's Dissertation Year Fellowship. P.G. acknowledges NSF grant AST-0307966, AST-0607852, and AST-0507483. C.S. acknowledges NSF grant AST-0607708. \n\nData herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nFacility: Keck II (DEIMOS)\n\nPublished - Kirby_2009_ApJ_705_328.pdf
Accepted Version - 0909.3092.pdf
", "abstract": "We present measurements of Fe, Mg, Si, Ca, and Ti abundances for 388 radial velocity member stars in the Sculptor dwarf spheroidal galaxy (dSph), a satellite of the Milky Way (MW). This is the largest sample of individual \u03b1 element (Mg, Si, Ca, and Ti) abundance measurements in any single dSph. The measurements are made from Keck/Deep Imaging Multi-Object Spectrometer medium-resolution spectra (6400-9000 \u00c5, R ~ 6500). Based on comparisons to published high-resolution (R \u2273 20,000) spectroscopic measurements, our measurements have uncertainties of \u03c3[Fe/H] = 0.14 and \u03c3[\u03b1/Fe] = 0.13. The Sculptor [Fe/H] distribution has a mean lang[Fe/H]rang = \u20131.58 and is asymmetric with a long, metal-poor tail, indicative of a history of extended star formation. Sculptor has a larger fraction of stars with [Fe/H] < \u20132 than the MW halo. We have discovered one star with [Fe/H] = \u20133.80 \u00b1 0.28, which is the most metal-poor star known anywhere except the MW halo, but high-resolution spectroscopy is needed to measure this star's detailed abundances. As has been previously reported based on high-resolution spectroscopy, [\u03b1/Fe] in Sculptor falls as [Fe/H] increases. The metal-rich stars ([Fe/H] ~ \u20131.5) have lower [\u03b1/Fe] than Galactic halo field stars of comparable metallicity. This indicates that star formation proceeded more gradually in Sculptor than in the Galactic halo. We also observe radial abundance gradients of \u20130.030 \u00b1 0.003 dex arcmin^(\u20131) in [Fe/H] and +0.013 \u00b1 0.003 dex arcmin^(\u20131) in [\u03b1/Fe] out to 11 arcmin (275 pc). Together, these measurements cast Sculptor and possibly other surviving dSphs as representative of the dwarf galaxies from which the metal-poor tail of the Galactic halo formed.", "date": "2009-11-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "705", "number": "1", "publisher": "American Astronomical Society", "pagerange": "328-346", "id_number": "CaltechAUTHORS:20190510-120908397", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120908397", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "University of California, Santa Cruz" }, { "agency": "NSF", "grant_number": "AST-0307966" }, { "agency": "NSF", "grant_number": "AST-0607852" }, { "agency": "NSF", "grant_number": "AST-0507483" }, { "agency": "NSF", "grant_number": "AST-0607708" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1088/0004-637x/705/1/328", "primary_object": { "basename": "0909.3092.pdf", "url": "https://authors.library.caltech.edu/records/ry0vg-9ba22/files/0909.3092.pdf" }, "related_objects": [ { "basename": "Kirby_2009_ApJ_705_328.pdf", "url": "https://authors.library.caltech.edu/records/ry0vg-9ba22/files/Kirby_2009_ApJ_705_328.pdf" } ], "resource_type": "article", "pub_year": "2009", "author_list": "Kirby, Evan N.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/scehr-qvk60", "eprint_id": 15497, "eprint_status": "archive", "datestamp": "2023-08-21 20:50:49", "lastmod": "2023-10-19 14:30:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hinderks-J-R", "name": { "family": "Hinderks", "given": "J. R." } }, { "id": "Ade-P", "name": { "family": "Ade", "given": "P." } }, { "id": "Bock-J-J", "name": { "family": "Bock", "given": "J." }, "orcid": "0000-0002-5710-5212" }, { "id": "Bowden-M", "name": { "family": "Bowden", "given": "M." } }, { "id": "Brown-M-L", "name": { "family": "Brown", "given": "M. L." } }, { "id": "Cahill-G", "name": { "family": "Cahill", "given": "G." } }, { "id": "Carlstrom-J-E", "name": { "family": "Carlstrom", "given": "J. E." }, "orcid": "0000-0002-2044-7665" }, { "id": "Castro-P-G", "name": { "family": "Castro", "given": "P. G." } }, { "id": "Church-S", "name": { "family": "Church", "given": "S." } }, { "id": "Culverhouse-T", "name": { "family": "Culverhouse", "given": "T." } }, { "id": "Friedman-R", "name": { "family": "Friedman", "given": "R." } }, { "id": "Ganga-K", "name": { "family": "Ganga", "given": "K." } }, { "id": "Gear-W-K", "name": { "family": "Gear", "given": "W. K." } }, { "id": "Gupta-S", "name": { "family": "Gupta", "given": "S." } }, { "id": "Harris-J", "name": { "family": "Harris", "given": "J." } }, { "id": "Haynes-V", "name": { "family": "Haynes", "given": "V." } }, { "id": "Keating-B-G", "name": { "family": "Keating", "given": "B. G." } }, { "id": "Kovac-J", "name": { "family": "Kovac", "given": "J." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E." }, "orcid": "0000-0001-6196-5162" }, { "id": "Lange-A-E", "name": { "family": "Lange", "given": "A. E." } }, { "id": "Leitch-E", "name": { "family": "Leitch", "given": "E." } }, { "id": "Mallie-O-E", "name": { "family": "Mallie", "given": "O. E." } }, { "id": "Melhuish-S", "name": { "family": "Melhuish", "given": "S." } }, { "id": "Memari-Y", "name": { "family": "Memari", "given": "Y." } }, { "id": "Murphy-A", "name": { "family": "Murphy", "given": "A." } }, { "id": "Orlando-A", "name": { "family": "Orlando", "given": "A." } }, { "id": "Schwarz-R", "name": { "family": "Schwarz", "given": "R." } }, { "id": "O'Sullivan-C", "name": { "family": "O'Sullivan", "given": "C." } }, { "id": "Piccirillo-L", "name": { "family": "Piccirillo", "given": "L." } }, { "id": "Pryke-C", "name": { "family": "Pryke", "given": "C." } }, { "id": "Rajguru-N", "name": { "family": "Rajguru", "given": "N." } }, { "id": "Rusholme-B", "name": { "family": "Rusholme", "given": "B." }, "orcid": "0000-0001-7648-4142" }, { "id": "Taylor-A-N", "name": { "family": "Taylor", "given": "A. N." } }, { "id": "Thompson-K-L", "name": { "family": "Thompson", "given": "K. L." } }, { "id": "Tucker-C", "name": { "family": "Tucker", "given": "C." } }, { "id": "Turner-A-H", "name": { "family": "Turner", "given": "A. H." } }, { "id": "Wu-E-Y-S", "name": { "family": "Wu", "given": "E. Y. S." } }, { "id": "Zemcov-M", "name": { "family": "Zemcov", "given": "M." }, "orcid": "0000-0001-8253-1451" } ] }, "title": "QUaD: A High-Resolution Cosmic Microwave Background Polarimeter", "ispublished": "pub", "full_text_status": "public", "keywords": "cosmic microwave background; instrumentation: polarimeters", "note": "\u00a9 2009 The American Astronomical Society. Received 2008 May 14; accepted 2008 October 2; published 2009 February 24. We acknowledge the staff of the Amundsen-Scott South Pole\nStation and all involved in the United States Antarctic Program\nfor their superb support during the construction and operation\nof this experiment. Special thanks go to our brave winter-over\nscientist Robert Schwarzwho has spent three consecutivewinter\nseasons with the QUaD. We also acknowledge the tremendous\nefforts of the Stanford University Physics Department machine\nshop in the construction of the focal plane assembly. J.R.H.