Cosmic birefringence (CB)---a rotation of photon-polarization plane in vacuum---is a generic signature of new scalar fields that could provide dark energy. Previously, WMAP observations excluded a uniform CB-rotation angle larger than a degree.
\r\n\r\nIn this thesis, we develop a minimum-variance--estimator formalism for reconstructing direction-dependent rotation from full-sky CMB maps, and forecast more than an order-of-magnitude improvement in sensitivity with incoming Planck data and future satellite missions. Next, we perform the first analysis of WMAP-7 data to look for rotation-angle anisotropies and report null detection of the rotation-angle power-spectrum multipoles below L=512, constraining quadrupole amplitude of a scale-invariant power to less than one degree. We further explore the use of a cross-correlation between CMB temperature and the rotation for detecting the CB signal, for different quintessence models. We find that it may improve sensitivity in case of marginal detection, and provide an empirical handle for distinguishing details of new physics indicated by CB.
\r\n\r\nWe then consider other parity-violating physics beyond standard models---in particular, a chiral inflationary-gravitational-wave background. We show that WMAP has no constraining power, while a cosmic-variance--limited experiment would be capable of detecting only a large parity violation. In case of a strong detection of EB/TB correlations, CB can be readily distinguished from chiral gravity waves.
\r\n\r\nWe next adopt our CB analysis to investigate patchy screening of the CMB, driven by inhomogeneities during the Epoch of Reionization (EoR). We constrain a toy model of reionization with WMAP-7 data, and show that data from Planck should start approaching interesting portions of the EoR parameter space and can be used to exclude reionization tomographies with large ionized bubbles.
\r\n\r\nIn light of the upcoming data from low-frequency radio observations of the redshifted 21-cm line from the EoR, we examine probability-distribution functions (PDFs) and difference PDFs of the simulated 21-cm brightness temperature, and discuss the information that can be recovered using these statistics. We find that PDFs are insensitive to details of small-scale physics, but highly sensitive to the properties of the ionizing sources and the size of ionized bubbles.
\r\n\r\nFinally, we discuss prospects for related future investigations.
\r\n\r\n", "doi": "10.7907/VZ0P-XD08", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7030", "collection": "thesis", "collection_id": "7030", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05152012-125430182", "primary_object_url": { "basename": "thesis_samuel_lee.pdf", "content": "final", "filesize": 3353790, "license": "other", "mime_type": "application/pdf", "url": "/7030/1/thesis_samuel_lee.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Three Paths to Particle Dark Matter", "author": [ { "family_name": "Lee", "given_name": "Samuel Kuhnman", "clpid": "Lee-Samuel-Kuhnman" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "thesis_committee": [ { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Hillenbrand", "given_name": "Lynne A.", "orcid": "0000-0001-8638-0320", "clpid": "Hillenbrand-L-A" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "In this thesis, we explore examples of each of the three primary strategies for the detection of particle dark matter: indirect detection, direct detection, and collider production.
\r\n\r\nWe first examine the indirect detection of weakly interacting massive particle (WIMP) dark matter via the gamma-ray photons produced by astrophysical WIMP annihilation. Such photons may be observed by the Fermi Gamma-ray Space Telescope. We propose the gamma-ray-flux probability distribution function (PDF) as a probe of the Galactic halo substructure predicted to exist by N-body simulations. The PDF is calculated for a phenomenological model of halo substructure; it is shown that the PDF may allow a statistical detection of substructure.
\r\n\r\nNext, we consider the direct detection of WIMPs. We explore the ability of directional nuclear-recoil detectors to constrain the local velocity distribution of WIMP dark matter by performing Bayesian parameter estimation on simulated recoil-event data sets. We discuss in detail how directional information, when combined with measurements of the recoil-energy spectrum, helps break degeneracies in the velocity-distribution parameters. Considering the possibility that velocity structures such as cold tidal streams or a dark disk may also be present in addition to the Galactic halo, we discuss the potential of upcoming experiments to probe such structures.
\r\n\r\nWe then study the collider production of light gravitino dark matter. Light gravitino production results in spectacular signals, including di-photons, delayed photons, kinked charged tracks, and heavy metastable charged particles. We find that observable numbers of light-gravitino events may be found in future collider data sets. Remarkably, this data is also well suited to distinguish between scenarios with light gravitino dark matter, with striking implications for early-Universe cosmology.
\r\n\r\nFinally, we investigate the related matter of radiative corrections to the decay rate of charged fermions caused by the presence of a thermal bath of photons. The cancellation of finite-temperature infrared divergences in the decay rate is described in detail. Temperature-dependent radiative corrections to the two-body decay of a hypothetical charged fermion and to electroweak decays of a muon are given. We touch upon possible implications of these results for charged particles in the early Universe.
", "doi": "10.7907/Q603-SH04", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:7060", "collection": "thesis", "collection_id": "7060", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05212012-141650110", "type": "thesis", "title": "Cosmological Consequences of Gravitation: Structure Formation and Gravitational Waves", "author": [ { "family_name": "Book", "given_name": "Laura Grace", "clpid": "Book-Laura-Grace" } ], "thesis_advisor": [ { "family_name": "Benson", "given_name": "Andrew J.", "orcid": "0000-0001-5501-6008", "clpid": "Benson-A-J" } ], "thesis_committee": [ { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" }, { "family_name": "Benson", "given_name": "Andrew J.", "orcid": "0000-0001-5501-6008", "clpid": "Benson-A-J" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Chen", "given_name": "Yanbei", "orcid": "0000-0002-9730-9463", "clpid": "Chen-Yanbei" }, { "family_name": "Adhikari", "given_name": "Rana", "orcid": "0000-0002-5731-5076", "clpid": "Adhikari-R" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "div_pma" } ], "abstract": "This thesis contains work on four topics which fit into two broad areas of research: the quest to understand structure formation and through it the properties of the dark matter, and the search for primordial gravitational radiation. The first project details the effect of an accretion shock on the colors of satellites in galaxy clusters. A new model of ram pressure stripping including an accretion shock with variable radius is developed and implemented in the Galform semi-analytic model of galaxy formation. A comparison of this model with previous models and with observations indicates that current data is unable to discriminate between models, though future observations will be able to place stronger constraints on the role of ram pressure stripping in and around clusters.
\r\n\r\nNext, an analysis of the angular momentum evolution of dark matter particles in high-resolution N-body simulations of dark matter halos is presented. We find that individual particle angular momentum is not conserved, and also that the angular momentum of radial shells varies over the age of the Universe by up to factors of a few. These results have serious implications for the validity of current analytical models that assume angular momentum conservation.
