Neutron stars are exceptional astrophysical objects, harboring likely the densest matter in the universe outside of black holes.
\r\n \r\nHowever, uncertainty in the properties of matter at the densities achieved inside of neutron stars means that the structure of neutron stars cannot be fully understood from first principles.
\r\n \r\nModern statistical and computational tools however, along with cutting-edge observational strategies have enabled the properties of neutron stars to be constrained using astrophysical data.
\r\n \r\nIn this thesis, I will discuss work I have carried out examining what can be learned about neutron stars, and the dense matter inside of them, using electromagnetic and gravitational-wave observations of neutron stars.
\r\n \r\nIn particular, I will discuss constraints on nonparametric models of the dense-matter equation of state, and why nonparametric models are an effective strategy for faithfully representing uncertainty.
\r\n \r\nI will also discuss the interplay between understanding the astrophysical channels for forming neutron stars, and the neutron-star matter equation of state, including how we can use our understanding of dense matter to classify objects.
\r\n \r\nFinally, I will discuss some considerations for simulating astrophysical neutron stars, which is necessary in order to interpret the full range of astrophysical observations of merging neutron stars, such as the neutron star merger GW170817.
" }, { "name": "Wang, Yijun", "degree": "PhD", "year": "2024", "title": "Topics in Gravitational Wave Physics: Lensing, Detection with Astrometry and Dark Siren Hubble Measurement", "advisor": "Chen, Yanbei; Dor\u00e9, Olivier P.; Chang, Tzu-Ching", "url": "https://resolver.caltech.edu/CaltechTHESIS:05302024-045951995", "creators": [ { "name": { "family": "Wang", "given": "Yijun" }, "id": "Wang-Yijun", "orcid": "0000-0002-5581-2001", "display_name": "Wang, Yijun" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" }, { "name": { "family": "Dor\u00e9", "given": "Olivier P." }, "id": "Dor\u00e9-O", "orcid": "0000-0001-7432-2932", "role": "co-advisor", "display_name": "Dor\u00e9, Olivier P." }, { "name": { "family": "Chang", "given": "Tzu-Ching" }, "id": "Chang-Tzu-Ching", "orcid": "0000-0001-5929-4187", "role": "co-advisor", "display_name": "Chang, Tzu-Ching" } ], "committee": [ { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "chair", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Chang", "given": "Tzu-Ching" }, "id": "Chang-Tzu-Ching", "orcid": "0000-0001-5929-4187", "role": "member", "display_name": "Chang, Tzu-Ching" }, { "name": { "family": "Dor\u00e9", "given": "Olivier P." }, "id": "Dor\u00e9-O", "orcid": "0000-0001-7432-2932", "role": "member", "display_name": "Dor\u00e9, Olivier P." }, { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "member", "display_name": "Adhikari, Rana" }, { "name": { "family": "Pardo", "given": "Kris" }, "id": "Pardo-Kris", "orcid": "0000-0002-9910-6782", "role": "member", "display_name": "Pardo, Kris" } ], "option_major": [ "physics" ], "doi": "10.7907/fjya-qm21", "abstract": "In this thesis, we study several subjects in gravitational wave (GW) physics, including gravitational wave lensing, detection with astrometry data and dark siren measurement of cosmological parameters.
\r\n\r\nWe investigate various lensing features and their detection prospects in third-generation gravitational-wave networks. Firstly, we focus on type II lensed images which are Hilbert transforms of regular images. We compute the waveform mismatch and quantify the distinguishable fraction given Bayes factor thresholds over a range of binary mass ratio and redshifted mass. We make forecast on the detectable and distinguishable type II images in aLIGO Voyager, Cosmic Explorer and Einstein Telescope. This work shows that a significant number of type II images can be distinguished from waveforms alone, and this strategy can contribute to future pipelines for more accurate GW event inference.
\r\n\r\nWe further model relativistic lensing in a large-inclination hierarchical triple system with a central Kerr supermassive black hole. We combine the elliptical integral formalism and optical scalar formalism to study image location and magnification. By analyzing the repeated lensing signature observed by the Decihertz Gravitational-wave Observatory, we examine the importance of relativistic images in detecting the presence of lensing or specifically the lens spin. We compute the detectable effective volume and estimate the upper limit for expected number of such events. This work demonstrates that lensing with relativistic images is a fruitful avenue where decihertz observation contributes to studies on intermediate-mass binary black holes and their galactic environment.
\r\n\r\nGW detection with astrometry was proposed as an alternative strategy that uses stellar astrometry data for GW measurement with flexible frequency coverage. We point out that surveys providing relative astrometry only can also be sensitive to GWs. We apply this method to the Roman Space Telescope Galactic Bulge Time Domain survey and make sensitivity forecast for both monochromatic GWs from supermassive binary black holes and stochastic GW background. We clarify the survey requirements and technical challenges for GW detection, and show that Roman will enable microhertz GW measurement for local sources. We also present on-going work to develop a data-processing pipeline to use Kepler archival data to search for GWs.
\r\n\r\nWith increasing number of events in GW catalog, the GW source population offers a unique perspective into cosmology and astrophysics. In the last chapter, we use a Fisher information formalism to quantify the astrophysical model error tolerance of GW dark siren measurement on cosmological parameters. We generate galaxy catalog based on realistic survey and population parameters, and we apply expected GW uncertainties in third-generation ground-based networks. Based on simulation results, we study dominating error factors and make suggestions to dark siren selection strategy given different total error requirements.
" }, { "name": "Shi, Yanlong", "degree": "PhD", "year": "2023", "title": "Assembly of Intermediate-Mass Black Holes Along Star Formation", "advisor": "Hopkins, Philip F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06072023-051240339", "creators": [ { "name": { "family": "Shi", "given": "Yanlong" }, "id": "Shi-Yanlong", "orcid": "0000-0002-0087-3237", "display_name": "Shi, Yanlong" } ], "advisors": [ { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "advisor", "display_name": "Hopkins, Philip F." } ], "committee": [ { "name": { "family": "Fuller", "given": "James" }, "id": "Fuller-J", "orcid": "0000-0002-4544-0750", "role": "chair", "display_name": "Fuller, James" }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "member", "display_name": "Hopkins, Philip F." }, { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "orcid": "0000-0002-4834-7260", "role": "member", "display_name": "Steidel, Charles C." }, { "name": { "family": "Dor\u00e9", "given": "Olivier P." }, "id": "Dor\u00e9-O", "orcid": "0000-0001-7432-2932", "role": "member", "display_name": "Dor\u00e9, Olivier P." } ], "option_major": [ "physics" ], "doi": "10.7907/thmn-7h07", "abstract": "Intermediate-mass black holes (IMBHs) are poorly observed and not as well understood as stellar-mass black holes (BHs) and supermassive black holes (SMBHs). However, they can be important to complement the formation scenario of massive BHs other than stellar-mass ones and reconcile the existence of some high-energy sources in the Universe. The thesis studies the assembly of IMBHs in star-forming giant molecular clouds (GMCs) of \u223c 5 \u2013 500 pc and \u223c 10\u2074 \u2013 10\u00b9\u2070 M_\u2299, which are realistic environments for some scenarios of IMBH formation, including runaway collisions in dense star clusters and super-Eddington accretion onto \u223c 100 M_\u2299 BH seeds like remnants of massive stars.
\r\n\r\nWe first inspect the runaway-collision scenario where IMBHs form as remnants of \u201cquasi-stars\u201d after stellar collisions. Density profiles of young massive clusters can be important for this scenario but are missing observational hints. We measure density profiles of cluster populations in star-formation simulations in GMCs and conduct both analytic derivations and Monte-Carlo simulations to estimate the mass of the quasi-star in different clusters. The analytic expression is in approximate agreement with observations.
\r\n\r\nThe following three chapters are about the super-Eddington accretion scenario. The first question to solve is the availability of super-Eddington accretion in turbulent and star-forming environments. We run simulations of BH accretion in GMCs with star formation based on FIRE-2 physics. We find that dense clumps generated by stellar feedback and turbulence can feed BHs at high accretion rates. We also conclude that GMCs with high surface densities are favored for super- or hyper-Eddington accretion, in which self-gravity dominates over stellar feedback.
\r\n\r\nAfter convincing the availability of super-Eddington accretion in dense GMCs, we study the self-regulation of BH accretion through its feedback. We construct a sub-grid model of BH accretion and feedback, including radiation, winds/jets, and relativistic diffusive cosmic rays. We find that super-Eddington accretion is still achievable with proper radiative feedback models but is challenged by BH mechanical feedback. We also quantify BH feedback effects and find that they can be analytically explained with momentum-driven arguments. Moreover, we study the effects of multiple sub-grid parameters and BH feedback\u2019s impact on star formation in GMCs.
\r\n\r\nFinally, we study another mode of accretion due to steady gas inflow towards BHs. This complements the missing interaction between stars and BHs in previous studies. Along with star formation, star clusters form and merge hierarchically, creating deep potential wells to capture BHs. At the late stage of the simulation, a \u223c 10 pc disk structures form. The gas inflow rate can be \u223c 10 M_\u2299/yr. We find a non-trivial strong toroidal magnetic field in the disk, which is thermally heated and ionized by feedback from stars.
" }, { "name": "Chen, Baoyi", "degree": "PhD", "year": "2022", "title": "Near-Horizon Black Hole Physics", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:08172021-040557487", "creators": [ { "name": { "family": "Chen", "given": "Baoyi" }, "id": "Chen-Baoyi", "orcid": "0000-0002-3927-6843", "display_name": "Chen, Baoyi" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" } ], "committee": [ { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "chair", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Cheung", "given": "Clifford W." }, "id": "Cheung-Clifford", "orcid": "0000-0002-9983-9425", "role": "member", "display_name": "Cheung, Clifford W." }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" } ], "option_major": [ "physics" ], "doi": "10.7907/8szr-9e68", "abstract": "This thesis studies the near-horizon black hole physics in depth from three perspectives.
\r\n\r\nAn important tool for studying perturbations of black hole spacetime is the linearized Einstein equations (LEE). In the Kerr spacetime, the variables in LEE do not separate, which poses a lot of difficulties to obtaining analytical solutions. By taking the near-horizon limit of extremal Kerr black holes, additional symmetries emerge to make the LEE separable. This is achieved by decomposing the metric perturbations using some basis functions adapted to the symmetry. I further show that in two string-inspired low-energy effective theories of gravity, LEE can be directly solved and analytical black hole solutions can be found.
\r\n\r\nNaively, the near-horizon perturbations of an extremal black hole may destroy the horizon and make the singularity expose itself. This is a direct challenge of the weak cosmic censorship conjecture (WCCC). Based on Wald\u2019s gendanken experiments to destroy black holes, I examine the WCCC for the extremal charged black hole in possible generalizations of Einstein-Maxwell theory due to the higher-order corrections, up to fourth-derivative terms. It turns out that, provided the null energy condition for the falling matter, the WCCC is preserved for all possible generalizations. I further find that for BTZ black holes, i.e. solutions to (2+1)-Einstein gravity with asymptotically AdS3 boundary, WCCC is always preserved. Through the AdS/CFT correspondence, this establishes the connections between black hole thermodynamics and WCCC.
\r\n\r\nFrom considerations of quantum gravity and quantum information, it has been conjectured that space-time geometry near the horizon can be modified, even at scales larger than the Planck scale. The resulting spacetime is commonly referred to as the exotic compact object (ECO). A viable method to look for the near- horizon quantum structures is searching for gravitational wave echoes in the GW signals. After discussing the stability issues associated with the ECOs, I build up the phenomenology for gravitational echoes. I also introduce a new framework to deal with the near-horizon boundaries by considering the tidal response of the ECO as experienced by zero-angular-momentum fiducial observers. It is then straightforward to apply the boundary condition to computing gravitational-wave echoes from exotic compact objects.
" }, { "name": "Mark, Zachary R.", "degree": "PhD", "year": "2021", "title": "Gravitational Wave Signatures of Black Hole Physics", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:06072021-070015547", "creators": [ { "name": { "family": "Mark", "given": "Zachary R." }, "id": "Mark-Zachary-R", "orcid": "0000-0003-2300-893X", "display_name": "Mark, Zachary R." } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" } ], "committee": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "chair", "display_name": "Adhikari, Rana" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Abu-Mostafa", "given": "Yaser S." }, "id": "Abu-Mostafa-Y-S", "role": "member", "display_name": "Abu-Mostafa, Yaser S." } ], "option_major": [ "physics" ], "doi": "10.7907/kh82-1q43", "abstract": "Gravitational wave observations are opening the door to test general relativity in regimes far less common than the weak gravitational fields that we experience in the solar system. The first part of this thesis addresses the broad issue of how different exotic predictions of general relativity imprint themselves in gravitational waves.
\r\n\r\nThe ringdown portion of a binary black hole merger is dominated by superposition of quasinormal modes, the resonant modes of a perturbed black hole. The quasinormal mode spectrum of a perturbed black hole mostly reflects the spacetime geometry near the photon orbits. Chapter 2 of this thesis develops a new method for calculating quasinormal mode frequencies for weakly charged, rotating black holes. Chapter 3 uses a variety of analytic approximations to calculate the charged, rotating quasinormal mode frequencies in other cases, including nearly extremal black holes.
\r\n\r\nThe event horizon is one of the most unique predictions of general relativity and it unsurprisingly does not imprint itself in gravitational wave emission. However, alternatives to black holes known as exotic compact objects do leave a unique signature in the form of echoes following the initial signal. Chapter 4 develops a formalism to understand and calculate these echoes.
\r\n\r\nThe second part of this thesis focuses on reducing the noise in gravitational wave measurements using neural networks. Chapter 5 demonstrates on mock data how simple neural networks can use auxiliary measurements from the detector to predict unmodeled noise which can be subtracted offline.
" }, { "name": "Giesler, Matthew David", "degree": "PhD", "year": "2020", "title": "Probing the Nature of Black Holes with Gravitational Waves", "advisor": "Teukolsky, Saul A.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05062020-201707675", "creators": [ { "name": { "family": "Giesler", "given": "Matthew David" }, "id": "Giesler-Matthew-David", "orcid": "0000-0003-2300-893X", "display_name": "Giesler, Matthew David" } ], "advisors": [ { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "advisor", "display_name": "Teukolsky, Saul A." } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "member", "display_name": "Adhikari, Rana" } ], "option_major": [ "physics" ], "doi": "10.7907/akwv-r373", "abstract": "In this thesis, I present a number of studies intended to improve our understanding of black holes using gravitational waves. Although black holes are relatively well understood from a theory perspective, many questions remain about the nature of the black holes in our Universe. According to general relativity, astrophysical black holes are fully described by just their mass and spin. Yet, relying on electromagnetic-based observatories alone, we still know very little about the distribution of black hole masses or spins. Moreover, as merging black holes are invisible to these electromagnetic observatories, we cannot rely on them to provide us with information about the binary black hole merger rate or binary black hole formation channels. However, by observing gravitational wave signals from these inherently dark binaries, we will soon have some answers to these questions. Indeed, the Laser Interferometer Gravitational-Wave Observatory (LIGO) has already revealed a great deal of new information about binary black holes; giving us an early glimpse into their mass and spin distributions and placing the first constraints on the binary black hole merger rate. This thesis contributes to the goal of probing the nature of black holes with gravitational waves.
\r\n\r\nBinary black holes can form as an isolated binary in the galactic field or through dynamical encounters in high-density environments. Dynamical formation can significantly alter the binary parameters, which then become imprinted on the gravitational waveform. By simulating varying black hole populations in high-density globular clusters, we identify a population of highly eccentric binary black hole mergers that are characteristic of dynamical formation. Although these systems would circularize by the time they are visible in LIGO's frequency band, the future Laser Interferometer Space Antenna (LISA) is capable of distinguishing this population of eccentric mergers from the circular mergers expected of isolated field-formed binaries. As these dynamically formed binaries depend on the size of the underlying black hole population in globular clusters, we can utilize the dynamically formed merger rate to infer globular cluster black hole populations -- allowing us to reveal information about binary black hole birth environments.
\r\n\r\nIn order to properly estimate the parameters of binary black holes from detected gravitational wave signals, such as their masses and spins, high-accuracy waveforms are a needed. The highest accuracy waveforms are those produced by numerical relativity simulations, which solve the full Einstein equations. Using the Spectral Einstein Code (SpEC), we expand the reach of numerical relativity to simulate binary black holes with nearly extremal spins, i.e., black holes with spins near the maximal value \u03c7 = 1. These waveforms are used to calibrate existing waveform approximants used in LIGO data analyses. This ensures that the systematic errors in these approximants are small enough that if highly-spinning systems are observed, the spins are recovered without bias. Although rapidly spinning binaries have remained elusive thus far, these waveforms ensure that the highest-spin systems can be detected in the quest to uncover the spin distribution of black holes.
\r\n\r\nThe end state of a binary black hole merger is a newly born, single black hole that rings down like a struck bell, sending its last few ripples of gravitational waves out into the spacetime. Embedded in this 'ringdown' signal are a multitude of specific frequencies. Einstein's theory of general relativity precisely predicts the ringdown frequencies of a black hole with a given mass and spin. The statement that a black hole is entirely described by just these two parameters is known as the no-hair theorem. For black holes that obey the laws of general relativity (and consequently, the no-hair theorem), these frequencies serve as a fingerprint for the black hole. However, if the objects we observe are not Einstein's black holes, but instead something more exotic, the frequencies will not have this property and this would be a spectacular surprise. A minimum of two tones are required for this test, each with an associated frequency and damping time that depend only on the mass and spin. The conventional no-hair test relies on the so-called 'fundamental' tones of a black hole. A test relying on the fundamental modes is not expected to be feasible for another ~10-15 years, after detector sensitivity has improved significantly. However, by analyzing the ringdown of high-accuracy numerical relativity waveforms, we show that modes beyond the fundamental, known as 'overtones', are detectable in current detectors. The overtones are short-lived, but this is countered by the fact that they can initially be much stronger than the fundamental mode. By measuring two tones in the ringdown of GW150914 we perform a first test of the no-hair theorem. While the current constraints are rather loose, this first test serves as a proof of principle. This is just one example of the powerful tests that can be employed with overtones using present day detectors and the even more precise tests that can be accomplished with LISA in the future.
" }, { "name": "Barkett, Kevin Michael Canice", "degree": "PhD", "year": "2019", "title": "Computational Methods for Gravitational Wave Physics: Spectral Cauchy-Characteristic Extraction and Tidal Splicing", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:02082019-160046031", "creators": [ { "name": { "family": "Barkett", "given": "Kevin Michael Canice" }, "id": "Barkett-Kevin-Michael-Canice", "orcid": "0000-0001-8230-4363", "display_name": "Barkett, Kevin Michael Canice" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" } ], "committee": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "chair", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/3DH5-7773", "abstract": "As the aLIGO and Virgo detectors continue to improve their sensitivity for observing gravitational waves from merging compact binaries, they will require ever more precise theoretical predictions to extract a detailed understanding of the physics governing these merging systems. This thesis discusses advancements within computing the gravitational waveforms along two avenues of research: the continued development of a spectral Cauchy-Characteristic Extraction (CCE) code and the presentation of a novel method called 'Tidal Splicing' for generating waveforms for binary neutron star (BNS), black hole-neutron star (BHNS), and even Beyond GR systems.
\r\n\r\nDue to the finite extents of typical 3+1 simulations of merging binaries, the waveforms they generate can suffer from near-zone effects and lingering gauge ambiguities. CCE was developed in order evolve radiating gravitational waves as they propagate outward to future null infinity, allowing studies connecting the dynamical spacetime of binary evolutions to effects seen by distant observers, such as superkicks, and angluar and linear momentum fluxes. A recent spectral version of CCE showed promising improvements in accuracy and efficiency over the older finite-differencing code, PittNull. However, lingering issues with the numerics and implementation of the theory prevented it from wide spread use. We detail the developments updated its initial release and demonstrate the enhancement in accuracy they yield beyond the capabilities of PittNull.
\r\n\r\nThe method of Tidal Splicing enhances the inexpensive Post-Newtonian (PN) tidal corrections with BBH waveforms from numerical simulations to generate waveforms corresponding to inpsiraling BNS or BHNS systems. This leverages the accuracy of numerical BBH waveforms to effectively replace the corresponding unknown PN terms. In addition, by picking individual terms in the PN tidal expansions to include, then comparing with existing numerical simulations, we are able to probe the significance of each contribution to the total difference in evolution between BBH and BNS or BHNS inspirals. We also demonstrate how the splicing concepts used for tidal effects can extended in order to model waveforms with corrections according to theories beyond GR using an example case of a resonating ultra-compact object.
" }, { "name": "Du, Song Ming", "degree": "PhD", "year": "2019", "title": "Fundamental Physics Through Gravitational Waves: From No-Hair Theorem to Quantum Structures of Black Holes", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:12132018-230901638", "creators": [ { "name": { "family": "Du", "given": "Song Ming" }, "id": "Du-Song-Ming", "orcid": "0000-0003-0083-7014", "display_name": "Du, Song Ming" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" } ], "committee": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "chair", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Porter", "given": "Frank C." }, "id": "Porter-F-C", "orcid": "0000-0003-1948-8889", "role": "member", "display_name": "Porter, Frank C." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/YSDX-J506", "abstract": "In general relativity, black hole is the simplest macroscopic object in the universe: any black hole can be completely described by its mass, charge and angular mo- mentum. However, such a simple picture might be changed if the gravitational field equations are modified or quantum effects are taken into consideration. These additional hairs of black hole, if exist, may provide valuable information to reveal the deepest mystery of the universe: quantum theory of gravity.
\r\n\r\nIn this thesis, we try to relate the hypothetical extra hairs of black hole with the ob- servational evidence as gravitational waves \u2013 another prediction of general relativity and are recently detected. In Chapter I, we provide a pedagogical introduction to the black hole hairs introduced by modified gravity and quantum mechanics, and lay out a mathematical framework to describe the gravitational wave emission with the existence of near-horizon quantum hair. In Chapter II we show that in scalar-tensor theory of gravity, the formation process of a black hole from gravitational collapse is accompanied with the emission of scalar hair. This mechanism gives rise to a scalar type memory effect of gravitational wave, which does not exist in general relativity. This phenomenon can further be used to study the parameter space of the scalar-tensor theory. In Chapter III, we find the scalar gravitational memory effect from stellar collapses provide the strongest sources for the stochastic gravita- tional wave background with scalar polarization in Brans-Dicke theory. The energy density spectrum for this background is provided and its model dependencies are studied. In Chapter IV, we provide a Green\u2019s function method to study the echoes, which are the gravitational waves reflected by the quantum hair near the event hori- zon of a black hole. In Chapter V, we build phenomenological models to describe the near-horizon quantum hair and predict its implication to the binary black hole stochastic gravitational wave background. Our study indicates that the existence of the quantum hair will significantly increases such a background and pins down the most relevant model parameter to be the area under the effective potential. Further, we also demonstrate that the result is rather robust against the uncertainties about the nature of the near-horizon quantum hair. In the end, a field theory based treatment to the gravitational waves in general relativity is provided as the appendix.
" }, { "name": "Helou, Bassam Mohamad", "degree": "PhD", "year": "2019", "title": "Testing Alternative Theories of Quantum Mechanics with Optomechanics, and Effective Modes for Gaussian Linear Optomechanics", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:12182018-142547647", "creators": [ { "name": { "family": "Helou", "given": "Bassam Mohamad" }, "id": "Helou-Bassam-Mohamad", "orcid": "0000-0003-2760-7622", "display_name": "Helou, Bassam Mohamad" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "advisor", "display_name": "Chen, Yanbei" } ], "committee": [ { "name": { "family": "Schwab", "given": "Keith C." }, "id": "Schwab-K-C", "role": "chair", "display_name": "Schwab, Keith C." }, { "name": { "family": "Painter", "given": "Oskar J." }, "id": "Painter-O", "role": "member", "display_name": "Painter, Oskar J." }, { "name": { "family": "Miao", "given": "Hiaoxing" }, "id": "Miao-Hiaoxing", "role": "member", "display_name": "Miao, Hiaoxing" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "appliedphys" ], "doi": "10.7907/KJ1K-9268", "abstract": "Optomechanics has made great strides in theory and experiments over the past decade, which culminated in the first direct detection of gravitational waves in 2015 by LIGO. This thesis explores how optomechanics can be used to test fundamental physics other than the theory of general relativity. Our emphasis will be on falsifiable theories (ultimately, only experiments can decide whether a theory is correct) that address two outstanding issues in quantum mechanics: the measurement problem, and reconciling quantum mechanics with the theory of general relativity. In particular, we show that the space experiment LISA pathfinder places aggressive bounds on two objective collapse models, which are non-linear stochastic modifications of the Schroedinger equation that can resolve the measurement problem. Moreover, we show that state-of-the-art torsion pendulum experiments can test the Schroedinger-Newton theory, which is the non-relativistic limit of a non-linear theory combining quantum mechanics with a fundamentally classical spacetime.
\r\n\r\nAlong the way, we propose how to resolve two major difficulties with determining the predictions of non-linear quantum mechanics in an actual experiment. First, we cannot use the density matrix formalism in non-linear quantum mechanics and so we have to suggest and justify a particular ensemble for the thermal bath. Separating out quantum and classical fluctuations helped us propose a reasonable ensemble. Second, most researchers believe that deterministic non-linear quantum mechanics must violate the no-signaling condition. We show this isn't necessarily the case because different interpretations of quantum mechanics make different predictions in non-linear quantum mechanics. We propose an interpretation, the causal-conditional prescription, that doesn't violate causality by noticing that once we fix an initial state, the evolution of a system under many non-linear theories is equivalent to evolution under a linear Hamiltonian with feedback. The mapping allows us to leverage the tools of quantum control, and it tells us that if the non-linear parameters of a non-linear Hamiltonian respond causally (i.e. with an appropriate delay) to measurement results, then the theory can be made causal.
\r\n\r\nWe also contribute to the theory of quantum optomechanics. We introduce two new bases that one can view environment modes with. In linear optomechanics a system interacts with an infinite number of bath modes. We show that the interaction can be reduced to one with finite degrees of freedom. Moreover, at any particular time, the system is correlated with only a finite number of bath modes. We show that if we make the assumption that we can measure any commuting environment modes, then this basis allows us to understand the one-shot quantum Cramer-Rao bound in a simple way, and allows us to sweep large parameter regimes and so find promising optomechanics topologies for quantum state preparation tasks that we can then analyze without the assumption of being able to measure any observable of the environment. We also use this basis to show that when we are interested in the conditional dynamics of a test mass, we can only adiabatically eliminate a lossy cavity when we measure the optomechanical system at a slow enough rate. Finally, we develop an analytic filter for obtaining the state of a generic optomechanical system that interacts linearly with its environment and is driven by Gaussian states, and where the outgoing light is measured with a non-linear photon-counting measurement. We hope that our work will help researchers explore optomechanics topologies that make use of photon counters.
\r\n" }, { "name": "Okounkova, Maria", "degree": "PhD", "year": "2019", "title": "Numerical Relativity Beyond General Relativity", "advisor": "Teukolsky, Saul A.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05102019-160621419", "creators": [ { "name": { "family": "Okounkova", "given": "Maria" }, "id": "Okounkova-Maria", "orcid": "0000-0001-7869-5496", "display_name": "Okounkova, Maria" } ], "advisors": [ { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "advisor", "display_name": "Teukolsky, Saul A." } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "member", "display_name": "Adhikari, Rana" }, { "name": { "family": "Gukov", "given": "Sergei" }, "id": "Gukov-S", "orcid": "0000-0002-9486-1762", "role": "member", "display_name": "Gukov, Sergei" }, { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." } ], "option_major": [ "physics" ], "doi": "10.7907/WPAT-PS25", "abstract": "Einstein\u2019s theory of general relativity has passed all precision tests to date. At some length scale, however, general relativity (GR) must break down and be reconciled with quantum mechanics in a quantum theory of gravity (a beyond-GR theory). Binary black hole mergers probe the non-linear, highly dynamical regime of gravity, and gravitational waves from these systems may contain signatures of such a theory. In this thesis, we seek to make gravitational wave predictions for binary black hole mergers in a beyond-GR theory. These predictions can then be used to perform model-dependent tests of GR with gravitational wave detections.
\r\n\r\nWe make predictions using numerical relativity, the practice of precisely numerically solving the equations governing spacetime. This allows us to probe the behavior of a binary black hole system through full inspiral, merger, and ringdown. We choose to work in dynamical Chern-Simons gravity (dCS), a higher-curvature beyond-GR effective field theory that couples spacetime curvature to a scalar field, and has motivations in string theory and loop quantum gravity. In order to obtain a well-posed initial value formalism, we perturb this theory around GR. We compute the leading-order behavior of the dCS scalar field in a binary black hole merger, as well as the leading-order dCS correction to the spacetime metric and hence gravitational radiation. We produce the first numerical relativity beyond-GR waveforms in a higher-curvature theory of gravity.
\r\n\r\nThis thesis contains additional results, all of which harness the power of numerical relativity to test GR. We compute black hole shadows in dCS gravity, numerically prove the leading-order stability of rotating black holes in dCS gravity, and lay out a formalism for determining the start time of binary black hole ringdown using information from the strong-field region of a binary black hole simulation.
\r\n" }, { "name": "Orr, Matthew Edward", "degree": "PhD", "year": "2019", "title": "Spatially Resolved Star Formation in Cosmological Zoom-in Simulations: Understanding the Role of Feedback in Scaling Relations", "advisor": "Hopkins, Philip F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05142019-152545186", "creators": [ { "name": { "family": "Orr", "given": "Matthew Edward" }, "id": "Orr-Matthew-Edward", "orcid": "0000-0003-1053-3081", "display_name": "Orr, Matthew Edward" } ], "advisors": [ { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "advisor", "display_name": "Hopkins, Philip F." } ], "committee": [ { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "role": "chair", "display_name": "Scoville, Nicholas Zabriskie" }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "member", "display_name": "Hopkins, Philip F." }, { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "role": "member", "display_name": "Steidel, Charles C." }, { "name": { "family": "Armus", "given": "Lee" }, "id": "Armus-L", "role": "member", "display_name": "Armus, Lee" } ], "option_major": [ "physics" ], "doi": "10.7907/WE1D-5586", "abstract": "To understand the night sky is to understand how galaxies form their stars. Cosmological zoom-in simulations, which self-consistently evolve a small number of galaxies at very high resolution by embedding them within a fully cosmological box, have evolved over the last 25 years to a level of realism where they can begin to tackle questions of spatially resolved star formation within galaxies. Whereas a decade ago simulations faced difficulty in matching even global properties of observed galaxies (e.g., the ratio of stellar mass to total halo mass), the state of the art is now able to meaningfully recover resolved quantities in galaxies that were not put into the simulations by hand (e.g., the Kennicutt-Schmidt star formation scaling relation).
\r\n\r\nThe research presented in this thesis seeks to understand how the physics of star formation and stellar feedback from massive stars shape and regulate the interstellar medium (ISM) within galaxies. Particularly, the focus lies on the scale of the largest coherent structures in galaxies -- the disk scale height. To explore these physics, the cosmological zoom-in simulations of the Feedback in Realistic Environments (FIRE) project (Hopkins et al. 2014, 2018) are used.
\r\n\r\nThe chapters of this thesis explore various topics in spatially resolved star formation, including: the Kennicutt-Schmidt relation (Schmidt 1959, Kennicutt 1998), an empirical relation between gas surface density and star formation rates, in the FIRE-1 simulations (Orr et al. 2018), including an examination what set the extent of the star-forming disks in the simulations (i.e., what causes star formation to fire up in the outskirts); an examination of the observational method of analyzing stacks of galaxy observations, finding that temporal variations in spatially resolved star formation rates within individual galaxies were more than enough to bias stacking analysis of star formation rate profiles; a semi-analytic model of non-equilibrium star formation rates, relating to the competition between the feedback timescale associated with star formation and local dynamical times (Orr et al. 2019), which explores this as a source of scatter in the Kennicutt-Schmidt relation; and finally, investigating how gas velocity dispersions and star formation rates relate in FIRE-2 Milky Way-mass disk galaxies, exploring whether or not feedback is primarily driving the velocity dispersions in galaxies, and how quickly local patches can self-regulate with star formation (Orr et al. in prep.).
" }, { "name": "Schmitz, Denise Marie", "degree": "PhD", "year": "2019", "title": "A Perturbative Model for the Intrinsic Alignments of Galaxies", "advisor": "Hopkins, Philip F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05312019-144001688", "creators": [ { "name": { "family": "Schmitz", "given": "Denise Marie" }, "id": "Schmitz-Denise-Marie", "orcid": "0000-0001-6297-9312", "display_name": "Schmitz, Denise Marie" } ], "advisors": [ { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "advisor", "display_name": "Hopkins, Philip F." } ], "committee": [ { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "orcid": "0000-0002-4834-7260", "role": "chair", "display_name": "Steidel, Charles C." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Mawet", "given": "Dimitri" }, "id": "Mawet-D", "orcid": "0000-0002-8895-4735", "role": "member", "display_name": "Mawet, Dimitri" }, { "name": { "family": "Dor\u00e9", "given": "Olivier P." }, "id": "Dor\u00e9-O", "orcid": "0000-0001-7432-2932", "role": "member", "display_name": "Dor\u00e9, Olivier P." }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "member", "display_name": "Hopkins, Philip F." } ], "option_major": [ "astrophys" ], "doi": "10.7907/HZ7G-1048", "abstract": "Intrinsic alignments (IA), correlations between the intrinsic shapes and orientations of galaxies on the sky, are both a significant systematic in weak lensing and a probe of the effect of large-scale structure on galactic structure and angular momentum. In the era of precision cosmology, it is thus especially important to model IA with high accuracy.
\r\n\r\nEfforts to use cosmological perturbation theory to model the dependence of IA on the large-scale structure have thus far been relatively successful. However, extant models have not been made fully self-consistent to arbitrary order in perturbation theory and do not consistently account for time evolution. In particular, advection of galaxies due to peculiar velocities alters the impact of IA, because galaxy positions when observed are generally different from their positions at the epoch when IA is believed to be set.
\r\n\r\nIn this work, we evolve the galaxy IA from the time of galaxy formation to the time at which they are observed, including the effects of this advection, and show how this process naturally leads to a dependence of IA on the velocity shear. We then incorporate this time evolution into a fully self-consistent perturbative formalism for a passively evolving IA model. We demonstrate this formalism first at second order as a proof of concept, then at third order for application to observationally relevant two-point correlations at one-loop order.