\nthanks David Chuss for useful comments on this draft and\nSimon Radford for providing the 350 \u03bcm tipper data. QUaD is\nfunded by the National Science Foundation in the USA, through\ngrants AST-0096778,ANT-0338138,ANT-0338335, and ANT-\n0338238, by the UK Science and technology Facilities Council\n(STFC) and its predecessor the Particle Physics and Astronomy Research Council (PPARC), and by the Science Foundation\nIreland.\nJ.R.H. acknowledges the support of an NSF Graduate Research\nFellowship, a Stanford Graduate Fellowship, and a\nNASA Postdoctoral Fellowship. M.L.B. and A.O. acknowledge\nthe award of PPARC fellowships. P.G.C. is funded by\nthe Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia. S.E.C. acknowledges\nsupport from a Stanford Terman Fellowship. J.M.K.\nacknowledges support from a John B. and Nelly L. Kilroy\nFoundation Fellowship. C.P. and J.E.C. acknowledge partial\nsupport from the Kavli Institute for Cosmological Physics\nthrough the grant NSF PHY-0114422. E.Y.W. acknowledges\nreceipt of an NDSEG fellowship. M.Z. acknowledges the support\nof a NASA Postdoctoral Fellowship. This research was\nsupported in part by appointments to the NASA Postdoctoral\nProgram at the Goddard Space Flight Center (J.R.H.) and the\nJet Propulsion Laboratory (M.Z.), administered by Oak Ridge\nAssociated Universities through a contract with NASA.\n\nPublished - Hinderks2009p66310.10880004-637X69221221.pdf
", "abstract": "We describe the QUaD experiment, a millimeter-wavelength polarimeter designed to observe the cosmic microwave background (CMB) from a site at the South Pole. The experiment comprises a 2.64 m Cassegrain telescope equipped with a cryogenically cooled receiver containing an array of 62 polarization-sensitive bolometers. The focal plane contains pixels at two different frequency bands, 100 GHz and 150 GHz, with angular resolutions of 5' and 35, respectively. The high angular resolution allows observation of CMB temperature and polarization anisotropies over a wide range of scales. The instrument commenced operation in early 2005 and collected science data during three successive Austral winter seasons of observation.", "date": "2009-02-24", "date_type": "published", "publication": "Astrophysical Journal", "volume": "692", "number": "2", "publisher": "American Astronomical Society", "pagerange": "1221-1246", "id_number": "CaltechAUTHORS:20090831-141710879", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090831-141710879", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-0096778" }, { "agency": "NSF", "grant_number": "ANT-0338138" }, { "agency": "NSF", "grant_number": "ANT-0338335" }, { "agency": "NSF", "grant_number": "ANT-0338238" }, { "agency": "Science and Technology Facilities Council (STFC)" }, { "agency": "Particle Physics and Astronomy Research Council (PPARC)" }, { "agency": "Science Foundation Ireland" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Stanford Graduate Fellowship" }, { "agency": "NASA Postdoctoral Fellowship" }, { "agency": "Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia" }, { "agency": "Stanford Terman Fellowship" }, { "agency": "John B. and Nelly L. Kilroy Foundation" }, { "agency": "NSF", "grant_number": "PHY-0114422" }, { "agency": "Kavli Institute for Cosmological Physics" } ] }, "doi": "10.1088/0004-637X/692/2/1221", "primary_object": { "basename": "Hinderks2009p66310.10880004-637X69221221.pdf", "url": "https://authors.library.caltech.edu/records/scehr-qvk60/files/Hinderks2009p66310.10880004-637X69221221.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Hinderks, J. R.; Ade, P.; et el." }, { "id": "https://authors.library.caltech.edu/records/70yxa-94k83", "eprint_id": 15354, "eprint_status": "archive", "datestamp": "2023-08-21 20:50:06", "lastmod": "2023-10-18 21:42:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Willman-B", "name": { "family": "Willman", "given": "Beth" }, "orcid": "0000-0003-2892-9906" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Strigari-L-E", "name": { "family": "Strigari", "given": "Louis E." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Law-D-R", "name": { "family": "Law", "given": "David R." }, "orcid": "0000-0002-9402-186X" }, { "id": "Strader-J", "name": { "family": "Strader", "given": "Jay" }, "orcid": "0000-0002-1468-9668" } ] }, "title": "The Least-Luminous Galaxy: Spectroscopy of the Milky Way Satellite Segue 1", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: dwarf; galaxies: individual (Segue 1); galaxies: kinematics and dynamics; Local Group", "note": "\u00a9 2009. The American Astronomical Society. \n\nReceived 2008 August 3, accepted for publication 2008 October 10. \nPublished 2009 February 24. \n\nWe acknowledge and appreciate conversations regarding this work with James Bullock, Raja Guhathakurta, Manoj Kaplinghat, Shane Walsh, and Adi Zolotov. E.N.K. acknowledges the support of an NSF Graduate Research Fellowship. J.D.S. gratefully acknowledges the support of a Millikan Fellowship provided by Caltech. L.E.S. by NASA through Hubble Fellowship grant HF-01225.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.\n\nPublished - Geha2009p66410.10880004-637X69221464.pdf
Accepted Version - 0809.2781.pdf