\r\n\r\nTwo methods for detecting the primordial gravitational wave (GW) background are then presented. Such a background, if detected, could greatly impact our understanding of the early universe. The first proposed method uses the apparent angular velocities of astrophysical objects induced by GWs, which may be detectable with upcoming astrometric missions such as the GAIA satellite. This work improves upon previous order-of-magnitude estimates, and presents a full calculation of the expected signal from a stochastic background of GWs.
\r\n\r\nThe second method uses bipolar spherical harmonics decomposition, a formalism to characterize departures from statistical isotropy and Gaussianity, to quantify the expected lensing of the cosmic microwave background (CMB) and 21 cm radiation by GWs. The lensing of the CMB by GWs is found to not be detectable, but that of future 21 cm surveys could give a very high quality measurement of the primordial GW background.
", "doi": "10.7907/3KPE-MW85", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:6374", "collection": "thesis", "collection_id": "6374", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05042011-123721947", "primary_object_url": { "basename": "Pullen_thesis.pdf", "content": "final", "filesize": 1876881, "license": "other", "mime_type": "application/pdf", "url": "/6374/1/Pullen_thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "A Survey of Results in Modern Precision Cosmology", "author": [ { "family_name": "Pullen", "given_name": "Anthony Robert", "clpid": "Pullen-Anthony-Robert" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "thesis_committee": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" }, { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "div_pma" } ], "abstract": "In this work, we evaluate the evidence for some of the more exotic ideas in cosmology for which scientists are searching today, these anomalies being dark matter, statistical anisotropy, and non-Gaussianity. Dark matter, which is estimated to comprise 83% of the matter in our universe, still remains undiscovered. We search data from the Energetic Gamma Ray Experiment Telescope for a gamma-ray line in the energy range 0.1-10 GeV from the 10X10 degree region around the Galactic center. Our null results lead to upper limits to the line flux from the Galactic center. We use these limits to place constraints on the particle's two-photon annihilation cross section as a function of its mass, which we show to produce stronger limits than those derived from measurements of the 511-keV line.
\r\n\r\nNext, we investigate the possibility that cosmic inflation deviates from statistical isotropy. Statistical isotropy is a common assumption that should be tested. We develop cosmic-microwave-background statistics for a direction-dependent primordial power spectrum. We then construct minimum-variance estimators for the coefficients of a spherical-harmonic expansion of the direction-dependence of the primordial power spectrum. We find that a power quadrupole as small as 2.0% can be detected by the Planck satellite. We also constrain statistical anisotropy of the quadrupolar form using a sample of photometric luminous red galaxies measured by the Sloan Digital Sky Survey. Not detecting evidence, we place limits on an axisymmetric quadrupole model. We find discrepancies between our results and a cosmic microwave background analysis that claimed a positive detection. We also find the quadrupolar asymmetry limits to be between -0.41 and 0.38 with 95% probability.
\r\n\r\nFinally, we prepare a search for evidence of non-Gaussianity in the the early universe. Scale-dependent bias has been shown to be a competitive probe of non-Gaussianity in large-scale structure, and constraints have been calculated using various tracers of the matter distribution. We seek to extend this analysis to the latest sample of photometric quasars measured by the Sloan Digital Sky Survey to search for evidence of scale-dependent bias in large-scale structure. Specifically we construct three data samples at various redshifts, removing various systematic effects. We calculate the cross-correlation angular power spectra between two of the data samples to search for any remaining systematics. We find a positive detection on large scales, which leads us to the conclusion that more systematics testing is needed to render this QSO catalog useful to constrain non-Gaussianity.
", "doi": "10.7907/VJ9N-0J70", "publication_date": "2011", "thesis_type": "phd", "thesis_year": "2011" }, { "id": "thesis:5995", "collection": "thesis", "collection_id": "5995", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08172010-183547836", "primary_object_url": { "basename": "Sullivan_thesis_(FINAL).pdf", "content": "final", "filesize": 34555058, "license": "other", "mime_type": "application/pdf", "url": "/5995/1/Sullivan_thesis_(FINAL).pdf", "version": "v4.0.0" }, "type": "thesis", "title": "CIBER: A Near-Infrared Probe of the Epoch of Reionization", "author": [ { "family_name": "Sullivan", "given_name": "Ian Sorensen", "clpid": "Sullivan-Ian-Sorensen" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Cooray", "given_name": "Asantha", "orcid": "0000-0002-3892-0190", "clpid": "Cooray-A" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The Cosmic Infrared Background Experiment (CIBER) is a NASA sounding rocket payload that was first launched in February 2009. CIBER consists of four co-aligned instruments designed to study the near-Infrared background by measuring fluctuations and the absolute spectrum. The platform of a sounding rocket enables observations of the near-Infrared background outside of narrow atmospheric windows that are uncontaminated by airglow.\r\n \r\nCIBER uses two spectrometers to measure the absolute brightness spectrum of the extragalactic near-Infrared background. One, a high-resolution Fabry-Perot spectometer, is tuned to the 854.5 nm CaII line of the solar spectrum, and is designed to measure the absolute brightness of the Zodiacal Light directly, which is the source of greatest uncertainty in the near-Infrared background spectrum. The second spectrometer measures the near-Infrared background spectrum from 700 nm to 1800 nm, spanning the wavelength range where a Lyman limit cutoff feature from reionization could appear. \r\n\r\nCIBER also houses two Infrared imaging telescopes, which have identical optics that give 2 x 2 degree field of views with 7 arcsecond pixels, but have different band defining filters. The first imager has a wide band centered at 1600 nm, and images the background at the expected peak of the spectrum. The imagers\u2019 wide field of view allows them to measure the distinctive power spectrum of first-light galaxy fluctuations peaking at 10 arcminutes. The second imager has a wide band centered at 1000 nm that is intended to image at wavelengths shorter than the Lyman cutoff, and provides a powerful systematic test for any detection made at 1600 nm. First-light fluctuations should have a distinctive spatial power spectrum with very red 1600 nm / 1000 nm color, distinctly redder than the approximately solar color of any residual fluctuations arising from Zodiacal light, Galactic starlight, or moderate-redshift galaxies.\r\n\r\nThis work describes the design and characterization of the instruments for the first launch, and the modifications and further characterization that have led to a second flight in July 2010 that successfully eliminated the most serious instrumental problems identified in the first flight.\r\n", "doi": "10.7907/EFS6-PJ64", "publication_date": "2011", "thesis_type": "phd", "thesis_year": "2011" }, { "id": "thesis:6404", "collection": "thesis", "collection_id": "6404", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05172011-165447651", "primary_object_url": { "basename": "yacine_thesis.pdf", "content": "final", "filesize": 3852550, "license": "other", "mime_type": "application/pdf", "url": "/6404/1/yacine_thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "A New Spin on Primordial Hydrogen Recombination and a Refined Model for Spinning Dust Radiation", "author": [ { "family_name": "Ali-Haimoud", "given_name": "Yacine", "clpid": "Ali-Haimoud-Yacine" } ], "thesis_advisor": [ { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" } ], "thesis_committee": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "orcid": "0000-0002-0438-3323", "clpid": "Scoville-N-Z" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "This thesis describes theoretical calculations in two subjects: the primordial recombination of the electron-proton plasma about 400,000 years after the Big Bang and electric dipole radiation from spinning dust grains in the present-day interstellar medium.