\r\n\r\nWe also discuss the implications of the time-evolved IA model for systematic errors in weak lensing as well as for studies of galaxy formation and evolution. We find that considering advection introduces nonlocality into the bispectrum, and that the degree of nonlocality represents the memory of a galaxy's path from the time of its formation to the time of observation. We discuss how this result can be used to constrain the redshift at which IA is determined and provide Fisher estimation for the relevant measurements using the example of SDSS-BOSS.
" }, { "name": "Su, Kung-Yi", "degree": "PhD", "year": "2019", "title": "Stellar Feedback, AGN Feedback and Fluid Microphysics in Galaxy Evolution", "advisor": "Hopkins, Philip F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05142019-161824896", "creators": [ { "name": { "family": "Su", "given": "Kung-Yi" }, "id": "Su-Kung-Yi", "orcid": "0000-0003-1598-0083", "display_name": "Su, Kung-Yi" } ], "advisors": [ { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "advisor", "display_name": "Hopkins, Philip F." } ], "committee": [ { "name": { "family": "Martin", "given": "D. Christopher" }, "id": "Martin-D-Christopher", "role": "chair", "display_name": "Martin, D. Christopher" }, { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "role": "member", "display_name": "Steidel, Charles C." }, { "name": { "family": "Kirby", "given": "Evan N." }, "id": "Kirby-E-N", "role": "member", "display_name": "Kirby, Evan N." }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "member", "display_name": "Hopkins, Philip F." } ], "option_major": [ "physics" ], "doi": "10.7907/RQG9-NT50", "abstract": "Understanding how the baryonic physics affects the formation and evolution of galaxies is one of the most critical questions in modern astronomy. Significant progress in understanding stellar feedback and modeling them explicitly in simulations have made it possible to reproduce a wide range of observed galaxy properties. However, there are still various pieces of missing physics and uncertainties in galaxies of different mass range.
\r\n\r\nIn this thesis, I will explore these missing pieces in baryonic physics on top of the Feedback in Realistic Environments (FIRE) stellar feedback in the cosmological hydrodynamic zoom-in simulations (FIRE-2 suite) and isolated galaxy simulations. These high-resolution simulations with FIRE physics capture multi-phase realistic interstellar medium (ISM) with gas cooling down to 10K, and star formations in dense clumps in giant molecular clouds. They are, therefore, an ideal tool for investigating the missing pieces in baryonic physics.
\r\n\r\nIn the first part of the thesis, Chapter 2, I will focus on the discrete effects of stellar feedback like individual supernovae, hypernovae, and initial mass function (IMF) sampling in dwarfs (109-1010 M\u2299). These discrete processes of stellar feedback can have maximum effects on the small galaxies without being averaged out. I will show that the discretization of supernovae (SNe) is absolutely necessary, while the effects from IMF sampling and hypernovae (HNe) is not apparent, due to the strong clustering nature of star formation.
\r\n\r\nIn the second part of the thesis, Chapter 3-4, I will focus on fluid microphysics, exploring their effects on galaxy properties and their interplay with stellar feedback in sub-L* galaxies. I will demonstrate that, once the stellar feedback is explicitly implemented as FIRE stellar feedback model, fluid microphysics such as magnetic fields, conduction, and viscosity only have minor effects on the galaxy properties like star formation rate (SFR), phase structure, or outflows. Stellar feedback also strongly alters the amplifications and morphology of the magnetic fields, resulting in much more randomly-oriented field lines. However, despite the stellar feedback, the amplification of magnetic fields in ISM gas is primarily dominated by flux-freezing compression.
\r\n\r\nIn the final part of my thesis, I focus on the massive cluster ellipticals of 1012-1014 M\u2299, where the physical mechanisms that regulate the observation-inferred cooling flows are highly uncertain -- the classic \"cooling flow problem\". I showed that solutions in the literature not associated with an active galactic nucleus (AGN), including stellar feedback, the cosmic ray from stellar feedback, magnetic fields, conduction, and morphological quenching, cannot possibly quench the galaxies, mostly because of the insufficient energy and the limited size of the affected region. After ruling out the non-AGN feedback solutions to the cooling flow problem, I will go into the most accessible, and perhaps promising solution: \"AGN feedback\", exploring the generic classes of AGN feedback models proposed in the literature. I am going to show that enhancing turbulence and injecting cosmic ray are probably the most important aspects of AGN feedback in galaxy quenching. Since they provide non-thermal pressure support that stably suppresses the core density, they can stably reduce the cooling flows without overheating the galactic cores.
" }, { "name": "Varma, Vadapalli Vijay S.", "degree": "PhD", "year": "2019", "title": "Black Hole Simulations: From Supercomputers to Your Laptop", "advisor": "Scheel, Mark; Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:05252019-040137906", "creators": [ { "name": { "family": "Varma", "given": "Vadapalli Vijay S." }, "id": "Varma-Vadapalli-Vijay-S", "orcid": "0000-0002-9994-1761", "display_name": "Varma, Vadapalli Vijay S." } ], "advisors": [ { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "advisor", "display_name": "Scheel, Mark" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" } ], "committee": [ { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "chair", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/YT07-Q639", "abstract": "In this thesis, I will present various advancements in the modeling of binary black holes (BBHs): two black holes (BHs) that are in orbit around each other. The BHs lose energy to gravitational waves, causing them to spiral towards each other until they eventually merge and leave behind a single BH. BBHs are primary sources for ground based detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO).
\r\n\r\nAs the BHs are about to merge, they are moving at about half the speed of light and the spacetime is highly dynamical. All analytical methods break down at this stage, and numerical relativity (NR) simulations of the full Einstein\u2019s equations are necessary. These simulations, however, are very expensive, with each simulation taking a month on a supercomputer. For direct data analysis applications with LIGO, we need a model that can be evaluated in a fraction of a second. Therefore, several approximate but fast models that are calibrated to NR simulations have been developed over the years.
\r\n\r\nSurrogate modeling provides a more powerful alternative: trained directly against the NR simulations without added assumptions, these models can reproduce the simulations as accurately as the simulations themselves, while taking only a fraction of a second to evaluate on a laptop. In short, surrogate models take BBH NR simulations from supercomputers to your laptop, without a loss of accuracy.
\r\n\r\nIn this thesis, I will present several state-of-the-art surrogate models including (i) the first NR based surrogate model to span the full range of frequencies for ground based detectors, (ii) the first surrogate model for the mass, spin, and kick velocity of the final black hole after merger, and (iii) extension of an existing precessing surrogate model to higher mass ratios. In addition, I will present some work in improving the BBH initial data used in NR simulations, as well as in understanding the systematic biases introduced by approximate waveform models in LIGO data analysis.
\r\n\r\nAs we head into the imminent era of high-precision gravitational wave astronomy, accurate yet fast models such as surrogate models will play a crucial role in maximizing the science output of our detectors.
" }, { "name": "Guszejnov, D\u00e1vid", "degree": "PhD", "year": "2018", "title": "On the Origin of Scales and Scaling Laws in Star Formation", "advisor": "Hopkins, Philip F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05142018-155029272", "creators": [ { "name": { "family": "Guszejnov", "given": "D\u00e1vid" }, "id": "Guszejnov-D\u00e1vid", "orcid": "0000-0001-5541-3150", "display_name": "Guszejnov, D\u00e1vid" } ], "advisors": [ { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "advisor", "display_name": "Hopkins, Philip F." } ], "committee": [ { "name": { "family": "Hillenbrand", "given": "Lynne A." }, "id": "Hillenbrand-L-A", "role": "chair", "display_name": "Hillenbrand, Lynne A." }, { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "orcid": "0000-0002-0438-3323", "role": "member", "display_name": "Scoville, Nicholas Zabriskie" }, { "name": { "family": "Keres", "given": "Dusan" }, "id": "Keres-Dusan", "role": "member", "display_name": "Keres, Dusan" }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "member", "display_name": "Hopkins, Philip F." } ], "option_major": [ "physics" ], "doi": "10.7907/WZ2G-R643", "abstract": "Stars are the fundamental objects of astrophysics and their formation is a key process that influences the evolution of galaxies and planets, and the development of life. Understanding how stars form is crucial even for seemingly unconnected fields of astronomy, as the interpretation of observed starlight from galaxies (even as a background) and other unresolved sources relies on our understanding of star formation. There is no comprehensive theory of star formation, despite intense effort on both the theoretical and observational sides, due to the complicated, non-linear physics involved (e.g., magnetohydrodynamics, gravity, radiation) and the enormous dynamic range of the problem. My goal has been to identify the role different physical processes (e.g., turbulence, feedback) play in star formation.
\r\n\r\nUsing the semi-analytical framework that I developed, I found that a large number of star formation models are inherently sensitive to the initial conditions of the progenitor clouds (e.g., temperature). This led to another study where I predicted the expected variation of the initial mass function (IMF) of stars in a Milky-Way-like galaxy for different star formation models. I showed that IMF models where the peak is either set by turbulent properties or cooling physics (using an effective equation of state) are unable to reproduce the universal IMF of the Milky Way. I also utilized my semi-analytical tools to predict higher-order statistics of star formation: stellar correlation, multiplicity and the companion mass distribution for binaries. I showed that due to observational biases all explored models could roughly reproduce the observed multiplicity and companion mass distributions. This means that observations are currently unable to differentiate between most models.
\r\n\r\nWhile working on these projects I found that several scaling relations (e.g., the slopes of IMF, stellar correlation function and gas column density distribution) are insensitive to our choice of physical model; they are universal. Inspired by this I developed an analytic model that I used to show that scale-free structure formation inherently leads to these scaling relations. This provides a deep physical reason why the mass functions and correlation functions of very different systems (e.g., stars, protostellar cores, star clusters, Dark matter halos) follow roughly the same power-law relations.
\r\n\r\nMy previous findings with my semi-analytical models indicated that isothermal collapse would lead to an infinite fragmentation cascade, i.e. there is no inherent low-mass cut-off. Part of the literature supports these findings and claims that additional physics is needed to imprint a mass scale into the problem, but there are theoretical models and simulations that claim that such a cut-off exists. Using GIZMO, a fully adaptive, meshless MHD code, I have carried out a convergence study and have shown that the isothermal fragmentation cascade continues to ever smaller scales without limit.
" }, { "name": "Lippuner, Jonas", "degree": "PhD", "year": "2018", "title": "r-Process Nucleosynthesis in Neutron Star Mergers with the New Nuclear Reaction Network SkyNet", "advisor": "Ott, Christian D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06072017-212011532", "creators": [ { "name": { "family": "Lippuner", "given": "Jonas" }, "id": "Lippuner-Jonas", "orcid": "0000-0002-5936-3485", "display_name": "Lippuner, Jonas" } ], "advisors": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "role": "advisor", "display_name": "Ott, Christian D." } ], "committee": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "role": "chair", "display_name": "Ott, Christian D." }, { "name": { "family": "Filippone", "given": "Bradley W." }, "id": "Filippone-B-W", "role": "member", "display_name": "Filippone, Bradley W." }, { "name": { "family": "Kulkarni", "given": "Shrinivas R." }, "id": "Kulkarni-S-R", "role": "member", "display_name": "Kulkarni, Shrinivas R." }, { "name": { "family": "Metzger", "given": "Brian D." }, "id": "Metzger-B-D", "role": "member", "display_name": "Metzger, Brian D." }, { "name": { "family": "Roberts", "given": "Luke F." }, "id": "Roberts-L-F", "role": "member", "display_name": "Roberts, Luke F." } ], "option_major": [ "physics" ], "doi": "10.7907/Z9V40SCS", "abstract": "At the Big Bang, only the lightest elements, mainly hydrogen and helium, were produced. Stars synthesize heavier elements, such as helium, carbon, and oxygen, from lighter ones through nuclear fusion. Iron-group elements are created in supernovae (both type Ia and core-collapse). It has been known for 60 years that the slow and rapid neutron capture processes (s- and r-process) are each responsible for creating about half of the elements beyond the iron group. The s-process is known to occur in asymptotic giant branch stars, but the astrophysical site of the r-process is still a mystery. Based on observations of heavy elements in old stars, it was theorized that r-process nucleosynthesis takes place in core-collapse supernovae (CCSNe). However, recent CCSN simulations indicate that the conditions required for the r-process are not obtained in CCSN. The focus has thus shifted to neutron star mergers (both binary neutron star and black hole-neutron star mergers), where the r-process easily synthesizes all the known heavy elements. Neutron star mergers are expected to be detected by the Laser Interferometer Gravitational Wave Observatory (LIGO) in the near future, which should either confirm or rule out their proposed association with radioactively powered transients called kilonovae or macronovae that are the observational signatures of r-process nucleosynthesis. To understand how the r-process operates in different astrophysical scenarios and what relative abundance patterns it produces, detailed nuclear reaction network calculations are needed that track thousands of isotopes and tens of thousands of nuclear reactions. In this thesis, I present SkyNet, a new general-purpose nuclear reaction network that can evolve an arbitrary list of nuclear species with an arbitrary set of nuclear reactions. I describe in detail the different physics that is implemented in SkyNet and I perform code tests and comparisons to other nuclear reaction networks. Then I use SkyNet to systematically investigate r-process nucleosynthesis as a function of the initial electron fraction, initial entropy, and expansion timescale of the fluid. Further, I present r-process nucleosynthesis calculations with SkyNet in the dynamical ejecta of a black hole\u2013neutron star merger with varying levels of neutrino irradiation. Finally, I study the r-process in the outflow of a neutron star merger remnant disk as a function of the lifetime of the central hypermassive neutron star (HMNS). SkyNet is easy to use and flexible and it is publicly available as open-source software. Multiple researchers are already using SkyNet for their work, and I hope that SkyNet will be a useful tool for the broader nuclear astrophysics community." }, { "name": "Ma, Xiangcheng", "degree": "PhD", "year": "2018", "title": "Understanding Galaxy Formation and Evolution with Realistic Simulations", "advisor": "Hopkins, Philip F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05232018-173148982", "creators": [ { "name": { "family": "Ma", "given": "Xiangcheng" }, "id": "Ma-Xiangcheng", "orcid": "0000-0001-8091-2349", "display_name": "Ma, Xiangcheng" } ], "advisors": [ { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "advisor", "display_name": "Hopkins, Philip F." } ], "committee": [ { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "role": "chair", "display_name": "Steidel, Charles C." }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "member", "display_name": "Hopkins, Philip F." }, { "name": { "family": "Kirby", "given": "Evan N." }, "id": "Kirby-E-N", "role": "member", "display_name": "Kirby, Evan N." }, { "name": { "family": "Quataert", "given": "Eliot" }, "id": "Quataert-Eliot", "role": "member", "display_name": "Quataert, Eliot" } ], "option_major": [ "physics" ], "doi": "10.7907/MX2D-6P63", "abstract": "Understanding the formation and evolution of galaxies from the Big Bang to the present day is one of the most important questions in modern astronomy. The tremendous amount of observational data accumulated in the past decade that probe various properties of galaxies across cosmic time demand a more detailed theoretical understanding of galaxy formation and evolution.
\r\n\r\nIn this thesis, I will investigate several open question in this field using state-of-the-art cosmological hydrodynamic zoom-in simulations of galaxy formation from the Feedback in Realistic Environments (FIRE) suite. These high-resolution simulations (10-104M\u2299, 0.1-10pc) include realistic models of the multi-phase ISM, star formation, and stellar feedback and explicitly capture gas cooling down to 10 K, star formation in dense clumps in giant molecular clouds, and feedback coupling on the smallest resolved scales. These simulations are powerful tools for studying the key physics governing galaxy formation and evolution and understanding the detailed observations of galaxy properties.
\r\n\r\nThe first half of this thesis presents three studies on galactic chemical evolution. Chapter 2 focuses on the origin and evolution of the galaxy mass-metallicity relation (MZR), one of the fundamental properties of galaxies. I will show that the FIRE simulations broadly agree with the observed galaxy MZR from z = 0-3. The slope of the MZR is mainly driven by the metal retention fraction in low-mass galaxies, while the amount of redshift evolution of the MZR is mostly determined by the star formation histories of galaxies. Chapter 3 attempts to understanding the diversity of gas-phase metallicity gradients found in intermediate-redshift (z ~ 0.6-3) galaxies. I will show that the metallicity gradient in a galaxy varies on small timescales driven by bursty star formation and feedback cycle at early times, naturally resulting in the observed diversity of metallicity gradients in z ~ 2 galaxies. The metallicity gradient only reflects the instantaneous dynamics of a galaxy. Chapter 4 will study the structure, stellar age and metallicity gradients, and formation history of Milky Way (MW)-like disk galaxies. At high redshift, star formation happens in a chaotic, bursty mode, which eventually forms a nearly spherical structure by z = 0. Since z \u227e 1, a stable gas disk emerged and stars formed in that disk thereafter. The thickness of the gas disk decreases with time due to lowering gas fraction. Stars formed earlier in this disk are kinematically heated to a thicker, flaring disk. Such a formation history leads to the age and stellar metallicity gradients consistent with what observed in the MW disk.
\r\n\r\nThe second half of this thesis focuses on galaxy formation in the first billion years of the Universe, known as the reionization era. Chapters 5 and 6 study the escape fraction of ionizing photons from galaxies at z \u2265 5, which is an important, yet poorly constrained parameter for understanding the reionization history. Most ionizing photons are emitted by the youngest stellar populations in the galaxy, which are usually embedded in their 'birth clouds'. Stellar feedback is required to clear these clouds in a few Myr before ionizing photons are allowed escape. In the meanwhile, the ionizing photon budget decreases rapidly as the most massive stars start to die. The competition of timescales between feedback and stellar evolution is thus the most important physics determines fesc. I will show that canonical single-star stellar population models such as STARBURST99 generally yield a fesc far below what is required for cosmic reionization. Binary models, in contrast, produce more ionizing photons at late times than single-star models and thus lead to a much higher fesc. Chapter 7 presents a new suite of high-resolution cosmological zoom-in simulations of z \u2265 5 galaxies that contains thousands of halos at any time in all zoom-in regions. I will present the stellar mass-halo mass relation, SFR-Mhalo relation, stellar mass-magnitude relation, stellar mass functions, and multi-band luminosity functions at z = 5-12. These prediction agree well with current observational constraints and can be further tested by future observations with the James Webb Space Telescope. Using these new simulations, Chapter 8 studies the morphology and size evolution of galaxies at z \u2265 5. I will show that the rest-frame UV light from z \u2265 5 galaxies is usually dominated by one or several star-forming clumps that are intrinsically bright and small. Current observations with moderate surface brightness limits tend to only pick up the intrinsically small galaxies or individual clumps but miss the diffuse light in the galaxies. Such a selection effect is likely to result in the extremely small sizes claimed for the faint galaxies in the Hubble Frontier Fields.
" }, { "name": "Murchikova, Elena M.", "degree": "PhD", "year": "2018", "title": "Astrophysical Applications of Quantum Mechanics", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechTHESIS:06082018-000259902", "creators": [ { "name": { "family": "Murchikova", "given": "Elena M." }, "id": "Murchikova-Elena-M", "orcid": "0000-0001-8986-5403", "display_name": "Murchikova, Elena M." } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "chair", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "role": "member", "display_name": "Scoville, Nicholas Zabriskie" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Fuller", "given": "James" }, "id": "Fuller-J", "orcid": "0000-0002-4544-0750", "role": "member", "display_name": "Fuller, James" } ], "option_major": [ "physics" ], "doi": "10.7907/PEBS-ZJ88", "abstract": "From an outside point of view, astrophysics and quantum mechanics as subclasses of the physical sciences could not be further from each other. Yet these two sides of nature are deeply intertwined. The influence of quantum mechanics on astrophysics and astrophysics on quantum mechanics has been profound: spectral lines as diagnostics, radiative transport, the interiors of celestial bodies, neutrino oscillations, constraints on neutrino mass and graviton mass. In this work, I discuss several applications of quantum mechanics in astrophysics: (1) I examine the use of submm recombination lines of H, He and He+ to probe the extreme ultraviolet luminosity of starbursts and Active Galactic Nuclei. (2) I use the hydrogen recombination line H30\u03b1 to study the accretion zone of the Milky Way's Galactic Center black hole. I discuss detection of an accretion disk of radius <0.008 pc, consisting of ~104 K gas the disk properties, and its importance in the context of accretion on the black hole. (3) I carry out an extensive study and comparison of M1 closure schemes for neutrino radiation transport, using the protoneutron star interior as a background. (4) I study first-order hydrodynamics of a chiral fluid on a vortex background, and in an external magnetic field, as the precursor for a study of neutron star interiors. I show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field.\r\n" }, { "name": "Richers, Sherwood Andrew, III", "degree": "PhD", "year": "2018", "title": "Neutrino Radiation Transport and Other Topics in High Energy Density Astrophysics", "advisor": "Ott, Christian D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:07212017-001528247", "creators": [ { "name": { "family": "Richers", "given": "Sherwood Andrew, III" }, "id": "Richers-Sherwood-Andrew-III", "orcid": "0000-0001-5031-6829", "display_name": "Richers, Sherwood Andrew, III" } ], "advisors": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "role": "advisor", "display_name": "Ott, Christian D." } ], "committee": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "role": "chair", "display_name": "Ott, Christian D." }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "role": "member", "display_name": "Hopkins, Philip F." }, { "name": { "family": "Filippone", "given": "Bradley W." }, "id": "Filippone-B-W", "role": "member", "display_name": "Filippone, Bradley W." }, { "name": { "family": "Kulkarni", "given": "Shrinivas R." }, "id": "Kulkarni-S-R", "role": "member", "display_name": "Kulkarni, Shrinivas R." }, { "name": { "family": "Kasen", "given": "Daniel" }, "id": "Kasen-D", "role": "member", "display_name": "Kasen, Daniel" } ], "option_major": [ "physics" ], "doi": "10.7907/Z9PC30JH", "abstract": "Neutron star mergers and the collapse of massive stars result in some of the universe\u2019s most violet explosions. However, the detailed mechanisms behind all of these astrophysical explosions remain elusive. Their strongly nonlinear and complicated nature makes them difficult and expensive to simulate, and the properties of matter in these extreme conditions are poorly constrained. I use a variety of computational tools to understand the detailed mechanisms behind both types of events.
\r\n\r\nI describe my relativistic time-independent multidimensional Monte Carlo neutrino radiation transport code Sedonu that provides an accurate account of the neutrino radiation fields and the interaction with neutrinos and background fluid. Though Sedonu calculations are time-independent, I demonstrate their utility in dynamical general relativistic variable Eddington tensor radiation hydrodynamics simulations.
\r\n\r\nI apply Sedonu to simulations of accretion disks following neutron star mergers to demonstrate that more realistic disk cooling and neutrino-driven mass ejection rates are larger than is predicted using approximate transport methods. I also reinforce that neutrino pair annihilation from these disk configurations is unlikely to be able to energize a gamma-ray burst jet.
\r\n\r\nI subject Sedonu to the first thorough comparison of Boltzmann neutrino radiation transport methods in multiple spatial dimensions in the context of core-collapse supernovae. The comparisons with the other highly accurate discrete ordinates-based transport scheme show remarkably similar results, verifying the accuracy of both methods and underscoring the importance of numerical fidelity.
\r\n\r\nI perform the first broad parameter study on how different descriptions of dense nuclear matter and star rotation rates influence the dynamics of, and hence gravitational waves from, the bounce and early post-bounce phase of rapidly rotating core collapse supernovae. Using the results of 1824 two-dimensional general relativistic core-collapse simulations, I demonstrate that the equation of state is unlikely to be constrained by LIGO observations. I show that the effect of the equation of state on the gravitational wave frequency can be described by a single universal relation.
\r\n\r\nFinally, I use results of three-dimensional general relativistic magnetohydrodynamics simulations of rapidly rotating core collapse to demonstrate that the polar magnetic structures that form are destroyed by a magnetohydrodynamic kink instability.
" }, { "name": "Blackman, Jonathan Lloyd", "degree": "PhD", "year": "2017", "title": "Surrogate Models of Gravitational Waves from Numerical Relativity Simulations of Binary Black Hole Mergers", "advisor": "Ott, Christian D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05242017-103834785", "creators": [ { "name": { "family": "Blackman", "given": "Jonathan Lloyd" }, "id": "Blackman-Jonathan-Lloyd", "orcid": "0000-0002-7113-0289", "display_name": "Blackman, Jonathan Lloyd" } ], "advisors": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "advisor", "display_name": "Ott, Christian D." } ], "committee": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "chair", "display_name": "Ott, Christian D." }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." } ], "option_major": [ "physics" ], "doi": "10.7907/Z93F4MPJ", "abstract": "The advanced LIGO detectors have made multiple detections of gravitational waves from the mergers of binary black hole systems, bringing us into the era of gravitational wave astronomy. From such gravitational wave detections, we can put constraints on deviations from general relativity (GR), as well as measure the masses and spins of the black holes involved in the mergers. Such measurements require knowledge of the gravitational waveforms predicted by GR for all relevant masses and spins. Numerical relativity (NR) simulations are now sufficiently robust that we can accurately simulate binary black hole mergers and obtain the waveform for all but the most extreme parameters, but they are too computationally expensive for a dense coverage of the parameter space. NR surrogate models rapidly and accurately interpolate the waveforms from a set of NR simulations over a subset of parameter space. Using the Spectral Einstein Code (SpEC), we have built several NR surrogate models for various subsets of the parameter space, culminating in a model which includes all 7 intrinsic parameter dimensions. The surrogate model waveforms are nearly as accurate as NR waveforms, and can be evaluated in milliseconds whereas a single NR simulation can take weeks.
" }, { "name": "Oklop\u010di\u0107, Antonija", "degree": "PhD", "year": "2017", "title": "Radiative Processes in Astrophysical Gases: From the Intergalactic and Interstellar Medium to Exoplanetary Atmospheres", "advisor": "Hirata, Christopher M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05312017-154839851", "creators": [ { "name": { "family": "Oklop\u010di\u0107", "given": "Antonija" }, "id": "Oklop\u010di\u0107-Antonija", "orcid": "0000-0002-9584-6476", "display_name": "Oklop\u010di\u0107, Antonija" } ], "advisors": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "advisor", "display_name": "Hirata, Christopher M." } ], "committee": [ { "name": { "family": "Hillenbrand", "given": "Lynne A." }, "id": "Hillenbrand-L-A", "role": "chair", "display_name": "Hillenbrand, Lynne A." }, { "name": { "family": "Hopkins", "given": "Philip F." }, "id": "Hopkins-P-F", "orcid": "0000-0003-3729-1684", "role": "member", "display_name": "Hopkins, Philip F." }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." }, { "name": { "family": "Mawet", "given": "Dimitri" }, "id": "Mawet-D", "orcid": "0000-0002-8895-4735", "role": "member", "display_name": "Mawet, Dimitri" }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." } ], "option_major": [ "astrophys" ], "doi": "10.7907/Z9GM85CS", "abstract": "This thesis presents theoretical investigations in three areas of astrophysics, all related to radiative processes and interactions between stellar radiation and gaseous media in the Universe, ranging from the intergalactic and interstellar medium to planetary atmospheres.
\r\n\r\nPart I of the thesis consists of two independent investigations in which we study the effects of stellar feedback in high-redshift environments. The topic of Chapter 2 is the intergalactic medium (IGM) in the epoch just after the formation of the first stars in the Universe, but before the cosmic reionization was completed. This epoch is of great interest for the ongoing and future experiments aimed at observing the neutral IGM via the redshifted 21 cm line of hydrogen. We study the effects of resonant scattering of Lyman-\u03b1 photons produced by early stars on the structure of temperature fluctuations in the IGM. In Chapter 3, we use cosmological hydrodynamic simulations of galaxy evolution to study the effects of stellar feedback on the clumpy structure of star-forming galaxies at z ~ 2. Observations of high-redshift galaxies show that their morphology is often dominated by a few giant clumps of intense star formation, but the nature and the importance of these clumps for the evolution of their host galaxies are uncertain. We present a detailed analysis of the properties of giant clumps in a high-redshift simulated galaxy from the FIRE project.
\r\n\r\nPart II of the thesis is devoted to the effects of Raman scattering of stellar radiation in the atmospheres of extrasolar planets. Spectral signatures of Raman scattering imprinted in the geometric albedo spectrum of a gaseous planet carry information about the properties of the planet's atmosphere---its composition, temperature, and the radiation-penetration depth. In Chapter 5, we present the results of radiative transfer calculations including the treatment of Raman scattering for different types of planetary atmospheres and analyze the feasibility of detecting the spectral signatures of Raman scattering in nearby exoplanets. The structure and the intensity of Raman spectral features depends on both the atmospheric properties and the shape of the stellar spectrum irradiating the atmosphere. In Chapter 6, we analyze the diversity of Raman features in the geometric albedo spectra of planets hosted by different types of stars.
" }, { "name": "Nerella, Tejaswi Venumadhav", "degree": "PhD", "year": "2016", "title": "The Astrophysics of Strongly Interacting Systems", "advisor": "Hirata, Christopher M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09042015-035149228", "creators": [ { "name": { "family": "Nerella", "given": "Tejaswi Venumadhav" }, "id": "Nerella-Tejaswi-Venumadhav", "orcid": "0000-0002-1661-2138", "display_name": "Nerella, Tejaswi Venumadhav" } ], "advisors": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "advisor", "display_name": "Hirata, Christopher M." } ], "committee": [ { "name": { "family": "Bock", "given": "James J." }, "id": "Bock-J-J", "orcid": "0000-0002-5710-5212", "role": "chair", "display_name": "Bock, James J." }, { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "member", "display_name": "Ott, Christian D." }, { "name": { "family": "Dor\u00e9", "given": "Olivier P." }, "id": "Dor\u00e9-O", "orcid": "0000-0001-7432-2932", "role": "member", "display_name": "Dor\u00e9, Olivier P." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." } ], "option_major": [ "physics" ], "doi": "10.7907/Z900001N", "abstract": "This thesis presents investigations in four areas of theoretical astrophysics: the production of sterile neutrino dark matter in the early Universe, the evolution of small-scale baryon perturbations during the epoch of cosmological recombination, the effect of primordial magnetic fields on the redshifted 21-cm emission from the pre-reionization era, and the nonlinear stability of tidally deformed neutron stars.
\r\n\r\nIn the first part of the thesis, we study the asymmetry-driven resonant production of 7 keV-scale sterile neutrino dark matter in the primordial Universe at temperatures T >~ 100 MeV. We report final DM phase space densities that are robust to uncertainties in the nature of the quark-hadron transition. We give transfer functions for cosmological density fluctuations that are useful for N-body simulations. We also provide a public code for the production calculation.
\r\n\r\nIn the second part of the thesis, we study the instability of small-scale baryon pressure sound waves during cosmological recombination. We show that for relevant wavenumbers, inhomogenous recombination is driven by the transport of ionizing continuum and Lyman-alpha photons. We find a maximum growth factor less than ≈ 1.2 in 107 random realizations of initial conditions. The low growth factors are due to the relatively short duration of the recombination epoch.
\r\n\r\nIn the third part of the thesis, we propose a method of measuring weak magnetic fields, of order 10-19 G (or 10-21 G if scaled to the present day), with large coherence lengths in the inter galactic medium prior to and during the epoch of cosmic reionization. The method utilizes the Larmor precession of spin-polarized neutral hydrogen in the triplet state of the hyperfine transition. We perform detailed calculations of the microphysics behind this effect, and take into account all the processes that affect the hyperfine transition, including radiative decays, collisions, and optical pumping by Lyman-alpha photons.
\r\n\r\nIn the final part of the thesis, we study the non-linear effects of tidal deformations of neutron stars (NS) in a compact binary. We compute the largest three- and four-mode couplings among the tidal mode and high-order p- and g-modes of similar radial wavenumber. We demonstrate the near-exact cancellation of their effects, and resolve the question of the stability of the tidally deformed NS to leading order. This result is significant for the extraction of binary parameters from gravitational wave observations.
\r\n" }, { "name": "Handmer, Casey John", "degree": "PhD", "year": "2015", "title": "Gauge Invariant Spectral Cauchy Characteristic Extraction of Gravitational Waves in Computational General Relativity", "advisor": "Chen, Yanbei; Ott, Christian D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05282015-131606315", "creators": [ { "name": { "family": "Handmer", "given": "Casey John" }, "id": "Handmer-Casey-John", "display_name": "Handmer, Casey John" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" }, { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "advisor", "display_name": "Ott, Christian D." } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "Szilagyi", "given": "Bela" }, "id": "Szilagyi-B", "orcid": "0000-0001-7744-6180", "role": "member", "display_name": "Szilagyi, Bela" }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Patterson", "given": "Ryan B." }, "id": "Patterson-R-B", "orcid": "0000-0002-5787-9517", "role": "member", "display_name": "Patterson, Ryan B." }, { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "member", "display_name": "Ott, Christian D." } ], "option_major": [ "physics" ], "doi": "10.7907/Z9NP22DZ", "abstract": "We present a complete system for Spectral Cauchy characteristic extraction (Spectral CCE). Implemented in C++ within the Spectral Einstein Code (SpEC), the method employs numerous innovative algorithms to efficiently calculate the Bondi strain, news, and flux.
\r\n\r\nSpectral CCE was envisioned to ensure physically accurate gravitational wave-forms computed for the Laser Interferometer Gravitational wave Observatory (LIGO) and similar experiments, while working toward a template bank with more than a thousand waveforms to span the binary black hole (BBH) problem\u2019s seven-dimensional parameter space.
\r\n\r\nThe Bondi strain, news, and flux are physical quantities central to efforts to understand and detect astrophysical gravitational wave sources within the Simulations of eXtreme Spacetime (SXS) collaboration, with the ultimate aim of providing the first strong field probe of the Einstein field equation.
\r\n\r\nIn a series of included papers, we demonstrate stability, convergence, and gauge invariance. We also demonstrate agreement between Spectral CCE and the legacy Pitt null code, while achieving a factor of 200 improvement in computational efficiency.
\r\n\r\nSpectral CCE represents a significant computational advance. It is the foundation upon which further capability will be built, specifically enabling the complete calculation of junk-free, gauge-free, and physically valid waveform data on the fly within SpEC.