", "abstract": "We present Keck/DEIMOS spectroscopy of Segue 1, an ultra-low-luminosity (M_V = \u20131.5^(+0.6)_(\u20130.8)) Milky Way satellite companion. While the combined size and luminosity of Segue 1 are consistent with either a globular cluster or a dwarf galaxy, we present spectroscopic evidence that this object is a dark matter-dominated dwarf galaxy. We identify 24 stars as members of Segue 1 with a mean heliocentric recession velocity of 206 \u00b1 1.3 km s^(\u20131). Although Segue 1 spatially overlaps the leading arm of the Sagittarius stream, its velocity is 100 km s^(\u20131) different from that predicted for recent Sagittarius tidal debris at this position. We measure an internal velocity dispersion of 4.3 \u00b1 1.2 km s^(\u20131). Under the assumption that these stars are gravitationally bound and in dynamical equilibrium, we infer a total mass of 4.5^(+4.7)_(\u20132.5) \u00d7 10^5 M_\u2609 in the mass-follow-light case; using a two-component maximum-likelihood model, we determine a mass within 50 pc of 8.7^(+13)_(\u20135.2) \u00d7 10^5 M_\u2609 . These imply mass-to-light (M/L) ratios of ln(M/L_V ) = 7.2^(+1.1)_(\u20131.2) (M/L_V = 1320^(+2680)_(\u2013940)) and M/L_V = 2440^(+1580)_(\u20131775), respectively. The error distribution of the M/L is nearly lognormal, thus Segue 1 is dark matter-dominated at a high significance. Although we cannot rule out the possibility that Segue 1 has been tidally disrupted, we do not find kinematic evidence supporting tidal effects. Using spectral synthesis modeling, we derive a metallicity for the single red giant branch star in our sample of [Fe/H] = \u20133.3 \u00b1 0.2 dex. Finally, we discuss the prospects for detecting gamma rays from annihilation of dark matter particles and show that Segue 1 is the most promising satellite for indirect dark matter detection. We conclude that Segue 1 is the least luminous of the ultra-faint galaxies recently discovered around the Milky Way, and is thus the least-luminous known galaxy.", "date": "2009-02-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "692", "number": "2", "publisher": "American Astronomical Society", "pagerange": "1464-1475", "id_number": "CaltechAUTHORS:20090827-110153354", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090827-110153354", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Caltech Millikan Fellowship" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-01225.01" }, { "agency": "NASA", "grant_number": "NAS 5-26555" } ] }, "doi": "10.1088/0004-637X/692/2/1464", "primary_object": { "basename": "Geha2009p66410.10880004-637X69221464.pdf", "url": "https://authors.library.caltech.edu/records/70yxa-94k83/files/Geha2009p66410.10880004-637X69221464.pdf" }, "related_objects": [ { "basename": "0809.2781.pdf", "url": "https://authors.library.caltech.edu/records/70yxa-94k83/files/0809.2781.pdf" } ], "resource_type": "article", "pub_year": "2009", "author_list": "Geha, Marla; Willman, Beth; et el." }, { "id": "https://authors.library.caltech.edu/records/h1sht-bxm92", "eprint_id": 95409, "eprint_status": "archive", "datestamp": "2023-08-22 13:34:33", "lastmod": "2023-10-20 20:12:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sawicki-M", "name": { "family": "Sawicki", "given": "Marcin" }, "orcid": "0000-0002-7712-7857" }, { "id": "Lemaux-B-C", "name": { "family": "Lemaux", "given": "Brian C." }, "orcid": "0000-0002-1428-7036" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Konidaris-N-P", "name": { "family": "Konidaris", "given": "Nicholas P." }, "orcid": "0000-0003-1905-2815" }, { "id": "Martin-C-L", "name": { "family": "Martin", "given": "Crystal L." } }, { "id": "Cooper-M-C", "name": { "family": "Cooper", "given": "Michael C." }, "orcid": "0000-0003-1371-6019" }, { "id": "Koo-David-C", "name": { "family": "Koo", "given": "David C." }, "orcid": "0000-0003-3385-6799" }, { "id": "Newman-J-A", "name": { "family": "Newman", "given": "Jeffrey A." }, "orcid": "0000-0001-8684-2222" }, { "id": "Weiner-B-J", "name": { "family": "Weiner", "given": "Benjamin J." } } ] }, "title": "The DEEP2 Redshift Survey: Ly\u03b1 Emitters in the Spectroscopic Database", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: evolution; galaxies: formation; galaxies: high-redshift; techniques: spectroscopic", "note": "\u00a9 2008. The American Astronomical Society. \n\nReceived 2007 October 12; accepted 2008 July 11. \n\nBased on data obtained at theW.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.\n\nWe wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community; we are most fortunate to have the opportunity to conduct observations from this mountain. We thank Alison Coil and Sandy Faber for useful discussions, and all the members of the DEEP2 team for their contributions to making possible the data used here. We thank Jerzy Sawicki for a careful reading of the manuscript and many useful comments. Parts of the analysis presented here made use of the Perl Data Language (PDL) that has been developed by K. Glazebrook, J. Brinchmann, J. Cerney, C. DeForest, D. Hunt, T. Jenness, T. Luka, R. Schwebel, and C. Soeller, which can be obtained from http://pdl.perl.org. PDL provides a high-level numerical functionality for the Perl scripting language (Glazebrook & Economou, 1997). This work was supported in part by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada, NSF grants AST 00-71198 and AST 05-07483 funding from the NASA/STScI and the Canadian Space Agency, and by the David and Lucile Packard Foundation.\n\nPublished - Sawicki_2008_ApJ_687_884.pdf
Accepted Version - 0807.1890.pdf