\r\n\r\nPrimordial hydrogen recombination has recently been the subject of a renewed attention because of the impact of its theoretical uncertainties on predicted cosmic microwave background (CMB) anisotropy power spectra. The physics of the primordial recombination problem can be divided into two qualitatively different aspects. On the one hand, a detailed treatment of the non-thermal radiation field in the optically thick Lyman lines is required for an accurate recombination history near the peak of the visibility function. On the other hand, stimulated recombinations and out-of equilibrium effects are important at late times and a multilevel calculation is required to correctly compute the low-redshift end of the ionization history. Another facet of the problem is the requirement of computational efficiency, as a large number of recombination histories must be evaluated in Markov chains when analyzing CMB data. In this thesis, an effective multilevel atom method is presented, that speeds up multilevel atom computations by more than 5 orders of magnitude. The impact of previously ignored radiative transfer effects is quantified, and explicitly shown to be negligible. Finally, the numerical implementation of a fast and highly accurate primordial recombination code partly written by the author is described.
\r\n\r\nThe second part of this thesis is devoted to one of the potential galactic foregrounds for CMB experiments: the rotational emission from small dust grains. The rotational state of dust grains is described, first classically, and assuming that grains are rotating about their axis of greatest inertia. This assumption is then lifted, and a quantum-mechanical calculation is presented for disk-like grains with a randomized nutation state. In both cases, the probability distribution for the total grain angular momentum is computed with a Fokker-Planck equation, and the resulting emissivity is evaluated, as a function of environmental parameters. These computations are implemented in a public code written by the author.
", "doi": "10.7907/QMFZ-0C90", "publication_date": "2011", "thesis_type": "phd", "thesis_year": "2011" }, { "id": "thesis:5892", "collection": "thesis", "collection_id": "5892", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05312010-162432249", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 6337361, "license": "other", "mime_type": "application/pdf", "url": "/5892/1/thesis.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "The Lukewarm Frontier: Some Cosmological Consequences of 'Low Energy' Physics", "author": [ { "family_name": "Grin", "given_name": "Daniel", "clpid": "Grin-Daniel" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "thesis_committee": [ { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" }, { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" }, { "family_name": "Johnson", "given_name": "John A.", "clpid": "Johnson-J-A" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "In this thesis, we present four projects featuring low characteristic energy scales relative to the scales relevant for supersymmetric dark matter production or inflation. We present a telescope search for decaying relic axions in the 3 \u2212 8 eV mass range. We utilize larger telescope exposure and superior cluster mass modeling to improve sensitivity. Our results impose new stringent limits to the two-photon coupling or relic density of axions. We extend these results to non-standard sterile neutrinos.
\r\n\r\nWe then reconsider cosmological constraints to axions. Our understanding of physics before big-bang nucleosynthesis is tenuous, and after arguing that a non-standard thermal history before nucleosynthesis is plausible and perhaps even natural, we calculate the abundance and typical momenta of thermal axions in such scenarios. We generalize existing cosmological constraints to axions, showing that the allowed axion mass range expands significantly in non-standard thermal histories. We then estimate the sensitivity of future experiments to axion masses and reheating temperatures.
\r\n\r\nWe then study the ~ eV-scale physics of cosmological hydrogen ~ 10^4 states of hydrogen up to a maximum n ~ 250, and studying the associated convergence problem. We show that the recombination history is sufficiently converged for analysis of microwave anisotropy data from the Planck satellite if the maximum n ~ 128, and that previously ignored electric quadrupole transitions are indeed negligible to the precision necessary for Planck.
\r\n\r\nWe conclude by presenting a new astrophysical limit to effective \ufb01eld theories of gravity in which the graviton propagator is damped at energies greater than a milli-eV.
\r\n", "doi": "10.7907/EN34-1095", "publication_date": "2010", "thesis_type": "phd", "thesis_year": "2010" }, { "id": "thesis:5212", "collection": "thesis", "collection_id": "5212", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282009-124109", "primary_object_url": { "basename": "Thesis_Hilke_Schlichting.pdf", "content": "final", "filesize": 822274, "license": "other", "mime_type": "application/pdf", "url": "/5212/1/Thesis_Hilke_Schlichting.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Understanding the Origin of Planetary Systems: Studying the Kuiper Belt and the Dynamics of Planet Formation", "author": [ { "family_name": "Schlichting", "given_name": "Hilke Elisabeth", "clpid": "Schlichting-Hilke-Elisabeth" } ], "thesis_advisor": [ { "family_name": "Sari", "given_name": "Re'em", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" } ], "thesis_committee": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Hillenbrand", "given_name": "Lynne A.", "clpid": "Hillenbrand-L-A" }, { "family_name": "Brown", "given_name": "Michael E.", "orcid": "0000-0002-8255-0545", "clpid": "Brown-M-E" }, { "family_name": "Sari", "given_name": "Re'em", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "This thesis presents theoretical and observational studies pertaining to the early solar system, planet formation and extrasolar planets.
\r\n\r\nFirst, we explore the dynamics of protoplanet formation. We find that the growth of protoplanets may be dominated by the accretion of a planetesimal disk that forms from planetesimal-planetesimal collisions, rather than direct planetesimal impacts onto the protoplanet. This has far reaching implications for the formation of planets, their growth rate and dynamics. We focus on the implications for planetary spins: it can explain the prevalence of prograde spins of planets and asteroids in the solar system, which is commonly believed to be an accident.
\r\n\r\nSecond, we present a series of investigations of the formation of multiple systems in the Kuiper Belt. Two of our studies are concerned with the formation of comparable mass binaries. We find that in a dynamically cold Kuiper Belt, binaries become bound predominantly by dynamical friction. This leads to a binary population with mostly retrograde mutual binary orbits. In a dynamically hot Kuiper Belt three-body gravitational interactions dominate the binary formation producing a roughly equal number of prograde and retrograde binaries. We propose a new formation scenario for Haumea\u2019s collisional family. In our scenario, the family members are ejected while in orbit around Haumea rather than directly from Haumea\u2019s surface as previously proposed. Our formation scenario offers an explanation for the observed velocity dispersion among the family members which is much smaller than Haumea\u2019s escape velocity. It is consistent with detecting just one collisional family in the Kuiper Belt and aids with explaining Haumea\u2019s initial giant impact.