" }, { "name": "Luan, Jing", "degree": "PhD", "year": "2015", "title": "Toward Understanding Astrophysical Phenomena", "advisor": "Goldreich, Peter Martin", "url": "https://resolver.caltech.edu/CaltechTHESIS:06052015-153743425", "creators": [ { "name": { "family": "Luan", "given": "Jing" }, "id": "Luan-Jing", "display_name": "Luan, Jing" } ], "advisors": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" } ], "committee": [ { "name": { "family": "Prince", "given": "Thomas A." }, "id": "Prince-T-A", "role": "chair", "display_name": "Prince, Thomas A." }, { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "role": "member", "display_name": "Ott, Christian D." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" } ], "option_major": [ "astrophys" ], "doi": "10.7907/Z97942NB ", "abstract": "Fast radio bursts (FRBs), a novel type of radio pulse, whose physics is not yet understood at all. Only a handful of FRBs had been detected when we started this project. Taking account of the scant observations, we put physical constraints on FRBs. We excluded proposals of a galactic origin for their extraordinarily high dispersion measures (DM), in particular stellar coronas and HII regions. Therefore our work supports an extragalactic origin for FRBs. We show that the resolved scattering tail of FRB 110220 is unlikely to be due to propagation through the intergalactic plasma. Instead the scattering is probably caused by the interstellar medium in the FRB's host galaxy, and indicates that this burst sits in the central region of that galaxy. Pulse durations of order ms constrain source sizes of FRBs implying enormous brightness temperatures and thus coherent emission. Electric fields near FRBs at cosmological distances would be so strong that they could accelerate free electrons from rest to relativistic energies in a single wave period. When we worked on FRBs, it was unclear whether they were genuine astronomical signals as distinct from 'perytons', clearly terrestrial radio bursts, sharing some common properties with FRBs. Recently, in April 2015, astronomers discovered that perytons were emitted by microwave ovens. Radio chirps similar to FRBs were emitted when their doors opened while they were still heating. Evidence for the astronomical nature of FRBs has strengthened since our paper was published. Some bursts have been found to show linear and circular polarizations and Faraday rotation of the linear polarization has also been detected. I hope to resume working on FRBs in the near future. But after we completed our FRB paper, I decided to pause this project because of the lack of observational constraints.
\r\n\r\n\r\nThe pulsar triple system, J0733+1715, has its orbital parameters fitted to high accuracy owing to the precise timing of the central ms pulsar. The two orbits are highly hierarchical, namely Porb,1 << Porb,2, where 1 and 2 label the inner and outer white dwarf (WD) companions respectively. Moreover, their orbital planes almost coincide, providing a unique opportunity to study secular interaction associated purely with eccentricity beyond the solar system. Secular interaction only involves effect averaged over many orbits. Thus each companion can be represented by an elliptical wire with its mass distributed inversely proportional to its local orbital speed. Generally there exists a mutual torque, which vanishes only when their apsidal lines are parallel or anti-parallel. To maintain either mode, the eccentricity ratio, e1/e2, must be of the proper value, so that both apsidal lines precess together. For J0733+1715, e1 << e2 for the parallel mode, while e1 >> e2 for the anti-parallel one. We show that the former precesses ~ 10 times slower than the latter. Currently the system is dominated by the parallel mode. Although only a little anti-parallel mode survives, both eccentricities especially e1 oscillate on ~ 103yr timescale. Detectable changes would occur within ~ 1\\yr. We demonstrate that the anti-parallel mode gets damped ~ 104 times faster than its parallel brother by any dissipative process diminishing e1. If it is the tidal damping in the inner WD, we proceed to estimate its tidal quantity parameter (Q) to be ~ 106, which was poorly constrained by observations. However, tidal damping may also happen during the preceding low-mass X-ray binary (LMXB) phase or hydrogen thermal nuclear flashes. But, in both cases, the inner companion fills its Roche lobe and probably suffers mass/angular momentum loss, which might cause e1 to grow rather than decay.
\r\n\r\n\r\nSeveral pairs of solar system satellites occupy mean motion resonances (MMRs). We divide these into two groups according to their proximity to exact resonance. Proximity is measured by the existence of a separatrix in phase space. MMRs between Io-Europa, Europa-Ganymede and Enceladus-Dione are too distant from exact resonance for a separatrix to appear. A separatrix is present only in the phase spaces of the Mimas-Tethys and Titan-Hyperion MMRs and their resonant arguments are the only ones to exhibit substantial librations. When a separatrix is present, tidal damping of eccentricity or inclination excites overstable librations that can lead to passage through resonance on the damping timescale. However, after investigation, we conclude that the librations in the Mimas-Tethys and Titan-Hyperion MMRs are fossils and do not result from overstability.
\r\n\r\n\r\nRubble piles are common in the solar system. Monolithic elements touch their neighbors in small localized areas. Voids occupy a significant fraction of the volume. In a fluid-free environment, heat cannot conduct through voids; only radiation can transfer energy across them. We model the effective thermal conductivity of a rubble pile and show that it is proportional the square root of the pressure, P, for P\u2264 \u03b53\u03bc where \u03b5 is the material's yield strain and \u03bc its shear modulus. Our model provides an excellent fit to the depth dependence of the thermal conductivity in the top 140 cm of the lunar regolith. It also offers an explanation for the low thermal inertias of rocky asteroids and icy satellites. Lastly, we discuss how rubble piles slow down the cooling of small bodies such as asteroids.
\r\n\r\n\r\nElectromagnetic (EM) follow-up observations of gravitational wave (GW) events will help shed light on the nature of the sources, and more can be learned if the EM follow-ups can start as soon as the GW event becomes observable. In this paper, we propose a computationally efficient time-domain algorithm capable of detecting gravitational waves (GWs) from coalescing binaries of compact objects with nearly zero time delay. In case when the signal is strong enough, our algorithm also has the flexibility to trigger EM observation before the merger. The key to the efficiency of our algorithm arises from the use of chains of so-called Infinite Impulse Response (IIR) filters, which filter time-series data recursively. Computational cost is further reduced by a template interpolation technique that requires filtering to be done only for a much coarser template bank than otherwise required to sufficiently recover optimal signal-to-noise ratio. Towards future detectors with sensitivity extending to lower frequencies, our algorithm's computational cost is shown to increase rather insignificantly compared to the conventional time-domain correlation method. Moreover, at latencies of less than hundreds to thousands of seconds, this method is expected to be computationally more efficient than the straightforward frequency-domain method.
" }, { "name": "Kaplan, Jeffrey Daniel", "degree": "PhD", "year": "2014", "title": "Where Tori Fear to Trend: Hypermassive Neutron Star Remnants and Absolute Event Horizons or Topics in Computational General Relativity", "advisor": "Ott, Christian D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:07122013-120734335", "creators": [ { "name": { "family": "Kaplan", "given": "Jeffrey Daniel" }, "id": "Kaplan-Jeffrey-Daniel", "display_name": "Kaplan, Jeffrey Daniel" } ], "advisors": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "advisor", "display_name": "Ott, Christian D." } ], "committee": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "chair", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Hallinan", "given": "Gregg W." }, "id": "Hallinan-G-W", "orcid": "0000-0002-7083-4049", "role": "member", "display_name": "Hallinan, Gregg W." }, { "name": { "family": "Scheel", "given": "Mark" }, "id": "Scheel-M-A", "orcid": "0000-0001-6656-9134", "role": "member", "display_name": "Scheel, Mark" }, { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "member", "display_name": "Ott, Christian D." } ], "option_major": [ "physics" ], "doi": "10.7907/WAB5-8460", "abstract": "Computational general relativity is a field of study which has reached maturity only within the last decade. This thesis details several studies that elucidate phenomena related to the coalescence of compact object binaries. Chapters 2 and 3 recounts work towards developing new analytical tools for visualizing and reasoning about dynamics in strongly curved spacetimes. In both studies, the results employ analogies with the classical theory of electricity and magnitism, first (Ch. 2) in the post-Newtonian approximation to general relativity and then (Ch. 3) in full general relativity though in the absence of matter sources. In Chapter 4, we examine the topological structure of absolute event horizons during binary black hole merger simulations conducted with the SpEC code. Chapter 6 reports on the progress of the SpEC code in simulating the coalescence of neutron star-neutron star binaries, while Chapter 7 tests the effects of various numerical gauge conditions on the robustness of black hole formation from stellar collapse in SpEC. In Chapter 5, we examine the nature of pseudospectral expansions of non-smooth functions motivated by the need to simulate the stellar surface in Chapters 6 and 7. In Chapter 8, we study how thermal effects in the nuclear equation of state effect the equilibria and stability of hypermassive neutron stars. Chapter 9 presents supplements to the work in Chapter 8, including an examination of the stability question raised in Chapter 8 in greater mathematical detail.\r\n" }, { "name": "Glu\u0161\u010devi\u0107, Vera", "degree": "PhD", "year": "2013", "title": "CMB as a Probe of New Physics and Old Times", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06032013-130145873", "creators": [ { "name": { "family": "Glu\u0161\u010devi\u0107", "given": "Vera" }, "id": "Glu\u0161\u010devi\u0107-Vera", "display_name": "Glu\u0161\u010devi\u0107, Vera" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "chair", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Johnson", "given": "John A." }, "id": "Johnson-J-A", "role": "member", "display_name": "Johnson, John A." }, { "name": { "family": "Carroll", "given": "Sean M." }, "id": "Carroll-S-M", "orcid": "0000-0002-4226-5758", "role": "member", "display_name": "Carroll, Sean M." }, { "name": { "family": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "member", "display_name": "Golwala, Sunil" }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." } ], "option_major": [ "astrophys" ], "doi": "10.7907/VZ0P-XD08", "abstract": "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" }, { "name": "Wegg, Christopher", "degree": "PhD", "year": "2013", "title": "The Dynamics of White Dwarfs, Black Holes and Stellar Cusps", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechTHESIS:08152012-212758368", "creators": [ { "name": { "family": "Wegg", "given": "Christopher" }, "id": "Wegg-Christopher", "display_name": "Wegg, Christopher" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "chair", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "orcid": "0000-0001-5501-6008", "role": "member", "display_name": "Benson, Andrew J." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Sargent", "given": "Wallace L. W." }, "id": "Sargent-W-L-W", "role": "member", "display_name": "Sargent, Wallace L. W." } ], "option_major": [ "physics" ], "doi": "10.7907/YCAT-ES15", "abstract": "This thesis contains topics related mostly to the dynamics of white dwarfs (chapter 2), the dynamics of stars around binary super massive black holes (chapters 4, 5 and 6) and dynamics in the singular isothermal sphere (chapter 7).
\r\n\r\nIn chapter 2 the kinematics of young (< 3x108yr) galactic white dwarfs are investigated. A relationship between the mass and kinematics of white dwarfs is demonstrated, whereby high- mass white dwarfs have low velocity dispersion. This is the result of less scattering during the shorter lifetime of their more massive precursors. The kinematics of the highest-mass white dwarfs (> 0.95 Msun) are also investigated, and it is shown that they are consistent with the majority being formed via single-star evolution from massive progenitor stars.
\r\n\r\nIn chapter 3 it is shown that the coolest, oldest white dwarfs can be identified photometrically from their unique colors, and five new ultracool white dwarfs are spectroscopically confirmed.
\r\n\r\nIn chapter 4 it is shown that close binary supermassive black holes (SMBHs) should produce a burst of tidal disruptions of up to 0.1 yr\u22121 as they form. The quiescent rate is ~10\u22125 yr\u22121 per galaxy, and it is therefore shown that binary SMBHs can potentially be identified via multiple tidal disruptions from the same system.\r\n
\r\n\r\nIn chapter 5 we perform more extensive simulations of the dynamics of stars around binary SMBHs to better quantify and understand the stellar dynamics. By incorporating general relativistic corrections, we also investigate the processes undergone by compact remnants orbiting the binary SMBHs, analyzing both objects that plunge directly into the SMBHs, and those that undergo extreme mass ratio inspirals (EMRIs). The potential used to mimic general relativistic precession in these simulations is novel, and more accurate for the type of nearly parabolic orbits considered in this work: It is described in chapter 6.\r\n
\r\n\r\nIn chapter 7 an analytic solution to the manner in which stars diffuse in the background of a singular isothermal sphere is developed. It is shown a self-similar solution should exist, and this solution is found.\r\n
" }, { "name": "Book, Laura Grace", "degree": "PhD", "year": "2012", "title": "Cosmological Consequences of Gravitation: Structure Formation and Gravitational Waves", "advisor": "Benson, Andrew J.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05212012-141650110", "creators": [ { "name": { "family": "Book", "given": "Laura Grace" }, "id": "Book-Laura-Grace", "display_name": "Book, Laura Grace" } ], "advisors": [ { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "orcid": "0000-0001-5501-6008", "role": "advisor", "display_name": "Benson, Andrew J." } ], "committee": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "chair", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "orcid": "0000-0001-5501-6008", "role": "member", "display_name": "Benson, Andrew J." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "member", "display_name": "Adhikari, Rana" } ], "option_major": [ "physics" ], "doi": "10.7907/3KPE-MW85", "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.
" }, { "name": "Krause, Anna Elisabeth", "degree": "PhD", "year": "2012", "title": "Topics in Large-Scale Structure", "advisor": "Hirata, Christopher M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:04272012-102231664", "creators": [ { "name": { "family": "Krause", "given": "Anna Elisabeth" }, "id": "Krause-Anna-Elisabeth", "display_name": "Krause, Anna Elisabeth" } ], "advisors": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "advisor", "display_name": "Hirata, Christopher M." } ], "committee": [ { "name": { "family": "Sargent", "given": "Wallace L. W." }, "id": "Sargent-W-L-W", "role": "chair", "display_name": "Sargent, Wallace L. W." }, { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "orcid": "0000-0001-5501-6008", "role": "member", "display_name": "Benson, Andrew J." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." }, { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "orcid": "0000-0002-0438-3323", "role": "member", "display_name": "Scoville, Nicholas Zabriskie" } ], "option_major": [ "astrophys" ], "doi": "10.7907/9HX2-RW58", "abstract": "This thesis presents my personal survey of topics and methods in large-scale structure, covering a range of cosmological probes and analytical, numerical, and observational techniques.
\r\n\r\nChapters 2--4 present analytic calculations of systematic effects relevant for the interpretation of data from upcoming large-scale structure surveys: In chapter 2 we derive the relation between measured galaxy ellipticities and the cosmic shear power spectrum up to fourth order in the matter density field, accounting for multiple deflections along the light path, reduced shear, and magnification bias. In chapter 3 we develop a new third-order cosmic shear statistics, which separates shear three point correlation functions exactly into E- and B-mode correlations on a finite interval. Chapter 4 considers the effect of tidal galaxy alignments on the projected galaxy bispectrum, which are found to bias the inferred galaxy bias parameters.
\r\n\r\nChapter 5 focusses on the halo-occupation distribution formalism, which constrains the relation between galaxy luminosities and the masses of their host halos through clustering measurements. We extend this method to model the cross-correlation functions between a galaxy sample of interest and multiple tracer populations simultaneously. This technique improves the accuracy of clustering analyses for sparse galaxy populations, and we apply it to constrain the environment of $(NUV-r)$ selected green valley galaxy samples. These galaxy samples are constructed by matching the Sloan Digital Sky Survey with the latest Galaxy Evolution Explorer source catalog which provides NUV photometry. We present cross-correlation function measurements and determine the halo occupation distribution of these transitional galaxies using the multiple tracer technique.
\r\n\r\nIn chapter 6 we examine sources of scatter in scaling relations between galaxy cluster mass and thermal Sunyaev-Zeldovich (SZ) effect using cluster samples extracted from cosmological hydrodynamical simulations. This sample enables us to study for the first time the detailed evolution of merging clusters around the scaling relation for a cosmologically representative distribution of merger parameters. We find major mergers to cause an asymmetric scatter such that the inferred mass of merging systems is biased low. As the fraction of dynamically disturbed clusters increases with redshift, this analysis indicates that mergers cause a redshift-dependent bias in cluster mass scaling relations.
" }, { "name": "Lee, Samuel Kuhnman", "degree": "PhD", "year": "2012", "title": "Three Paths to Particle Dark Matter", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05152012-125430182", "creators": [ { "name": { "family": "Lee", "given": "Samuel Kuhnman" }, "id": "Lee-Samuel-Kuhnman", "display_name": "Lee, Samuel Kuhnman" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "chair", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "member", "display_name": "Golwala, Sunil" }, { "name": { "family": "Hillenbrand", "given": "Lynne A." }, "id": "Hillenbrand-L-A", "orcid": "0000-0001-8638-0320", "role": "member", "display_name": "Hillenbrand, Lynne A." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." } ], "option_major": [ "astrophys" ], "doi": "10.7907/Q603-SH04", "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.
" }, { "name": "O'Connor, Evan Patrick", "degree": "PhD", "year": "2012", "title": "Topics in Core-Collapse Supernova Theory: The Formation of Black Holes and the Transport of Neutrinos", "advisor": "Ott, Christian D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06012012-103948541", "creators": [ { "name": { "family": "O'Connor", "given": "Evan Patrick" }, "id": "OConnor-Evan-Patrick", "display_name": "O'Connor, Evan Patrick" } ], "advisors": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "advisor", "display_name": "Ott, Christian D." } ], "committee": [ { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "chair", "display_name": "Ott, Christian D." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Harrison", "given": "Fiona A." }, "id": "Harrison-F-A", "orcid": "0000-0003-2992-8024", "role": "member", "display_name": "Harrison, Fiona A." }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" } ], "option_major": [ "physics" ], "doi": "10.7907/RAAR-4C77", "abstract": "Core-Collapse Supernovae are one of the most complex astrophysical systems in the universe. They deeply entwine aspects of physics and astrophysics that are rarely side by side in nature. To accurately model core-collapse supernovae one must self-consistently combine general relativity, nuclear physics, neutrino physics, and magneto-hydrodynamics in a symmetry-free computational environment. This is a challenging task, as each one of these aspects on its own is an area of great study. We take an open approach in an effort to encourage collaboration in the core-collapse supernovae community.
\r\n\r\nIn this thesis, we develop a new open-source general-relativistic spherically-symmetric Eulerian hydrodynamics code for studying stellar collapse, protoneutron star formation, and evolution until black hole formation. GR1D includes support for finite temperature equations of state and an efficient and qualitatively accurate treatment of neutrino leakage. GR1D implements spherically-symmetric rotation, allowing for the study of slowly rotating stellar collapse. GR1D is available at http://www.stellarcollapse.org
\r\n\r\nWe use GR1D to perform an extensive study of black hole formation in failing core-collapse supernovae. Over 100 presupernova models from various sources are used in over 700 total simulations. We systematically explore the dependence of black hole formation on the input physics: initial zero-age main sequence (ZAMS) mass and metallicity, nuclear equation of state, rotation, and stellar mass loss rates. Assuming the core-collapse supernova mechanism fails and a black hole forms, we find that the outcome, for a given equation of state, can be estimated, to first order, by a single parameter, the compactness of the stellar core at bounce. By comparing the protoneutron star structure at the onset of gravitational instability with solutions of the Tolman-Oppenheimer-Volkof equations, we find that thermal pressure support in the outer protoneutron star core is responsible for raising the maximum protoneutron star mass by up to 25% above the cold neutron star value. By artificially increasing neutrino heating, we find the critical neutrino heating efficiency required for exploding a given progenitor structure and connect these findings with ZAMS conditions. This establishes, albeit approximately, for the first time based on actual collapse simulations, the mapping between ZAMS parameters and the outcome of core collapse.
\r\n\r\nWe also use GR1D to study proposed progenitors of long-duration gamma-ray bursts. We find that many of the proposed progenitors have core structures similar to garden-variety core-collapse supernovae. These are not expected to form black holes, a key ingredient of the collapsar model of long-duration gamma-ray bursts. The small fraction of proposed progenitors that are compact enough to form black holes have fast rotating iron cores, making them prone to a magneto-rotational explosion and the formation of a protomagnetar rather than a black hole.
\r\n\r\nFinally, we present preliminary work on a fully general-relativistic neutrino transport code and neutrino-interaction library. Following along with the trends explored in our black hole formation study, we look at the dependence of the neutrino observables on the bounce compactness. We find clear relationships that will allow us to extract details of the core structure from the next galactic supernova. Following the open approach of GR1D, the neutrino transport code will be made open-source upon completion. The open-source neutrino-interaction library, NuLib, is already available at http://www.nulib.org.
" }, { "name": "Tseliakhovich, Dmitriy", "degree": "PhD", "year": "2012", "title": "The Cosmic Stories: Beginning, Evolution and Present Days of the Universe", "advisor": "Hirata, Christopher M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:01042012-160039824", "creators": [ { "name": { "family": "Tseliakhovich", "given": "Dmitriy" }, "id": "Tseliakhovich-Dmitriy", "display_name": "Tseliakhovich, Dmitriy" } ], "advisors": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "advisor", "display_name": "Hirata, Christopher M." } ], "committee": [ { "name": { "family": "Sargent", "given": "Wallace L. W." }, "id": "Sargent-W-L-W", "role": "chair", "display_name": "Sargent, Wallace L. W." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Ellis", "given": "Richard S." }, "id": "Ellis-R-S", "role": "member", "display_name": "Ellis, Richard S." }, { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "orcid": "0000-0002-4834-7260", "role": "member", "display_name": "Steidel, Charles C." }, { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "orcid": "0000-0001-5501-6008", "role": "member", "display_name": "Benson, Andrew J." } ], "option_major": [ "astrophys" ], "doi": "10.7907/T279-PV49", "abstract": "This work presents three studies of independent astrophysical phenomena which cover a full timeline of the universe from the epoch of inflation to the present day. Along with our results we provide concise overviews of the considered phenomena and outline major open questions.
\r\n\r\nThe first part of this work is focused on the epoch of inflation. We analyze the evolution of early density fluctuations which originate during inflation and connect physical fields driving inflation with observable parameters. We study several inflationary scenarios, specifically one field inflation, in which the only field present during that epoch is the inflaton field and two field inflation, in which along with the inflaton field the epoch of inflation is effected by the second scalar field - curvaton field. Single field inflationary models predict nearly Gaussian initial conditions and hence a detection of non-Gaussianity would be a signature of more complex inflationary scenarios. In this work we study the effect of primordial non-Gaussianity on the cosmic microwave background (CMB) and on large-scale structure in a two-field inflationary model in which both the inflaton and curvaton fields contribute to the primordial density fluctuations. We show that in addition to the previously described enhancement of the galaxy bias on large scales, this setup results in large-scale stochasticity. We provide joint constraints on the local non-Gaussianity parameter f nl and the ratio of the amplitude of primordial perturbations due to the inflaton and curvaton using WMAP and Sloan Digital Sky Survey (SDSS) data.
\r\n\r\nThe second and largest part of this study is focused on the formation of the first cosmic structures and the effect of relative velocity between dark matter and baryonic fluids. In that part we discuss a very important and previously unnoticed effect which significantly changes the process of structure formation in the early universe. At the time of recombination, baryons and photons decoupled and the sound speed in the baryonic fluid dropped from relativistic, to the thermal velocity of the hydrogen atoms. This is less than the relative velocity of baryons and dark matter computed via linear perturbation theory, so we infer that there are supersonic coherent flows of the baryons relative to the underlying potential wells created by the dark matter. As a result, the advection of small-scale perturbations (near the baryonic Jeans scale) by large-scale velocity flows is important for the formation of the first structures. This effect involves a quadratic term in the cosmological perturbation theory equations and hence has not been included in studies based on linear perturbation theory. We show that the relative motion suppresses the abundance of the first bound objects, even if one only investigates dark matter halos, and leads to qualitative changes in their spatial distribution, such as introducing scale-dependent bias and stochasticity. We further discuss possible observable implications of this effect for high-redshift galaxy clustering and reionization. Specifically we discuss in detail the effect of the relative velocity on the gas content in the early galaxies, minihaloes and the first stars. This part of the thesis also includes a concise overview of the recent studies that investigated various aspects of the relative velocity effect and showed its importance for topics ranging from star formation to precision cosmology.
\r\n\r\nThe third and final part of the thesis covers interaction between expanding shocks of the supernovae explosions with the interstellar medium. The shocks of supernovae remnants represent a unique cosmic environment which allows detailed studies of plasma physics and high-energy astrophysics phenomena in conditions unreachable in the Earth-based laboratories. Specifically, shocks of supernovae remnants are associated with production of cosmic rays - the most energetic particles that we can observe. In our study we are specifically focused on the science of Balmer-dominated shocks (BDS) - a subset of collisionless, fast shocks dominated by hydrogen line emission with both broad and narrow components. The unique feature of BDS is that they are directly observable and their observations provide an opportunity for direct testing of the phase space structure and ion velocity distribution inside of shocks.
\r\n\r\nUnderstanding of physical phenomena occurring inside of astrophysical shocks requires precise knowledge of cross sections for high-nl proton-hydrogen collisions. Until now scientists have been using approximations for these cross sections which fall short of the precision needed for robust analysis of the observed data and can no longer satisfy needs of the astrophysical community. Guided by the demand in high-precision calculations of the cross sections we developed and implemented a robust method for direct solution of the Schroedinger partial differential equation on a grid. In this work we provide a detailed description of our computational algorithm for calculating cross sections in high-nl proton-hydrogen collisions and show results for n ≤ 4. We describe the code we developed, show the results of consistency tests and describe possible extensions. Finally, we show how our results are applied to the studies of Balmer-dominated shocks and specifically how the precise cross sections for n ≤ 4 can be used in computing Balmer decrement - the ratio of Halpha and Hbeta line intensities.
\r\n" }, { "name": "Ali-Haimoud, Yacine", "degree": "PhD", "year": "2011", "title": "A New Spin on Primordial Hydrogen Recombination and a Refined Model for Spinning Dust Radiation", "advisor": "Hirata, Christopher M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05172011-165447651", "creators": [ { "name": { "family": "Ali-Haimoud", "given": "Yacine" }, "id": "Ali-Haimoud-Yacine", "display_name": "Ali-Haimoud, Yacine" } ], "advisors": [ { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "advisor", "display_name": "Hirata, Christopher M." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." }, { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "orcid": "0000-0002-0438-3323", "role": "member", "display_name": "Scoville, Nicholas Zabriskie" }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." } ], "option_major": [ "astrophys" ], "doi": "10.7907/QMFZ-0C90", "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.
" }, { "name": "Bode, Jason Nathaniel", "degree": "PhD", "year": "2011", "title": "Black Hole Mergers and Their Electromagnetic Counterparts", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechTHESIS:05312011-152117816", "creators": [ { "name": { "family": "Bode", "given": "Jason Nathaniel" }, "id": "Bode-Jason-Nathaniel", "display_name": "Bode, Jason Nathaniel" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "chair", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Prince", "given": "Thomas A." }, "id": "Prince-T-A", "role": "member", "display_name": "Prince, Thomas A." }, { "name": { "family": "Steidel", "given": "Charles C." }, "id": "Steidel-C-C", "role": "member", "display_name": "Steidel, Charles C." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/YVVG-R137", "abstract": "Over the past ten years it has become increasingly clear that most, if not all, galaxies have super-massive black holes lurking in their cores. The implications for this are large as they not only have significant effects on the host galaxies, far beyond what would have been naively expected, but would provide several significant gravitational wave sources to the Laser Interferometer Space Antenna (LISA). This thesis is primarily concerned with these gravitational wave sources and the possible electromagnetic counterparts. In particular, when two galaxies merge, it leads to the ultimate merger of their individual SMBHs. If gas is present near the time of merger a circumbinary disk forms around the binary. By assuming the disk is pressureless, and looking at the limits of this approximation, in Chapter 2 we develop an analytic theory of the reaction of such a gaseous disk to the gravitational wave mass loss and recoil kicks which occur during a SMBH merger. However, to understand the effects of finite pressure, in Chapter 3 we develop a one-dimensional hydrodynamic code. The efficiency of the code and the power of the analytic solution allow us to explain the entirety of possible reactions. These results are also favorably compared with far more complicated 3D relativistic magneto-hydrodynamics simulations. LISA will not see only the mergers of two SMBHs, it would also see the inspirals of stellar-mass objects into a SMBH. In Chapter 4 we discuss a new channel of formation of these extreme mass ratio inspirals (EMRIs). This new channel of EMRI formation is rich physically and, in particular, almost always requiring either the Kozai mechanism or an as-of-yet unnoticed phenomenon which we dub the reverse Kozai mechanism. We find that this channel of EMRI formation produces modest numbers of EMRIs when compared to the primary channel of EMRI formation, which, under optimistic detection scenarios for the most recent LISA design, results in the plausible detection of several. Finally, an unrelated project that considers solving the self-similar Type-II strong-shock problem in slightly asymmetric media is given in Chapter 5. We show that the results can even be applied to explosions along weak discontinuities in the density. " }, { "name": "Pullen, Anthony Robert", "degree": "PhD", "year": "2011", "title": "A Survey of Results in Modern Precision Cosmology", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05042011-123721947", "creators": [ { "name": { "family": "Pullen", "given": "Anthony Robert" }, "id": "Pullen-Anthony-Robert", "display_name": "Pullen, Anthony Robert" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "member", "display_name": "Golwala, Sunil" } ], "option_major": [ "physics" ], "doi": "10.7907/VJ9N-0J70", "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.
" }, { "name": "Grin, Daniel", "degree": "PhD", "year": "2010", "title": "The Lukewarm Frontier: Some Cosmological Consequences of 'Low Energy' Physics", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05312010-162432249", "creators": [ { "name": { "family": "Grin", "given": "Daniel" }, "id": "Grin-Daniel", "display_name": "Grin, Daniel" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Ellis", "given": "Richard S." }, "id": "Ellis-R-S", "role": "chair", "display_name": "Ellis, Richard S." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Johnson", "given": "John A." }, "id": "Johnson-J-A", "role": "member", "display_name": "Johnson, John A." } ], "option_major": [ "astrophys" ], "doi": "10.7907/EN34-1095", "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" }, { "name": "Collins, Benjamin Forster", "degree": "PhD", "year": "2009", "title": "Understanding the Solar System with Numerical Simulations and L\u00e9vy Flights", "advisor": "Sari, Re'em", "url": "https://resolver.caltech.edu/CaltechETD:etd-05292009-130440", "creators": [ { "name": { "family": "Collins", "given": "Benjamin Forster" }, "id": "Collins-Benjamin-Forster", "display_name": "Collins, Benjamin Forster" } ], "advisors": [ { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "advisor", "display_name": "Sari, Re'em" } ], "committee": [ { "name": { "family": "Stevenson", "given": "David John" }, "id": "Stevenson-D-J", "role": "chair", "display_name": "Stevenson, David John" }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "member", "display_name": "Sari, Re'em" }, { "name": { "family": "Kulkarni", "given": "Shrinivas R." }, "id": "Kulkarni-S-R", "role": "member", "display_name": "Kulkarni, Shrinivas R." } ], "option_major": [ "physics" ], "doi": "10.7907/840K-TD87", "abstract": "This thesis presents several investigations into the formation of planetary systems and the dynamical evolution of the small bodies left over from this process.
\r\n\r\nWe develop a numerical integration scheme with several optimizations for studying the late stages of planet formation: adaptive time steps, accurate treatment of close encounters between particles, and the ability to add non-conservative forces. Using this code, we simulate the phase of planet formation known as \"oligarchic growth.\" We find that when the dynamical friction from planetesimals is strong, the annular feeding zones of the protoplanets are inhabited by not one but several oligarchs on nearly the same semimajor axis. We systematically determine the number of co-orbital protoplanets sharing a feeding zone and the width of these zones as a function of the strength of dynamical friction and the total mass of the disk. The increased number of surviving protoplanets at the end of this phase qualitatively affects their subsequent evolution into full-sized planets.
\r\n\r\nWe also investigate the distribution of the eccentricities of the protoplanets in the runaway growth phase of planet formation. Using a Boltzmann equation, we find a simple analytic solution for the distribution function followed by the eccentricity. We show that this function is self-similar: it has a constant shape while the scale is set by the balance between mutual excitation and dynamical friction. The type of evolution described by this distribution function is known as a Levy flight.
\r\n\r\nWe use the Boltzmann equation framework to study the nearly circular orbits of Kuiper Belt binaries and the nearly radial orbits of comets during the formation of the Oort cloud. We calculate the distribution function of the eccentricity of Kuiper belt systems, like the moons of Pluto, given the stochastic perturbations caused by close encounters with other Kuiper belt objects. For Oort cloud comets, we find the distribution function of the angular momentum as it is excited by perturbations from passing stars in the Galaxy. Both systems evolve as Levy flights. This work unifies the effects of stochastic stellar encounters and the smooth torque from the Galactic potential on Oort cloud comets.
" }, { "name": "Erickcek, Adrienne Lynn", "degree": "PhD", "year": "2009", "title": "The Consequences of Modifying Fundamental Cosmological Theories", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05292009-132414", "creators": [ { "name": { "family": "Erickcek", "given": "Adrienne Lynn" }, "id": "Erickcek-Adrienne-Lynn", "orcid": "0000-0002-0901-3591", "display_name": "Erickcek, Adrienne Lynn" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "role": "member", "display_name": "Benson, Andrew J." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Carroll", "given": "Sean M." }, "id": "Carroll-S-M", "role": "member", "display_name": "Carroll, Sean M." } ], "option_major": [ "physics" ], "doi": "10.7907/ST6B-1S91", "abstract": "In this work, we examine alternatives to three fundamental cosmological theories: extended Press-Schechter merger theory, general relativity, and single-field inflation, and derive their observational consequences. The extended Press-Schechter merger rate for dark matter haloes is mathematically inconsistent and double-valued, and yet it has been widely applied in cosmology. One such application is the merger rate of supermassive black holes, and we show that the two predictions for this rate from extended Press-Schechter merger theory are nearly equal. We then compare the supermassive-black-hole merger rate derived from the extended Press-Schechter merger formalism to the rate derived from an alternate theory, in which halo merger rates are obtained by inverting the coagulation equation.
\r\n\r\nNext, we show how two modifications to general relativity may be tested inside the Solar System. First we consider f(R) gravity, which was proposed to explain late-time cosmic acceleration. We find that several forms of f(R) gravity are inconsistent with observations, and we establish a set of criteria that determines whether or not a given form of f(R) gravity is ruled out by Solar System gravitational tests. Second, we study Chern-Simons gravity: a parity-violating theory inspired by string theory. We find that Chern-Simons gravity predicts orbital precessions that are different from those predicted by general relativity, and we use the motion of satellites to constrain the Chern-Simons coupling parameter.
\r\n\r\nFinally, we consider an alternative to single-field inflation; in the curvaton scenario, the inflaton does not generate all of the primordial perturbations. Using this theory, we propose an origin for the hemispherical power asymmetry that has been observed in the cosmic microwave background on large angular scales. While this asymmetry cannot be produced by a superhorizon fluctuation in the inflaton field, it may be generated by a superhorizon fluctuation in the curvaton field. A superhorizon fluctuation would also induce large-scale anisotropies in the cosmic microwave background; we analyze this effect and prove that our model is consistent with observations. We also show how the power asymmetry may be suppressed on smaller scales if the curvaton creates isocurvature perturbations when it decays.