", "abstract": "We present the first results of a search for Ly\u03b1 emitters (LAEs) in the DEEP2 spectroscopic database that uses a search technique that is different from but complementary to traditional narrowband imaging surveys. We have visually inspected ~20% of the available DEEP2 spectroscopic data and have found nine high-quality LAEs with clearly asymmetric line profiles and an additional 10 objects of lower quality, some of which may also be LAEs. Our survey is most sensitive to LAEs at z = 4.4\u20134.9 and that is indeed where all but one of our high-quality objects are found. We find the number density of our spectroscopically discovered LAEs to be consistent with those found in narrowband imaging searches. The combined, averaged spectrum of our nine high-quality objects is well fit by a two-component model, with a second, lower amplitude component redshifted by ~420 km s^(\u22121) with respect to the primary Ly\u03b1 line, consistent with large-scale outflows from these objects. We conclude by discussing the advantages and future prospects of blank-sky spectroscopic surveys for high-z LAEs.", "date": "2008-11-10", "date_type": "published", "publication": "Astrophysical Journal", "volume": "687", "number": "2", "publisher": "American Astronomical Society", "pagerange": "884-898", "id_number": "CaltechAUTHORS:20190510-120908504", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120908504", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "NSF", "grant_number": "AST 00-71198" }, { "agency": "NSF", "grant_number": "AST 05-07483" }, { "agency": "NASA" }, { "agency": "Canadian Space Agency (CSA)" }, { "agency": "David and Lucile Packard Foundation" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1086/591779", "primary_object": { "basename": "Sawicki_2008_ApJ_687_884.pdf", "url": "https://authors.library.caltech.edu/records/h1sht-bxm92/files/Sawicki_2008_ApJ_687_884.pdf" }, "related_objects": [ { "basename": "0807.1890.pdf", "url": "https://authors.library.caltech.edu/records/h1sht-bxm92/files/0807.1890.pdf" } ], "resource_type": "article", "pub_year": "2008", "author_list": "Sawicki, Marcin; Lemaux, Brian C.; et el." }, { "id": "https://authors.library.caltech.edu/records/akfh3-62z49", "eprint_id": 13467, "eprint_status": "archive", "datestamp": "2023-08-22 13:06:58", "lastmod": "2023-10-17 23:55:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Simon-J-D", "name": { "family": "Simon", "given": "Joshua D." } }, { "id": "Geha-M-C", "name": { "family": "Geha", "given": "Marla" }, "orcid": "0000-0002-7007-9725" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Frebel-A", "name": { "family": "Frebel", "given": "Anna" }, "orcid": "0000-0002-2139-7145" } ] }, "title": "Uncovering extremely metal-poor stars in the Milky Way's ultrafaint dwarf spheroidal satellite galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: abundances; galaxies: dwarf", "note": "\u00a9 2008 The American Astronomical Society. \n\nReceived 2008 May 2; accepted 2008 August 13; published 2008 September 5. \n\nData herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nWe thank Jennifer Johnson, Kim Venn, and the referee for valuable advice. We acknowledge National Science Foundation grants AST 03-07966 and AST 06-07852 and NASA/STScI grants GO-10265.02 and GO-10134.02. E. N. K. is supported by a NSF Graduate Research Fellowship. A. F. acknowledges support through the W. J. McDonald Fellowship of the McDonald Observatory.\n\nPublished - KIRapjl08.pdf
Accepted Version - 0807.1925.pdf
", "abstract": "We present new metallicity measurements for 298 individual red giant branch stars in eight of the least luminous dwarf spheroidal galaxies (dSphs) in the Milky Way (MW) system. Our technique is based on medium-resolution Keck DEIMOS spectroscopy coupled with spectral synthesis. We present the first spectroscopic metallicities at [Fe/H] < -3.0 of stars in a dwarf galaxy, with individual stellar metallicities as low as [Fe/H] = -3.3. Because our [Fe/H] measurements are not tied to empirical metallicity calibrators and are sensitive to arbitrarily low metallicities, we are able to probe this extremely metal-poor regime accurately. The metallicity distribution of stars in these dSphs is similar to the MW halo at the metal-poor end. We also demonstrate that the luminosity-metallicity relation previously seen in more luminous dSph galaxies (Mv = -13.4 to -8.8) extends smoothly down to an V absolute magnitude of Mv = -3.7. The discovery of extremely metal-poor stars in dSphs lends support to the \u039bCDM galaxy assembly paradigm wherein dwarf galaxies dissolve to form the stellar halo of the MW.", "date": "2008-09-20", "date_type": "published", "publication": "Astrophysical Journal", "volume": "685", "number": "1", "publisher": "American Astronomical Society", "pagerange": "L43-L46", "id_number": "CaltechAUTHORS:KIRapjl08", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:KIRapjl08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST 03-07966" }, { "agency": "NSF", "grant_number": "AST 06-07852" }, { "agency": "NASA", "grant_number": "GO-10265.02" }, { "agency": "NASA", "grant_number": "GO-10134.02" }, { "agency": "McDonald Observatory" }, { "agency": "W. M. Keck Foundation" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1086/592432", "primary_object": { "basename": "0807.1925.pdf", "url": "https://authors.library.caltech.edu/records/akfh3-62z49/files/0807.1925.pdf" }, "related_objects": [ { "basename": "KIRapjl08.pdf", "url": "https://authors.library.caltech.edu/records/akfh3-62z49/files/KIRapjl08.pdf" } ], "resource_type": "article", "pub_year": "2008", "author_list": "Kirby, Evan N.; Simon, Joshua D.; et el." }, { "id": "https://authors.library.caltech.edu/records/ar5xe-6hv93", "eprint_id": 95414, "eprint_status": "archive", "datestamp": "2023-08-22 12:41:13", "lastmod": "2023-10-20 20:12:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Sneden-C", "name": { "family": "Sneden", "given": "Christopher" }, "orcid": "0000-0002-3456-5929" } ] }, "title": "Metallicity and Alpha\u2010Element Abundance Measurement in Red Giant Stars from Medium\u2010Resolution Spectra", "ispublished": "pub", "full_text_status": "public", "keywords": "globular clusters: individual (M13 M15 M71 M79 NGC 2419 NGC 7006 NGC 7492); stars: abundances", "note": "\u00a9 2008. The American Astronomical Society. \n\nReceived 2008 February 22; accepted 2008 April 21. \n\nThe authors gratefully acknowledge P. B. Stetson for providing photometry of all of the spectroscopic targets in this article and J. Simon and M. Geha for providing the DEIMOS observations of M79 and NGC 2419. We thank R. Kraft, D. Lai, C. Rockosi, I. Ivans, and M. Shetrone for extremely useful discussions. \n\nWe acknowledge National Science Foundation grants AST 06-07708, AST 03-07966, and AST 06-07852 and NASA/STScI grants GO-10265.02 and GO-10134.02. E. N. K. is supported by a NSF Graduate Research Fellowship. Data herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The analysis pipeline used to reduce the DEIMOS data was developed at UC Berkeley with support from NSF grant AST 00-71048. \n\nFacilities: Keck:II(DEIMOS)\n\nPublished - Kirby_2008_ApJ_682_1217.pdf