\r\n\r\nWe conclude with observational work that aims to detect sub-km sized Kuiper Belt objects and to measure their size-distribution. Our results provide the best constraint on the surface density of small Kuiper Belt objects to date. Our findings support the idea that small Kuiper Belt objects underwent collisional evolution that modified their size distribution. We present our first candidate occultation event and show that it is unlikely to be due to instrumental artifacts or statistical fluctuations in the data.
", "doi": "10.7907/SGJJ-9V78", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:4187", "collection": "thesis", "collection_id": "4187", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-10192008-143041", "primary_object_url": { "basename": "elina_brobeck_thesis.pdf", "content": "final", "filesize": 6632848, "license": "other", "mime_type": "application/pdf", "url": "/4187/1/elina_brobeck_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Measurement of Ultra-High Energy Cosmic Rays with CHICOS", "author": [ { "family_name": "Brobeck", "given_name": "Elina", "clpid": "Brobeck-Elina" } ], "thesis_advisor": [ { "family_name": "McKeown", "given_name": "Robert D.", "clpid": "McKeown-R-D" } ], "thesis_committee": [ { "family_name": "Stone", "given_name": "Edward C.", "orcid": "0000-0002-2010-5462", "clpid": "Stone-E-C" }, { "family_name": "Harrison", "given_name": "Fiona A.", "orcid": "0000-0003-2992-8024", "clpid": "Harrison-F-A" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "McKeown", "given_name": "Robert D.", "clpid": "McKeown-R-D" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The California HIgh school Cosmic ray ObServatory (CHICOS) is a ground-based scintillator array designed to measure the extended air showers of ultra-high energy cosmic rays. The goal of the project is to gain insight into the origin of ultra-high energy cosmic rays by measuring the energy spectrum and the distribution of arrival directions.
\r\n\r\nThe CHICOS array has been in operation since 2003. It consists of 77 pairs of scintillator dectectors deployed at schools in the San Fernando and San Gabriel valleys near Los Angeles, and is designed to observe cosmic ray air showers at energies of 10^18 eV and above. In addition, the Chiquita subarray is designed to observe smaller showers in the energy range of 1016 - 1019 eV.
\r\n\r\nWe present new descriptions of the air shower lateral distribution function and time distribution function, which have been derived from AIRES-generated simulated air showers. The new functions are specific to the CHICOS altitude and allow for a maximum likelihood shower reconstruction method, which is more appropriate to the CHICOS data than the \u03c72 minimization method. We present several analyses of the accuracy of the reconstruction software in the energy ranges available to the Chiquita and CHICOS arrays.
\r\n\r\nThe energy spectrum between 1017 eV and 1019 eV has been measured by the Chiquita subarray. At the lowest energy range, it is found to agree with previous measurements, while the measured flux falls below previous experiments for energies greater than approximately 1017.5 eV. The CHICOS energy spectrum above 1018.4 eV is found to agree with previous results published by AGASA. However, we do not observe the cutoff in the spectrum at 1020 eV reported more recently by the Auger and HiRes Collaborations.
\r\n\r\nA correlation analysis between CHICOS data and nearby active galactic nuclei (AGN) was performed. No excess of cosmic rays was observed in the vicinity of nearby AGN. The maximum correlation was observed for cosmic ray events with E > 1020 eV and for AGN with z < 0.009, with Pchance = 21%. This is consistent with random correlations from an isotropic distribution, a result also found by HiRes, but in disagreement with Auger.
\r\n", "doi": "10.7907/9YH6-N064", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:5055", "collection": "thesis", "collection_id": "5055", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-12182007-120046", "primary_object_url": { "basename": "jmb_thesis.pdf", "content": "final", "filesize": 4892114, "license": "other", "mime_type": "application/pdf", "url": "/5055/1/jmb_thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Childhood to Adolescence: Dust and Gas Clearing in Protoplanetary Disks", "author": [ { "family_name": "Brown", "given_name": "Joanna Margaret", "clpid": "Brown-Joanna-Margaret" } ], "thesis_advisor": [ { "family_name": "Blake", "given_name": "Geoffrey A.", "orcid": "0000-0003-0787-1610", "clpid": "Blake-G-A" } ], "thesis_committee": [ { "family_name": "Brown", "given_name": "Michael E.", "orcid": "0000-0002-8255-0545", "clpid": "Brown-M-E" }, { "family_name": "Blake", "given_name": "Geoffrey A.", "orcid": "0000-0003-0787-1610", "clpid": "Blake-G-A" }, { "family_name": "Sargent", "given_name": "Anneila Isabel", "orcid": "0000-0002-4633-5098", "clpid": "Sargent-A-I" }, { "family_name": "Steidel", "given_name": "Charles C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Disks are ubiquitous around young stars. Over time, disks dissipate, revealing planets that formed hidden by their natal dust. Since direct detection of young planets at small orbital radii is currently impossible, other tracers of planet formation must be found. One sign of disk evolution, potentially linked to planet formation, is the opening of a gap or inner hole in the disk. In this thesis, I have identified and characterized several cold disks with large inner gaps but retaining massive primordial outer disks. While cold disks are not common, with ~5% of disks showing signs of inner gaps, they provide proof that at least some disks evolve from the inside-out. These large gaps are equivalent to dust clearing from inside the Earth's orbit to Neptune's orbit or even the inner Kuiper belt. Unlike more evolved systems like our own, the central star is often still accreting and a large outer disk remains.
\r\n\r\nI identified four cold disks in Spitzer 5-40 \u00b5m spectra and modeled these disks using a 2-D radiative transfer code to determine the gap properties. Outer gap radii of 20-45 AU were derived. However, spectrophotometric identification is indirect and model-dependent. To validate this interpretation, I observed three disks with a submillimeter interferometer and obtained the first direct images of the central holes. The images agree well with the gap sizes derived from the spectrophotometry. One system, LkH&alpha 330, has a very steep outer gap edge which seems more consistent with gravitational perturbation rather than gradual processes, such as grain growth and settling. Roughly 70% of cold disks show CO v=1&rarr 0 gas emission from the inner 1 AU and therefore are unlikely to have evolved due to photoevaporation. The derived rotation temperatures are significantly lower for the cold disks than disks without gaps. Unresolved (sub)millimeter photometry shows that cold disks have steeper colors, indicating that they are optically thin at these wavelengths, unlike their classical T Tauri star counterparts. The gaps are cleared of most ~100 \u00b5m sized grains as well as the ~10 \u00b5m sized grains visible in the mid-infrared as silicate emission features.