" }, { "name": "Li, Chao", "degree": "PhD", "year": "2009", "title": "Topics in Theoretical Astrophysics", "advisor": "Chen, Yanbei; Thorne, Kip S.; Cooray, Asantha", "url": "https://resolver.caltech.edu/CaltechETD:etd-10142008-155140", "creators": [ { "name": { "family": "Li", "given": "Chao" }, "id": "Li-Chao", "display_name": "Li, Chao" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." }, { "name": { "family": "Cooray", "given": "Asantha" }, "id": "Cooray-A", "orcid": "0000-0002-3892-0190", "role": "co-advisor", "display_name": "Cooray, Asantha" } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Cooray", "given": "Asantha" }, "id": "Cooray-A", "orcid": "0000-0002-3892-0190", "role": "member", "display_name": "Cooray, Asantha" }, { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "member", "display_name": "Adhikari, Rana" }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/CWB8-VF13", "abstract": "This thesis presents a study of various interesting problems in theoretical astrophysics, including gravitational wave astronomy, gamma ray bursts and cosmology. Chapters 2, 3 and 4 explore prospects for detecting gravitational waves from stellar-mass compact objects spiraling into intermediate-mass black holes with ground-based observatories. It is shown in chapter 2 that if the central body is not a BH but its metric is stationary, axisymmetric, reflection symmetric and asymptotically flat, then the waves will likely be triperiodic, as for a BH. Chapters 3 and 4 show that the evolutions of the waves' three fundamental frequencies and of the complex amplitudes of their spectral components encode (in principle) details of the central body's metric, the energy and angular momentum exchange between the central body and the orbit, and the time-evolving orbital elements. Chapter 5 studies a local readout method to enhance the low frequency sensitivity of detuned signal-recycling interferometers. We provide both the results of improvement in quantum noise and the implementation details in Advanced LIGO. Chapter 6 applies and generalizes causal Wiener filter to data analysis in macroscopic quantum mechanical experiments. With the causal Wiener filter method, we demonstrate that in theory we can put the test masses in the interferometer to its quantum mechanical ground states. Chapter 7 presents some analytical solutions for expanding fireballs, the common theoretical model for gamma ray bursts and soft gamma ray repeaters. We apply our results to SGR 1806-20 and rediscover the mismatch between the model and the afterglow observations. Chapter 8 discusses the reconstruction of the scalar-field potential of the dark energy. We advocate direct reconstruction of the scalar field potential as a way to minimize prior assumptions on the shape, and thus minimize the introduction of bias in the derived potential. Chapter 9 discusses gravitational lensing modifications to cosmic microwave background anisotropies and polarization, produced by a stochastic background of primordial gravitational waves between us and the last scattering surface. Chapter 10 calculates the non-Gaussian covariance of CMB B-modes of polarization.\r\n" }, { "name": "Schlichting, Hilke Elisabeth", "degree": "PhD", "year": "2009", "title": "Understanding the Origin of Planetary Systems: Studying the Kuiper Belt and the Dynamics of Planet Formation", "advisor": "Sari, Re'em", "url": "https://resolver.caltech.edu/CaltechETD:etd-05282009-124109", "creators": [ { "name": { "family": "Schlichting", "given": "Hilke Elisabeth" }, "id": "Schlichting-Hilke-Elisabeth", "display_name": "Schlichting, Hilke Elisabeth" } ], "advisors": [ { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "orcid": "0000-0002-1084-3656", "role": "advisor", "display_name": "Sari, Re'em" } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Blain", "given": "Andrew W." }, "id": "Blain-A-W", "role": "co-chair", "display_name": "Blain, Andrew W." }, { "name": { "family": "Hillenbrand", "given": "Lynne A." }, "id": "Hillenbrand-L-A", "role": "member", "display_name": "Hillenbrand, Lynne A." }, { "name": { "family": "Brown", "given": "Michael E." }, "id": "Brown-M-E", "orcid": "0000-0002-8255-0545", "role": "member", "display_name": "Brown, Michael E." }, { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "orcid": "0000-0002-1084-3656", "role": "member", "display_name": "Sari, Re'em" } ], "option_major": [ "astrophys" ], "doi": "10.7907/SGJJ-9V78", "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.
" }, { "name": "Mandel, Ilya", "degree": "PhD", "year": "2008", "title": "The Three Ss of Gravitational-Wave Astronomy: Sources, Signals, Searches", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-03112008-012506", "creators": [ { "name": { "family": "Mandel", "given": "Ilya" }, "id": "Mandel-Ilya", "orcid": "0000-0002-6134-8946", "display_name": "Mandel, Ilya" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Cutler", "given": "Curt J." }, "id": "Cutler-C-J", "orcid": "0000-0002-2080-1468", "role": "member", "display_name": "Cutler, Curt J." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" } ], "option_major": [ "physics" ], "doi": "10.7907/GABY-T236", "abstract": "As gravitational wave astronomy prepares for the first detections of gravitational waves from compact-object binary inspirals, theoretical work is required on the study of (i) gravitational-wave sources, (ii) the signals emitted by those sources, and (iii) the searches for those signals in detector data. This thesis describes work on all three fronts. (i) We discuss intermediate-mass-ratio inspirals (IMRIs) of black holes or neutron stars into intermediate-mass black holes (IMBHs) that could be detected with Advanced LIGO. We analyze different mechanisms of IMRI formation and compute IMRI event rates of up to tens of events per year for Advanced LIGO. We study the spin evolution of IMBHs that grow through a series of minor mergers. We explore how a deviation of an IMRI's central body from a Kerr black hole influences geodesics, including the possibility of chaotic orbital dynamics. We also address the scientific consequences of extreme-mass-ratio inspiral (EMRI) detections by LISA for astrophysics and general relativity, and the difficulties associated with detecting and analyzing EMRI signals. (ii) We study the periodic standing-wave approximation (PSWA), which can potentially provide accurate waveforms in the last inspiral cycles of a comparable-mass black-hole binary. Using a simple model, we find that the solution to Einstein's equations for inspiraling black holes can be recovered to a high accuracy by the addition a perturbative radiation-reaction field to the standing-wave, noninspiraling solution. (iii) We demonstrate the utility of searching for and analyzing tracks in time-frequency spectrograms of a gravitational-wave signal as a means of estimating the parameters of a massive black-hole binary inspiral, as observed by LISA." }, { "name": "Smith, Tristan Laine", "degree": "PhD", "year": "2008", "title": "The Gravity of the Situation", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05282008-153540", "creators": [ { "name": { "family": "Smith", "given": "Tristan Laine" }, "id": "Smith-Tristan-Laine", "orcid": "0000-0003-2685-5405", "display_name": "Smith, Tristan Laine" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Lange", "given": "Andrew E." }, "id": "Lange-A-E", "role": "member", "display_name": "Lange, Andrew E." }, { "name": { "family": "Cooray", "given": "Asantha" }, "id": "Cooray-A", "orcid": "0000-0002-3892-0190", "role": "member", "display_name": "Cooray, Asantha" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "member", "display_name": "Thorne, Kip S." } ], "option_major": [ "physics" ], "doi": "10.7907/SY21-6Z52", "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" }, { "name": "Suyu, Sherry Hsuan", "degree": "PhD", "year": "2008", "title": "Dissecting the Gravitational Lens B1608+656: Implications for the Hubble Constant", "advisor": "Blandford, Roger D.; Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-09132007-122424", "creators": [ { "name": { "family": "Suyu", "given": "Sherry Hsuan" }, "id": "Suyu-Sherry-Hsuan", "orcid": "0000-0001-5568-6052", "display_name": "Suyu, Sherry Hsuan" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "co-chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Cohen", "given": "Judith G." }, "id": "Cohen-J-G", "role": "member", "display_name": "Cohen, Judith G." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." } ], "option_major": [ "physics" ], "doi": "10.7907/MQS2-Y860", "abstract": "Strong gravitational lens systems provide a tool for probing galaxy mass distributions (independent of their light profiles) and for measuring cosmological parameters. In a strong lens system, the background source intensity distribution is multiply imaged. If the source intensity is time varying, then the multiple images of the variable source are delayed in time relative to each other due to the different light travel time along the multiple light paths. One can use lens systems to measure the Hubble constant by obtaining the relative time delays between the multiple images and modeling the lens potential. B1608+656 is a quadruply imaged gravitational lens system with a spatially extended source intensity distribution and two interacting galaxy lenses. This system is unique in that the three relative time delays between the four images were measured accurately with errors of only a few percent, and it thus provides an opportunity to measure the Hubble constant with high precision. The extended source intensity distribution in B1608+656 provides additional constraints on the lens potential, though simultaneous determination of the source intensity and lens potential distribution is needed. The presence of dust and interacting galaxy lenses further complicate this system. We present a comprehensive analysis in a Bayesian framework that takes into account the extended source intensity distribution, interacting galaxy lenses, and the presence of dust for reconstructing the lens potential. Using the deep HST ACS observations on B1608+656, the resulting statistical uncertainty on H_0 associated with the lens modeling is limited by the uncertainty in the best time delay measurement (~3%). The dominant systematic error on H_0 is due to the effects of the environment on B1608+656 (mass-sheet degeneracy). By using the measured velocity dispersion of the lens galaxies and considering the mass structures along the line of sight to B1608+656, we place constraints on the external convergence associated with galaxy groups and mass structure along the line of sight. The resulting Hubble constant from B1608+656 is H_0 = 72 \u00b1 2 (stat.) \u00b1 4 (syst.) km s^-1 Mpc^-1.\r\n" }, { "name": "Fang, Hua", "degree": "PhD", "year": "2007", "title": "Topics in Gravitational Physics: Tidal Coupling in Gravitational Wave Searches and Mach\u2019s Principle", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05212007-004257", "creators": [ { "name": { "family": "Fang", "given": "Hua" }, "id": "Fang-Hua", "display_name": "Fang, Hua" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Cutler", "given": "Curt J." }, "id": "Cutler-C-J", "orcid": "0000-0002-2080-1468", "role": "member", "display_name": "Cutler, Curt J." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" } ], "option_major": [ "physics" ], "doi": "10.7907/D99H-J577", "abstract": "The gravitational waves emitted by a compact object inspirling into a massive central body (e.g., a massive black hole) contain exquisite information about the spacetime geometry around that body and the tidal interaction (energy and angular momentum transfer) between the body and the inspiraling object's orbit. The first part (chapter 2--4) of this thesis studies several topics in the frame work of gravitation-wave search. In chapter 2 (in collaboration with G. Lovelace), we study the tidal interaction between a non-rotating black hole and circularly orbiting moon. Our analysis shows that the static induced quadrupole moment of the black hole is inherently ambiguous. In chapter 3, we give a survey of initial explorations of the prospects for using Advanced LIGO to detect gravitational waves from intermediate-mass-ratio inspirals (IMRIs))---analogous to the extreme-mass-ratio inspirals (EMRIs) targeted by LISA. We describe initial estimates of the detection range and the number of IMRI wave cycles in the Advanced LIGO band. We also give a detailed analysis of Advanced LIGO's accuracy for measuring the tide-induced energy transfer between the central black hole and the orbit. In chapter 4 (in collaboration with S. Babak, J. R. Gair, K. Glampedakis, and S. Hughes), we describe a new waveform-generating scheme in the context of LISA's data analysis for EMRI waves. The result is a family of \"Numerical Kludge\" waveforms, which share remarkable agreement with the more rigorous, but more computational-intensive Teukolsky-based waveforms.
\r\n\r\nThe second part (chapter 5) of this thesis (in collaboration with K. S. Thorne) discusses another prediction from general relativity, the dragging of inertial frames, in connection with Mach's principle. We idealize our universe as a homogeneous, isotropic expanding, and slowly rotating sphere, surrounded by vacuum. We find that as the universe expands, the frame dragging weakens at its center; and that at later times inertia at the center completely breaks free of the grip of the universe's rotating matter.
" }, { "name": "Lovelace, Geoffrey Mark", "degree": "PhD", "year": "2007", "title": "Topics in Gravitational-Wave Physics", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05232007-115433", "creators": [ { "name": { "family": "Lovelace", "given": "Geoffrey Mark" }, "id": "Lovelace-Geoffrey-Mark", "orcid": "0000-0002-7084-1070", "display_name": "Lovelace, Geoffrey Mark" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Lindblom", "given": "Lee A." }, "id": "Lindblom-L", "orcid": "0000-0002-3018-1098", "role": "member", "display_name": "Lindblom, Lee A." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" } ], "option_major": [ "physics" ], "doi": "10.7907/94TE-3B59", "abstract": "Together with ongoing experimental efforts to detect gravitational waves, several fronts of theoretical research are presently being pursued, including second-generation detector design, data analysis, and numerical-relativity simulations of sources. This thesis presents a study in each of these topics: i) The noise in the most sensitive frequency bands in second-generation ground-based gravitational-wave interferometers is dominated by the thermal noise of the test masses. One way to reduce test-mass thermal noise is to modify shape of the laser beam so that it better averages over the thermal fluctuations. When edge effects are neglected, the test-mass thermal noise is related to the beam shape by simple scaling laws. This thesis presents a rigorous derivation of these laws, along with estimates of the errors made by neglecting edge effects. ii) An important class of gravitational-wave sources for space-based gravitational-wave interferometers is extreme-mass-ratio inspirals (EMRIs). These are binaries in which an object of a few solar masses spirals into a (typically million-solar-mass) supermassive black hole (or, if any exist, other type of massive body). Ryan (1995) proved that, under certain simplifying assumptions, the spacetime geometry is redundantly encoded in EMRI waves. One of Ryan's assumptions was negligible tidal coupling. After first finding that only the time-varying part of the induced tide is unambiguously defined when the central body is a black hole, this thesis extends Ryan's theorem by showing that both the spacetime geometry and details of the tidal coupling are encoded in EMRI waves. iii) Merging black holes with comparable masses are important sources of gravitational waves for ground-based detectors. The gravitational waves near the time of merger can only be predicted by numerically solving the Einstein equations. Initial data in numerical simulations must contain the desired physical content but also satisfy the Einstein constraint equations. But conventional binary-black-hole initial data has physical flaws: a nonzero orbital eccentricity and an initial, unphysical pulse of spurious gravitational radiation. Using the Caltech-Cornell pseudospectral code, this thesis develops and implements methods to reduce both of these effects.
" }, { "name": "Pritchard, Jonathan Robin", "degree": "PhD", "year": "2007", "title": "Extracting the Cosmic History from Diffuse Backgrounds", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05292007-112654", "creators": [ { "name": { "family": "Pritchard", "given": "Jonathan Robin" }, "id": "Pritchard-Jonathan-Robin", "orcid": "0000-0003-4127-5353", "display_name": "Pritchard, Jonathan Robin" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Benson", "given": "Andrew J." }, "id": "Benson-A-J", "role": "member", "display_name": "Benson, Andrew J." }, { "name": { "family": "Lange", "given": "Andrew E." }, "id": "Lange-A-E", "role": "member", "display_name": "Lange, Andrew E." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "role": "member", "display_name": "Wise, Mark B." } ], "option_major": [ "physics" ], "doi": "10.7907/W3BF-8Q61", "abstract": "The modern picture of the Universe resembles a detective novel with the first page and the middle chapters removed and the ending unwritten. Observations of the cosmic microwave background (CMB) have given cosmologists a snapshot of the Universe when it was only a few hundred thousand years old. At the same time, large galaxy surveys, such as SDSS and 2dF, have shed light on the distribution of matter in the local Universe. From the combination of these two data sets, cosmological parameters can be measured to percent accuracy. Two main frontiers remain: inflation, the domain of high-energy physics, and the epoch of reionization, the period connecting the linear age of the CMB with that of the present day. Added to this are the indications from supernovae of an acceleration in the expansion rate suggesting modifications to gravity or the presence of an esoteric new form of energy.
\r\n\r\nIn this work, we investigate uses of various radiation backgrounds for probing the different epochs of this cosmic history. We examine (i) the use of B-mode polarization of the CMB induced by an inflationary gravitational wave background to probe inflation, (ii) the importance of higher Lyman series photons in pumping of the 21 cm line and the consequences for the 21 cm signal from the first stars, (iii) the atomic physics of Lyman series photon scattering in the intergalactic medium and the consequences for heating and coupling of the 21 cm line, (iv) the possibility of using the 21 cm line to probe inhomogeneous X-ray heating of the IGM by a population of early X-ray sources, and (v) the impact of inhomogeneous reionization on galaxy formation and the consequences for our ability to use large galaxy surveys to constrain dark energy. Together, these chapters significantly extend our understanding of important windows into the early Universe.
" }, { "name": "Liu, Junjun", "degree": "PhD", "year": "2006", "title": "Interaction of Magnetic Field and Flow in the Outer Shells of Giant Planets", "advisor": "Stevenson, David John; Goldreich, Peter Martin; Ingersoll, Andrew P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05252006-223939", "creators": [ { "name": { "family": "Liu", "given": "Junjun" }, "id": "Liu-Junjun", "display_name": "Liu, Junjun" } ], "advisors": [ { "name": { "family": "Stevenson", "given": "David John" }, "id": "Stevenson-D-J", "role": "advisor", "display_name": "Stevenson, David John" }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Ingersoll", "given": "Andrew P." }, "id": "Ingersoll-A-P", "role": "advisor", "display_name": "Ingersoll, Andrew P." } ], "committee": [ { "name": { "family": "Ingersoll", "given": "Andrew P." }, "id": "Ingersoll-A-P", "orcid": "0000-0002-2035-9198", "role": "chair", "display_name": "Ingersoll, Andrew P." }, { "name": { "family": "Stevenson", "given": "David John" }, "id": "Stevenson-D-J", "orcid": "0000-0001-9432-7159", "role": "member", "display_name": "Stevenson, David John" }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "orcid": "0000-0002-1084-3656", "role": "member", "display_name": "Sari, Re'em" }, { "name": { "family": "Schneider", "given": "Tapio" }, "id": "Schneider-T", "orcid": "0000-0001-5687-2287", "role": "member", "display_name": "Schneider, Tapio" } ], "option_major": [ "plansci" ], "doi": "10.7907/4PVM-0G30", "abstract": "This study of the interaction of magnetic field and flow in the outer shells of giant planets consists of three parts.
\r\n\r\nPart one: The atmospheres of Jupiter and Saturn exhibit strong and stable zonal winds. Busse suggested that they might be the surface expression of deep flows on cylinders. However, the deep flow hypothesis experiences difficulty when account is taken of the electrical conductivity of molecular hydrogen as measured in shockwave experiments. The deep zonal flow of an electrically conducting fluid would produce a toroidal magnetic field, an associated poloidal electrical current, and Ohmic dissipation. In steady state, the total Ohmic dissipation cannot exceed the planet's net luminosity. If we assume that the observed zonal flow penetrates along cylinders until it is truncated to (near) zero at some spherical radius, the upper bound on Ohmic dissipation constrains this radius to be no smaller than 0.95 Jupiter radius and 0.87 Saturn radius. The truncation of the cylindrical flow in the convective envelope requires an appropriate force to break the Taylor-Proudman constraint. We have been unable to identify any plausible candidate. Thus we conclude that deep-seated cylindrical flows do not exist.
\r\n\r\nPart two: A fluid shell with sufficient electrical conductivity and azimuthal velocity shear outside of the dynamo generation region can attenuate the non-axisymmetric component of the magnetic field. However, the interaction of the axisymmetric component of the magnetic field and the zonal flow is able to reduce the magnitude of zonal flow. The dimensionless number characterizing this reduction is the Chandrasekhar number. The smaller Saturnian field may allow a larger velocity shear and a greater attenuation of the non-axisymmetric field, thereby providing a possible explanation for the nearly axisymmetric field.
\r\n\r\nPart three: Combining the study for the attenuation effect produced by the semi-conducting layer and the observation of the magnetic field by Galileo and Voyager, we find the possible outer boundary of the dynamo generation zone is at 0.86 Jupiter radius. The magnetic fields generated in the outer shell are dictated by a length scale comparable to the scale height of electrical conductivity, which is much smaller than the radius of the planet.
" }, { "name": "Pan, Margaret Whei-Jie", "degree": "PhD", "year": "2006", "title": "Slices of Theoretical Astrophysics: Solar System Dynamics and Relativistic Explosions", "advisor": "Sari, Re'em", "url": "https://resolver.caltech.edu/CaltechETD:etd-05252006-181025", "creators": [ { "name": { "family": "Pan", "given": "Margaret Whei-Jie" }, "id": "Pan-Margaret-Whei-Jie", "display_name": "Pan, Margaret Whei-Jie" } ], "advisors": [ { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "advisor", "display_name": "Sari, Re'em" } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Brown", "given": "Michael E." }, "id": "Brown-M-E", "role": "member", "display_name": "Brown, Michael E." }, { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "role": "member", "display_name": "Scoville, Nicholas Zabriskie" }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "member", "display_name": "Sari, Re'em" } ], "option_major": [ "astrophys" ], "doi": "10.7907/40AE-N743", "abstract": "This thesis presents studies in two distinct areas of theoretical astrophysics: dynamics of planetary systems and relativistic fluid flows from shocks emerging from stellar envelopes. The first pertains to the early solar system, planet formation, and extrasolar planets; the second is related to extreme explosions like gamma-ray bursts and supernovae.
\r\n\r\nWe present two investigations of the dynamics and population evolution of small solar system bodies. First, we explore the dynamics of mean-motion resonances for a test particle moving in a highly eccentric long-period orbit in the restricted circular planar three-body problem --- a scenario relevant to the scattered Kuiper belt and the formation of the Oort cloud. We find an infinite number of analogues to the Lagrange points; a simple explanation for the presence and absence of asymmetric librations in particular mean-motion resonances; and a criterion for the onset of chaotic motion at large semimajor axes.
\r\n\r\nSecond, we study the size distribution of Kuiper belt objects (KBOs), which is observed to be a broken power law. We apply a simple mass conservation argument to the KBO collisional cascade to get the power-law slope for KBOs below the break; our result agrees well with observations if we assume KBOs are held together by self-gravity rather than material strength. We also explain the location and time evolution of the break in the size distribution.
\r\n\r\nWe also present investigations of the flow which results when a relativistic shock propagates through and then breaks out of a stellar envelope with a polytropic density profile. This work informs predictions of the speed of and energy carried by the relativistic ejecta in supernovae and perhaps in gamma-ray bursts. We find the asymptotic solution for the flow as the shock reaches the star's edge and find a new self-similar solution for flow of hot fluid after the shock breakout. Since the post-breakout flow acclerates by converting its thermal energy into bulk kinetic energy, the fluid in the flow eventually cools to non-relativistic temperatures. We derive a second new self-similar solution which includes the cold portions of the flow. This second solution gives an exact relation between the terminal Lorentz factor of each fluid element and the Lorentz factor it acquired upon being shocked before breakout.
" }, { "name": "Pan, Yi", "degree": "PhD", "year": "2006", "title": "Topics of LIGO Physics: Template Banks for the Inspiral of Precessing, Compact Binaries, and Design of the Signal-Recycling Cavity for Advanced LIGO", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05242006-025220", "creators": [ { "name": { "family": "Pan", "given": "Yi" }, "id": "Pan-Yi", "display_name": "Pan, Yi" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "member", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Lindblom", "given": "Lee A." }, "id": "Lindblom-L", "orcid": "0000-0002-3018-1098", "role": "member", "display_name": "Lindblom, Lee A." }, { "name": { "family": "Whitcomb", "given": "Stanley E." }, "id": "Whitcomb-S-E", "role": "member", "display_name": "Whitcomb, Stanley E." } ], "option_major": [ "physics" ], "doi": "10.7907/TJB1-PQ24", "abstract": "In the next decade, the detection of gravitational-wave signals by ground-based laser interferometric detectors (e.g., the Laser Interferometer Gravitational-Wave Observatory, or LIGO) will provide new information on the structure and dynamics of compact objects such as neutron stars (NS) and black holes (BH), both isolated and in binary systems. Efforts to detect the intrinsically weak gravitational-wave signals involve the development of high-quality detectors, the precise modeling of expected signals, and the development of efficient data analysis techniques. This thesis concerns two topics in these areas: methods to detect signals from the inspiral of precessing NS-BH and BH-BH binaries, and the design of the signal-recycling cavity for Advanced LIGO (the second generation LIGO detector).
\r\n\r\nThe detection of signals from the inspiral of precessing binaries using the standard matched filter technique, is complicated by the large number (12 at least) of parameters required to describe the complex orbital-precession dynamics of the binary and the consequent modulations of the gravitational-wave signals. To extract these signals from the noisy detector output requires a discrete bank of a huge number of signal templates that cover the 12-dimensional parameter space; and processing data with all these templates requires computational power far exceeding what is available with current technology. To solve this problem, Buonanno, Chen, and Vallisneri (BCV) proposed the use of detection template families (DTFs) --- phenomenological templates that are capable of mimicking rather accurately the inspiral waveform calculated by the post-Newtonian (PN) approach, while having a simpler functional form to reduce the computational cost. In particular, BCV proposed the so called BCV2 DTF for the precessing-binary inspiral, which has 12 parameters (most of them phenomenological). Of these, 8 are extrinsic parameters that can be searched over analytically, and only four of them are intrinsic parameters that need be searched over in a numerical one-by-one manner. The signal-matching efficiency of the BCV2 DTF has been shown to be satisfactory for signals from comparable mass BH-BH binaries.
\r\n\r\nIn Chapter 2 (in collaboration with Alessandra Buonanno, Yanbei Chen, Hideyuki Tagoshi, and Michele Vallisneri), I test the signal-matching efficiency of the BCV2 DTF for signals from a wide sample of precessing BH-BH and NS-BH binaries that covers the parameter range of interest for LIGO and other ground-based gravitational-wave detectors, and I study the mapping between the physical and phenomenological parameters. My colleagues and I calculate the template-match metric, propose the template-placement strategy in the intrinsic parameter space and estimate the number of templates needed (and thus equivalently the computational cost) to cover the parameter space. We also propose a so called BCV2P DTF that replaces the phenomenological parameters in the BCV2 DTF by physical parameters, which can be used to estimate the actual parameters of the binary that emitted any detected signal.
\r\n\r\nIn Chapters 3 and 4 (in collaboration with Alessandra Buonanno, Yanbei Chen, and Michele Vallisneri), I investigate a physical template family (PTF) suggested by BCV. This PTF uses the most accurate known waveforms for inspiraling, precessing binaries (the adiabatic PN waveforms), formulated using a new precessing convention such that five parameters become extrinsic. PTF has the obvious advantages over the DTFs of a perfect match with target signals, a lower false-alarm rate at fixed threshold, and an ability to directly estimate the physical parameters of any detected signal.
\r\n\r\nIn Chapter 3, we focus on the simpler single-spin binaries in which only four parameters out of nine remain intrinsic. We propose a two-stage scheme to search over the five extrinsic parameters quickly, and investigate the false-alarm statistics in each of the two stages. We define and calculate the metric of the full template space, and the projected metric and average metric of the intrinsic parameter subspace, and use these metrics to develop the method of template placement. Finally, we estimate that the number of templates needed to detect single-spin binary inspirals is within the reach of the current available computational power.
\r\n\r\nIn Chapter 4, we generalize the use of the single-spin PTF to double-spin binaries, based on the fact that most double-spin binaries have similar dynamics to the single-spin ones. Since the PTF in this case is, strictly speaking, only quasi-physical, we test and eventually find satisfactory signal-matching performance. We also investigate, both analytically and numerically, the difference between the single-spin and double-spin dynamics, and gain an intuition into where in the parameter space the PTF works well. We estimate the number of templates needed to cover all BH-BH and NS-BH binaries of interest to ground-based detectors, which turns out to be roughly at the limit of currently available computational power. Since the PTF is not exactly physical for double-spin binaries, it introduces systematic errors in parameter estimation. We investigate these, and find that they are either comparable to or overwhelmed by statistical errors, for events with moderate signal-to-noise ratio. BCV and I are currently systematically investigating parameter estimation with the PTF.
\r\n\r\nThe second part of this thesis concerns the design of the signal-recycling cavity for Advanced LIGO. In the planned Advanced-LIGO-detector upgrades from the first-generation LIGO, a signal-recycling mirror (SRM) is introduced at the dark output port. This SRM forms a signal-recycling cavity (SRC) with the input test masses. This signal-recycling design offers several advantages and brings new physics to LIGO. However, there is a problem in the current design of the SRC: the SRC is nearly degenerate, i.e., it does not distinguish transverse optical modes; and as a result, mode coupling due to mirror deformation will strongly reduce the optical power in the fundamental mode, and thus reduce the signal strength, which is roughly proportional to it.
\r\n\r\nIn Chapter 5, I investigate this problem using a numerical simulation of the propagation of the optical field in an Advanced LIGO interferometer. I find that if the current degenerate design for the SRC is used, there will be a serious and perhaps unattainable constraint on the magnitude of mirror deformations, in order to keep the reduction of signal-to-noise ratio below a few percent. This conclusion is consistent with previous order of magnitude estimates. This constraint poses practical difficulties on the quality of mirror polishing and the control of thermal aberration of the mirrors. Based on my simulation results, for a range of degeneracies of the SRC, I find the optimal level of degeneracy, which minimizes the reduction of signal-to-noise ratio. That optimum is nearly non-degenerate. I also discuss possible modifications to the current design that can achieve this optimal degeneracy.
" }, { "name": "Farmer, Alison Jane", "degree": "PhD", "year": "2005", "title": "Adventures in Theoretical Astrophysics", "advisor": "Goldreich, Peter Martin", "url": "https://resolver.caltech.edu/CaltechETD:etd-05232005-155338", "creators": [ { "name": { "family": "Farmer", "given": "Alison Jane" }, "id": "Farmer-Alison-Jane", "display_name": "Farmer, Alison Jane" } ], "advisors": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" } ], "committee": [ { "name": { "family": "Cohen", "given": "Judith G." }, "id": "Cohen-J-G", "role": "chair", "display_name": "Cohen, Judith G." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "member", "display_name": "Sari, Re'em" }, { "name": { "family": "Sargent", "given": "Wallace L. W." }, "id": "Sargent-W-L-W", "role": "member", "display_name": "Sargent, Wallace L. W." } ], "option_major": [ "astrophys" ], "doi": "10.7907/JJKJ-J144", "abstract": "This thesis is a tour of topics in theoretical astrophysics, unified by their diversity and their pursuit of physical understanding of astrophysical phenomena.
\r\n\r\nIn the first chapter, we raise the possibility of the detection of white dwarfs in transit surveys for extrasolar Earths, and discuss the peculiarities of detecting these more massive objects.
\r\n\r\nA population synthesis calculation of the gravitational wave background from extragalactic binary stars is then presented. In this study, we establish a firm understanding of the uncertainties in such a calculation and provide a valuable reference for planning the Laser Interferometer Space Antenna mission.
\r\n\r\nThe long-established problem of cosmic ray confinement to the Galaxy is addressed in another chapter. We introduce a new wave damping mechanism, due to the presence of background turbulence, that prevents the confinement of cosmic rays by the resonant streaming instability.
\r\n\r\nWe also investigate the spokes in Saturn's B ring, an electrodynamic mystery that is being illuminated by new data sent back from the Cassini spacecraft. In particular, we present assessments of the presence of charged dust near the rings, and the size of currents and electric fields in the ring system. We make inferences from the Cassini discovery of oxygen ions above the rings. In addition, the previous leading theory for spoke formation is demonstrated to be unphysical.
\r\n\r\nIn the final chapter, we explain the wayward motions of Prometheus and Pandora, two small moons of Saturn. Previously found to be chaotic as a result of mutual interactions, we account for their behavior by analogy with a parametric pendulum. We caution that this behavior may soon enter a new regime.
" }, { "name": "Kesden, Michael Henry", "degree": "PhD", "year": "2005", "title": "To the Horizon and Beyond:Weak Lensing of the CMB and Binary Inspirals into Horizonless Objects", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05232005-160004", "creators": [ { "name": { "family": "Kesden", "given": "Michael Henry" }, "id": "Kesden-Michael-Henry", "orcid": "0000-0002-5987-1471", "display_name": "Kesden, Michael Henry" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." } ], "option_major": [ "physics" ], "doi": "10.7907/BQMR-4C14", "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.
" }, { "name": "Rathore, Yasser", "degree": "PhD", "year": "2005", "title": "Resonant Excitation of White Dwarf Oscillations in Compact Object Binaries", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05272005-160411", "creators": [ { "name": { "family": "Rathore", "given": "Yasser" }, "id": "Rathore-Yasser", "display_name": "Rathore, Yasser" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "member", "display_name": "Sari, Re'em" } ], "option_major": [ "physics" ], "doi": "10.7907/0726-4X92", "abstract": "White dwarfs are ubiquitous in the known Universe. They are frequently found in binary systems with ordinary stars, giants, or compact objects as companions. Depending upon their histories, such systems may have significantly eccentric orbits. Because of gravitational radiation, a white dwarf-compact object binary will shrink and circularize with time. If the system is initially close enough, then the inspiral will occur on a time-scale shorter than a Hubble time. As an eccentric system inspirals, it will pass through resonances when harmonics of the orbital period match one of the white dwarf's normal mode eigenfrequencies. At these tidal resonances, energy can be transferred from the orbit to the white dwarf normal modes, and the system will pass through a sequence of such resonances for each mode. If the amplitude of a mode is driven high enough, the modes may damp due to non-linear processes and heat the white dwarf. If the temperature of the white dwarf can be raised in this way to a critical value, then the star may undergo a thermonuclear detonation that results in a Type Ia supernova. In order to determine whether such a scenario is possible, and what other observable consequences of tidal resonances may be, it is necessary to understand the resonant energy transfer and the non-linear evolution of modes on a white dwarf in some detail.
\r\n\r\nA variational approach to the excitation of dynamical tides is presented. This is then used to study the energy transfer in the resonant excitation of tides. The energy transfer problem is complicated by the fact that a mode perturbs the orbit as it is resonantly excited, effectively creating a non-linear feedback loop. We call this effect 'back reaction.' In the present work, the problem is considered both in the approximation when back reaction is neglected, and when it is included. It is found that back reaction changes the resonant energy transfer both qualitatively and quantitatively. In particular, unlike the no back reaction case, the energy transfer with back reaction is shown to be always positive to lowest order in the rate of dissipation by gravitational radiation, and any initial energy in the mode before resonance is shown to increase the energy transfer.
\r\n\r\nNumerical simulations of resonant mode excitation and non-linear evolution of white dwarf oscillations are also considered. An adiabatic, parallel hydrodynamic code is described for this. Results from several test problems and preliminary simulations of resonant tidal excitation are presented.