Accepted Version - 0804.3590
", "abstract": "We present a technique that applies spectral synthesis to medium-resolution spectroscopy (MRS; R ~ 6000) in the red (6300 \u00c5 < \u03bb < 9100 \u00c5) to measure [Fe/H] and [\u03b1/Fe] of individual red giant stars over a wide metallicity range. We apply our technique to 264 red giant stars in seven Galactic globular clusters and demonstrate that it reproduces the metallicities and \u03b1-enhancements derived from high-resolution spectroscopy (HRS). The MRS technique excludes the three Ca II triplet lines and instead relies on a plethora of weaker lines. Unlike empirical metallicity estimators, such as the equivalent width of the Ca II triplet, the synthetic method presented here is applicable over an arbitrarily wide metallicity range and is independent of assumptions about the \u03b1-enhancement. Estimates of cluster mean [Fe/H] from different HRS studies show typical scatter of ~0.1 dex but can be larger than 0.2 dex for metal-rich clusters. The scatter in HRS abundance estimates among individual stars in a given cluster is also comparable to 0.1 dex. By comparison, the scatter among MRS [Fe/H] estimates of individual stars in a given cluster is ~0.1 dex for most clusters but 0.17 dex for the most metal-rich cluster, M71 (\u3008 [ Fe/H ] \u3009 = \u2212 0.8). A star-by-star comparison of HRS versus MRS [\u03b1/Fe] estimates indicates that the precision in [ \u03b1/Fe ]_(MRS) is 0.05 dex. The errors in [ Fe/H ]_(MRS) and [ \u03b1/Fe ]_(MRS) increase beyond 0.25 dex only below signal-to-noise ratios of 20 \u00c5^(\u22121), which is typical for existing MRS of the red giant stars in Leo I, one of the most distant Milky Way satellites (250 kpc).", "date": "2008-08-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "682", "number": "2", "publisher": "American Astronomical Society", "pagerange": "1217-1233", "id_number": "CaltechAUTHORS:20190510-120909003", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120909003", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST 06-07708" }, { "agency": "NSF", "grant_number": "AST 03-07966" }, { "agency": "NSF", "grant_number": "AST 06-07852" }, { "agency": "NASA", "grant_number": "GO-10265.02" }, { "agency": "NASA", "grant_number": "GO-10134.02" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "W. M. Keck Foundation" }, { "agency": "NSF", "grant_number": "AST 00-71048" } ] }, "doi": "10.1086/589627", "primary_object": { "basename": "0804.3590", "url": "https://authors.library.caltech.edu/records/ar5xe-6hv93/files/0804.3590" }, "related_objects": [ { "basename": "Kirby_2008_ApJ_682_1217.pdf", "url": "https://authors.library.caltech.edu/records/ar5xe-6hv93/files/Kirby_2008_ApJ_682_1217.pdf" } ], "resource_type": "article", "pub_year": "2008", "author_list": "Kirby, Evan N.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/f7afc-ahr21", "eprint_id": 17770, "eprint_status": "archive", "datestamp": "2023-08-22 09:01:20", "lastmod": "2023-10-20 00:13:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Konidaris-N-P", "name": { "family": "Konidaris", "given": "N. P." }, "orcid": "0000-0003-1905-2815" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "P." }, "orcid": "0000-0001-8867-4234" }, { "id": "Bundy-K-A", "name": { "family": "Bundy", "given": "K." }, "orcid": "0000-0001-9742-3138" }, { "id": "Coil-A-L", "name": { "family": "Coil", "given": "A. L." } }, { "id": "Conselice-C-J", "name": { "family": "Conselice", "given": "C. J." }, "orcid": "0000-0003-1949-7638" }, { "id": "Cooper-M-C", "name": { "family": "Cooper", "given": "M. C." }, "orcid": "0000-0003-1371-6019" }, { "id": "Eisenhardt-P-R-M", "name": { "family": "Eisenhardt", "given": "P. R. M." } }, { "id": "Huang-J-S", "name": { "family": "Huang", "given": "J.-S." } }, { "id": "Ivison-R-J", "name": { "family": "Ivison", "given": "R. J." }, "orcid": "0000-0001-5118-1313" }, { "id": "Kassin-S-A", "name": { "family": "Kassin", "given": "S. A." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E. N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Lotz-J-M", "name": { "family": "Lotz", "given": "J. M." }, "orcid": "0000-0003-3130-5643" }, { "id": "Newman-J-A", "name": { "family": "Newman", "given": "J. A." }, "orcid": "0000-0001-8684-2222" }, { "id": "Noeske-K-G", "name": { "family": "Noeske", "given": "K. G." } }, { "id": "Rich-R-M", "name": { "family": "Rich", "given": "R. M." }, "orcid": "0000-0003-0427-8387" }, { "id": "Small-T-A", "name": { "family": "Small", "given": "T. A." } }, { "id": "Willmer-C-N-A", "name": { "family": "Willmer", "given": "C. N. A." } }, { "id": "Willner-S-P", "name": { "family": "Willner", "given": "S. P." }, "orcid": "0000-0002-9895-5758" } ] }, "title": "AEGIS: Galaxy Spectral Energy Distributions from the X-Ray to Radio", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies : evolution; galaxies : general; infrared : galaxies; radio continuum : galaxies; ultraviolet : galaxies; X-rays : galaxies", "note": "\u00a9 2007 The American Astronomical Society. \n\nReceived 2006 June 7; accepted 2006 September 15; published 2007 April 11. \n\nThe authors wish to thank D. C. Koo for conceiving and helping with this Letter and the anonymous referee for valuable comments. N. P. K. and J. M. L. are supported by NASA grant HST-GO-10314.18-A. A. L. C. and J. A. N. are supported by NASA through Hubble Fellowship grants HF-01182.01-A and HF-01182.01-A. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\n\nPublished - KONapjl07.pdf
Submitted - 0608378.pdf