\r\n", "doi": "10.7907/560K-TZ76", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:2214", "collection": "thesis", "collection_id": "2214", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282008-153540", "primary_object_url": { "basename": "tristan_smith_thesis.pdf", "content": "final", "filesize": 4173861, "license": "other", "mime_type": "application/pdf", "url": "/2214/1/tristan_smith_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Gravity of the Situation", "author": [ { "family_name": "Smith", "given_name": "Tristan Laine", "orcid": "0000-0003-2685-5405", "clpid": "Smith-Tristan-Laine" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "thesis_committee": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Lange", "given_name": "Andrew E.", "clpid": "Lange-A-E" }, { "family_name": "Cooray", "given_name": "Asantha", "orcid": "0000-0002-3892-0190", "clpid": "Cooray-A" }, { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "div_pma" } ], "abstract": "In this thesis we examine several ways in which we can explore the early universe through gravitational-waves and the fundamental nature of gravity through cosmology and observations of dynamics within the solar system. Both of these topics have taken center stage, as we are living at a unique time which promises to bring fundamental insights into the nature of gravity with the discovery of new binary pulsar systems, the building of increasingly precise solar system and tabletop experiments and the birth of gravitational-wave observatories-- to name a few recent and upcoming advances.
\r\n\r\nWe first discuss whether we may be able to directly detect gravitational waves from inflation using future space-based interferometers. We then describe how the direct detection of inflationary gravitational waves will allow us to probe the fundamental physics that operated at the earliest moments of the universe. Next, a new constraint to a general cosmological gravitational wave background is presented using the observations of the cosmic microwave background. Moving away from general relativity, we consider alternative theories of gravity. One reason to consider alternative theories of gravity is the observation that the expansion of the universe is currently accelerating. It is possible that this accelerated expansion is due to a modification of gravity. However, any theory that modifies gravity in order to produce accelerated expansion must also conform to the dynamics that we observe within the Solar System. We discuss how the observation of the deflection of light around the Sun places severe limitations on a particular modified gravity theory, known as f(R) gravity. Our discussion of f(R) gravity leads us to ask whether the parameterized post Newtonian parameter, \u03b3PPN, takes on a universal value. We identify measurements made of strong lensing around early type galaxies in the Sloan Lens ACS (SLACS) survey as a first step in performing this new test of gravity. Finally, we explore some consequences of Chern-Simons gravity. One of the unique aspects of Chern-Simons gravity is that it introduces parity violation into the gravitational sector. As a consequence, it predicts a different gravitomagnetic field around the rotating Earth than is predicted in general relativity. We show how recent measurements of this gravitomagnetic field made by observing the two LAser GEOdynamics Satellites (LAGEOS) and Gravity Probe B satellites constrain Chern-Simons gravity. Finally, we discuss how future observations of binary pulsar systems may allow for a more general exploration of the gravitomagnetic structure around rotating objects.
\r\n", "doi": "10.7907/SY21-6Z52", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:1953", "collection": "thesis", "collection_id": "1953", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05222007-105100", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 1139633, "license": "other", "mime_type": "application/pdf", "url": "/1953/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Topics in Theoretical Particle Physics and Cosmology", "author": [ { "family_name": "Salem", "given_name": "Michael Phillip", "clpid": "Salem-Michael-Phillip" } ], "thesis_advisor": [ { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" } ], "thesis_committee": [ { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" }, { "family_name": "Weinstein", "given_name": "Alan Jay", "orcid": "0000-0002-0928-6784", "clpid": "Weinstein-Alan-J-Physics" }, { "family_name": "Preskill", "given_name": "John P.", "orcid": "0000-0002-2421-4762", "clpid": "Preskill-J" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "Caltech Theory" }, { "literal": "div_pma" } ], "abstract": "We first delve into particle phenomenology with a study of soft-collinear effective theory (SCET), an effective theory for Quantum Chromodynamics for when all particles are approximately on their light-cones. In particular, we study the matching of SCET(I) involving ultrasoft and collinear particles onto SCET(II) involving soft and collinear particles. We show that the modes in SCET(II) are sufficient to reproduce all of the infrared divergences of SCET(I), a result that was previously in contention.
\r\n\r\nNext we move into early universe cosmology and study alternative mechanisms for generating primordial density perturbations. We study the inhomogeneous reheating mechanism and extend it to describe the scenario where the freeze-out process for a heavy particle is modulated by sub-dominant fields that received fluctuations during inflation. This scenario results in perturbations that are comparable to those generated by the original inhomogeneous reheating scenarios. In addition, we study yet another alternative to single field inflation whereby the curvature perturbation is generated by interactions at the end of inflation, as opposed to when inflaton modes exit the horizon. We clarify the circumstances under which this process can dominate over the standard one and we show that it may result in a spectrum with an observable level of non-Gaussianities.
\r\n\r\nWe then turn to studies of the landscape paradigm, which hypothesizes that the observed universe is just one among a multitude of possibilities that are realized in separate causal regions. Such a landscape has been used to explain the smallness of the cosmological constant, at least when only it scans across the landscape. We study the scenario where both the cosmological constant and the strength of gravity, parameterized by the effective Planck mass, scan across the landscape. We find that selection effects acting on the cosmological constant are significantly weaker in this scenario and we find the measured value of the Planck mass to be exponentially unlikely under certain plausible assumptions about the landscape. Finally, we study some other models of the landscape as part of a possible explanation for quark-sector flavor parameters in the Standard Model. In this picture quark Yukawa couplings result from overlap integrals involving quark and Higgs wavefunctions in compactified extra dimensions, and the values we measure result from random selection from a landscape of possibilities. We find that many of the salient features of the measured flavor parameters are typical of the landscape distribution.
", "doi": "10.7907/BQ6Q-DA17", "publication_date": "2007", "thesis_type": "phd", "thesis_year": "2007" }, { "id": "thesis:1972", "collection": "thesis", "collection_id": "1972", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05232005-160004", "primary_object_url": { "basename": "main.pdf", "content": "final", "filesize": 1173634, "license": "other", "mime_type": "application/pdf", "url": "/1972/1/main.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "To the Horizon and Beyond:Weak Lensing of the CMB and Binary Inspirals into Horizonless Objects", "author": [ { "family_name": "Kesden", "given_name": "Michael Henry", "orcid": "0000-0002-5987-1471", "clpid": "Kesden-Michael-Henry" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "thesis_committee": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "div_pma" } ], "abstract": "This thesis examines two predictions of general relativity: weak lensing and gravitational waves. The cosmic microwave background (CMB) is gravitationally lensed by the large-scale structure between the observer and the last-scattering surface. This weak lensing induces non-Gaussian correlations that can be used to construct estimators for the deflection field. The error and bias of these estimators are derived and used to analyze the viability of lensing reconstruction for future CMB experiments.