\r\n\r\nThe formalism developed for resonant tidal excitation is applied to studying the feasibility of a tidally triggered supernova via resonant excitation of quadrupolar f-modes. It is found that a 1.4 solar mass companion to the white dwarf is not viable, which rules out double degenerates and white dwarf-neutron star binaries as potential progenitors. However, it is found that with a companion mass of ten to hundred thousand solar masses, there exist regions in the parameter space where the white dwarf can be detonated before tidal disruption. It is calculated that the ejecta from such a detonation would remain trapped in orbit around the companion for the majority of cases, and would presumably be accreted eventually.
\r\n\r\nA preliminary calculation of the importance of tidal effects for gravitational wave observations of capture sources with central masses of about a million solar masses is also presented. The resonant excitation of f-modes is found to be unimportant because of the long orbital periods at the last stable orbits. It is, however, found that the excitation of g-modes could introduce significant errors in the parameter estimation for such systems, though it would probably not affect detection capability. The exact magnitude of the errors depends upon the density of resonances during the period of observation, and therefore depends upon details of the white dwarf model.
" }, { "name": "Sigurdson, Kris Raymond", "degree": "PhD", "year": "2005", "title": "Variations on the Standard Model of the Universe", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05272005-141451", "creators": [ { "name": { "family": "Sigurdson", "given": "Kris Raymond" }, "id": "Sigurdson-Kris-Raymond", "orcid": "0000-0002-6729-0765", "display_name": "Sigurdson, Kris Raymond" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "chair", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "role": "member", "display_name": "Golwala, Sunil" } ], "option_major": [ "physics" ], "doi": "10.7907/52QC-H668", "abstract": "In the past decade, due to compelling measurements of the angular power spectrum of the cosmic microwave background (CMB) radiation, the large-scale matter distribution, the recent acceleration of the expansion rate of the Universe over cosmic time, and the current expansion rate (the Hubble constant), cosmology has culminated in a standard model of the Universe. By connecting this standard cosmological model with predictive theories of physics we can hope to look for signatures of these theories in the data. Along this line of inquiry we consider in this thesis: (i) the effects on CMB temperature and polarization anisotropies of spatial fluctuations of the fine-structure parameter alpha between causally disconnected regions of the Universe at the time of recombination, (ii) the suppression of the small-scale matter power spectrum due to the decay of charged matter to dark matter prior to recombination, (iii) the consequences of a neutral dark-matter particle with a nonzero electric and/or magnetic dipole moment, (iv) how charged-particles decaying in the early Universe can induce a scale-dependent or 'running' spectral index in the small-scale matter power spectrum and examples of this effect in minimal supersymmetric models in which the lightest neutralino is a viable cold-dark-matter candidate. With improved tests and cross-checks of standard-cosmological-model predictions we can search for anomalies that may reveal the character of the underlying physics. In this direction we propose in this thesis: (v) a new method for removing the effect of gravitational lensing from maps of CMB polarization anisotropies using observations of anisotropies or structures in the cosmic 21-cm radiation, (vi) that measurements of fluctuations in the absorption of CMB photons by hydrogen in the 21-cm line and deuterium in the 92-cm line during the cosmic dark ages could be used to determine the primordial deuterium abundance." }, { "name": "Weinberg, Nevin Nachum", "degree": "PhD", "year": "2005", "title": "I. Ash Injection and Exposure During Radius Expansion Type I X-Ray Bursts. II. Stellar Dynamics at the Galactic Center. III. Weak Gravitational Lensing by Dark Matter Concentrations", "advisor": "Kamionkowski, Marc P.", "url": "https://resolver.caltech.edu/CaltechETD:etd-06022005-151603", "creators": [ { "name": { "family": "Weinberg", "given": "Nevin Nachum" }, "id": "Weinberg-Nevin-Nachum", "orcid": "0000-0001-9194-2084", "display_name": "Weinberg, Nevin Nachum" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "advisor", "display_name": "Kamionkowski, Marc P." } ], "committee": [ { "name": { "family": "Sari", "given": "Re'em" }, "id": "Sari-R", "role": "chair", "display_name": "Sari, Re'em" }, { "name": { "family": "Blain", "given": "Andrew W." }, "id": "Blain-A-W", "role": "member", "display_name": "Blain, Andrew W." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Kulkarni", "given": "Shrinivas R." }, "id": "Kulkarni-S-R", "role": "member", "display_name": "Kulkarni, Shrinivas R." } ], "option_major": [ "astronomy" ], "doi": "10.7907/V8PX-AE66", "abstract": "The studies presented herein are on three distinct topics in astrophysics:
\r\n\r\nI. We solve for the evolution of the vertical extent of the convective region of a neutron star atmosphere during a type I X-ray burst. The convective region is well-mixed with ashes of nuclear burning, and its extent determines the burst rise time. We show that the maximum extent of the convective region during photospheric radius expansion (PRE) bursts can be sufficiently great that some ashes of burning are: (1) ejected by the radiation-driven wind during the PRE phase and, (2) exposed at the neutron star surface following the PRE phase. We calculate the expected column density of ashes in hydrogen-like states and find that the resulting photoionization edges should be detectable with current high spectral resolution X-ray telescopes. A detection would probe the burst nuclear burning processes and might enable a measurement of the neutron star gravitational redshift.
\r\n\r\nII. We discuss physical experiments achievable via the monitoring of stellar dynamics near the massive black hole (MBH) at the Galactic center with a next-generation, extremely large telescope (ELT). We use the Markov Chain Monte Carlo method to evaluate the constraints that the monitoring of these orbits will place on the matter content at the Galactic center. We compare these future constraints with those obtained with the current data. We also describe how the monitoring of stellar proper motions can be used to probe directly the masses of isolated stellar remnants near the MBH.
\r\n\r\nIII. We calculate the abundance of dark-matter concentrations that are sufficiently overdense to produce a detectable weak-gravitational-lensing signal. Most of these overdensities are virialized halos containing identifiable X-ray and/or optical clusters. However, a significant fraction are nonvirialized, cluster-mass overdensities still in the process of gravitational collapse---these should produce significantly weaker or no X-ray emission. Our predicted abundance of such dark clusters is consistent with the abundance implied by the detection of apparent dark lenses. We also examine the prospect of using weak gravitational lenses to constrain the dark energy equation-of-state parameter.
\r\n" }, { "name": "Broderick, Avery Earl", "degree": "PhD", "year": "2004", "title": "Radiative Transfer in Accreting Environments", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05262004-231543", "creators": [ { "name": { "family": "Broderick", "given": "Avery Earl" }, "id": "Broderick-Avery-Earl", "orcid": "0000-0002-3351-760X", "display_name": "Broderick, Avery Earl" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." } ], "option_major": [ "physics" ], "doi": "10.7907/H2PF-K590", "abstract": "Accretion onto compact objects plays a central role in high-energy astrophysics. The process of accretion can substantially affect the magnetic field strength and geometry (e.g, via the magneto-rotational instability or dynamo processes) and the accreting plasma density. The presence of the compact object itself can significantly affect the character and structure of the accreting plasma as well as its emission. This is especially true, in the case of an accreting black hole, when a significant fraction of the emission originates or passes near the horizon. To address this, we develop a manifestly covariant magnetoionic theory, capable of tracing rays in the geometric optics approximation through a magnetized plasma in a general relativistic environment. This is discussed for both the cold and warm, ion and pair plasmas. We also address the problem of performing polarized radiative transfer covariantly in these environments, considering in particular the anisotropic nature of magnetized plasmas, the gravitational redshift and Doppler shift, the transport of the polarization vector along the ray, and the ellipticity of the plasma eigenmodes.
\r\n\r\nThe presence of relativity qualitatively changes the dispersion relation, introducing a third branch. In addition it significantly augments various polarized emission and transfer effects in strongly sheared flows, such as jets. Additionally, we demonstrate that it is possible, due to refraction coupled with the existence of a horizon, to generate a net circular polarization regardless of the intrinsic polarization of the emission mechanism. We find that this is not likely to be of significant importance for circular polarization in AGN (including the Galactic center and M81). However, in the context of X-ray binaries, this may produce measurable circular polarizations in the infrared.
\r\n\r\nWe also develop a formalism for performing polarized radiative transfer through tangled magnetic fields. We find that for Faraday thick plasmas with a net magnetic helicity (but not necessarily a net magnetic field) it is possible to generate a circular polarization fraction which increases with frequency, as is observed to be the case in the Galactic center. In this case the handedness of the circular polarization is determined by the angular momentum of the accretion disk. This mechanism can be applied to extragalactic AGN and naturally explains the low degrees of circular polarization observed. As with the refractive mechanism, this may also be applied to X-ray binaries, and predicts ~10% polarization fractions at infrared wavelengths. Again, this provides a significant motivation for the development of infrared polarimetry.
" }, { "name": "O'Shaughnessy, Richard William", "degree": "PhD", "year": "2004", "title": "Topics in Gravitational-Wave Astronomy", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-08052003-161044", "creators": [ { "name": { "family": "O'Shaughnessy", "given": "Richard William" }, "id": "O'Shaughnessy-Richard-William", "orcid": "0000-0001-5832-8517", "display_name": "O'Shaughnessy, Richard William" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Lindblom", "given": "Lee A." }, "id": "Lindblom-L", "orcid": "0000-0002-3018-1098", "role": "member", "display_name": "Lindblom, Lee A." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" } ], "option_major": [ "physics" ], "doi": "10.7907/4C1K-VZ17", "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.
" }, { "name": "Santos, Michael Robert", "degree": "PhD", "year": "2004", "title": "Galaxy Formation Near the Epoch of Reionization", "advisor": "Kamionkowski, Marc P.; Ellis, Richard S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05182004-154315", "creators": [ { "name": { "family": "Santos", "given": "Michael Robert" }, "id": "Santos-Michael-Robert", "display_name": "Santos, Michael Robert" } ], "advisors": [ { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "advisor", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Ellis", "given": "Richard S." }, "id": "Ellis-R-S", "role": "co-advisor", "display_name": "Ellis, Richard S." } ], "committee": [ { "name": { "family": "Sargent", "given": "Wallace L. W." }, "id": "Sargent-W-L-W", "role": "chair", "display_name": "Sargent, Wallace L. W." }, { "name": { "family": "Blain", "given": "Andrew W." }, "id": "Blain-A-W", "role": "member", "display_name": "Blain, Andrew W." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Ellis", "given": "Richard S." }, "id": "Ellis-R-S", "role": "member", "display_name": "Ellis, Richard S." } ], "option_major": [ "astronomy" ], "doi": "10.7907/X9XT-YT35", "abstract": "I present five explorations of the formation of early galaxies near the epoch of reionization: observable phenomena that demonstrate the interaction between galaxy formation and the intergalactic medium.
\r\n\r\nI calculated the contribution of the first stars (Pop III) to the cosmic infrared background (CIRB). Pop III stars produced the observed unexplained component of the NIR CIRB if they were very massive and formed efficiently over a redshift range 25 \u2273 z \u2273 7. A small escape fraction of ionizing photons from the nebular gas immediately surrounding the Pop III stars enhances the Pop III CIRB signal.
\r\n\r\nI calculated the effect of radiative transfer through the intergalactic medium (IGM) on the observed properties of Lyman alpha emission lines from z \u2273 6 galaxies. The detection of a Lyman alpha emitting galaxy at z = 6.5 resulted in claims that the universe was mostly ionized there. With existing information about the source galaxy it is almost impossible to deduce the ionization state of the z = 6.5 IGM, especially if there were galactic-scale super-winds.
\r\n\r\nI present a method to infer the stellar population responsible for completing reionization. We simulated helium and hydrogen absorption along lines-of-sight toward high-redshift QSOs assuming either Pop II or Pop III stars dominated the UV background at z=5. The final SDSS quasar sample may contain a quasar/line-of-sight combination that constrains the nature of the dominant ionizing sources only 300 Myr after the end of reionization.
\r\n\r\nI present an observational survey of low-luminosity Lyman alpha emitting galaxies at 4.5 < z < 6.7. This unprecedented survey utilized strong lensing by rich clusters of galaxies at intermediate redshifts to discover six likely Lyman alpha emitting galaxies. The z ~ 5 Lyman alpha luminosity function may be flatter than the mass function of dark matter halos, a sign of suppression of the star-formation efficiency in low-mass halos. However, our data by themselves are consistent with the slope of the halo mass function.
\r\n\r\nI modeled the formation of metal-poor globular cluster systems (GCSs), invoking reionization to explain the bimodality observed in GCS metallicity distributions. The model reproduces the mass and spatial extent of the Milky Way metal-poor GCS, and also the increasing number of metal-poor globular clusters per unit galaxy mass for galaxies in richer environments, as observed.
" }, { "name": "Chen, Yanbei", "degree": "PhD", "year": "2003", "title": "Topics of LIGO Physics: Quantum Noise in Advanced Interferometers and Template Banks for Compact-Binary Inspirals", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05302003-044325", "creators": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "display_name": "Chen, Yanbei" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Mabuchi", "given": "Hideo" }, "id": "Mabuchi-H", "role": "member", "display_name": "Mabuchi, Hideo" }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "role": "member", "display_name": "Kamionkowski, Marc P." } ], "option_major": [ "physics" ], "doi": "10.7907/VQH0-QA78", "abstract": "This thesis deals with the planning for advanced interferometric gravitational-wave detectors, as well as the detection of inspiral waves using first-generation interferometers.\r\n\r\nIn Chapters 2 -- 4 (in collaboration with Alessandra Buonanno), the the signal recycling interferometer proposed for LIGO-II is studied in the two-photon formalism. This study reveals the optical spring effect, which allows the interferometer to beat the standard quantum limit, while in the same time introduces a dynamical instability. A classical control system is designed to suppress this instability. In Chapter 5 (in collaboration with Alessandra Buonanno and Nergis Mavalvala), the quantum noise in heterodyne readout schemes for advanced interferometers is studied. In Chapter 6 (in collaboration with Patricia Purdue), a QND Speed-Meter interferometer with Michelson topology is proposed, analyzed and shown to be a promising candidate for third-generation interferometers (LIGO-III or EURO). This design requires adding a kilometer-scale cavity into the interferometer. In Chapter 7, Sagnac interferometers are analyzed and shown to exhibit a similar broadband QND performance without the need of additional cavity --- as expected since these interferometers are sensitive only to time-dependent mirror displacement, and are automatic speed meters.\r\n\r\nIn Chapter 8 (in collaboration with Alessandra Buonanno and Michele Vallisneri), the Post-Newtonian (PN) breakdown at late-stage inspirals of non-spinning binary black holes is studied. We propose the use of Detection Template Families (DTFs) --- extensions of ordinary PN templates that can mimic all different PN waveforms and hence are plausible to catch the real waveform, yet do not provide straightforward parameter estimation. In Chapter 9 (in collaboration with Alessandra Buonanno and Michele Vallisneri), binaries carrying spins are studied using an adiabatic PN model. Based on features of the precession dynamics, we construct a DTF, using a modified Apostolatos' ansatz, that can mimic the modulated waveforms reasonably well, while keeping a small number of parameters to be searched over one by one, with the rest searched over automatically. We also propose a (computationally) plausible way of searching over the entire physical parameter space of neutron-star--black-hole binaries." }, { "name": "Hartl, Michael David", "degree": "PhD", "year": "2003", "title": "Dynamics of Spinning Compact Binaries in General Relativity", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechETD:etd-05222003-161626", "creators": [ { "name": { "family": "Hartl", "given": "Michael David" }, "id": "Hartl-Michael-David", "display_name": "Hartl, Michael David" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "chair", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Marsden", "given": "Jerrold E." }, "id": "Marsden-J-E", "role": "member", "display_name": "Marsden, Jerrold E." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "member", "display_name": "Blandford, Roger D." } ], "option_major": [ "physics" ], "doi": "10.7907/KZ5M-MR27", "abstract": "This thesis investigates the dynamics of binary systems composed of spinning compact objects (such as white dwarfs, neutron stars, and black holes) in the context of general relativity. In particular, we use the method of Lyapunov exponents to determine whether such systems are chaotic. Compact binaries are promising sources of gravitational radiation for both ground- and space-based gravitational-wave detectors, and radiation from chaotic orbits would be difficult to detect and analyze. For chaotic orbits, the number of waveform templates needed to match a given gravitational-wave signal would grow exponentially with increasing detection sensitivity, rendering the preferred matched filter detection method computationally impractical. It is therefore urgent to understand whether the binary dynamics can be chaotic, and, if so, how prevalent this chaos is.
\r\n\r\nWe first consider the dynamics of a spinning compact object orbiting a much more massive rotating black hole, as modeled by the Papapetrou equations in Kerr spacetime. We find that many initial conditions lead to positive Lyapunov exponents, indicating chaotic dynamics. The Lyapunov exponents come in positive/negative pairs, a characteristic of Hamiltonian dynamical systems. Despite the formal existence of chaotic solutions, we find that chaos occurs only for physically unrealistic values of the small body's spin. As a result, chaos will not affect theoretical templates in the extreme mass-ratio limit for which the Papapetrou equations are valid. Chaos will therefore not affect the ability of space-based gravitational-wave detectors (such as LISA, the Laser Interferometer Space Antenna) to perform precision tests of general relativity using extreme mass-ratio inspirals.
\r\n\r\nWe next consider the dynamics of spinning black-hole binaries, as modeled by the post-Newtonian (PN) equations, which are valid for orbital velocities much smaller than the speed of light. We study thoroughly the special case of quasi-circular orbits with comparable mass ratios, which are particularly relevant from the perspective of gravitational wave generation for LIGO (the Laser Interferometer Gravitational-wave Observatory) and other ground-based interferometers. In this case, unlike the extreme mass-ratio case, we find chaotic solutions for physically realistic values of the spin. On the other hand, our survey shows that chaos occurs in a negligible fraction of possible configurations, and only for such small radii that the PN approximation is likely to be invalid. As a result, at least in the case of comparable mass black-hole binaries, theoretical templates will not be significantly affected by chaos.
\r\n\r\nIn a final, self-contained chapter, we discuss various methods for the calculation of Lyapunov exponents in systems of ordinary differential equations. We introduce several new techniques applicable to constrained dynamical systems, developed in the course of studying the dynamics of spinning compact binaries.
\r\n\r\nConsidering the Papapetrou and post-Newtonian systems together, our most important general conclusion is that we find no chaos in any relativistic binary system for orbits that clearly satisfy the approximations required for the equations of motion to be physically valid.
" }, { "name": "Liu, Yuk Tung", "degree": "PhD", "year": "2003", "title": "Dynamical Stability of Nascent Neutron Stars", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:03112014-101628149", "creators": [ { "name": { "family": "Liu", "given": "Yuk Tung" }, "id": "Liu-Yuk-Tung", "display_name": "Liu, Yuk Tung" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "member", "display_name": "Blandford, Roger D." }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Lindblom", "given": "Lee A." }, "id": "Lindblom-L", "orcid": "0000-0002-3018-1098", "role": "member", "display_name": "Lindblom, Lee A." } ], "option_major": [ "physics" ], "doi": "10.7907/61ZS-XQ28", "abstract": "This thesis presents a study of the dynamical stability of nascent neutron stars resulting from the\r\naccretion induced collapse of rapidly rotating white dwarfs.
\r\n\r\nChapter 2 and part of Chapter 3 study the equilibrium models for these neutron stars. They are\r\nconstructed by assuming that the neutron stars have the same masses, angular momenta, and specific\r\nangular momentum distributions as the pre-collapse white dwarfs. If the pre-collapse white dwarf is\r\nrapidly rotating, the collapsed object will contain a high density central core of size about 20 km,\r\nsurrounded by a massive accretion torus extending to hundreds of kilometers from the rotation axis.\r\nThe ratio of the rotational kinetic energy to gravitational binding energy, \u03b2, of these neutron stars\r\nis all found to be less than 0.27.
\r\n\r\nChapter 3 studies the dynamical stability of these neutron stars by numerically evolving the\r\nlinearized hydrodynamical equations. A dynamical bar-mode instability is observed when the \u03b2 of\r\nthe star is greater than the critical value \u03b2d \u2248 0.25. It is expected that the unstable mode will\r\npersist until a substantial amount of angular momentum is carried away by gravitational radiation.\r\nThe detectability of these sources is studied and it is estimated that LIGO II is unlikely to detect\r\nthem unless the event rate is greater than 10-6/year/galaxy.
\r\n\r\nAll the calculations on the structure and stability of the neutron stars in Chapters 2 and 3\r\nare carried out using Newtonian hydrodynamics and gravity. Chapter 4 studies the relativistic\r\neffects on the structure of these neutron stars. New techniques are developed and used to construct\r\nneutron star models to the first post-Newtonian (1PN) order. The structures of the 1PN models\r\nare qualitatively similar to the corresponding Newtonian models, but the values of \u03b2 are somewhat\r\nsmaller. The maximum \u03b2 for these 1PN neutron stars is found to be 0.24, which is 8% smaller than\r\nthe Newtonian result (0.26). However, relativistic effects will also change the critical value \u03b2d. A\r\ndetailed post-Newtonian stability analysis has yet to be carried out to study the relativistic effects\r\non the dynamical stability of these neutron stars.
" }, { "name": "Purdue, Patricia Marie", "degree": "PhD", "year": "2003", "title": "Topics in LIGO-Related Physics: Interferometric Speed Meters and Tidal Work", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:03062014-090212906", "creators": [ { "name": { "family": "Purdue", "given": "Patricia Marie" }, "id": "Purdue-Patricia-Marie", "display_name": "Purdue, Patricia Marie" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/0YKJ-SW34", "abstract": "In the quest to develop viable designs for third-generation optical interferometric gravitational-wave\r\ndetectors, one strategy is to monitor the relative momentum or speed of the test-mass mirrors,\r\nrather than monitoring their relative position. The most straightforward design for a speed-meter\r\ninterferometer that accomplishes this is described and analyzed in Chapter 2. This design (due\r\nto Braginsky, Gorodetsky, Khalili, and Thorne) is analogous to a microwave-cavity speed meter\r\nconceived by Braginsky and Khalili. A mathematical mapping between the microwave speed meter\r\nand the optical interferometric speed meter is developed and used to show (in accord with the speed\r\nbeing a quantum nondemolition observable) that in principle the interferometric speed meter can\r\nbeat the gravitational-wave standard quantum limit (SQL) by an arbitrarily large amount, over an\r\narbitrarily wide range of frequencies . However, in practice, to reach or beat the SQL, this specific\r\nspeed meter requires exorbitantly high input light power. The physical reason for this is explored,\r\nalong with other issues such as constraints on performance due to optical dissipation.
\r\n\r\nChapter 3 proposes a more sophisticated version of a speed meter. This new design requires\r\nonly a modest input power and appears to be a fully practical candidate for third-generation LIGO.\r\nIt can beat the SQL (the approximate sensitivity of second-generation LIGO interferometers) over\r\na broad range of frequencies (~ 10 to 100 Hz in practice) by a factor h/hSQL ~ \u221aW^(SQL)_(circ)/Wcirc.\r\nHere Wcirc is the light power circulating in the interferometer arms and WSQL \u2243 800 kW is the\r\ncirculating power required to beat the SQL at 100 Hz (the LIGO-II power). If squeezed vacuum\r\n(with a power-squeeze factor e-2R) is injected into the interferometer's output port, the SQL can\r\nbe beat with a much reduced laser power: h/hSQL ~ \u221aW^(SQL)_(circ)/Wcirce-2R. For realistic parameters\r\n(e-2R \u2243 10 and Wcirc \u2243 800 to 2000 kW), the SQL can be beat by a factor ~ 3 to 4 from 10\r\nto 100 Hz. [However, as the power increases in these expressions, the speed meter becomes more\r\nnarrow band; additional power and re-optimization of some parameters are required to maintain the\r\nwide band.] By performing frequency-dependent homodyne detection on the output (with the aid\r\nof two kilometer-scale filter cavities), one can markedly improve the interferometer's sensitivity at\r\nfrequencies above 100 Hz.
\r\n\r\nChapters 2 and 3 are part of an ongoing effort to develop a practical variant of an interferometric\r\nspeed meter and to combine the speed meter concept with other ideas to yield a promising third-\r\ngeneration interferometric gravitational-wave detector that entails low laser power.
\r\n\r\nChapter 4 is a contribution to the foundations for analyzing sources of gravitational waves for\r\nLIGO. Specifically, it presents an analysis of the tidal work done on a self-gravitating body (e.g., a\r\nneutron star or black hole) in an external tidal field (e.g., that of a binary companion). The change\r\nin the mass-energy of the body as a result of the tidal work, or \"tidal heating,\" is analyzed using the\r\nLandau-Lifshitz pseudotensor and the local asymptotic rest frame of the body. It is shown that the\r\nwork done on the body is gauge invariant, while the body-tidal-field interaction energy contained\r\nwithin the body's local asymptotic rest frame is gauge dependent. This is analogous to Newtonian\r\ntheory, where the interaction energy is shown to depend on how one localizes gravitational energy,\r\nbut the work done on the body is independent of that localization. These conclusions play a role\r\nin analyses, by others, of the dynamics and stability of the inspiraling neutron-star binaries whose\r\ngravitational waves are likely to be seen and studied by LIGO.
" }, { "name": "Alvi, Kashif Siddiq", "degree": "PhD", "year": "2002", "title": "Topics in General Relativity: Binary Black Holes and Hyperbolic Formulations of Einstein's Equations", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:01202012-112836824", "creators": [ { "name": { "family": "Alvi", "given": "Kashif Siddiq" }, "id": "Alvi-Kashif-Siddiq", "display_name": "Alvi, Kashif Siddiq" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." }, { "name": { "family": "Lindblom", "given": "Lee A." }, "id": "Lindblom-L", "orcid": "0000-0002-3018-1098", "role": "member", "display_name": "Lindblom, Lee A." }, { "name": { "family": "Mabuchi", "given": "Hideo" }, "id": "Mabuchi-H", "orcid": "0000-0002-5156-7678", "role": "member", "display_name": "Mabuchi, Hideo" } ], "option_major": [ "physics" ], "doi": "10.7907/5S0S-MF65", "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.
" }, { "name": "Lithwick, Yoram", "degree": "PhD", "year": "2002", "title": "Topics in MHD Turbulence", "advisor": "Goldreich, Peter Martin; Readhead, Anthony C. S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:01302012-162107660", "creators": [ { "name": { "family": "Lithwick", "given": "Yoram" }, "id": "Lithwick-Yoram", "orcid": "0000-0003-4450-0528", "display_name": "Lithwick, Yoram" } ], "advisors": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "advisor", "display_name": "Readhead, Anthony C. S." } ], "committee": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "chair", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "member", "display_name": "Blandford, Roger D." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Scoville", "given": "Nicholas Zabriskie" }, "id": "Scoville-N-Z", "orcid": "0000-0002-0438-3323", "role": "co-chair", "display_name": "Scoville, Nicholas Zabriskie" }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." } ], "option_major": [ "physics" ], "doi": "10.7907/FP3Q-EZ29", "abstract": "I consider two topics in MHD turbulence. First, I work out the theory of compressible MHD turbulence, including kinetic effects. I use this theory to understand features of interstellar scintillation that have hitherto been unexplained. Second, I work out the theory of imbalanced weak MHD turbulence." }, { "name": "Vallisneri, Michele", "degree": "PhD", "year": "2002", "title": "Modeling and Detecting Gravitational Waves from Compact Stellar Objects", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05292002-113750", "creators": [ { "name": { "family": "Vallisneri", "given": "Michele" }, "id": "Vallisneri-Michele", "orcid": "0000-0002-4162-0033", "display_name": "Vallisneri, Michele" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Lindblom", "given": "Lee A." }, "id": "Lindblom-L", "orcid": "0000-0002-3018-1098", "role": "member", "display_name": "Lindblom, Lee A." }, { "name": { "family": "Kamionkowski", "given": "Marc P." }, "id": "Kamionkowski-M-P", "orcid": "0000-0001-7018-2055", "role": "member", "display_name": "Kamionkowski, Marc P." } ], "option_major": [ "physics" ], "doi": "10.7907/JN6M-BW40", "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" }, { "name": "Creighton, Teviet David", "degree": "PhD", "year": "2000", "title": "From the Big Bang to Tumbleweeds: Analysis of Signals from Relic Gravitons, Neutron Stars, and Terrestrial Gravitational Noise in Gravitational Wave Detectors", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08302017-093459499", "creators": [ { "name": { "family": "Creighton", "given": "Teviet David" }, "id": "Creighton-Teviet-David", "display_name": "Creighton, Teviet David" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/6xcj-0z64", "abstract": "This dissertation explores three separate issues in the field of gravitational-wave astronomy: optimal detection algorithms for quasi-periodic signals, gravitational-wave signatures of the equation of state in the early universe, and local Newtonian gravitational noise from nearby airborne masses as possible contaminants of the gravitational-wave signal.
\r\n\r\n\r\nContinuous quasi-periodic signals are waveforms that maintain phase coherence over times longer than practical observation times, although the phase may drift in a way that can be modeled with few parameters. Sensitivity to such signals is limited by the computational cost of the analysis, especially since the detection algorithm must search over many values of the parameters in the phase model; it is therefore crucial to develop computationally efficient search strategies. One such strategy is a hierarchical stack search: a technique combining coherent phase corrections on short stretches of data with incoherent frequency drift corrections among several such stretches. The procedure is repeated at least twice, with each pass increasing the confidence in any putative signal. This dissertation discusses how to choose parameter values and observation times for greatest sensitivity, and shows how several astrophysically interesting sources may be detectable by this method.
\r\n\r\n\r\nA background of gravitational waves originating in the Big Bang or a pre-Big-Bang collapsing universe will not thermalize in any cosmological epoch, but may be amplified by an intermediate epoch when the wavelengths were stretched outside the Hubble radius. The present-day spectral index is related simply and generically to the initial spectrum, and to the cosmological equation of state at the beginning and end of the intermediate epoch. This dissertation derives this relation, and compares it to related but more model-specific formulae in the current literature.
\r\n\r\n\r\nFinally, this dissertation considers two atmospheric sources of background Newtonian gravita\u00adtional noise (infrasonic pressure waves and wind-advected density perturbations), and two sources of transient Newtonian gravitational signals (atmospheric shockwaves and massive airborne bodies, especially tumbleweeds). Neither background noise source will exceed the noise floor for advanced detectors, but sonic booms and wind-borne debris striking the detector can both produce detectable spurious signals through their gravitational effects. Possible corrective measures arc discussed.
" }, { "name": "Krasnopolsky, Ruben", "degree": "PhD", "year": "2000", "title": "Hydromagnetic astrophysical outflows", "advisor": "Blandford, Roger D.; Goldreich, Peter Martin", "url": "https://resolver.caltech.edu/CaltechETD:etd-09172008-092907", "creators": [ { "name": { "family": "Krasnopolsky", "given": "Ruben" }, "id": "Krasnopolsky-R", "display_name": "Krasnopolsky, Ruben" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "astronomy" ], "doi": "10.7907/j2ak-0b24", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\n\r\nThe launching, acceleration and stability of MHD outflows were studied numerically in two and three dimensions using a parallelized version of the ZEUS code.\r\n\r\nThe launching from Keplerian accretion disks was investigated using time-dependent simulations, to determine parameter dependence and stability to 3D perturbations. The most critical factors controlling the cold outflows from the disk surface were found to be the poloidal magnetic field profile and the mass discharge rate: together they determine the acceleration of gas away from the disk, and the location of the Alfven surface, which, in turn, fixes the angular momentum loss and the asymptotic speed. The flows were found to be remarkably stable in 3D against perturbations of the initial conditions, at least in the formation region of the jet before the Alfven surface. This is surprising in the context of previous studies.\r\n\r\nIntermittent flows are found when the mass discharge rate is too large for a given magnetic field profile. This may be relevant to some observed episodic sources. This intermittency can be suppressed if the mass loading has the angular dependence suggested by the magnetocentrifugal mechanism, namely that the discharge is a function of the angle \u03b8 between the poloidal fieldline threading the disk and the rotation axis, turning off when \u03b8[...]30\u00b0. The mechanism of intermittency sets up a maximum mass loading to the observed smooth jets, may explain those that are pulsed, and shows a possible transition back and forth between both regimes. The result presented here may be compared to some recently published papers which suggest that intermittency could occur if the mass loading is too small: here it occurs when it is too large. If both results are generic, mass loading is bracketed for steady flows.\r\n\r\nLaunching from disks was simulated using a cold disk and atmosphere. The number of boundary conditions that was imposed on the disk surface is what is necessary and sufficient to take into account information propagating upstream from the fast and Alfven critical surfaces, avoiding over-determination of the flow and unphysical effects, such as numerical \"boundary layers\" that otherwise isolate the disk from the flow, produce impulsive accelerations and confuse the connection between the disk parameters and the flow.\r\n\r\nThe solar wind provides another example of an MHD outflow, using the high solar latitude observations by the satellite Ulysses. The simulations performed here allowed an estimate of the mean value of the azimuthal velocity, which is not directly accessible to measurement, and is necessary to estimate the torque of the solar wind. The Alfven point was found to be located at ~11R[...]. Similar outflows from faster rotators were simulated, and found to be collimated along the rotational axis.\r\n" }, { "name": "Levin, Yuri", "degree": "PhD", "year": "1999", "title": "Topics in Physics and Astrophysics of LIGO", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08292017-115000442", "creators": [ { "name": { "family": "Levin", "given": "Yuri" }, "id": "Levin-Yuri", "display_name": "Levin, Yuri" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/ped8-ec41", "abstract": "This thesis deals with three topics, all of which are related to the generation or detection of gravitational waves:
\r\n\r\n(I) The Standard Quantum Limit (SQL) for LIGO and Quantum Non\u00ad demolition (QND) measurements, which allow one to overcome the SQL. Two particular QND measurement schemes are considered: (i) a Speed Meter, in which a small Fabry-Perot cavity attached to a LIGO test mass produces a phase shift proportional to the test mass's speed; and (ii) the Braginsky-Khalili nonlinear meter (BK-meter), in which a gravity-wave-induced motion of the nodes of the light beam inside a LIGO optical cavity is read out using a nonlinear medium which couples light to a microwave readout device. Our analysis shows that
\r\n\r\n(a) Using the Speed Meter one can perform naturally a broad-band QND mea\u00adsurement of a force acting on the test mass; however, this requires circulating light power which is unrealistically high for LIGO.
\r\n\r\n(b) The BK-meter can provide a natural way to perform a narrow-band QND measurement of a force acting on the mirrors of the optical cavity.
\r\n\r\nWhile neither of these QND measurement schemes can be immediately imple\u00ad mented for LIGO, they might provide conceptual steps towards the design of a prac\u00adtical QND interferometer.