", "abstract": "The All-Wavelength Extended Groth Strip International Survey (AEGIS) team presents broadband spectral energy distributions (SEDs), from X-ray to radio wavelengths, for 71 galaxies spanning the redshift range 0.55-1.16 ( ~ 0.7). Galaxies with secure redshifts are selected from a small (22 arcmin^2) subsection of the Keck/DEIMOS Galaxy Redshift Survey in the Extended Groth Strip field that has also been targeted for deep panchromatic imaging by ultraviolet (120-250 nm), optical (360-900 nm), optical/near-infrared (440-1600 nm), near-infrared (1200-2200 nm), mid/far-infrared (3.6-70 \u03bcm), and radio (6-20 cm). A typical galaxy in our sample is M_B = -19.82. The ultraviolet to mid-infrared portion of their SEDs are found to be bracketed by two stellar-only model SEDs: (1) an early burst followed by passive evolution and (2) a constant star formation rate since early times. This suggests that few of these galaxies are undergoing major starbursts. Approximately half the galaxies show a mid- to far-infrared excess relative to the model SEDs, consistent with thermal emission from interstellar dust. Two objects have power-law SEDs, indicating that they are dominated by active galactic nuclei; both are detected in X-rays. SEDs, from the ultraviolet to the infrared, follow expected trends: redder SEDs are associated with red U - B, early-type morphology, and low [O II] emission, and vice versa for blue SEDs.", "date": "2007-05-01", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "660", "number": "1", "publisher": "American Astronomical Society", "pagerange": "L7-L10", "id_number": "CaltechAUTHORS:20100318-100220460", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100318-100220460", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "HST-GO-10314.18-A" }, { "agency": "NASA Hubble Fellowship", "grant_number": "HF-01182.01-A" } ] }, "doi": "10.1086/517929", "primary_object": { "basename": "0608378.pdf", "url": "https://authors.library.caltech.edu/records/f7afc-ahr21/files/0608378.pdf" }, "related_objects": [ { "basename": "KONapjl07.pdf", "url": "https://authors.library.caltech.edu/records/f7afc-ahr21/files/KONapjl07.pdf" } ], "resource_type": "article", "pub_year": "2007", "author_list": "Konidaris, N. P.; Guhathakurta, P.; et el." }, { "id": "https://authors.library.caltech.edu/records/a1avn-zc198", "eprint_id": 95411, "eprint_status": "archive", "datestamp": "2023-08-22 09:02:01", "lastmod": "2023-10-20 20:12:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "Evan N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "Puragra" }, "orcid": "0000-0001-8867-4234" }, { "id": "Faber-S-M", "name": { "family": "Faber", "given": "S. M." }, "orcid": "0000-0003-4996-214X" }, { "id": "Koo-David-C", "name": { "family": "Koo", "given": "David C." }, "orcid": "0000-0003-3385-6799" }, { "id": "Weiner-B-J", "name": { "family": "Weiner", "given": "Benjamin J." } }, { "id": "Cooper-M-C", "name": { "family": "Cooper", "given": "Michael C." }, "orcid": "0000-0003-1371-6019" } ] }, "title": "DEEP2 Galaxy Redshift Survey: Redshift Identification of Single\u2010Line Emission Galaxies", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: distances and redshifts; line: identification", "note": "\u00a9 2007. The American Astronomical Society. \n\nReceived 2006 December 28; accepted 2007 January 29. \n\nWe thank the referee for a helpful report. We also thank J. A. Newman for providing statistics on repeat observations, and we thank C. M. Pierce for carefully reading a draft of this paper. We acknowledge National Science Foundation grants AST 05-07483 and AST 05-07428. E. N. K. is supported by a NSF Graduate Research Fellowship. Data herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.\n\nPublished - Kirby_2007_ApJ_660_62.pdf
Accepted Version - 0701747.pdf
", "abstract": "We present two methods for determining spectroscopic redshifts of galaxies in the DEEP2 survey which display only one identifiable feature, an emission line, in the observed spectrum (\"single-line galaxies\"). First, we assume each single line is one of the four brightest lines accessible to DEEP2: H\u03b1, [O III] \u03bb5007, H\u03b2, or [O II] \u03bb3727. Then, we supplement spectral information with BRI photometry. The first method, parameter-space proximity (PSP), calculates the distance of a single-line galaxy to galaxies of known redshift in (B - R), (R - I), R, \u03bb_(observed) parameter space. The second method is an artificial neural network (ANN). Prior information, such as allowable line widths and ratios, rules out one or more of the four lines for some galaxies in both methods. Based on analyses of evaluation sets, both methods are nearly perfect at identifying blended [O II] doublets. Of the lines identified as H\u03b1 in the PSP and ANN methods, 91.4% and 94.2%, respectively, are accurate. Although the methods are not this accurate at discriminating between [O III] and H\u03b2, they can identify a single line as one of the two, and the ANN method in particular unambiguously identifies many [O III] lines. From a sample of 640 single-line spectra, the methods determine the identities of 401 (62.7%) and 472 (73.8%) single lines, respectively, at accuracies similar to those found in the evaluation sets.", "date": "2007-05-01", "date_type": "published", "publication": "Astrophysical Journal", "volume": "660", "number": "1", "publisher": "American Astronomical Society", "pagerange": "62-71", "id_number": "CaltechAUTHORS:20190510-120908727", "issn": "0004-637X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190510-120908727", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST 05-07483" }, { "agency": "NSF", "grant_number": "AST 05-07428" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "W. M. Keck Foundation" } ] }, "doi": "10.1086/513464", "primary_object": { "basename": "0701747.pdf", "url": "https://authors.library.caltech.edu/records/a1avn-zc198/files/0701747.pdf" }, "related_objects": [ { "basename": "Kirby_2007_ApJ_660_62.pdf", "url": "https://authors.library.caltech.edu/records/a1avn-zc198/files/Kirby_2007_ApJ_660_62.pdf" } ], "resource_type": "article", "pub_year": "2007", "author_list": "Kirby, Evan N.; Guhathakurta, Puragra; et el." }, { "id": "https://authors.library.caltech.edu/records/2f3e3-wjh52", "eprint_id": 16631, "eprint_status": "archive", "datestamp": "2023-08-22 09:01:04", "lastmod": "2023-10-19 