\r\n\r\nWeak lensing also affects the one-point probability distribution function of the CMB. The skewness and kurtosis induced by lensing and the Sunayev-Zel'dovich (SZ) effect are calculated as functions of the angular smoothing scale of the map. While these functions offer the advantage of easy computability, only the skewness from lensing-SZ correlations can potentially be detected, even in the limit of the largest amplitude fluctuations allowed by observation.
\r\n\r\nLensing estimators are also essential to constrain inflation, the favored explanation for large-scale isotropy and the origin of primordial perturbations. B-mode polarization is considered to be a \"smoking-gun\" signature of inflation, and lensing estimators can be used to recover primordial B-modes from lensing-induced contamination. The ability of future CMB experiments to constrain inflation is assessed as functions of survey size and instrumental sensitivity.
\r\n\r\nA final application of lensing estimators is to constrain a possible cutoff in primordial density perturbations on near-horizon scales. The paucity of independent modes on such scales limits the statistical certainty of such a constraint. Measurements of the deflection field can be used to constrain at the 3-sigma level the existence of a cutoff large enough to account for current CMB observations.
\r\n\r\nA final chapter of this thesis considers an independent topic: the gravitational-wave (GW) signature of a binary inspiral into a horizonless object. If the supermassive objects at galactic centers lack the horizons of traditional black holes, inspiraling objects could emit GWs after passing within their surfaces. The GWs produced by such an inspiral are calculated, revealing distinctive features potentially observable by future GW observatories.
", "doi": "10.7907/BQMR-4C14", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:1716", "collection": "thesis", "collection_id": "1716", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05102005-102535", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 29088900, "license": "other", "mime_type": "application/pdf", "url": "/1716/2/thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "A Measurement of the Temperature and Polarization Anisotropies in the Cosmic Microwave Background Radiation", "author": [ { "family_name": "Jones", "given_name": "William Claude", "orcid": "0000-0002-3636-1241", "clpid": "Jones-William-Claude" } ], "thesis_advisor": [ { "family_name": "Lange", "given_name": "Andrew E.", "clpid": "Lange-A-E" } ], "thesis_committee": [ { "family_name": "Lange", "given_name": "Andrew E.", "clpid": "Lange-A-E" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "We describe the design and performance of the Boomerang experiment, and report on measurements of the temperature and polarization anisotropies of the Cosmic Microwave Background (CMB) obtained during the January 2003 flight of Boomerang (B2K). To enable these studies, we have developed a bolometric detector which is intrinsically sensitive to linear polarization. The receiver consists of a pair of co-located silicon nitride micromesh absorbers which couple anisotropically to linearly polarized radiation through a corrugated waveguide structure. This system allows simultaneous background limited measurements of the Stokes I and Q parameters over ~30% bandwidths at frequencies from ~60 to 400 GHz.
\r\n\r\nThe science results reported here are derived from 195 hours of observation with four 145 GHz Polarization Sensitive Bolometer (PSB) pairs. The data include 75 hours of observations distributed over 1.8% of the sky with an additional 120 hours concentrated on the central portion of the field, itself representing 0.22% of the full sky. The B2K data improve significantly on existing measurements of the CMB temperature power spectrum at angular scales of 500 < l < 1100. In addition we have measured a spectrum of curl-free polarization anisotropies which, in the context of the most simple adiabatic inflationary models, are consistent with the predictions of the currently favored LCDM cosmology
", "doi": "10.7907/88BF-1W23", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:2191", "collection": "thesis", "collection_id": "2191", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282004-140350", "primary_object_url": { "basename": "main.pdf", "content": "final", "filesize": 2998326, "license": "other", "mime_type": "application/pdf", "url": "/2191/1/main.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Data Analysis of and Results from Observations of the Cosmic Microwave Background with the Cosmic Background Imager", "author": [ { "family_name": "Sievers", "given_name": "Jonathan LeRoy", "orcid": "0000-0001-6903-5074", "clpid": "Sievers-Jonathan-LeRoy" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Steidel", "given_name": "Charles C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Pearson", "given_name": "Timothy J.", "orcid": "0000-0001-5213-6231", "clpid": "Pearson-T-J" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present results from observations of the Cosmic Microwave Background (CMB) with the Cosmic Background Imager (CBI), a sensitive 13-element interferometer located high in the Chilean Andes. We also discuss methods of analyzing the data from the CBI, including an improved way of measuring the true power spectrum using maximum likelihood estimation. This improved method leads to a saving of a factor of two in memory usage, and an increase in speed of order the number of points in the spectrum. The initial results are discussed, in which the fall-off in power at ell > 1000 (the \"damping tail\") was first observed. We also present the results from the first year of observations with the CBI, and discuss cosmological intepretations both alone and in concert with the results from other experiments. These provide tight constraints on cosmological parameters, including a Hubble constant of 69 +/- 4 km/s/Mpc, an age of the universe of 13.7 +/- 0.2 billion years, and a denisty of dark energy of 0.70 +/- 0.05 of the critical density of the universe. Finally, we discuss an alternate method of data compression, with great flexibility in what information is kept, while being computationally tractable. We then apply this method to the CBI data to constrain the potential emission from foreground contaminants contributing to the observed CMB radiation. We find that the data is consistent with zero foreground, with a maximum allowed foreground contribution between about 8% and 12% of the total signal (at an ell of 600 and frequency of 30 GHz), depending on the spectral index of foreground emission.\r\n", "doi": "10.7907/8706-VY52", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:3017", "collection": "thesis", "collection_id": "3017", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08052003-161044", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 1513234, "license": "other", "mime_type": "application/pdf", "url": "/3017/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Topics in Gravitational-Wave Astronomy", "author": [ { "family_name": "O'Shaughnessy", "given_name": "Richard William", "orcid": "0000-0001-5832-8517", "clpid": "O'Shaughnessy-Richard-William" } ], "thesis_advisor": [ { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" } ], "thesis_committee": [ { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" }, { "family_name": "Libbrecht", "given_name": "Kenneth George", "orcid": "0000-0002-8744-3298", "clpid": "Libbrecht-K-G" }, { "family_name": "Lindblom", "given_name": "Lee A.", "orcid": "0000-0002-3018-1098", "clpid": "Lindblom-L" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "LIGO" }, { "literal": "div_pma" } ], "abstract": "Both the Laser Interferometer Gravitational Wave Observatory (LIGO) and the Laser Interferometer Space Antenna (LISA) will over the next decade detect gravitational waves emitted by the motion of compact objects (e.g. black hole and neutron star binaries). This thesis presents methods to improve (i) LIGO detector quality, (ii) our knowledge of waveforms for certain LIGO and LISA sources, and (iii) models for the rate of detectability of a particular LISA source.