\r\n\r\n(II) Mechanical thermal noise in LIGO. We develop a new method of calcu\u00ad lating thermal noise in mechanical systems, which is based on a direct application of the Fluctuation-Dissipation theorem. This method is capable of handling mechanical systems with inhomogeneous dissipation, by contrast with previous met hods (based on decomposing motion of the system into normal modes), which give incorrect results when the dissipation is inhomogeneous.
\r\n\r\nWe apply our direct method to an internal thermal noise in LIGO test masses.\r\nWe find that:
\r\n\r\n(a) The test-mass surface defects will make a larger contribution to thermal noise than was previously inferred by combining the (incorrect) mode-sum met hod with measurements of the Q's of the test masses' modes.
\r\n\r\n(b)Our direct met hod is more precise and computationally less expensive for small beam sizes than the previous mode-sum method.
\r\n\r\nWe also apply our direct method of analysis to suspension thermal noise in LIGO. We find that by careful positioning the laser beam spot on the mirror face and by monitoring independently the motion of the suspension wires, it may be possible to reduce the suspension thermal noise by a factor ~ 100 in spectral density.
\r\n\r\n(III) R-modes in Neutron Stars (NS) in Low-Mass X-ray Binaries (LMXBs). We study the suggestion that the accretion of gas onto a neutron star in an LMXB triggers an instability in which the star's r-modes are amplified by gravitational-wave emission. We find that if this is the case, then the subsequent neutron-star evolution depends critically on whether the neutron-star viscosity decreases with temperature, or is temperature-independent.
\r\n\r\nIn the former case, the Neutron Star goes through runaway cycles of rapid (~ 1 month) heating-rapid (~ 1 month) spindown-slow (~ 105 years) cooling-slow (~ 106 years) spin-up. In this scenario the duration of the gravitational radiation from the unstable r-modes is so short that even LIGO-III interferometers are unlikely to be able to catch a single LMXB in the throes of its gravitational-wave emission.
\r\n\r\nIn the latter (temperature-independent) case, however, the Neutron Star probably settles down into an equilibrium state with constant spin rate and temperature, and becomes a steady emitter of gravitational waves, which might be detectible by LIGO\u00ad II interferometers.
\r\n\r\nAll the capters in this thesis, except the introductory chapter I, have been published or are in press.
\r\n\r\n\r\n\r\n" }, { "name": "Bernstein, Rebecca A.", "degree": "PhD", "year": "1998", "title": "The HST/LCO measurement of the mean flux of the extragalactic background light (3000-8000\u00c5)", "advisor": "", "url": "https://resolver.caltech.edu/CaltechETD:etd-09242008-105539", "creators": [ { "name": { "family": "Bernstein", "given": "Rebecca A." }, "id": "Bernstein-R-A", "display_name": "Bernstein, Rebecca A." } ], "advisors": [], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." } ], "option_major": [ "astronomy" ], "doi": "10.7907/4cy1-bw30", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\n\r\nWe present the first detection of the optical extragalactic background light (EBL) at 3000, 5500, and 8000[...] using simultaneous observations taken from Hubble Space Telescope (HST) and the du Pont 2.5m telescope at Las Campanas Observatory (LCO). The total background flux of the night sky was measured from space using the Wide Field Planetary Camera 2 (WFPC2), thereby avoiding terrestrial airglow which is the dominant foreground component from the ground and the primary obstacle in previous efforts to measure the EBL. Foregrounds which contribute to the surface brightness of the night sky from HST are zodiacal light and diffuse galactic light. We have measured the absolute surface brightness of the zodiacal light using spectrophotometry taken with the du Pont 2.5m telescope at LCO and using the Faint Object Spectrograph (FOS) on HST. We minimize the contribution from diffuse galactic light by conducting the measurement in a target field with a low column density of galactic dust and neutral hydrogen, both of which are traced by 100\u03bc emission in the IRAS maps. The small remaining galactic contribution has been modeled using known correlations between the diffuse thermal emission from the dust at 100\u03bc and the diffuse optical light due to starlight scattered off the same dust. Because galaxies brighter than V = 23 AB mag are statistically poorly sampled in the WFPC2 field of view, we define the EBL as the total flux from objects fainter than V = 23 AB mag. We find the following mean levels for the EBL as a function of wavelength (in units of ergs s[superscript -1]cm[superscript -2]sr[superscript -1][...][superscript -1], with 1 \u03c3 rms errors): I\u03bb(3000[...])=4.0(\u00b11.9)x10[superscript -9], I\u03bb(5500[...])=2.8 (\u00b10.8)x10(superscript -9], I\u03bb(8000[...])=2.3 (\u00b10.6)x10[superscript -9], with systematic errors of 1-2x10[superscript -9] at each wavelength. The total flux detected at each wavelength is at least 2-3 times the integrated flux in published galaxy counts. The implications of this detection are discussed.\r\n" }, { "name": "Hogg, David Wardell", "degree": "PhD", "year": "1998", "title": "On the Evolution of Field Galaxies", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09222017-145437571", "creators": [ { "name": { "family": "Hogg", "given": "David Wardell" }, "id": "Hogg-David-Wardell", "display_name": "Hogg, David Wardell" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/4s4s-gv41", "abstract": "This thesis presents the analysis of spectroscopic and photometric data on faint galaxies\r\nin an 8-arcmin diameter region centered on the Hubble Deep Field. Source detection and \r\nphotometry is performed in the Un, G, R and Ks-band images to create\r\ncatalogs complete to Un = 25, G = 26, R = 25.5 and Ks = 20 mag. \r\nNumber counts and color distributions are consistent with those found in other, similar imaging\r\nsurveys. Keck Telescope spectroscopy exists for 483 sources in the sample.
\r\n\r\n\r\nThe rest-frame equivalent widths of the [O II] 3727 \u00c5 emission line are measured\r\nas a function of galaxy flux, color and redshift. The probability that a source of\r\na given flux, color and redshift has its [O II] line detected is estimated. [O II] line\r\nluminosity functions and integrated [O II] line luminosity densities are computed;\r\nthey show strong evolution, implying a much higher star formation rate density at redshifts\r\nz > 0.6 than locally.
\r\n\r\n\r\nThe spectroscopic survey is incomplete; not all selected sources have been observed\r\nspectroscopically, and not all observed sources have redshifts. Four methods for\r\nestimating the luminosity function in an incomplete survey are developed, three based\r\non the maximum-likelihood method. Simulated catalogs which accurately reproduce\r\nthe redshift structure and redshift-incompleteness found in real redshift surveys are\r\ncreated and used to test the methods for bias. All methods are biased for \"steep\"\r\n(i.e., dwarf-rich) luminosity functions.
\r\n\r\n\r\nThe B-band luminosity function for the R-selected sample is computed using an\r\nestimate of the probability that a source is assigned a redshift given that it has been\r\nobserved spectroscopically, based on the [O II] detection probability. The luminosity\r\nfunction is flat (constant number per log luminosity) and consistent with local\r\ndeterminations except for a higher overall normalization. No evidence is found for\r\ndependence of the luminosity function on redshift or environment, but the blue galaxy\r\nluminosity function is more dwarf-rich than the red.
\r\n\r\nIt is argued that, taken together, the observations support the existence of a dwarf-dominated, strongly star forming galaxy population in the past which merged into (or otherwise became physically associated with) the luminous galaxies observed locally.
\r\n" }, { "name": "Hughes, Scott Alexander", "degree": "PhD", "year": "1998", "title": "Gravitational-Wave Astronomy: Aspects of the Theory of Binary Sources and Interferometric Detectors", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08302017-134937434", "creators": [ { "name": { "family": "Hughes", "given": "Scott Alexander" }, "id": "Hughes-Scott-Alexander", "display_name": "Hughes, Scott Alexander" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/smxp-aw47", "abstract": "This thesis presents a study of several problems and issues in the nascent field of gravitational-wave astronomy. Multi-kilometer baseline interferometers are being built in the United States [the LIGO (Laser Interferometer Gravitational-wave Observatory) project] and similar projects are underway in Europe (the VIRGO and GE0600 projects) and Japan (the TAMA300 project). LIGO will begin operations very soon (the first science run is scheduled for 2002), and detectors in other countries will begin soon as well. We are thus about 5 years from using gravitational waves as a new window to probe astrophysical processes in the universe.
\r\n\r\n\r\nChapters 2, 3, and 4 of this thesis study gravitational waves from coalescences of compact bi\u00adnaries. Chapters 2 and 3 are a detailed examination, in collaboration with \u00c9anna \u00c9. Flanagan, of binary black hole (BBH) coalescences. The birth rate of BBH systems in the universe is highly uncertain, so it is not immediately apparent how relevant they are to gravitational-wave astronomy. If such systems do in fact exist, we find that they will be visible to extremely large distances, far greater than the distances to which binary neutron star systems, for example, will be visible. This heightened visibility may compensate for the possible dearth of such binaries, making them an ex\u00adtremely important and interesting source. We suggest ways in which numerical modeling of BBHs may aid gravitational-wave data analysis, and techniques that can be used in BBH event searches and waveform analysis. Chapter 4 analyzes the measurement of gravitational waves from the final merger of binary neutron star systems. Such waves depend on details of the composition of neutron stars, such as their equation of state, and may be driven by hydrodynamic and nuclear processes that occur in the final merger. Unfortunately, these waves are emitted at high frequencies where LIGO\u00ad type detectors have poor sensitivity. Measuring such waves will require specialty \"narrow-band\" detectors. In this chapter, I present an algorithm for optimally configuring a network of multiple LIGO-type and narrow-band detectors to measure these merger waves. I find that improved \r\ntheoret\u00adical modeling of the final merger will play an important role in designing such networks and in the analysis of their data. In Chapter 5, in collaboration with Patrick R. Brady, I analyze the stability of binary neutron star systems as they coalesce. Some rather controversial numerical calculations have found that neutron stars in binary systems are rendered unstable by their companion, and may collapse into black holes long before their final merger. This would have a huge impact on the gravitational waves such systems emit. The claimed effect is first-order in a particular expansion. Motivated by this claim, Brady and I perform a first-order expansion of the fluid and field equations of general relativity, in the limit in which one star is much smaller than the other. We find that no such effect can exist. Finally, Chapter 6 is an analysis, in collaboration with Kip S. Thorne, of seismic gravity-gradient noise, a noise source that may be of concern to future detector designs. This noise source arises from fluctuations in the density of the earth near and below a LIGO-type interferometer's test masses. It is gravitational in origin, and thus cannot be shielded. By carefully studying the geological structures in the earth near the two LIGO sites, considering the propagation of elastodynamic waves in such structures, and computing the gravitational fluctuations such waves cause, we find seismic gravity-gradient noise is likely to become unavoidable at frequencies below roughly 5 Hertz. This has strong implications on plans to improve the low frequency sensitivity of the LIGO detectors.
\r\n \r\n\r\n\r\n\r\n" }, { "name": "Lyutikov, Maxim", "degree": "PhD", "year": "1998", "title": "Coherent emission mechanisms in radio pulsars", "advisor": "", "url": "https://resolver.caltech.edu/CaltechETD:etd-09232008-092435", "creators": [ { "name": { "family": "Lyutikov", "given": "Maxim" }, "id": "Lyutikov-M", "display_name": "Lyutikov, Maxim" } ], "advisors": [], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." } ], "option_major": [ "astronomy" ], "doi": "10.7907/3y39-fz45", "abstract": "In this work we investigate some possible mechanisms for pulsar radio emission. First we analyze the normal modes of a strongly magnetized electron-positron plasma taking into account a possible difference in the distribution functions of electrons and positrons. The dispersion relations, polarization properties and various regimes of beam instabilities in pair plasma are considered. We argue that kinetic instabilities of electromagnetic modes are more promising candidates for the pulsar radio emission mechanism than electrostatic instabilities (which occur in the hydrodynamic regime). We elucidate the microphysical processes underlying cyclotron-Cherenkov and Cherenkov-drift emission, stressing the importance of collective plasma effects involving all the particles of a medium. We show that cyclotron-Cherenkov emission at the anomalous Doppler effect can account for various observed phenomena of the \"core\" emission. Cherenkov-drift emission is a likely candidate for the \"cone\" emission.\r\n\r\nWe developed a new description that treats Cherenkov-drift emission in cylindrical coordinates. This approach describes consistently the resonant wave-particle interaction and provides a link between the Cherenkov, curvature and drift emission mechanisms recovering them as a limiting cases of the Cherenkov-drift emission process.\r\n\r\nWe also consider two possible nonlinear stages of the development of the cyclotron-Cherenkov instability: quasilinear diffusion and induced Raman scattering. We calculate the asymptotic particle distribution and emerging spectra for the cyclotron-Cherenkov instability and also show that induced Raman scattering may be important for the wave propagation and nonlinear saturation of electromagnetic instabilities. Finally, we considered the escape of waves from a pulsar magnetosphere taking into account cyclotron, Cherenkov and Cherenkov-drift absorption processes.\r\n" }, { "name": "Mahajan, Sanjoy Sondhi", "degree": "PhD", "year": "1998", "title": "Order of Magnitude Physics: A Textbook with Applications to the Retinal Rod and the Density of Prime Numbers", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechTHESIS:10302009-110303489", "creators": [ { "name": { "family": "Mahajan", "given": "Sanjoy Sondhi" }, "id": "Mahajan-Sanjoy-Sondhi", "display_name": "Mahajan, Sanjoy Sondhi" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "chair", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Frautschi", "given": "Steven C." }, "id": "Frautschi-S-C", "role": "member", "display_name": "Frautschi, Steven C." }, { "name": { "family": "Hopfield", "given": "John J." }, "id": "Hopfield-J-J", "role": "member", "display_name": "Hopfield, John J." }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Mead", "given": "Carver" }, "id": "Mead-C-A", "orcid": "0000-0003-4051-0462", "role": "member", "display_name": "Mead, Carver" } ], "option_major": [ "physics" ], "doi": "10.7907/8MJZ-A984", "abstract": "I develop tools to amplify our mental senses: our intuition and reasoning abilities. The first five chapters\u2014based on the Order of Magnitude Physics class taught at Caltech by Peter Goldreich and Sterl Phinney\u2014form part of a textbook on dimensional analysis, approximation, and physical reasoning. The text is a resource of intuitions, problem-solving methods, and physical interpretations. By avoiding mathematical complexity, order-of-magnitude techniques increase our physical understanding, and allow us to study otherwise difficult or intractable problems. The textbook covers: (1) simple estimations, (2) dimensional analysis, (3) mechanical properties of materials, (4) thermal properties of materials, and (5) water waves.
\r\n\r\nAs an extended example of order-of-magnitude methods, I construct an analytic model for the flash sensitivity of a retinal rod. This model extends the flash-response model of Lamb and Pugh with an approximate model for steady-state response as a function of background light Ib. The combined model predicts that the flash sensitivity is proportional to Ib-1.3. This result roughly agrees with experimental data, which show that the flash sensitivity follows the Weber-Fechner behavior of Ib-1 over an intensity range of 100. Because the model is simple, it shows clearly how each biochemical pathway determines the rod's response.
\r\n\r\nThe second example is an approximate model of primality, the square-root model. Its goal is to explain features of the density of primes. In this model, which is related to the Hawkins' random sieve, divisibility and primality are probabilistic. The model implies a recurrence for the probability that a number n is prime. The asymptotic solution to the recurrence is (log n)-1, in agreement with the prime-number theorem. The next term in the solution oscillates around (log n)-1 with a period that grows superexponentially. These oscillations are a model for oscillations in the density of actual primes first demonstrated by Littlewood, who showed that the number of primes \u2264 n crosses its natural approximator, the logarithmic integral, infinitely often. No explicit crossing is known; the best theorem, due to to Riele, says that the first crossing happens below 7 x 10370. A consequence of the square-root model is the conjecture that the first crossing is near 1027.
\r\n" }, { "name": "Owen, Benjamin James", "degree": "PhD", "year": "1998", "title": "Gravitational Waves from Compact Objects", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08302017-132619494", "creators": [ { "name": { "family": "Owen", "given": "Benjamin James" }, "id": "Owen-Benjamin-James", "display_name": "Owen, Benjamin James" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/63nf-9z58", "abstract": "This thesis addresses problems in the generation and detection of gravitational waves\r\nfrom two types of sources: inspiraling compact binaries and rapidly rotating young\r\nneutron stars.
\r\n\r\nChapters 2 and 3 estimate the computational costs of a basic matched filtering strategy to search for inspiraling compact binaries. Chapter 2 (written in 1995) sets up the machinery for calculating costs and makes a rough estimate based on the waveforms and noise spectra available at the time. It also systematizes previously published methods of choosing the filters. Chapter 3 (written with B. S. Sathyapra\u00ad kash in 1998) fine-tunes the machinery and updates the estimates of Chapter 2 using more current waveforms and noise spectra.
\r\n\r\nChapter 4 (written with Hideyuki Tagoshi and Akira Ohashi) concerns the post\u00ad Newtonian generation of gravitational waveforms from inspiraling compact binaries whose component objects spin about their own axes. It lays out a method of cal\u00ad culating post-Newtonian spin effects and calculates the lowest-order such effect not previously known (the second-post-Newtonian spin-orbit contribution to the wave\u00ad forms in the absence of precession).
\r\n\r\nChapters 5 and 6 concern the Chandrasekhar-Friedman-Schutz (CFS) gravita\u00adtional radiation instability as it applies to the \u03c4-modes of rapidly rotating young neutron stars. Chapter 5 (written with Lee Lindblom and Sharon M. Morsink) com\u00ad putes the viscous damping and gravitational radiation timescales of the \u03c4-modes and shows that viscosity does not suppress the CFS instability in hot young neutron stars. Chapter 6 (written with Lee Lindblom, Curt Cutler, Bernard F. Schutz, Alberto Vec\u00adchio, and Nils Andersson) computes approximate gravitational waveforms from young neutron stars spinning down due to the \u03c4-mode instability and estimates that these gravitational waves can be detected by the \"enhanced\" LIGO interferometers if a suitable data analysis strategy is developed.
" }, { "name": "Kennefick, Daniel John", "degree": "PhD", "year": "1997", "title": "Radiation Reaction in Binary Systems in General Relativity", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08222017-154459722", "creators": [ { "name": { "family": "Kennefick", "given": "Daniel John" }, "id": "Kennefick-Daniel-John", "display_name": "Kennefick, Daniel John" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/jzcp-a525", "abstract": "This thesis is concerned with current problems in, and historical aspects of, the problem of radiation reaction in stellar binary systems in general relativity. Part I addresses current issues in the orbital evolution due to gravitational radiation damping of compact binaries. A particular focus is on the inspiral of small bodies orbiting large black holes, employing a perturbation formalism. In addition, the merger, at the end of the insprial, of comparable mass compact binaries, such as neutron star binaries is also discussed. The emphasis of Part I is on providing detailed descriptions of sources and signals with a view to optimising signal analysis in gravitational wave detectors, whether ground- or space-based interferometers, or resonant mass detectors.
\r\n\r\n\r\nPart II of the thesis examines the historical controversies surrounding the prob\u00adlem of gravitational waves, and gravitational radiation damping in stellar binaries. In particular, it focuses on debates in the mid 20th-century on whether binary star systems would really exhibit this type of damping and emit gravitational waves, and on the \"quadrupole formula controversy\" of the 1970s and 1980s, on the question whether the standard formular describing energy loss due to emission of gravita\u00adtional waves was correctly derived for such systems. The study sheds light on the role of analogy in science, especially where its use is controversial, on the importance of style in physics and on the problem of identity in science, as the use of history as a rhetorical device in controversial debate is examined. The concept of the Theo\u00adretician's Regress is introduced to explain the difficulty encountered by relativists in closing debate in this controversy, which persisted in one form or another for several decades.
" }, { "name": "Ryan, Fintan Danh", "degree": "PhD", "year": "1997", "title": "Searching for Black Holes and Other Massive, Compact Bodies Using the Gravitational Waves from Binary Inspirals", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09062017-160111338", "creators": [ { "name": { "family": "Ryan", "given": "Fintan Danh" }, "id": "Ryan-Fintan-Danh", "display_name": "Ryan, Fintan Danh" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/3n38-zg42", "abstract": "We consider several issues involved with searching for and studying different types of compact bodies using the gravitational waves from binary inspirals. In Chapter 2, we use a radiation\u00ad reaction force formalism to compute (to leading post-Newtonian order) the inspiral evolution of a circular, nonequatorial orbit around a spinning black hole. We find that an initially circular orbit remains circular under radiation reaction and is driven towards anti-alignment with the black hole's spin direction. In Chapter 3, we apply this same formalism to orbits which are elliptical as well as nonequatorial. In addition, we prove that circular orbits remain circular exactly. In Chapter 4, we show that all the multipole moments of a massive, compact body (whose gravita\u00adtional field is stationary, axially symmetric, and reflection symmetric across the equatorial plane) can be determined from the gravitational waves produced by a much less massive, compact object inspiraling in a contracting circle in the equatorial plane. We show that the moments are encoded in the waves' evolution in (at least) four independent functions of the gravitational-wave frequency: the gravitational-wave energy, the precession frequency of the orbit when slightly eccentric, the precession frequency of the orbit when slightly nonequatorial, and the gravitational-wave phase evolution. In Chapter 5, we compute the structure and the multipole moments of a spinning boson star with large self-interaction. We find that only three moments are needed to specify all the star's properties, and that the pattern of moments is very different from that for black holes. In Chapter 6, we estimate how accurately a gravitational-wave detector can estimate the multipole moments of the central body from the gravitational waves produced by an inspiraling compact object. We find that, typically, a space-based detector such as LISA (as opposed to an Earth-based detector such as LIGO) is necessary to get accurate enough measurements of the multipole moments so as to search for massive, compact, non-black-hole objects. In Chapter 7, as a model for computing the full details of the gravitational waves from an orbital inspiral, we compute the scalar waves produced by a scalar charge in a circular, equatorial orbit around a body with arbitrary multipole moments." }, { "name": "Hansen, Bradley Miles Stougaard", "degree": "PhD", "year": "1996", "title": "The ages, speeds and offspring of pulsars", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechETD:etd-09102008-134917", "creators": [ { "name": { "family": "Hansen", "given": "Bradley Miles Stougaard" }, "id": "Hansen-B-M-S", "display_name": "Hansen, Bradley Miles Stougaard" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "astronomy" ], "doi": "10.7907/69DE-D262", "abstract": "We investigate the cooling of low mass white dwarfs with helium cores. We construct a detailed numerical model using the most modern input physics, including our own calculations of low temperature hydrogen opacities. We use our models to constrain the ages of binary millisecond pulsars from the optical observations of their white dwarf companions. We use this to place limits on the initial spin periods, magnetic field decay times and accretion histories of the millisecond pulsars. Our models can also be used along with observations of spectroscopic gravities and radial velocities to place interesting constraints on the neutron star equation of state. We provide grids of temperature and luminosity as a function of age for various white dwarf masses and surface compositions to facilitate future analyses.\r\n\r\nWe have investigated the effect of the pulsar wind on the atmospheric composition of binary companions. The spallation of atmospheric helium to hydrogen increases the cooling age of the white dwarf. We find that all white dwarf companions in binaries with orbital period < 300 days should cool as DA (hydrogen surface layer) white dwarfs, irrespective of their original hydrogen content. We investigate the effect of various wind compositions and note that, if almost all the hydrogen on the surface of a pulsar companion is the result of spallation of an ionic wind, then the D/H ratio is large.\r\n\r\nWe investigate the processes by which planets might form around a millisecond pulsar such as PSR B1257+12. We study the evolution of accretion disks of different mass, angular momentum and composition, corresponding to various proposed formation scenarios. We find that most formation scenarios require a high efficiency of conversion of metal-rich material into planets if they are to produce the observed parameters of the 1257+12 planetary system.\r\n\r\nWe have studied the distribution of pulsar proper motions in the light of the recent analysis of Lyne & Lorimer (1994). Using a simulation of the selection effects of the various surveys, and treating the censored data using survival statistics, we arrive at an estimate of the characteristic pulsar birth velocity ~ 300 km.s[superscript -1], 2/3 that of Lyne & Lorimer. We also show that the older pulsar population shows the effects of the asymmetric drift, indicating that it must be dynamically old.\r\n" }, { "name": "Small, Todd Andrew", "degree": "PhD", "year": "1996", "title": "The Norris survey of the Corona Borealis supercluster", "advisor": "Sargent, Wallace L. W.; Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechETD:etd-09102008-111656", "creators": [ { "name": { "family": "Small", "given": "Todd Andrew" }, "id": "Small-T-A", "display_name": "Small, Todd Andrew" } ], "advisors": [ { "name": { "family": "Sargent", "given": "Wallace L. W." }, "id": "Sargent-W-L-W", "role": "advisor", "display_name": "Sargent, Wallace L. W." }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "astronomy" ], "doi": "10.7907/sy8m-7r36", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nWe describe the design, construction, and first results of the Norris Survey of the Corona Borealis Supercluster, a redshift survey of a 6[...] x 6[...] region in the core of the Corona Borealis supercluster.\r\n\r\nThe redshift survey has been conducted with the 176-fiber Norris Spectrograph on the Hale 5m telescope. The input catalog is based on machine scans of Schmidt plates and consists of over 5 x 10[...] objects calibrated in the Gunn g and r bands. We chose to observe 36 20' diameter fields arranged in a 6 x 6 grid across the core of the supercluster. We have completed observations of 23 of these fields, plus an additional 9 fields which were closely spaced along the ridge of galaxies between Abell 2061 and Abell 2067. We have measured redshifts for 1491 extragalactic objects, 420 with [...] 8[...] resolution and the remainder with [...] 4[...] resolution. Our newly measured redshifts were augmented with 163 from the literature, yielding 1654 redshifts for the entire survey. The faintest galaxies in the survey have magnitudes of [...] 22.5[...], and the most distant galaxies have redshifts of [...] 0.7.\r\n\r\nWe have measured an unexpectedly small number of redshifts (528) in the Corona Borealis supercluster since the supercluster is not as dense as originally believed and since a background supercluster at [...] 0.11 makes a substantial contribution to the projected surface density of galaxies. Despite the small number of redshifts for galaxies in the supercluster, we are able to draw the following conclusions about the dynamics and structure of the Corona Borealis supercluster. (1) The galaxy distribution within the supercluster is far from smooth. The galaxy density falls rapidly away from the Abell cluster cores. (2) The virial mass of the supercluster is [...], which yields a B band mass-to-light ratio of [...]. (3) The dynamics of the supercluster, as revealed through an analysis of the two-point correlation function, suggest that the supercluster has not yet generated large mean flows towards itself and that, therefore, the supercluster has only recently begun to break away from the Hubble expansion.\r\n\r\nSince the sample of redshifts extends to z = 0.5, we have been able to investigate the evolution of large-scale structure and of the galaxy population. By computing the projected two-point spatial correlation function [...], we have measured the correlation length [...] and the power-law index [...] of the real space correlation function [...] as a function of redshift. We find that the correlation length declines dramatically with increasing redshift. Incorporating measurements of [...] from other surveys, we measure the evolutionary parameter [...] to be 2.25 [...] 0.1 for [...] = 1.7, well in excess of the linear theory prediction [...] = [...] - 1. We do not see evolution in the clustering of red galaxies; the clustering evolution is limited to the blue galaxies.\r\n\r\nWe have also measured the pairwise velocity dispersion [...] on a scale of [...] Mpc through an analysis of the two-point spatial correlation function computed as a function of pair separations along and perpendicular to the line-of-sight. Although [...] is quite sensitive to the treatment of rich clusters in the survey, we conclude that [...] is significantly larger than the canonical value of 340 [...] 40 [...] computed by Davis and Peebles (1983). This result is in accord with other recent estimates of [...].\r\n\r\nWe have characterized structure on scales of [...] Mpc by measuring the one-dimensional power spectrum of our survey. We measure a significant peak on scales of [...] Mpc. The structures responsible for the peak are readily identifiable in redshift-right- ascension cone diagrams: superclusters are separated by large underdense regions.\r\n\r\nUsing 598 field galaxies with [...] from our survey, we have computed the field galaxy luminosity function as a function of color and redshift. We find compelling evidence that the B band field galaxy luminosity function evolves with redshift. The evolution is limited to blue galaxies; the red galaxies show no sign of change to z = 0.5. The evolution of the luminosity function of blue galaxies, which is corroborated by a [...] test, is reflected in the blueward shift of the median galaxy color with redshift and in the increasing fraction of galaxies displaying the star-formation indicators [0 II] and [...] with redshift.\r\n" }, { "name": "Apostolatos, Theocaris A.", "degree": "PhD", "year": "1995", "title": "Topics in general relativity : naked singularities, and theoretical aspects of gravitational waves from merging compact binaries", "advisor": "", "url": "https://resolver.caltech.edu/CaltechETD:etd-09112007-132644", "creators": [ { "name": { "family": "Apostolatos", "given": "Theocaris A." }, "id": "Apostolatos-T-A", "display_name": "Apostolatos, Theocaris A." } ], "advisors": [], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." } ], "option_major": [ "astronomy" ], "doi": "10.7907/2x5m-b994", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nTwo topics in classical general relativity are discussed: a) The clothing of singularities by event horizons, and b) various issues in the evolution of coalescing compact binaries, as sources of gravitational waves to be detected by the LIGO/VIRGO/GEO ground-based detectors and/or the LISA space-based detector. More specifically:\r\n\r\nWe investigate a problem related to an important conjecture of classical relativity, namely the existence of a \"cosmic censorship\" that forbids the formation of naked singularities, and always clothes them with event horizons that causally hide them from the rest of the Universe. Under consideration is the role of rotation in an infinite cylindrical shell consisting of collisionless dust particles, half of which rotate clockwise and half counterclockwise. We show that, although such a shell without any rotation is known to collapse into a line singularity, the presence of an arbitrarily small amount of rotation is sufficient to halt the collapse. Such a shell, starting from a non equibrium configuration, will \"breath\" radially, emitting gravitational waves, and will finally settle down to an equilibrium radius at which gravity is balanced by centrifugal forces. This suggests the essential role that rotation might play in halting the gravitational collapse of an elongated distribution of mass and preventing the formation of a naked singularity. However, this is a highly idealized example, and it can, by no means, ensure the validity of the \"cosmic censorship\" hypothesis.\r\n\r\nOn a separate topic, we explore the details of how gravitational radiation reaction drives the evolution of a slightly eccentric orbit of a small body around nonrotating supermassive black holes. A combination of analytic and numerical results arise from the solution of the Teukolsky perturbation equation. It is shown that in the fully relativistic situation, as in the Newtonian quadrupole approximation, there is a tendency for circularization of the orbit down to an orbital radius [...], where M is the mass of the black hole, and G and c are Newton's gravitation constant and the speed of light. It is further shown that for radii smaller than [...] the eccentricity increases.\r\n\r\nFinally, an attempt is made to understand and construct analytic expressions that, based on the laws of general relativity, approximately describe the simultaneous precession in rapidly spinning black hole and/or neutron star and inspiral binaries with circular orbits. The precession is produced by general relativistic spin-orbit and spin-spin coupling; the inspiral, by gravitational radiation reaction. We derive the corresponding approximate waveforms to be received by the network of LIGO, VIRGO, and GEO earth-based gravitational-wave detectors. We then go on to investigate the adequateness of various \"families of templates,\" to detect these spin-modulated waveforms by the method of \"matching filters,\" We introduce a \"fitting factor\" FF as a measure of templates' adequateness, and show the complete inadequateness, for the task of detection, of the \"Newtonian template family\" (the set of the waveforms derived from the Newtonian, quadrupole approximation formalism). Another template family with an extra parameter is suggested that performs much better." }, { "name": "Lee, Hee-Won", "degree": "PhD", "year": "1995", "title": "Polarization of resonantly scattered lines in active galactic nuclei", "advisor": "", "url": "https://resolver.caltech.edu/CaltechETD:etd-10162007-104350", "creators": [ { "name": { "family": "Lee", "given": "Hee-Won" }, "id": "Lee-H-W", "display_name": "Lee, Hee-Won" } ], "advisors": [], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." } ], "option_major": [ "physics" ], "doi": "10.7907/xxz3-xa64", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nMost Active Galactic Nuclei are characterized by prominent UV emission lines in their spectra, and the line photons are believed to be resonantly scattered many times before emerging along the line of sight. The polarization of these line photons, which is sensitive to the atomic physics, can be an important tool for investigating the scattering geometry and kinematics of the line-emitting region. The principle of resonance scatterings are discussed in order to elucidate the relation between the emergent polarization, the atomic transitions and the anisotropy of the radiation field. When the ratio of collision frequency to radiative excitation rate is much larger than 1, collisional mixing occurs and the ground state sublevels are equally populated. The opposite case is radiative mixing, where the anisotropic radiation field may induce uneven population in the ground state sublevels, leading to enhancement of polarization. A density matrix is introduced to deal with the photon polarization state and the level population of the ions.\r\n\r\nA density matrix formalism based Monte Carlo approach is adopted and used to compute the polarization of emission lines emerging from anisotropic clouds or anisotropically expanding clouds. The effect of both spatial diffusion and geometric anisotropy on polarization is considered. It is shown that semi-forbidden [...], which has a moderate optical depth ranging 1 - 10 in the broad emission line region, can be polarized, whereas most permitted UV lines having large scattering optical depth are negligibly polarized.\r\n\r\nThe same code is modified to incorporate the Sobolev approximation and polarization of the broad absorption line troughs in broad absorption line quasars. Both bipolar flow and equatorial flow are examined. Up to 15 percent polarization in the absorption trough is obtained in the doublet transition [...] for an equatorial flow model, and from a bipolar flow model, a lower degree of polarization is obtained. A higher polarization is obtained for the singlet transition case [...], which should be a good diagnostic to test whether the polarization is caused by resonance scattering. Recent spectropolarimetry is briefly summarized, and observational ramifications are discussed.\r\n\r\nFinally the conditions necessary to produce significant polarization from outflowing gas from quasars are studied. Multiplet transitions with radiative mixing are considered and compared to the polarization from a singlet transitions which produce the highest polarization. The steep rise in the polarized flux shortward of [...] observed in a radio quiet quasar PG 1630+377 is interpreted in terms of resonance line scattering.\r\n" }, { "name": "Rauch, Kevin Patrick", "degree": "PhD", "year": "1995", "title": "Black holes and accretion disks in active galactic nuclei : microlensing, caustics, and collisional stellar dynamics", "advisor": "", "url": "https://resolver.caltech.edu/CaltechETD:etd-10222007-142133", "creators": [ { "name": { "family": "Rauch", "given": "Kevin Patrick" }, "id": "Rauch-K-P", "display_name": "Rauch, Kevin Patrick" } ], "advisors": [], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." } ], "option_major": [ "astronomy" ], "doi": "10.7907/cpyq-cr33", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nInteractions between and the structure of black holes, accretion disks, and dense star clusters are investigated. Observed rapid gravitational microlensing variability in the quasar Q2237+0305 is used in conjunction with numerical simulations of microlensed quasar accretion disks to determine whether the observations constrain theoretical accretion disk models. It is found that blackbody disks are at least three times too large to account for the observed variability, and on that basis it is argued that the optical emission is either nonthermal or optically thin.\r\n\r\nAccurate, efficient, and general-purpose routines to compute geodesic trajectories in the Kerr spacetime describing rotating black holes are implemented and applied to several problems. The optical caustic structure of the Kerr metric describing rotating black holes is determined and its possible relevance to rapid X-ray variability in active galactic nuclei is discussed. It is found that the (primary) caustic is a small tube with an asteroid cross section which extends behind the black hole asymptotically parallel to the optic axis but displaced from it by an amount proportional to the spin of the hole, and that the angular magnification is unexpectedly high everywhere inside the caustic. Sample point source light curves and the appearance of thick accretion disks around Kerr black holes are calculated and the influence of caustics on them is assessed.\r\n\r\nThe dynamical evolution of the core of a dense star cluster around a Kerr black hole and under the influence of star-disk interactions is examined. It is shown that there are astrophysically plausible regimes in which star-disk interactions can dominate all other dynamical processes. The effects of star-disk interactions on single orbits are illustrated. It is found that star-disk interactions steepen the initial density profile towards an equilibrium [...] profile and simultaneously increase the central density by up to two orders of magnitude. It is argued that this process could self limit when densities climb to such a level that collisions between stars become important.\r\n\r\nSimulations of the dynamical evolution of the density cusp of a star cluster around a massive black hole in a regime where stellar collisions dominate other dynamical processes are performed. The calculations are done using a discrete cluster of stars and a fully relativistic formalism. Versatile numerical methods are developed and applied to this problem. A modified form of Kepler's Equation asymptotically valid in the Kerr geometry is derived. It is found that collisions produce a constant density core which is mainly populated by stars on highly radial orbits, in contrast to previous Fokker-Planck analyses in which an [...] profile has been found. Collisional refilling of the loss cone is seen. Additional applications of the numerical algorithms are suggested.\r\n" }, { "name": "Flanagan, Eanna E.", "degree": "PhD", "year": "1994", "title": "Topics in general relativity : the hoop conjecture and theoretical aspects of gravitational wave detection", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-11132006-095610", "creators": [ { "name": { "family": "Flanagan", "given": "Eanna E." }, "id": "Flanagan-E-E", "display_name": "Flanagan, Eanna E." } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Soifer", "given": "B. Thomas" }, "id": "Soifer-B-T", "role": "member", "display_name": "Soifer, B. Thomas" } ], "option_major": [ "physics" ], "doi": "10.7907/7SW7-8076", "abstract": "The body of this thesis consists of four chapters (2 through 5), each of which is a paper that has been published in or submitted for publication to Physical Review D. I am the sole author of chapters 2, 3, and 4; Curt Cutler coauthored chapter 5 with me.\r\n\r\nThese four chapters deal with two topics in general relativity: the formation of horizons in nonspherical gravitational collapse (chapters 2 and 3), and some theoretical aspects of the effort to detect gravitational waves from cosmic sources (chapters 4 and 5). These four chapters were written largely for experts in the topics they cover. As an aid to general readers, I shall give in this introductory chapter some background information about chapters 2 through 5 and a nontechnical overview of their contents." }, { "name": "Markovi\u0107, Dragoljub", "degree": "PhD", "year": "1994", "title": "Black holes in the early universe, in compact binaries, and as energy sources inside solar-type stars", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05092013-084229368", "creators": [ { "name": { "family": "Markovi\u0107", "given": "Dragoljub" }, "id": "Markovi\u0107-D", "display_name": "Markovi\u0107, Dragoljub" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/ms5q-kt36", "abstract": "This thesis consists of three separate studies of roles that black holes might\r\nplay in our universe.