22:26:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Davis-M-E-Astro", "name": { "family": "Davis", "given": "M." } }, { "id": "Guhathakurta-P", "name": { "family": "Guhathakurta", "given": "P." }, "orcid": "0000-0001-8867-4234" }, { "id": "Konidaris-N-P", "name": { "family": "Konidaris", "given": "N. P." }, "orcid": "0000-0003-1905-2815" }, { "id": "Newman-J-A", "name": { "family": "Newman", "given": "J. A." }, "orcid": "0000-0001-8684-2222" }, { "id": "Ashby-M-L-N", "name": { "family": "Ashby", "given": "M. L. N." }, "orcid": "0000-0002-3993-0745" }, { "id": "Biggs-A-D", "name": { "family": "Biggs", "given": "A. D." }, "orcid": "0000-0002-1117-9961" }, { "id": "Barmby-P", "name": { "family": "Barmby", "given": "P." }, "orcid": "0000-0003-2767-0090" }, { "id": "Bundy-K-A", "name": { "family": "Bundy", "given": "K." }, "orcid": "0000-0001-9742-3138" }, { "id": "Chapman-S-C", "name": { "family": "Chapman", "given": "S. C." } }, { "id": "Coil-A-L", "name": { "family": "Coil", "given": "A. L." } }, { "id": "Conselice-C-J", "name": { "family": "Conselice", "given": "C. J." }, "orcid": "0000-0003-1949-7638" }, { "id": "Cooper-M-C", "name": { "family": "Cooper", "given": "M. C." }, "orcid": "0000-0003-1371-6019" }, { "id": "Croton-D-J", "name": { "family": "Croton", "given": "D. J." }, "orcid": "0000-0002-5009-512X" }, { "id": "Eisenhardt-P-R-M", "name": { "family": "Eisenhardt", "given": "P. R. M." } }, { "id": "Ellis-R-S", "name": { "family": "Ellis", "given": "R. S." }, "orcid": "0000-0001-7782-7071" }, { "id": "Faber-S-M", "name": { "family": "Faber", "given": "S. M." }, "orcid": "0000-0003-4996-214X" }, { "id": "Fang-T", "name": { "family": "Fang", "given": "T." } }, { "id": "Fazio-G-G", "name": { "family": "Fazio", "given": "G. G." }, "orcid": "0000-0002-0670-0708" }, { "id": "Georgakakis-A", "name": { "family": "Georgakakis", "given": "A." } }, { "id": "Gerke-B-F", "name": { "family": "Gerke", "given": "B. F." } }, { "id": "Goss-W-M", "name": { "family": "Goss", "given": "W. M." } }, { "id": "Gwyn-S-D-J", "name": { "family": "Gwyn", "given": "S." }, "orcid": "0000-0001-8221-8406" }, { "id": "Harker-J", "name": { "family": "Harker", "given": "J." } }, { "id": "Hopkins-A-M", "name": { "family": "Hopkins", "given": "A. M." }, "orcid": "0000-0002-6097-2747" }, { "id": "Huang-J-S", "name": { "family": "Huang", "given": "J.-S." } }, { "id": "Ivison-R-J", "name": { "family": "Ivison", "given": "R. J." }, "orcid": "0000-0001-5118-1313" }, { "id": "Kassin-S-A", "name": { "family": "Kassin", "given": "S. A." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E. N." }, "orcid": "0000-0001-6196-5162" }, { "id": "Koekemoer-A-M", "name": { "family": "Koekemoer", "given": "A. M." }, "orcid": "0000-0002-6610-2048" }, { "id": "Koo-David-C", "name": { "family": "Koo", "given": "D. C." }, "orcid": "0000-0003-3385-6799" }, { "id": "Laird-E-S", "name": { "family": "Laird", "given": "E. S." } }, { "id": "Le-Floc'h-Emeric", "name": { "family": "Le Floc'h", "given": "E." } }, { "id": "Lin-Lin", "name": { "family": "Lin", "given": "L." }, "orcid": "0000-0001-6860-9566" }, { "id": "Lotz-J-M", "name": { "family": "Lotz", "given": "J. M." }, "orcid": "0000-0003-3130-5643" }, { "id": "Marshall-P-J", "name": { "family": "Marshall", "given": "P. J." } }, { "id": "Martin-D-Christopher", "name": { "family": "Martin", "given": "D. C." }, "orcid": "0000-0002-8650-1644" }, { "id": "Metevier-A-J", "name": { "family": "Metevier", "given": "A. J." } }, { "id": "Moustakas-L-A", "name": { "family": "Moustakas", "given": "L. A." }, "orcid": "0000-0003-3030-2360" }, { "id": "Nandra-K", "name": { "family": "Nandra", "given": "K." }, "orcid": "0000-0002-7150-9192" }, { "id": "Noeske-K-G", "name": { "family": "Noeske", "given": "K. G." } }, { "id": "Papovich-C", "name": { "family": "Papovich", "given": "C." }, "orcid": "0000-0001-7503-8482" }, { "id": "Phillips-A-C", "name": { "family": "Phillips", "given": "A. C." } }, { "id": "Rich-R-M", "name": { "family": "Rich", "given": "R. M." }, "orcid": "0000-0003-0427-8387" }, { "id": "Rieke-G-H", "name": { "family": "Rieke", "given": "G. H." }, "orcid": "0000-0003-2303-6519" }, { "id": "Rigopoulou-D", "name": { "family": "Rigopoulou", "given": "D." }, "orcid": "0000-0001-6854-7545" }, { "id": "Salim-S", "name": { "family": "Salim", "given": "S." }, "orcid": "0000-0003-2342-7501" }, { "id": "Schiminovich-D", "name": { "family": "Schiminovich", "given": "D." } }, { "id": "Simard-L", "name": { "family": "Simard", "given": "L." } }, { "id": "Smail-Ian-R", "name": { "family": "Smail", "given": "I." }, "orcid": "0000-0003-3037-257X" }, { "id": "Small-T-A", "name": { "family": "Small", "given": "T. A." } }, { "id": "Weiner-B-J", "name": { "family": "Weiner", "given": "B. J." } }, { "id": "Willmer-C-N-A", "name": { "family": "Willmer", "given": "C. N. A." } }, { "id": "Willner-S-P", "name": { "family": "Willner", "given": "S. P." }, "orcid": "0000-0002-9895-5758" }, { "id": "Wilson-G-W", "name": { "family": "Wilson", "given": "G." }, "orcid": "0000-0002-6572-7089" }, { "id": "Wright-E-L", "name": { "family": "Wright", "given": "E. L." }, "orcid": "0000-0001-5058-1593" }, { "id": "Yan-Renbin", "name": { "family": "Yan", "given": "R." } } ] }, "title": "The All-Wavelength Extended Groth Strip International Survey (AEGIS) Data Sets", "ispublished": "pub", "full_text_status": "public", "keywords": "galaxies: photometry; infrared: galaxies; radio continuum: galaxies; surveys; ultraviolet: galaxies; X-rays: galaxies", "note": "\u00a9 2007 American Astronomical Sociey. \n\nReceived 2006 June 23, accepted for publication 2007 March 8.\nPublished 2007 April 13. \n\nThis research has made use of NASA's Astrophysics Data System Bibliographic Services. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. A. L. C. and J. A. N. are supported by NASA through Hubble fellowship grants HF-01182 and HF-01165 awarded by STScI, which is operated by AURA, Inc., for NASA, under contract NAS 5-26555. J. M. L. acknowledges support from the NOAO Leo Goldberg Fellowship, NASA/STScI grants GO-10134 and AR-10675, NASA NAG5-11513 grant to P. Madau, and a Calspace grant to D. C. Koo. L. A. M.'s work was carried out at JPL/Caltech, under a contract with NASA. S. A. K. would like to thank Eddie Bergeron for assistance with reducing and calibrating the NICMOS data.\n\nPublished - DAVapjl07a.pdf