\r\n\t\t\t\t\t\t\t\t\t \r\n1) Plunge of compact object into a supermassive black hole: LISA should detect many inspirals of compact objects into supermassive black holes (~ 10\u2075-10\u2077 M\u2299). Since the inspiral of each compact object terminates shortly after the inspiralling object reaches its last stable orbit, the late-stage inspiral waveform provides insight into the location of the last stable orbit and strong-field relativity. I discovered that while LISA will easily see the overall inspiral (consisting of many cycles before plunge), the present LISA design will just miss detecting the waves emitted from the transition from inspiral to plunge.
\r\n\r\n2) Scheme to reduce thermoelastic noise in advanced LIGO: After its first upgrade, LIGO will have its sensitivity limited by thermoelastic noise. [Thermoelastic noise occurs because milimeter-scale thermal fluctuations in the mirror bulk expand and contract, causing the mirror surface to shimmer.] The interferometer's sensitivity could be enhanced substantially by reducing thermoelastic noise. In collaboration with Kip Thorne, Erika d'Ambrosio, Sergey Vyatchanin, and Sergey Strigin, I developed a proposal to reduce thermoelastic noise in advanced-LIGO by switching the LIGO cavity optics from simple spherical mirrors to a new, Mexican-hat shape.
\r\n\t\t\t\t\t\t\t\t\t \r\n3) Geometric-optics-based analysis of stability of symmetric-hyperbolic formulations of Einstein's equations: Einstein's equations must be evolved numerically to predict accurate waveforms for the late stages of binary black hole inspiral and merger. But no matter which representation of Einstein's equations is used, numerical simulations rarely run long. For examle, for first-order symmetric-hyperbolic (FOSH) formulations of Einstein's evolution equations, sometimes exact but unphysical solutions grow so large that the evolution fails. For FOSH formulations, I found easily-understood solutions (wave packets) and used them to predict which formulations will be particularly ill-behaved.
", "doi": "10.7907/4C1K-VZ17", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:6771", "collection": "thesis", "collection_id": "6771", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01202012-112836824", "primary_object_url": { "basename": "Alvi_k_2002.pdf", "content": "final", "filesize": 21554023, "license": "other", "mime_type": "application/pdf", "url": "/6771/1/Alvi_k_2002.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Topics in General Relativity: Binary Black Holes and Hyperbolic Formulations of Einstein's Equations", "author": [ { "family_name": "Alvi", "given_name": "Kashif Siddiq", "clpid": "Alvi-Kashif-Siddiq" } ], "thesis_advisor": [ { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" } ], "thesis_committee": [ { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Lindblom", "given_name": "Lee A.", "orcid": "0000-0002-3018-1098", "clpid": "Lindblom-L" }, { "family_name": "Mabuchi", "given_name": "Hideo", "orcid": "0000-0002-5156-7678", "clpid": "Mabuchi-H" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "This thesis consists of three projects in general relativity on topics related to binary black holes\r\nand the gravitational waves they emit. The first project involves calculating a four-metric that is an approximate solution to Einstein's equations representing two widely separated nonrotating black holes in a circular orbit. This metric is constructed by matching a post-Newtonian metric to\r\ntwo tidally distorted Schwarzschild metrics using the framework of matched asymptotic expansions. The four-metric presented here provides physically realistic initial data that are tied to the binary's inspiral phase and can be evolved numerically to determine the gravitational wave output during the late stages of inspiral as well as the merger.
\r\n\r\nThe second project is on the tidal interaction of binary black holes during the inspiral phase. The holes' tidal distortion results in the flow of energy and angular momentum into or out of the holes in a process analogous to Newtonian tidal friction in a planet-moon system. The changes in the black holes' masses, spins, and horizon areas during inspiral are calculated for a circular binary with holes of possibly comparable masses. The absorption or emission of energy and angular momentum by the holes is shown to have a negligible influence on the binary 's orbital evolution when the holes have comparable masses. The tidal-interaction analysis presented in this thesis is applicable to a black hole in a binary with any companion body (e.g., a neutron star) that is well separated from\r\nthe hole.
\r\n\r\nThe final project is on first-order hyperbolic formulations of Einstein's equations, which are promising as a basis for numerical simulation of binary black holes. This thesis presents two first-order symmetrizable hyperbolic systems that include the lapse and shift as dynamical fields and have only physical characteristic speeds. The first system may be useful in numerical work; the second system allows one to show that any solution to Einstein's equations in any gauge can be obtained\r\nusing hyperbolic evolution of the entire metric, including the gauge fields.
", "doi": "10.7907/5S0S-MF65", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:120", "collection": "thesis", "collection_id": "120", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01112002-085240", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 3981058, "license": "other", "mime_type": "application/pdf", "url": "/120/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Observations of Carbon Monoxide in the Starburst Galaxy M82 with a 690 GHz Wide Spectral Bandwidth Receiver", "author": [ { "family_name": "Ward", "given_name": "John Strawn", "clpid": "Ward-John-Strawn" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "orcid": "0000-0002-0438-3323", "clpid": "Scoville-N-Z" }, { "family_name": "Phillips", "given_name": "Thomas G.", "clpid": "Phillips-T-G" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "A 690 GHz wide spectral bandwidth heterodyne receiver was developed to observe the J=6-5 rotational emission line of carbon monoxide (CO) in extragalactic sources. This receiver is based on a niobium superconductor-insulator-superconductor (SIS) mixer with a twin-slot antenna in a superconducting NbTiN ground plane. A 4-8 GHz low-noise amplifier was developed to amplify the intermediate frequency (IF) signal from the mixer with a spectral bandwidth of 1,700 km/s, enough to comfortably observe the entire emission line of the broadest extragalactic submillimeter sources with a single receiver tuning. This amplifier is a quasi-monolithic microwave integrated circuit (QMMIC); three 160 micron gate InP high-electron-mobility transistors (HEMTs) were bump-bonded to a thin-film GaAs substrate containing passive tuning and DC bias circuitry. The measured amplifier gain is 32 dB and the noise is approximately 8 Kelvin from 4 to 8 GHz at a physical temperature of 4 Kelvin. The complete receiver achieves a measured uncorrected double-sideband noise temperature of 180 Kelvin.