\r\n\r\nIn the first part we formulate a statistical method for inferring the cosmological\r\nparameters of our universe from LIGO/VIRGO measurements of the gravitational\r\nwaves produced by coalescing black-hole/neutron-star binaries. This method is\r\nbased on the cosmological distance-redshift relation, with \"luminosity distances\"\r\ndetermined directly, and redshifts indirectly, from the gravitational waveforms.\r\nUsing the current estimates of binary coalescence rates and projected \"advanced\"\r\nLIGO noise spectra, we conclude that by our method the Hubble constant should\r\nbe measurable to within an error of a few percent. The errors for the mean density\r\nof the universe and the cosmological constant will depend strongly on the size of\r\nthe universe, varying from about 10% for a \"small\" universe up to and beyond\r\n100% for a \"large\" universe. We further study the effects of random gravitational\r\nlensing and find that it may strongly impair the determination of the cosmological\r\nconstant.
\r\n\r\nIn the second part of this thesis we disprove a conjecture that black holes cannot\r\nform in an early, inflationary era of our universe, because of a quantum-field-theory induced\r\ninstability of the black-hole horizon. This instability was supposed to arise\r\nfrom the difference in temperatures of any black-hole horizon and the inflationary\r\ncosmological horizon; it was thought that this temperature difference would make\r\nevery quantum state that is regular at the cosmological horizon be singular at\r\nthe black-hole horizon. We disprove this conjecture by explicitly constructing a\r\nquantum vacuum state that is everywhere regular for a massless scalar field. We\r\nfurther show that this quantum state has all the nice thermal properties that one\r\nhas come to expect of \"good\" vacuum states, both at the black-hole horizon and\r\nat the cosmological horizon.
\r\n\r\nIn the third part of the thesis we study the evolution and implications of a hypothetical\r\nprimordial black hole that might have found its way into the center of the\r\nSun or any other solar-type star. As a foundation for our analysis, we generalize\r\nthe mixing-length theory of convection to an optically thick, spherically symmetric\r\naccretion flow (and find in passing that the radial stretching of the inflowing fluid\r\nelements leads to a modification of the standard Schwarzschild criterion for convection).\r\nWhen the accretion is that of solar matter onto the primordial hole, the\r\nrotation of the Sun causes centrifugal hangup of the inflow near the hole, resulting\r\nin an \"accretion torus\" which produces an enhanced outflow of heat. We find, however, that the turbulent viscosity, which accompanies the convective transport\r\nof this heat, extracts angular momentum from the inflowing gas, thereby buffering\r\nthe torus into a lower luminosity than one might have expected. As a result, the\r\nsolar surface will not be influenced noticeably by the torus's luminosity until at\r\nmost three days before the Sun is finally devoured by the black hole. As a simple\r\nconsequence, accretion onto a black hole inside the Sun cannot be an answer to\r\nthe solar neutrino puzzle.
\r\n" }, { "name": "Biehle, Garrett T.", "degree": "PhD", "year": "1993", "title": "Studies of stars with neutron cores and of x-ray binaries displaying quasi-periodic oscillations", "advisor": "Thorne, Kip S.; Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:12042012-092833556", "creators": [ { "name": { "family": "Biehle", "given": "Garrett T." }, "id": "Biehle-G-T", "display_name": "Biehle, Garrett T." } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Mould", "given": "Jeremy R." }, "id": "Mould-J-R", "role": "member", "display_name": "Mould, Jeremy R." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Vogel", "given": "Petr" }, "id": "Vogel-P", "role": "member", "display_name": "Vogel, Petr" } ], "option_major": [ "physics" ], "doi": "10.7907/sx31-ra11", "abstract": "This thesis contains the results of two investigations: one into the nature of stars with degenerate neutron cores and the other into the interpretation of the phenomenology of luminous low-mass X-ray binaries (LMXBs) displaying slow\r\nquasi-periodic oscillations (QPOs) in their X-ray flux.
\r\n\r\nA star with a degenerate neutron core would be a red giant or supergiant. In this thesis we investigate the structure of such a supergiant, particularly examining\r\nthe energy production and seeking an identifying observational signature. This star is convective from near the photosphere down to the base of the envelope just\r\noutside the degenerate core (radius 10 km). The star's luminosity comes from the rp-process in a convective burning region within 100 km of the base of the envelope. The convection brings fuel for the rp-process into the burning region from throughout the envelope and deposits the products of rp-burning back into the envelope, including the photosphere. After about 10^5 years, the abundances of Br, Rb, Y, and Nb at the surface of the star will be about 200 times greater than their solar abundances, and that of Mo, over 1000 times solar. A suitable observational signature would be the strong enhancement of absorption lines for these elements in the star's spectrum. As many as 10 of the nearest 100 red\r\nsupergiants (those within 5 kpc) could have neutron cores.
\r\n\r\nThe other investigation concerns a model of rapid accretion onto an unmagnetized neutron star with radius somewhat less than 6GM/c^2. This model is applied to the phenomenology of a class of LMXBs displaying slow (\u223c 6 Hz)\r\nQPOs in X-ray flux. These sources are highly luminous (approximately Eddington) and display what appears to be three modes (\"branches\") of accretion. In this model, at low accretion rates, the neutron star lies within the inner edge of the accretion disk, and matter is dripped onto the neutron star from the inner edge. As the accretion rate increases, the transition from the \"horizontal branch\"\r\nto the \"normal branch\" occurs when the disk thickens and its inner edge touches the star and forms a boundary layer. The formation of a boundary layer changes the structure of the inner disk and the spectral character of the escaping X-rays. The transition from the normal branch to the \"flaring branch\" occurs when the boundary layer covers the whole surface of the neutron star and radiation escapes\r\nprimarily through convective instabilities. This thesis presents an exploration of this model, with an emphasis on establishing the plausibility that a neutron star could indeed lie inside an accretion disk accreting at the observed rate and that a change of mass accretion rate could push the inner radius onto the surface of the\r\nstar.
\r\n" }, { "name": "Echeverria, Fernando", "degree": "PhD", "year": "1993", "title": "Topics in general relativity theory : gravitational-wave measurements of black-hole parameters; gravitational collapse of a cylindrical body; and classical-particle evolution in the presence of closed, timelike curves", "advisor": "", "url": "https://resolver.caltech.edu/CaltechETD:etd-12082008-095402", "creators": [ { "name": { "family": "Echeverria", "given": "Fernando" }, "id": "Echeverria-F", "display_name": "Echeverria, Fernando" } ], "advisors": [], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." } ], "option_major": [ "physics" ], "doi": "10.7907/BEV7-NS85", "abstract": "In this thesis I present three separate studies on three different topics in General Relativity.\r\n\r\nThe first study investigates the accuracy with which the mass and angular momentum of a black hole can be determined by measurements of gravitational waves from the hole, using a laser-interferometer gravitational-wave detector. The black hole is assumed to have been strongly perturbed, perhaps by coalescence with a binary companion, and the detector measures the waves produced by its resulting vibration and ring-down. The uncertainties in the measured mass and angular momentum arise from the unavoidable presence of noise in the detector. It is found that the faster the hole rotates, the more accurate the measurements will be, with the uncertainty in the angular momentum decreasing rapidly with increasing rotation speed. It is also found that the errors in the mass and angular momentum are highly correlated.\r\n\r\nThe second study is an analysis of the gravitational collapse of an infinitely long, cylindrical dust shell. This analysis is expected to be helpful in understanding the behavior during collapse of more realistic, finite-length bodies. It is found that the collapse evolves into a naked singularity in finite time, as measured by a distant observer or by one riding on the shell. Analytical expressions for the variables describing the collapse are found at late times, near the singularity. The picture is completed with a numerical simulation that follows the collapse from the start until very close to the singularity. The singularity is found to be strong, in the sense that an observer riding on the shell will be infinitely stretched in the direction parallel to the symmetry axis, and infinitely compressed in the azimuthal direction. The gravitational waves emitted from the collapse are also analyzed.\r\n\r\nThe last study focuses on a different kind of phenomenon, namely, the consequences of the existence of closed timelike curves in a spacetime that contains a wormhole. One might expect that the closed timelike curves would cause difficulty for the initial value problem for systems that evolve in such a spacetime: a system with apparently well-posed initial conditions might have no self-consistent solutions to its evolution equations. We study the simple case of a macroscopic, classical particle with a hard-sphere potential (a \"billiard ball\"), and we focus attention on initial conditions for which the evolution, if followed naively, is self- inconsistent: the ball enters one mouth of the wormhole and then comes out of the other mouth at an earlier time, then collides with its younger self, preventing itself from ever entering the first mouth. We find, surprisingly, that for all such \"dangerous\" initial conditions, there are an infinite number of self-consistent evolutionary solutions, involving a glancing collision and any number of wormhole traversals. We also find that for many non-dangerous initial conditions, there also exist an infinity of possible evolutions.\r\n" }, { "name": "Quillen, Alice C.", "degree": "PhD", "year": "1993", "title": "The Kinematics of Molecular Gas and Dust in the Nearby Galaxies Centaurus A and M82", "advisor": "Unknown, Unknown", "url": "https://resolver.caltech.edu/CaltechTHESIS:01042013-155931345", "creators": [ { "name": { "family": "Quillen", "given": "Alice C." }, "id": "Quillen-Alice-C", "display_name": "Quillen, Alice C." } ], "advisors": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/r0q2-h886", "abstract": "This thesis presents a kinematical study of the molecular gas and dust in the\r\nnearby radio galaxy Centaurus A (NGC 5128) and the nearby starburst M82.
\r\n\r\nThe CO (2-1) emission along the inner dust lane of Centaurus A, observed\r\nwith the Caltech Submillimeter Observatory on Mauna Kea, shows the molecular\r\ngas to be in a thin disk, with a velocity dispersion of only about 10 km s^(-1) . The\r\nobserved line profiles are broadened considerably due to beam smearing of the\r\ngas velocity field. The profile shapes are inconsistent with planar circular and\r\nnoncircular motion. However, a warped disk in a prolate potential provides a\r\ngood fit to the profile shapes. The morphology and kinematics of the molecular\r\ngas is similar to that of the ionized material, seen in Ha. The best fitting warped\r\ndisk model not only matches the optical appearance of the dustlane, but also\r\nagrees with the large scale map of the CO emission, and is consistent with HI\r\nmeasurements at larger radii.
\r\n\r\nWe present infrared images of Cen A (NGC5128) in the J,H, and K bands\r\nobserved with the 1.5 m telescope at CTIO. The infrared morphology is primarily\r\ndetermined by the presence of a thin absorptive warped disk. By integrating the\r\nlight of the underlying prolate galaxy through such a disk, we construct models\r\nwhich we compare with infrared and X-ray data. The geometry of the warped disk\r\nneeded to fit the IR data is consistent with a warped disk which has evolved as a\r\nresult of differential precession in a prolate potential. The disk has an inclination,\r\nwith respect to the principal axis of the underlying elliptical galaxy, that is higher\r\nat large radii than in the inner region.
\r\n\r\nA scenario is proposed where a small gas rich galaxy infalling under the force\r\nof dynamical friction is tidally stripped. Stripping occurs at different times during\r\nits infall. The orientation of the resulting gas disk depends upon the angular\r\nmomentum of the infalling galaxy. We find that the resulting precession angle of\r\nthe disk is well described by the precession model, but that the inclination angle\r\nmay vary as a function of radius. We propose an orbit for the infalling galaxy\r\nthat is consistent with the geometry of the warped disk needed to fit our infrared\r\ndata, rotation observed in the outer part of the galaxy and the location of the\r\nstellar shells in the same region.
\r\n\r\nWe model the kinematics of the molecular gas in the nearly edge-on disk\r\nm M82, by considering velocity and surface density perturbations caused by a\r\npossible rotating kpc long bar. A model with a bar that has an Inner Linblad\r\nResonance at r ~ 10\" ~ 150 pc fits the molecular observations of the inner torus.\r\nThis model is consistent with the angle of the bar inferred from the K (2.2\u00b5m)\r\nisophotes. The clouds have a cloud-cloud velocity dispersion of ~ 30 km s^(-1) implying\r\nthat the disk is unstable to short timescale axisymmetric perturbations.\r\nThis is consistent with the hypothesis that the high star formation efficiencies in\r\nstarbursts are due to the the short timescales of gravitational instability. It is\r\nlikely that the bar has mediated the starburst.
\r\n\r\nThere are serious deviations from our model at large radii. It is likely that\r\nthere are two components of molecular material which were not considered by our\r\nmodel: (i) a component at large radii that is in the galactic plane and has low\r\nline-of-sight velocities due to a larger scale bar or due to the fact that there is\r\na lack of molecular gas over a large range of radius (perhaps due to a previous\r\ninteraction which caused a large fraction of the gas to sink into the nucleus),\r\nand (ii) a molecular wind with velocities of the order of the observed line widths\r\n(80 - 120 km s^(-1)). While dense gas can be accelerated in a galactic superwind to\r\nvelocities of this order of magnitude, it is unclear how this gas interacts with the\r\nsuperwind.
\r\n\r\n" }, { "name": "Klinkhammer, Gunnar Ulrich", "degree": "PhD", "year": "1992", "title": "Multiply connected spacetimes and closed timelike curves in semiclassical gravity", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08302011-113709010", "creators": [ { "name": { "family": "Klinkhammer", "given": "Gunnar Ulrich" }, "id": "Klinkhammer-G-U", "display_name": "Klinkhammer, Gunnar Ulrich" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/694e-b162", "abstract": "In this thesis, we present three studies motivated by the recent interest in spacetimes with closed timelike curves (\"CTC's\").\r\n\r\nFirst, it has been shown that certain energy conditions must be violated if spacetime is to develop CTC's. We initiate a study of whether quantum field theory permits such violations by proving that, in Minkowski spacetime, a free scalar field will satisfy the weak and strong energy conditions averaged along any complete null or timelike geodesic. We remark that in fiat, but topologically nontrivial spacetimes, the averaged weak energy condition can be violated.\r\n\r\nSecond, it has been argued that the most likely way by which Nature might prevent the creation of CTC's is a divergent vacuum polarization at the chronology\r\nhorizon where such CTC's first arise. We derive the form of the vacuum polarization of a conformal scalar field and of a spin-1/2 field near a closed null geodesic from which the null generators of a generic compactly generated chronology horizon spring forth. We show that the tensorial structure of the polarization and its degree of divergence are the same for scalar and for spin-1/2 fields and are independent\r\nof the details of the spacetime geometry. We also show that in generic cases, there will be no cancellation of this divergence for a combination of scalar and spin-1/2 fields that has equal numbers of Fermi and Bose degrees of freedom.\r\n\r\nThird, in anticipation of the possibility that Nature might permit CTC's, we demonstrate that for a classical body with a hard-sphere potential and no internal degrees of freedom (a \"billiard ball\") traveling nonrelativistically in a wormhole spacetime with CTC's, the Cauchy problem is ill-posed in a peculiar way. For certain (\"dangerous\") initial data, there would appear to be no self-consistent\r\nsolution to the equations of motion because the ball collides with its younger self after having traversed the wormhole. However, we show that for a wide range of dangerous and non-dangerous initial data, there is an infinity of self-consistent solutions, each involving one self-collision. No initial data are found for which\r\nthere is no self-consistent solution.\r\n" }, { "name": "Sigurdsson, Steinn", "degree": "PhD", "year": "1992", "title": "Dynamics of neutron stars and binaries in globular clusters or, M\u00e9nages \u00e0 trois: revitalizing burnt out degenerates through partner swapping", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechTHESIS:08312011-085802800", "creators": [ { "name": { "family": "Sigurdsson", "given": "Steinn" }, "id": "Sigurdsson-Steinn", "display_name": "Sigurdsson, Steinn" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/gcf0-px44", "abstract": "Interaction cross-sections and collision cross-sections for a set of hard multi-mass binary-single star interactions are calculated in order to estimate three-body collision cross-sections in galactic globular clusters. The cross-sections are calculated by direct integration of binary-single star encounters, using Monte Carlo sampling to average over the three-body phase space. A number of mass-ratios physically relevant to the globular cluster environment are used. Differential energy transfer rates due to three-body interactions are calculated. Parametric\r\napproximations for the various cross-sections calculated are found.\r\n\r\nThe results of the cross-sections are used to evaluate various formation scenarios for the pulsars PSR2127+11C (M15C) and PSR1744-24A (TER5A). In addition the contribution of the globular cluster system to the galactic birthrate of PSR1913+16 type systems is estimated.\r\n\r\nThe dynamics and interactions of a test binary population in a number of globular cluster models are calculated in a static background. The cluster method used are isotropic multi-mass King models of varying concentration and density.\r\nThe model developed is generalisable to an arbitrary cluster distribution function, including one evolving in time. Relative probabilities of different encounters are\r\nfound for binaries on arbitrary trajectories in the various cluster models. The actual interaction rates of the test population are calculated by direct integration, using Monte Carlo sampling to average over the initial binary parameters. The number of neutron stars expected to be recycled in different concentration clusters is estimated with a particular view to understanding the pulsar population observed in clusters 47Tuc and M15.\r\n\r\nEstimates are also made of the binary density profile of the different concentration class clusters, and the final distribution in binary parameters. The production rate of \"blue stragglers\" and the interaction rate of (sub)giants and white dwarfs in the various clusters are also estimated." }, { "name": "Zuo, Lin", "degree": "PhD", "year": "1992", "title": "QSO Absorption Lines and the Ionizing Field at High Redshifts", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechETD:etd-09232008-081252", "creators": [ { "name": { "family": "Zuo", "given": "Lin" }, "id": "Zuo-Lin", "display_name": "Zuo, Lin" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "astronomy" ], "doi": "10.7907/vsk7-nv30", "abstract": "In this thesis we explore the relationship between the QSO absorption line systems and the metagalactic ionizing field at high redshifts.
\r\n\r\nIn the first introductory chapter we describe the recent developments in the field of QSO absorption lines and the ionizing radiation background. We concentrate on compiling the new observational results and address why studies of QSO absorption line systems and ionizing field are important to our understandings of the formation and evolution of the large scale structure of the universe.
\r\n\r\nIn the second chapter Markoff's method has been used to derive a general formalism to deal with the absorptions produced by randomly distributed discrete clouds, such as the QSO absorption line systems. Some analytical forms are obtained for the effective optical depth \u03c4eff, the count reduction factor fc, and the optical depth probability distribution function P(\u03c4). We demonstrate that the spectrum of ionizing background is very different from the intrinsic source spectrum. We calculate the QSO contributions to J\u03bdL(Zobs) by using simple analytical expressions. We show that because of the Lyman continuum absorption produced by QSO absorption line systems, it is very difficult to find a \"clear\" line of sight to conduct the Hell Gunn-Peterson test. We have also found that dust grains in the QSO damped Ly\u03b1 systems produce a marginally significant obscuration for z = 3 quasars: the count reduction factor is 1⁄1.7 at z = 3. The reddening is shown to be small for a flux limited QSO sample.
\r\n\r\nIn the following two chapters we discuss fluctuations and intensity correlation in the ionizing field. We derive the intensity probability distribution function P(J) for randomly distributed point sources. We show that absorptions by QSO absorption line systems reduce the total number of sources involved in producing the ionizing background and therefore enhance the fluctuation significantly, if QSOs are the main ionizing sources. We have calculated the intensity correlation function \u03bej for randomly distributed QSOs. The QSO Ly\u03b1 clouds can be used as intensity indicators to reveal the intensity correlation at high redshifts. We have measured the equivalent width correlation function \u03be1⁄w for several selected QSOs and have found, in some cases, strong correlation signals at small separations. Careful examination shows that such signals are mainly generated by the lines near the QSO emission redshifts. One explanation is that the high S⁄N near QSO emission red-shifts enable us to detect very weak lines which result in the correlation signal. The other explanation is that the correlated intensities of ionizing field near QSOs have caused the observed equivalent width correlation. If this latter explanation is correct, from the affected range by QSOs we conclude that J\u03bdL is less than 10-21 ergs s-1cm-2Hz-1sr-1 at z ~ 3.5.
\r\n\r\nThe last two chapters deal with the ionization structure of the QSO Ly\u03b1 clouds. We solve the coupled ionization balance and radiation transfer problem (the \"inverse HII region\" problem) for the non-uniform spherical absorbing clouds and calculate the HI column density distribution f(N). We show that with an appropriate density gradient in the clouds we can reproduce the observed overall power law distribution and the apparent excess of absorption systems with N \u2265 2 x 1020cm-2. The calculated f(N) is not sensitive to the input ionizing spectra and is a generic feature of the density profile. In our model all QSO absorption lines have the same origin: the ionized outer envelopes produce the Ly\u03b1 forest lines while the neutral cores result in damped Ly\u03b1 systems. We discuss the consequences of such models and propose star-forming dwarf galaxies as primary candidates for QSO absorption line systems. Our calculations also suggest that uniform cloud models are highly unlikely. To calculate the absorptions produced by HeI and HeII in QSO Ly\u03b1 clouds we also solve the ionization structure for the clouds containing both H and He. We explore the variation of HeI and HeII distributions under different input ionizing spectra and discuss how to get a self-consistent spectral shape for the ionizing background.
" }, { "name": "van Putten, Maurice H. P. M.", "degree": "PhD", "year": "1992", "title": "MHD in divergence form : a computational method for astrophysical flow", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechETD:etd-08152007-144037", "creators": [ { "name": { "family": "van Putten", "given": "Maurice H. P. M." }, "id": "van-Putten-M-H-P-M", "orcid": "0000-0002-9212-411X", "display_name": "van Putten, Maurice H. P. M." } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "appliedmath" ], "doi": "10.7907/263j-a556", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThe equations of MHD in curved space-time are presented in divergence form for the purpose of numerical implementation. This result follows from a covariant divergence form of the single fluid theory of electro-magneto-hydrodynamics in curved space-time with general constitutive relations.\r\n\r\nSome one- and two-dimensional shock computations are given. A pseudospectral method with weak smoothing is used in all of our computations. The pseudo-spectral method is constructed by consideration of Riemann problems in one dimension. The power of MHD in divergence form is brought about by using uniform grid-spacing and explicit time-stepping. The problems considered are shock-tube problems in transverse MHD with analytical comparison solution and a coplanar Riemann problem as discussed for nonrelativistic MHD in Brio and Wu [37]. In a limit of nonrelativistic velocities comparison is made of the results of the latter with those in [37]. In two dimensions cylindrically symmetric problems are considered for test of isotropy, independence of coordinate system and convergence (using comparison results in polar coordinates). We conclude with a computation of a shock induced vortex in jet flow with [...] 2.35, a relativistic jet computation with [...] 3.25 and, finally, computations on magnetic pressure dominated stagnation points in a 2D shock problem in nontransverse MHD.\r\n\r\nThis work is proposed for numerical study of astrophysical flows, and in particular as a \"vehicle\" towards the origin of jets." }, { "name": "Coppi, Paolo Severo", "degree": "PhD", "year": "1991", "title": "Radiative processes in active galactic nuclei", "advisor": "Blandford, Roger D.; Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechETD:etd-06202007-132612", "creators": [ { "name": { "family": "Coppi", "given": "Paolo Severo" }, "id": "Coppi-Paolo-Severo", "display_name": "Coppi, Paolo Severo" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "chair", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "member", "display_name": "Phinney, E. Sterl" } ], "option_major": [ "physics" ], "doi": "10.7907/GDMQ-Q829", "abstract": "A study of processes relevant to the electron-positron pair plasmas thought to exist in Active Galactic Nuclei is undertaken. The processes considered include: Compton scattering, pair annihilation, two photon pair production, synchrotron emission, e-e bremsstrahlung, and Coulomb scattering. Approximations used in the past to treat these processes in the context of a kinetic code are examined, and improvements are presented. A two-moment scattering formalism is presented to allow for important energy dispersion effects in scattering. This improved treatment of microphysical processes is implemented in a time-dependent, kinetic code incorporating Klein-Nishina effects on both the pair and photon distributions, relativistic thermal Comptonization, and synchrotron reabsorption.\r\n\r\nThe effects of pair plasma reprocessing on the emergent radiation spectrum are examined. Time-varying and stationary spectra are computed. Good qualitative agreement with previous calculations is found, except when the differences are attributable to the improved treatment of the microphysics. These differences can be substantial, particularly in the \"photon-starved\" regime where the effects of Coulomb scattering by suprathermal pairs off thermal pairs significantly modify the spectra. The spectral response of the pair plasma to variations in the particle injection is found to depend sensitively on the plasma parameters. A transitional spectrum may look very different from the spectra of either the stationary initial or final states. The highest energies (gamma-rays) are found to respond most rapidly to changes and should vary more than the X-rays. Pair plasmas can produce soft X-ray excesses. This happens under conditions independently favored by current pair plasma-Compton reflection models of the hard X-ray spectrum.\r\n" }, { "name": "Miller, Michael Coleman", "degree": "PhD", "year": "1990", "title": "Radiative transfer in very strong magnetic fields", "advisor": "Phinney, E. Sterl", "url": "https://resolver.caltech.edu/CaltechETD:etd-06272007-101041", "creators": [ { "name": { "family": "Miller", "given": "Michael Coleman" }, "id": "Miller-Michael-Coleman", "display_name": "Miller, Michael Coleman" } ], "advisors": [ { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "advisor", "display_name": "Phinney, E. Sterl" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/9t01-q903", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThe study of the cooling of neutron stars has been undertaken by many researchers in the past twenty-five years, but this study has been made difficult by the inherent theoretical and observational uncertainties; most observations of their thermal X-ray flux have yielded only upper limits. More sensitive satellites such as ROSAT and AXAF may provide more positive flux information, and it is important to know how to interpret these data in terms of surface temperature. One of the most important factors in this interpretation is the effect of the surface magnetic field.\r\n\r\nYoung neutron stars are believed to have extremely strong magnetic fields, on the order of 10(12)G. These fields dominate the physics of the atmosphere. In particular, atoms in the atmospheres of neutron stars have much greater binding energies than in the zero-field case, and they are constrained to move along the field lines. We use a multiconfigurational Hartree-Fock code, modified for very strong magnetic fields, to calculate wavefunctions, energies and oscillator strengths for several atoms in representative values of the magnetic field.\r\n\r\nWe then use these simulations to construct model atmospheres for neutron stars. Because of the low mass necessary for optical depth unity in the soft X-rays (typically [...]) and because of the short time scale for gravitational separation (~ 1 - 100s), the photosphere is likely to consist of a pure element. Numerous processes could cause many elements to be important, so we investigate atmospheres consisting of pure hydrogen, helium, carbon, nitrogen and silicon in magnetic fields of 9.4 x 10(11)G, 2.35 x 10(12)G, and 4.7 x 10(12)G.\r\n\r\nWe also use the high-field energies to investigate soft X-ray lines in gamma-ray bursts. Highly ionized elements could create absorption lines in the 1-15keV range, and the identification of such lines in conjunction with cyclotron lines would determine the magnetic field and gravitational redshift on the surface of the star, which would provide clues to the equation of state on the interior. We conclude with a discussion of the prospect of identifying these lines with future satellites." }, { "name": "Zhang, Xiao-He", "degree": "PhD", "year": "1990", "title": "Multipole moments in general relativity and dynamical perturbations of black-hole magnetospheres", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:03172015-154851912", "creators": [ { "name": { "family": "Zhang", "given": "Xiao-He" }, "id": "Zhang-Xiao-He", "display_name": "Zhang, Xiao-He" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/ra46-aj38", "abstract": "This thesis consists of two parts. In Part I, we develop a multipole moment formalism in general relativity and use it to analyze the motion and precession of compact bodies. More specifically, the generic, vacuum, dynamical gravitational field of the exterior universe in the vicinity of a freely moving body is expanded in positive powers of the distance r away from the body's spatial origin (i.e., in the distance r from its timelike-geodesic world line). The expansion coefficients, called \"external multipole moments,'' are defined covariantly in terms of the Riemann curvature tensor and its spatial derivatives evaluated on the body's central world line. In a carefully chosen class of de Donder coordinates, the expansion of the external field involves only integral powers of r ; no logarithmic terms occur. The expansion is used to derive higher-order corrections to previously known laws of motion and precession for black holes and other bodies. The resulting laws of motion and precession are expressed in terms of couplings of the time derivatives of the body's quadrupole and octopole moments to the external moments, i.e., to the external curvature and its gradient.
\r\n\r\nIn part II, we study the interaction of magnetohydrodynamic (MHD) waves in a black-hole magnetosphere with the \"dragging of inertial frames\" effect of the hole's rotation - i.e., with the hole's \"gravitomagnetic field.\" More specifically: we first rewrite the laws of perfect general relativistic magnetohydrodynamics (GRMHD) in 3+1 language in a general spacetime, in terms of quantities (magnetic field, flow velocity, ...) that would be measured by the ''fiducial observers\u201d whose world lines are orthogonal to (arbitrarily chosen) hypersurfaces of constant time. We then specialize to a stationary spacetime and MHD flow with one arbitrary spatial symmetry (e.g., the stationary magnetosphere of a Kerr black hole); and for this spacetime we reduce the GRMHD equations to a set of algebraic equations. The general features of the resulting stationary, symmetric GRMHD magnetospheric solutions are discussed, including the Blandford-Znajek effect in which the gravitomagnetic field interacts with the magnetosphere to produce an outflowing jet. Then in a specific model spacetime with two spatial symmetries, which captures the key features of the Kerr geometry, we derive the GRMHD equations which govern weak, linealized perturbations of a stationary magnetosphere with outflowing jet. These perturbation equations are then Fourier analyzed in time t and in the symmetry coordinate x, and subsequently solved numerically. The numerical solutions describe the interaction of MHD waves with the gravitomagnetic field. It is found that, among other features, when an oscillatory external force is applied to the region of the magnetosphere where plasma (e+e-) is being created, the magnetosphere responds especially strongly at a particular, resonant, driving frequency. The resonant frequency is that for which the perturbations appear to be stationary (time independent) in the common\r\nrest frame of the freshly created plasma and the rotating magnetic field lines. The\r\nmagnetosphere of a rotating black hole, when buffeted by nonaxisymmetric magnetic fields anchored in a surrounding accretion disk, might exhibit an analogous resonance. If so then the hole's outflowing jet might be modulated at resonant frequencies \u03c9=(m/2) \u03a9H where m is an integer and \u03a9H is the hole's angular velocity.