", "abstract": "In this the first of a series of Letters, we present a panchromatic data set in the Extended Groth Strip region of the sky. Our survey, the All-Wavelength Extended Groth Strip International Survey (AEGIS), aims to study the physical properties and evolutionary processes of galaxies at z ~ 1. It includes the following deep, wide-field imaging data sets: Chandra/ACIS X-ray, GALEX ultraviolet, CFHT/MegaCam Legacy Survey optical, CFHT/CFH12K optical, Hubble Space Telescope/ACS optical and NICMOS near-infrared, Palomar/WIRC near-infrared, Spitzer/IRAC mid-infrared, Spitzer/MIPS far-infrared, and VLA radio continuum. In addition, this region of the sky has been targeted for extensive spectroscopy using the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10 m telescope. Our survey is compared to other large multiwavelength surveys in terms of depth and sky coverage.", "date": "2007-05-01", "date_type": "published", "publication": "Astrophysical Journal Letters", "volume": "660", "number": "1", "publisher": "American Astronomical Society", "pagerange": "L1-L6", "id_number": "CaltechAUTHORS:20091109-151802988", "issn": "2041-8205", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091109-151802988", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "HF-01182" }, { "agency": "NASA", "grant_number": "HF-01165" }, { "agency": "NASA", "grant_number": "NAS 5-26555" }, { "agency": "National Optical Astronomy Observatory (NOAO)" }, { "agency": "NASA", "grant_number": "GO-10134" }, { "agency": "NASA", "grant_number": "AR-10675" }, { "agency": "NASA", "grant_number": "NAG5-11513" }, { "agency": "California Space Grant Consortium" } ] }, "local_group": { "items": [ { "id": "Space-Astrophysics-Laboratory" } ] }, "doi": "10.1086/517931", "primary_object": { "basename": "DAVapjl07a.pdf", "url": "https://authors.library.caltech.edu/records/2f3e3-wjh52/files/DAVapjl07a.pdf" }, "resource_type": "article", "pub_year": "2007", "author_list": "Davis, M.; Guhathakurta, P.; et el." }, { "id": "https://authors.library.caltech.edu/records/f0dey-n4290", "eprint_id": 100191, "eprint_status": "archive", "datestamp": "2023-08-22 03:26:49", "lastmod": "2023-10-18 19:09:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Murphy-J-A", "name": { "family": "Murphy", "given": "J. A." } }, { "id": "Gleeson-E", "name": { "family": "Gleeson", "given": "E." } }, { "id": "Cahill-G", "name": { "family": "Cahill", "given": "G." } }, { "id": "Lanigan-W", "name": { "family": "Lanigan", "given": "W." } }, { "id": "O'Sullivan-C", "name": { "family": "O'Sullivan", "given": "C." } }, { "id": "Cartwright-E", "name": { "family": "Cartwright", "given": "E." } }, { "id": "Church-S-E", "name": { "family": "Church", "given": "S. E." } }, { "id": "Hinderks-J", "name": { "family": "Hinderks", "given": "J." } }, { "id": "Kirby-E-N", "name": { "family": "Kirby", "given": "E." }, "orcid": "0000-0001-6196-5162" }, { "id": "Thompson-K", "name": { "family": "Thompson", "given": "K." } }, { "id": "Rusholme-B", "name": { "family": "Rusholme", "given": "B." }, "orcid": "0000-0001-7648-4142" }, { "id": "Gear-W-K", "name": { "family": "Gear", "given": "W. K." } }, { "id": "Maffei-B", "name": { "family": "Maffei", "given": "B." } }, { "id": "Ade-P-A-R", "name": { "family": "Ade", "given": "P. A. R." }, "orcid": "0000-0002-5127-0401" }, { "id": "Tucker-C-E", "name": { "family": "Tucker", "given": "C." } }, { "id": "Jones-B", "name": { "family": "Jones", "given": "B." } } ] }, "title": "Millimeter-Wave Profiled Corrugated Horns for the Quad Cosmic Background Polarization Experiment", "ispublished": "pub", "full_text_status": "restricted", "keywords": "profiled corrugated horn antennas; polarization; CMB", "note": "\u00a9 2005 Springer Science+Business Media, Inc. \n\nReceived 27 December 2004; First Online 21 March 2005. \n\nThe authors would like to express their thanks to the Irish Research Council for Science Engineering and Technology, Enterprise Ireland and Science Foundation Ireland for their support of this project through a Basic Research Grant, an International Collaboration Travel grant and an Investigator award. Emily Gleeson would also like to acknowledge the Daniel O'Connell Scholarship award funded by NUI Maynooth.", "abstract": "In this paper we report on the design and validation process for the profiled corrugated horn antennas, which feed the bolometer array of a cosmology experiment known as QUaD located at the South Pole. This is a cosmic background radiation polarization project, which demands precise knowledge and control of the optical coupling to the signal in order to map the feeble E- and B-polarization mode structure. The system will operate in two millimeter wavelength bands at 100 and 150 GHz. The imaging horn array collects the incoming signal via on-axis front-end optics and a Cassegrain telescope, with a cold stop in front of the array to terminate side-lobe structure at an edge taper of \u221220dB. The corrugated horn design process was undertaken using in-house analytical software tools, based on modal scattering, specially developed for millimeter -wave profiled horn antennas. An important part of the instrument development was the validation of the horn design, in particular to verify low edge taper levels and the required well-defined band edges. Suitable feed horn designs were measured and were found to be in excellent agreement with theoretical predictions.", "date": "2005-04", "date_type": "published", "publication": "International Journal of Infrared and Millimeter Waves", "volume": "26", "number": "4", "publisher": "Springer", "pagerange": "505-523", "id_number": "CaltechAUTHORS:20191204-151845332", "issn": "0195-9271", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191204-151845332", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Irish Research Council for Science Engineering and Technology" }, { "agency": "Enterprise Ireland" }, { "agency": "Science Foundation, Ireland" }, { "agency": "National University of Ireland, Maynooth" } ] }, "doi": "10.1007/s10762-005-4069-7", "resource_type": "article", "pub_year": "2005", "author_list": "Murphy, J. A.; Gleeson, E.; et el." } ]