\r\n\r\nPrior to this development effort, a versatile microwave simulation package was written to calculate and optimize the signal and noise performance of high-frequency circuits, especially those containing superconductors and superconducting tunnel junctions. Using this package, called SuperMix, C++ programs can be written to simulate and optimize circuits of arbitrary size, complexity, and topology. SuperMix was used to simulate the complete 690 GHz SIS receiver.
\r\n\r\nThe receiver was used at the Caltech Submillimeter Observatory (CSO) to map the 12CO J=6-5 emission line in the central kiloparsec of the nearby starburst galaxy M82 at a resolution of 14 arc seconds. Hot spots were found on either side of the dynamical center. A novel deconvolution technique was used to compute a 12CO J=6-5 / 12CO J=2-1 line ratio map based on high-resolution J=2-1 interferometer data. The 12CO J=6-5 map, along with observations of 12CO J=4-3, 12CO J=3-2, 13CO J=3-2, an upper limit for 13CO J=6-5, and five other measured CO lines from the literature, were analyzed in the context of a two-component large velocity gradient (LVG) excitation model. Likelihood curves were calculated for each of the model parameters as well as a variety of related physical quantities for the two hot spots based on the measured line intensities and their associated uncertainties. This approach reveals in an unbiased way how well various quantities can be constrained by the CO observations. The results of this analysis suggest that the warm gas is less dense than the cool gas, and that over half of the total molecular gas mass in these nuclear regions is warmer than 50 K.
", "doi": "10.7907/5S4X-NV83", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:2226", "collection": "thesis", "collection_id": "2226", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05292002-113750", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 2118011, "license": "other", "mime_type": "application/pdf", "url": "/2226/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Modeling and Detecting Gravitational Waves from Compact Stellar Objects", "author": [ { "family_name": "Vallisneri", "given_name": "Michele", "orcid": "0000-0002-4162-0033", "clpid": "Vallisneri-Michele" } ], "thesis_advisor": [ { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" } ], "thesis_committee": [ { "family_name": "Thorne", "given_name": "Kip S.", "orcid": "0000-0002-9475-4318", "clpid": "Thorne-K-S" }, { "family_name": "Libbrecht", "given_name": "Kenneth George", "orcid": "0000-0002-8744-3298", "clpid": "Libbrecht-K-G" }, { "family_name": "Lindblom", "given_name": "Lee A.", "orcid": "0000-0002-3018-1098", "clpid": "Lindblom-L" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "LIGO" }, { "literal": "div_pma" } ], "abstract": "In the next few years, the first detections of gravity-wave signals using Earth-based interferometric detectors will begin to provide precious new information about the structure, dynamics, and evolution of compact bodies, such as neutron stars and black holes, both isolated and in binary systems. The intrinsic weakness of gravity-wave signals requires a proactive approach to modeling the prospective sources and anticipating the shape of the signals that we seek to detect. Full-blown 3-D numerical simulations of the sources are playing and will play an important role in planning the gravity-wave data-analysis effort. This thesis explores the interplay between numerical source modeling and data analysis, looking closely at three case studies.
\r\n\r\n1. I evaluate the prospects for extracting equation-of-state information from neutron-star tidal disruption in neutron-star\u2013black-hole binaries with LIGO-II, and I estimate that the observation of disrupting systems at distances that yield about one event per year should allow the determination of the neutron-star radius to about 15%, which compares favorably to the currently available electromagnetic determinations.
\r\n\r\n2. In collaboration with Lee Lindblom and Joel Tohline, I perform numerical simulations of the nonlinear dynamics of the r-mode instability in young, rapidly spinning neutron stars, and I find evidence that nonlinear couplings to other modes will not pose a significant limitation to the growth of the r-mode amplitude.
\r\n\r\n3. In collaboration with Alessandra Buonanno and Yanbei Chen, I study the problem of detecting gravity waves from solar-mass black-hole\u2013black-hole binaries with LIGO-I, and I construct two families of detection templates that address the inadequacy of standard post-Newtonian theory to predict reliable waveforms for these systems.
\r\n", "doi": "10.7907/JN6M-BW40", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:38", "collection": "thesis", "collection_id": "38", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01062003-061357", "primary_object_url": { "basename": "book_main_old.pdf", "content": "final", "filesize": 5286035, "license": "other", "mime_type": "application/pdf", "url": "/38/1/book_main_old.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Toward an Understanding of the Progenitors of Gamma-Ray Bursts", "author": [ { "family_name": "Bloom", "given_name": "Joshua Simon", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-Joshua-Simon" } ], "thesis_advisor": [ { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" } ], "thesis_committee": [ { "family_name": "Harrison", "given_name": "Fiona A.", "orcid": "0000-0003-2992-8024", "clpid": "Harrison-F-A" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-G" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "orcid": "0000-0002-0438-3323", "clpid": "Scoville-N-Z" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The various possibilities for the origin (\"progenitors\") of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized long-duration GRBs are connected with otherwise normal star-forming galaxies at moderate redshifts of order unity. Using high-mass binary stellar population synthesis models, I quantify the expected spatial extent around galaxies of coalescing neutron stars, one of the leading contenders for GRB progenitors. I then test this scenario by examining the offset distribution of GRBs about their apparent hosts making extensive use of ground-based optical data from Keck and Palomar and space-based imaging from the Hubble Space Telescope. The offset distribution appears to be inconsistent with the coalescing neutron star binary hypothesis (and, similarly, black-hole-neutron star coalescences); instead, the distribution is statistically consistent with a population of progenitors that closely traces the ultra-violet light of galaxies. This is naturally explained by bursts which originate from the collapse of massive stars (\"collapsars\"). This claim is further supported by the unambiguous detections of intermediate-time (approximately three weeks after the bursts) emission \"bumps\" which appear substantially more red than the afterglows themselves. I claim that these bumps could originate from supernovae that occur at approximately the same time as the associated GRB; if true, GRB 980326 and GRB 011121 provide strong observational evidence connecting cosmological GRBs to high-redshift supernovae and implicate massive stars as the progenitors of at least some long-duration GRBs. Regardless of the true physical origin of these bumps, it appears that all viable alternative models of these bumps (such as dust scattering of the afterglow light) require a substantial amount of circumburst matter that is distributed as a wind-stratified medium; this too, implicates massive stars. Also suggested herein are some future observations which could further solidify or refute the supernova claim. In addition to the observational and modeling work, I also constructed the Jacobs Camera (JCAM), a dual-beam optical camera for the Palomar 200-inch Telescope designed to follow-up rapid GRB localizations.
\r\n", "doi": "10.7907/GKHP-2K61", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" } ]