\r\n" }, { "name": "Kochanek, Christopher Sharpe", "degree": "PhD", "year": "1989", "title": "Studies in Gravitational Lensing and Numerical Hydrodynamics", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechETD:etd-05222007-073908", "creators": [ { "name": { "family": "Kochanek", "given": "Christopher Sharpe" }, "id": "Kochanek-Christopher-Sharpe", "display_name": "Kochanek, Christopher Sharpe" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Leonard", "given": "Anthony" }, "id": "Leonard-A", "role": "member", "display_name": "Leonard, Anthony" }, { "name": { "family": "Schmidt", "given": "Maarten" }, "id": "Schmidt-M", "role": "member", "display_name": "Schmidt, Maarten" }, { "name": { "family": "Whaling", "given": "Ward" }, "id": "Whaling-W", "role": "member", "display_name": "Whaling, Ward" } ], "option_major": [ "physics" ], "doi": "10.7907/fpn8-g713", "abstract": "(1) The gravitational lensing cross sections for multiple imaging by elliptical galaxy potentials is examined. Lenses are found to divide into strong and marginal lenses. Three image systems form either allied geometries in which the two brightest images lie on the same side of the lens, or opposed geometries in which the two brightest images lie on opposite sides of the lens. Strong lenses are dominated by the three image opposed geometry at low amplifications and the five image geometry at high amplifications. Marginal lenses are dominated by the three image allied geometry.
\r\n\r\n(2) The cross sections for multiple imaging are integrated over the expected distribution of lenses and sources. The sources are taken to be quasars with a standard number-magnitude relation. Approximately one in one thousand quasars will be multiply imaged. Bright lensed quasars are likely to have five images due to the effects of amplification bias.
\r\n\r\n(3) Approximately one to ten percent of lens systems will involve more than one lensing galaxy either at the same or at a different redshift. The statistical properties of such \"two screen\" gravitational lenses are evaluated.
\r\n\r\n(4) An inversion technique for resolved gravitational lenses is developed and applied to the radio ring image MG1131+0456. The technique works both for intensity and polarization maps. The velocity dispersion, position, ellipticity and position angle of the lens are tightly constrained - typically to within ten percent or two tenths of an arc second.
\r\n\r\n(5) The propagation of a precessing hydrodynamic jet is studied using finite difference techniques in an axisymmetric system. The implications for the precessing jet in SS433 is examined. It is unlikely that the SS433 jet can be hydrodynamic in nature unless the kinetic luminosity is much lower than that required to form the lobes of the W50 remnant.
\r\n\r\n(6) The tidal disruption of a star on a parabolic orbit past a supermassive black hole is examined using smooth particle hydrodynamics. The spectrum of specific energies for the debris is in close agreement with analytic expectations. Processes leading to the formation of an accretion disk are discussed.
" }, { "name": "Yurtsever, Ulvi Hamit", "degree": "PhD", "year": "1989", "title": "Singularities and Horizons in the Collisions of Gravitational Waves", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:10242013-145903390", "creators": [ { "name": { "family": "Yurtsever", "given": "Ulvi Hamit" }, "id": "Yurtsever-Ulvi-Hamit", "display_name": "Yurtsever, Ulvi Hamit" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "orcid": "0000-0002-9656-4032", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Schmidt", "given": "Maarten" }, "id": "Schmidt-M", "role": "member", "display_name": "Schmidt, Maarten" }, { "name": { "family": "Preskill", "given": "John P." }, "id": "Preskill-J", "orcid": "0000-0002-2421-4762", "role": "member", "display_name": "Preskill, John P." } ], "option_major": [ "physics" ], "doi": "10.7907/zm5n-g882", "abstract": "This thesis presents a study of the dynamical, nonlinear interaction of colliding gravitational waves, as described by classical general relativity. It is focused mainly on two fundamental questions: First, what is the general structure of the singularities and Killing-Cauchy horizons produced in the collisions of exactly plane-symmetric gravitational waves? Second, under what conditions will the collisions of almost-plane gravitational waves (waves with large but finite transverse sizes) produce singularities?
\r\n\r\nIn the work on the collisions of exactly-plane waves, it is shown that Killing horizons in any plane-symmetric spacetime are unstable against small plane-symmetric perturbations. It is thus concluded that the Killing-Cauchy horizons produced by the collisions of some exactly plane gravitational waves are nongeneric, and that generic initial data for the colliding plane waves always produce \"pure\" spacetime singularities without such horizons. This conclusion is later proved rigorously (using the full nonlinear theory rather than perturbation theory), in connection with an analysis of the asymptotic singularity structure of a general colliding plane-wave spacetime. This analysis also proves that asymptotically the singularities created by colliding plane waves are of inhomogeneous-Kasner type; the asymptotic Kasner axes and exponents of these singularities in general depend on the spatial coordinate that runs tangentially to the singularity in the non-plane-symmetric direction.
\r\n\r\nIn the work on collisions of almost-plane gravitational waves, first some general properties of single almost-plane gravitational-wave spacetimes are explored. It is shown that, by contrast with an exact plane wave, an almost-plane gravitational wave cannot have a propagation direction that is Killing; i.e., it must diffract and disperse as it propagates. It is also shown that an almost-plane wave cannot be precisely sandwiched between two null wavefronts; i.e., it must leave behind tails in the spacetime region through which it passes. Next, the occurrence of spacetime singularities in the collisions of almost-plane waves is investigated. It is proved that if two colliding, almost-plane gravitational waves are initially exactly plane-symmetric across a central region of sufficiently large but finite transverse dimensions, then their collision produces a spacetime singularity with the same local structure as in the exact-plane-wave collision. Finally, it is shown that a singularity still forms when the central regions are only approximately plane-symmetric initially. Stated more precisely, it is proved that if the colliding almost-plane waves are initially sufficiently close to being exactly plane-symmetric across a bounded central region of sufficiently large transverse dimensions, then their collision necessarily produces spacetime singularities. In this case, nothing is now known about the local and global structures of the singularities.
" }, { "name": "Morris, Michael Scott", "degree": "PhD", "year": "1988", "title": "The R +\u025bR\u00b2 Cosmology", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:02202013-144403198", "creators": [ { "name": { "family": "Morris", "given": "Michael Scott" }, "id": "Morris-Michael-Scott", "display_name": "Morris, Michael Scott" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Preskill", "given": "John P." }, "id": "Preskill-J", "role": "member", "display_name": "Preskill, John P." }, { "name": { "family": "Phillips", "given": "Thomas G." }, "id": "Phillips-T-G", "role": "member", "display_name": "Phillips, Thomas G." } ], "option_major": [ "physics" ], "doi": "10.7907/h44f-9639", "abstract": "This thesis presents the study of a model cosmology based on the R +\u025bR\u00b2 gravitational Lagrangian. It may be roughly divided into two distinct parts. First, the classical inflationary scenario is developed. Then, the formalism of quantum cosmology is employed to determine initial conditions for the classical model.
\r\n\r\nIn the work on the classical model, the evolution equations for an isotropic and homogeneous universe are solved to exhibit both early-time inflation and a smooth transition to subsequent radiation-dominated behavior. Then perturbations on this isotropic background are evolved through the model to provide constraints on the model parameters from the observational limits on anisotropy today. This study concludes that such an inflationary model will prove a viable description for our universe if the initial Hubble parameter Hi is bounded from below, Hi > 10\u207b\u2075 lPl\u207b\u00b9, and if \u025b > 10\u00b9\u00b9 lPl\u00b2.
\r\n\r\nIn the work on the wave function, the two boundary conditions of Vilenkin (\"tunneling from nothing\") and Hartle and Hawking (\"no boundary\") are compared. The wave functions obtained are restricted to the initial edge of classical Lorentzian inflationary trajectories as distributions over initial conditions for the classical inflationary model. It is found that Vilenkin's wave function prefers the universe to undergo a great deal of inflation, whereas Hartle and Hawking's wave function prefers the universe to undergo little inflation. Finally, both boundary conditions are shown to require that inhomogeneous perturbative modes start out in their ground states.
" }, { "name": "Finn, Lee Samuel", "degree": "PhD", "year": "1987", "title": "Relativistic Stellar Pulsations", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-08262008-093129", "creators": [ { "name": { "family": "Finn", "given": "Lee Samuel" }, "id": "Finn-Lee-Samuel", "display_name": "Finn, Lee Samuel" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Zachariasen", "given": "Fredrik" }, "id": "Zachariasen-F", "role": "member", "display_name": "Zachariasen, Fredrik" } ], "option_major": [ "physics" ], "doi": "10.7907/T7VS-8648", "abstract": "This thesis consists of studies on the topic of relativistic stellar pulsations.
\r\n\r\ni) A new formalism for the numerical study of g-modes in neutron stars is developed. This formalism avoids pitfalls associated with previous formalisms when applied to the study of these low-frequency modes. The formalism involves a new choice of perturbation variables, the introduction of an \"instantaneous gravity\" approximation to the field outside the star, and an energy principle for determining gravitational radiation damping times. The formalism is used to study g-modes that arise because of chemical inhomogeneities in neutron star crusts. g-mode frequencies associated with chemical inhomogeneities are found to be much higher than those associated with finite temperature.
\r\n\r\nii) The relativistic Cowling approximation, introduced by McDermott, Van Horn, and Scholl (1983) and analogous to the Newtonian Cowling approximation, is refined to make it more accurate in the regime of highly relativistic stars. The approximation is used to prove a host of useful theorems regarding the non-radial modes of relativistic stars.
\r\n\r\niii) Realistic neutron stars have a solid crust, and this will seriously affect their g-modes. The first steps toward developing a theory of non-radial relativistic pulsations in stars with a solid crust is reported on here: the calculation of the shear strain and stress during a pulsation, the introduction of the shear stress into the Einstein field equations as a source and to the equations of motion as a force, and the development of a Lagrangian and variational principle for studying non-radial relativistic pulsations in stars with a solid crust.
\r\n\r\niv) Solar five-minute oscillations are a weak source of gravitational radiation. The inner part of the solar system is actually in the transition zone of the solar oscillation gravitational field, and future space-based beam detectors might be able to measure the solar \"transition-zone radiation.\" The transition-zone gravitational field is explored for four relativistic gravity theories: a spin-zero theory (Nordst\u00f8m's theory), a spin-one theory (analogous to electromagnetism), a spin-two theory (general relativity), and a mixed spin-zero/spin-one theory (Jordan-Brans-Dicke theory). From the transition-zone gravitational field, it is possible to determine experimentally the spin content of relativistic gravity.
\r\n" }, { "name": "Lind, Kevin Robert", "degree": "PhD", "year": "1987", "title": "Observations and Gas Dynamics of Extragalactic Radio Jets", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechETD:etd-09092008-091639", "creators": [ { "name": { "family": "Lind", "given": "Kevin Robert" }, "id": "Lind-Kevin-Robert", "display_name": "Lind, Kevin Robert" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Cohen", "given": "Donald S." }, "id": "Cohen-D-S", "role": "member", "display_name": "Cohen, Donald S." }, { "name": { "family": "Phinney", "given": "E. Sterl" }, "id": "Phinney-E-S", "role": "member", "display_name": "Phinney, E. Sterl" }, { "name": { "family": "Sturtevant", "given": "Bradford" }, "id": "Sturtevant-B", "role": "member", "display_name": "Sturtevant, Bradford" } ], "option_major": [ "astronomy" ], "doi": "10.7907/wnqa-gn45", "abstract": "This thesis is a combined observational and theoretical study of extragalactic radio jets. Jets are defined observationally as extended, center-brightened features, which are observed in radio images at all resolution scales. They are defined theoretically as momentum-dominated, well-collimated plasma flows. There is now little debate as to the basic interpretation of radio jets as actual plasma outflows, but the detailed dynamics of the jets, or even whether the kiloparsec-scale jets are relativistic, are still uncertain. The resolution of the details of the physics of jets requires improved radio images, especially at the base of the jet, and detailed models of jets. Maps of the base of the radio jet can only be obtained with VLBI observations; detailed jet models require numerical simulations on a supercomputer.
\r\n\r\nThe observational work was a large global VLBI observation of the N galaxy 3C371. The goal was to detect and, if possible, map the underlying jet. This was done, and the results compared with a previous VLBI map, and with maps from other interferometers at lower resolution. No conclusions could be drawn regarding the nature of the jet, although it was clear that the jet was active, and appeared to vary on short time scales.
\r\n\r\nThe theoretical work was in two parts, both of which were directed toward refining existing theories. The first part was to calculate the emission for relativistically moving patterns which themselves contain relativistic flows, to determine how much the flux as a function of viewing angle may vary between realistic models of the knots in relativistic jets. It was found that considerable variation was possible, and that superluminal expansion rates were not necessarily good determiners of the bulk flow rate. The second part was to develop a code to simulate axisymmetric magnetized jets propagating into a uniform medium. This was implemented for the case of toroidal field only, and run for a moderately magnetized injected jet. It was found that, although most of the jet dynamics was determined by the nonmagnetic forces, the influence of the magnetic tension focused the flow sufficiently to significantly increase the speed of advance of the jet.
\r\n" }, { "name": "Romani, Roger William", "degree": "PhD", "year": "1987", "title": "Neutron Stars Observations as Astrophysical Probes", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09222017-142706466", "creators": [ { "name": { "family": "Romani", "given": "Roger William" }, "id": "Romani-Roger-William", "orcid": "0000-0001-6711-3286", "display_name": "Romani, Roger William" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Tombrello", "given": "Thomas A." }, "id": "Tombrello-T-A", "role": "member", "display_name": "Tombrello, Thomas A." }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." } ], "option_major": [ "physics" ], "doi": "10.7907/txfg-q107", "abstract": "Several aspects of observations of neutron stars and compact extragalactic radio sources are considered, with particular regard to their use in constraining certain astrophysical phenomena.
\r\n\r\nA theoretical treatment of the pulse arrival time analysis of millisecond pulsars is made; we consider how a detailed timing analysis can be used to quantitatively probe noise processes affecting the pulsar period and the propagation of the radiation. The intrinsic noise may be used to study the neutron star interior, while propagation effects due to gravitational perturbations of the neutron star and interstellar refraction of the emitted radio waves provide probes of the pulsar environment and the intervening plasma. In addition, important constraints on the background of cosmological gravitational radiation can be derived from timing such pulsars.
\r\n\r\nWe consider the thermal X-rays emitted from a warm (105K \u2272 Teff \u2272 3 x 106 K) neutron star, either cooling from its initial formation or heated by internal dissipation, accretion, etc. Constructing model atmospheres appropriate to such stars with various effective temperatures and elemental abundances, we calculate their emergent spectra and the bolometric correction for observation bands of various X-ray satellites. We conclude that the present limits on neutron star surface flux are even more constraining than those derived assuming that the spectra are blackbody and examine how this effects models of neutron star interiors, formation and cooling. We also examine the consequences of similar X-ray observations for neutron star models of various gamma-ray stars.
\r\n\r\nThe refraction of radio waves from pulsars and other compact sources by interstellar plasma is also studied. We show how pulsar observations, in particular, can be used to characterise the large scale inhomogeneities in the ionized ISM and compute a number of observable effects for various electron density perturbation spectra. It is shown how similar refraction can account for the low and intermediate frequency variation of compact extragalactic radio sources. We argue that the observations indicate that more power is present in the large scale fluctuations than previously believed. In addition, single ~1014 cm scale clouds in a previously unrecognized dense, ionised phase of the ISM can apparently dominate the refractive scintillation for some lines of sight.
" }, { "name": "Hernquist, Lars Eric", "degree": "PhD", "year": "1985", "title": "Thermal and Magnetic Properties of Neutron Stars", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechETD:etd-09112008-091427", "creators": [ { "name": { "family": "Hernquist", "given": "Lars Eric" }, "id": "Hernquist-Lars-Eric", "orcid": "0000-0001-6950-1629", "display_name": "Hernquist, Lars Eric" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Tombrello", "given": "Thomas A." }, "id": "Tombrello-T-A", "role": "member", "display_name": "Tombrello, Thomas A." }, { "name": { "family": "Stevenson", "given": "David John" }, "id": "Stevenson-D-J", "orcid": "0000-0001-9432-7159", "role": "member", "display_name": "Stevenson, David John" } ], "option_major": [ "physics" ], "doi": "10.7907/ajp7-kr29", "abstract": "The interaction of the magnetic field with the heat flux in neutron stars is investigated.
\r\n\r\nIt is proposed that the magnetic field develops as a result of thermal processes in the liquid and solid phases of neutron star envelopes. Necessary conditions for the growth to occur are derived and it is shown that surface fields comparable to those observed would result. The magnetization of neutron stars in binary systems (which have magnetic properties differing substantially from those of isolated pulsars) can be explained by thermal processes associated with accretion flows.
\r\n\r\nIn order to study magnetic effects on neutron star cooling a number of subsidiary issues are considered.
\r\n\r\nThe thermal structure of unmagnetized neutron star envelopes is examined using approximate analytical models. From the results it is possible to justify a number of simplifying assumptions and extend them to the magnetized case. For example, it is shown that an accurate treatment of photon transport is not required in order to determine the relation between the heat flux and the core temperature of neutron stars.
\r\n\r\nThe effect of the field on the magnetic properties of the electron gas in neutron star crusts is considered. It is shown that the gas is unstable to the formation of domains of alternating magnetization. It is further argued that the domain structure will have a negligible influence on the heat flux because of the small free energy associated with the domains.
\r\n\r\nThe influence of the field on the electron transport properties of neutron star envelopes is examined in detail. Accurate expressions are derived for all components of the relevant transport tensors, taking into account quantum mechanical and relativistic effects. In addition, allowance is made for arbitrary degree of degeneracy and scattering mechanism.
\r\n\r\nFinally, these results are used to study the thermal structure of magnetized neutron star envelopes. It is shown that the enhancement in the heat flux due to quantum effects is almost completely canceled by the suppression of the heat flux due to geometrical effects. Thus the magnetic field is expected to play only a minor role in neutron star cooling, contrary to earlier claims.
\r\n" }, { "name": "Schumaker, Bonny Laura", "degree": "PhD", "year": "1985", "title": "Theoretical Investigations in Nonlinear Quantum Optics, Theory of Measurement, and Pulsations of General Relativistic Models of Neutron Stars", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09062017-132307035", "creators": [ { "name": { "family": "Schumaker", "given": "Bonny Laura" }, "id": "Schumaker-Bonny-Laura", "display_name": "Schumaker, Bonny Laura" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Phillips", "given": "Thomas G." }, "id": "Phillips-T-G", "role": "chair", "display_name": "Phillips, Thomas G." }, { "name": { "family": "Whitcomb", "given": "Stanley E." }, "id": "Whitcomb-S-E", "role": "member", "display_name": "Whitcomb, Stanley E." }, { "name": { "family": "Caves", "given": "Carlton M." }, "id": "Caves-C-M", "orcid": "0000-0001-8876-1186", "role": "member", "display_name": "Caves, Carlton M." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "member", "display_name": "Thorne, Kip S." } ], "option_major": [ "physics" ], "doi": "10.7907/fwvz-7t26", "abstract": "This thesis is a collection of six papers. The first four constitute the heart of the thesis; they are concerned with quantum mechanical properties of certain harmonic-oscillator states. The first paper is a discourse on single-mode and two-mode Gaussian pure states (GPS), states produced when harmonic oscillators in their ground states are exposed to potentials that are linear or quadratic in oscillator position and moment um variables (creation and annihilation operators). The second and third papers develop a formalism for analyzing two-photon devices (e.g., parametric amplifiers and phase-conjugate mirrors), in which photons in the ouput modes arise from two-photon transitions, i.e., are created or destroyed two at a time. The states produced by such devices are single-mode and two-mode \"squeezed states\", special kinds of GPS whose low-noise properties make them attractive for applications in such fields as optical communications and gravitational wave detection. The fourth paper is an analysis of the noise in homodyne detection, a phase-sensitive detection scheme in which the special properties of (single-mode) squeezed states are revealed as an improved signal-to-noise ratio relative to that obtained with coherent states (the states produced, e.g., by a laser).
\r\n\r\nThe fifth and sixth papers deal with problems of a different nature from that of the previous papers. The fifth paper considers the validity of the \"standard quantum limit\" (SQL) for measurements which monitor the posi\u00adtion of a free mass. It shows specifically that when the pre-measurement wave functions of the free mass and the measuring apparatus(es) are Gaus\u00adsian (in the general sense, which includes so-called \"contractive states\"), measurements described by linear couplings to the position or to both the position and momentum are limited by the SQL. The sixth paper develops the mathematical theory of torsional (toroidal) oscillations in fully general relativistic, nonrotating, spherical stellar models, and of the gravitational waves they emit.
" }, { "name": "Suen, Wai Mo", "degree": "PhD", "year": "1985", "title": "Dynamical Electromagnetic Fields Near Black Holes and Multipole Moments of Stationary, General Relativistic Systems", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09012017-090944275", "creators": [ { "name": { "family": "Suen", "given": "Wai Mo" }, "id": "Suen-Wai-Mo", "display_name": "Suen, Wai Mo" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Schwarz", "given": "John H." }, "id": "Schwarz-J-H", "orcid": "0000-0001-9861-7559", "role": "member", "display_name": "Schwarz, John H." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Cowan", "given": "Eugene W." }, "id": "Cowan-E-W", "role": "member", "display_name": "Cowan, Eugene W." } ], "option_major": [ "physics" ], "doi": "10.7907/xayq-7806", "abstract": "This dissertation contains two works; one of the behavior of dynamical electromagnetic fields in the stationary spacetime generated by a black hole, and the other on the structure of a general stationary vacuum spacetime itself.
\r\n\r\nThe study of electromagnetic field is carried out in terms of the \"membrane formalism\" for black holes; and it is part of a series of papers with the aim of developing that formalism into a complete, self-consistent description of electromagnetic and gravitational fields in a black hole background. Various model problems are presented as aids in understanding the interactions of electromagnetic fields with a black hole, and special attention is paid to the concept of the \"stretched horizon\" which is vital for the membrane formalism.
\r\n\r\nThe second work develops a multipole moment formalism for a general stationary system in general relativity. The multipole moments are defined in terms of a general formal series solution of the stationary Einstein equation, in analogy to multipole moments in the Newtonian theory of gravity. These relativistic moments exhibit many desirable properties and are shown to be useful in studying the interactions between a gravitating body and an external gravitational field. A model calculation applying the formalism to a black hole interacting with an external multipole field shows that the interaction can be understood in terms of \"elastic moduli\" of the black-hole horizon.
" }, { "name": "Macdonald, Douglas Alan", "degree": "PhD", "year": "1984", "title": "Black-Hole Electrodynamics", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09012017-133647841", "creators": [ { "name": { "family": "Macdonald", "given": "Douglas Alan" }, "id": "Macdonald-Douglas-Alan", "display_name": "Macdonald, Douglas Alan" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Cowan", "given": "Eugene W." }, "id": "Cowan-E-W", "role": "member", "display_name": "Cowan, Eugene W." }, { "name": { "family": "Wise", "given": "Mark B." }, "id": "Wise-M-B", "orcid": "0000-0002-9125-801X", "role": "member", "display_name": "Wise, Mark B." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "member", "display_name": "Thorne, Kip S." } ], "option_major": [ "physics" ], "doi": "10.7907/vv78-at49", "abstract": "This dissertation considers several aspects of the structure and dynamics of electromagnetic fields around black holes. The four-dimensional, covariant laws of electrodynamics are reformulated in a 3 + 1 (space+time) language in which the key quantities are three-dimensional vectors lying in hypersurfaces of a constant global time t. This formulation is applied to the Blandford-Znajek model of power generation in quasars, which consists of a supermassive black hole surrounded by an accretion disk that holds a magnetic field on the hole, with the rotational energy and angular momentum of the hole and disk being extracted by electromagnetic torques. The 3 + 1 formalism allows the theory of stationary, axisymmetric black holes and their magnetospheres to be couched in an \"absolute-space/universal-time\" language very similar to the flat\u00ad spacetime theory of pulsar electrodynamics; and this similarity allows fiat-space pulsar concepts to be extended to curved-space black holes. The Blandford\u00ad-Znajek quasar model is reformulated in terms of a DC circuit-theory analysis, and action principles describing the overall structure of the magnetosphere and the field distribution on the horizon are developed. A general prescription for constructing global models of force-free magnetospheres is developed and this prescription is used to generate numerical models of black-hole magneto\u00adspheres for a variety of field configurations and black-hole angular velocities. The electromagnetic boundary conditions at the horizon of a black hole are described in terms of a recently developed \"membrane viewpoint\". The necess\u00adity and efficacy of using a \"stretched horizon\" in the membrane viewpoint is discussed, and is illustrated by two simple dynamical problems involving electromagnetic fields near black-hole horizons.
" }, { "name": "Redmount, Ian H.", "degree": "PhD", "year": "1984", "title": "Topics in Black-Hole Physics: Geometric Constraints on Noncollapsing, Gravitating Systems and Tidal Distortions of a Schwarzschild Black Hole", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08232017-105535039", "creators": [ { "name": { "family": "Redmount", "given": "Ian H." }, "id": "Redmount-Ian-H", "orcid": "0000-0002-7063-336X", "display_name": "Redmount, Ian H." } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Frautschi", "given": "Steven C." }, "id": "Frautschi-S-C", "role": "chair", "display_name": "Frautschi, Steven C." }, { "name": { "family": "Price", "given": "Richard H." }, "id": "Price-Richard-H", "role": "member", "display_name": "Price, Richard H." }, { "name": { "family": "Phillips", "given": "Thomas G." }, "id": "Phillips-T-G", "role": "member", "display_name": "Phillips, Thomas G." }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "member", "display_name": "Thorne, Kip S." } ], "option_major": [ "physics" ], "doi": "10.7907/mp3n-4r06", "abstract": "This dissertation consists of two studies on the general-relativistic theory of black holes. The first work concerns the fundamental issue of black-hole forma\u00adtion: in it I seek geometric constraints on gravitating matter systems, in the special case of axial symmetry, which determine whether or not those systems undergo gravitational collapse to form black holes. The second project deals with mechanical behavior of a black hole: specifically, I study the tidal deforma\u00adtion of a static black hole by the gravitational fields of external bodies.
\r\n\r\nIn the first paper I approach the problem of geometric constraints deter\u00admining gravitational collapse or non-collapse through the initial-value formalism of general relativity. I construct initial-value data representing noncollapsing, nonsingular, axisymmetric matter systems and examine the constraints imposed on this construction by the initial-value equation derived from the Ein\u00adstein field equations. The construction consists of a nonsingular, momentarily static interior geometry with nonnegative mass-energy density, matched smoothly to a static, vacuum exterior geometry (described by a Weyl solution of the Einstein field equations) at a boundary surface. The initial-value equation is found to impose restrictions on the choice of the boundary surface for such a system. Two such constraints are obtained here, appropriate to spherical and toroidal interior-region topologies. These constraints are studied by applying them to simple examples of Weyl exterior geometries. The \"hoop conjecture\" for the general geometric-constraints problem states that a system must collapse to a black hole unless its circumference in some direction exceeds a lower bound of the order of the system's mass. The examples examined here show, however, that the constraints derived in this study are not generally correlated with any simple measure of system size, and thus that they do not embody the hoop conjecture.
\r\n\r\nThe second paper examines the tidal distortion of a Schwarzschild black hole by bodies (\"moons\") suspended above the horizon on \"ropes.\" A solution of the Einstein field equations is constructed describing this configuration, using the Weyl formalism for axisymmetric, static, vacuum geometries. The intrinsic geometry of the tidally deformed black-hole horizon is obtained from this solu\u00adtion; I construct embedding diagrams to represent the shape of the horizon and the tidal bulges raised on it for both weak and strong perturbations. The rela\u00adtions among the masses of the hole and moons, the binding energy of the sys\u00adtem, and the rope density and tension are calculated from the solution and shown to be mutually consistent. Also, the Riemann curvature tensor represent\u00ading the tidal fields near the horizon is calculated. This solution is found to agree with a previous calculation by Hartle of black-hole tides, in the limit of perturb\u00ading moons far from the horizon. In the opposite case of moons very near the horizon, this solution approaches the static limit of the distorted horizon in Rindler space calculated by Suen and Price. The results of this study thus sup\u00adport the use of the Rindler approximation to Schwarzschild spacetime in calcu\u00adlating static black-hole tides, and its extension to dynamical situations.
" }, { "name": "G\u00fcrsel, Halis Yekta", "degree": "PhD", "year": "1983", "title": "Stability of Spherically Symmetric, Charged Black Holes and Multipole Moments for Stationary Systems", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-03132009-081222", "creators": [ { "name": { "family": "G\u00fcrsel", "given": "Halis Yekta" }, "id": "G\u00fcrsel-Halis-Yekta", "display_name": "G\u00fcrsel, Halis Yekta" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Frautschi", "given": "Steven C." }, "id": "Frautschi-S-C", "role": "member", "display_name": "Frautschi, Steven C." }, { "name": { "family": "Whitcomb", "given": "Stanley E." }, "id": "Whitcomb-S-E", "role": "member", "display_name": "Whitcomb, Stanley E." }, { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "member", "display_name": "Goldreich, Peter Martin" } ], "option_major": [ "physics" ], "doi": "10.7907/e9t6-dr05", "abstract": "This dissertation is written in two parts. Part I deals with the question of stability of a spherically symmetric, charged black hole against scalar, electromagnetic, and gravitational perturbations. It consists of two papers written in collaboration with Igor D. NoVikov, Vernon D. Sandberg and A. A. Starobinsky. In these papers we describe the dynamical evolution of these perturbations on the interior of a Reissner-Nordstrom black hole. The instability of the hole's Cauchy horizon is discussed in detail in terms of the energy densities of the test fields as measured by a freely falling observer approaching the Cauchy horizon. We conclude that the Cauchy horizon of the analytically extended Reissner-Nordstrom solution is highly unstable and not a physical feature of a realistic gravitational collapse. Part II of this dissertation addresses two problems closely connected with muitipole structure of stationary, asymptotically flat spacetimes. It consists of two papers written in collaboration with Kip S. Thorne despite the fact that his name does not appear on one of them. The first one (Paper III in this thesis) shows the equivalence of the moments defined by Kip S. Thorne and the moments defined by Robert Geroch and Richard Hansen. The second (Paper IV in this thesis) proves a conjecture by Kip S. Thorne: In the limit of \"slow\" motion, general relativistic gravity produces no changes whatsoever in the classical Euler equations of rigid body motion. We prove this conjecture by giving an algorithm for generating rigidly rotating solutions of Einstein's equations from nonrotating, static solutions.
\r\n" }, { "name": "Nugent, John Joseph, Jr.", "degree": "PhD", "year": "1983", "title": "Non-Equilibrium X-Ray Emission from Young Supernova Remnants", "advisor": "Garmire, Gordon Paul", "url": "https://resolver.caltech.edu/CaltechTHESIS:09252017-104936539", "creators": [ { "name": { "family": "Nugent", "given": "John Joseph, Jr." }, "id": "Nugent-John-Joseph-Jr", "display_name": "Nugent, John Joseph, Jr." } ], "advisors": [ { "name": { "family": "Garmire", "given": "Gordon Paul" }, "id": "Garmire-G-P", "role": "advisor", "display_name": "Garmire, Gordon Paul" } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Stone", "given": "Edward C." }, "id": "Stone-E-C", "orcid": "0000-0002-2010-5462", "role": "member", "display_name": "Stone, Edward C." }, { "name": { "family": "Whaling", "given": "Ward" }, "id": "Whaling-W", "role": "member", "display_name": "Whaling, Ward" }, { "name": { "family": "Garmire", "given": "Gordon Paul" }, "id": "Garmire-G-P", "role": "member", "display_name": "Garmire, Gordon Paul" } ], "option_major": [ "physics" ], "doi": "10.7907/mees-s868", "abstract": "A computer model (NIE model) has been developed to predict the the x-ray spectra from the hot (106-8 K), shock-heated plasmas that are found in the rem\u00adnants of supernovae. The model accounts for the lack of collisional ionization equilibrium and for the possible lack of thermal equilibrium between the elec\u00adtrons and ions behind the shock fronts. Both of these effects are potentially important in determining the emergent x-ray spectrum of young (\u2272 104 years old) supernova remnants (SNR). Both a spectral component arising from the supernova ejecta and a component arising from the shocked interstellar medium (ISM) surrounding the supernova are calculated.
\r\n\r\nThe NIE model has been fit to the spectral data from two young SNR's, MSH 14-63 and RCW 103. The data from MSH 14-63 were collected with the HEAO A-2 experiment and spans an energy range from 0.18 - 15 keV. Spectral resolu\u00adtion varies over this range. For example, \u0394E/E = 32% FWHM at 1.5 keV, and \u0394E/E = 15% FWHM at 7 keV. Important results from applying the model are: a significant non-Coulomb, ion-electron interaction is occurring in the remnant, presumably at the shock front; the data can be fit by a model with little or no emission from any source other than the shocked ISM with an age which is con\u00adsistent with that of MSH 14-63; anomalous abundances of heavy elements and possible discrepancies in the centroid and shape of the Fe K\u03b1 feature could be explained by inhomogenities in the ISM density or by ejecta that have come to thermal equilibrium with the shocked ISM; and under the assumptions of the model, the distance to the MSH 14-63 is inconsistent with distance measured to an OB star group that is suggested to be associated with the remnant.
\r\n\r\nThe data for RCW 103 were obtained using the Solid State Spectrometer (SSS) on board the HEAO-2 spacecraft. This data set had a more limited spectral range than above (0.8 - 2.5 keV) but enhanced spectral resolution (\u0394E/E \u2248 10%). In addition, the data had limited spatial resolution. The principal results from this work are: no variation can be detected in the spectrum collected from different regions of the remnant; the data cannot be used to determine whether non-Coulomb electron-ion energy exchange processes may be present behind the shock front; and assuming that non-Coulomb processes are present - a likely hypothesis given results from other young SNR's, the data are consistent with the idea that the emission is all from the shocked interstellar medium with approximately solar composition of heavy elements.
\r\n" }, { "name": "Flammang, Richard Alan", "degree": "PhD", "year": "1982", "title": "Stationary Spherical Optically Thick Accretion into Black Holes", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08252017-133002176", "creators": [ { "name": { "family": "Flammang", "given": "Richard Alan" }, "id": "Flammang-Richard-Alan", "display_name": "Flammang, Richard Alan" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "orcid": "0000-0002-9475-4318", "role": "chair", "display_name": "Thorne, Kip S." }, { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "member", "display_name": "Blandford, Roger D." }, { "name": { "family": "Whitcomb", "given": "Stanley E." }, "id": "Whitcomb-S-E", "role": "member", "display_name": "Whitcomb, Stanley E." }, { "name": { "family": "Simon", "given": "Barry M." }, "id": "Simon-B", "orcid": "0000-0003-2561-8539", "role": "member", "display_name": "Simon, Barry M." } ], "option_major": [ "physics" ], "doi": "10.7907/t73p-2e81", "abstract": "As its title indicates, this thesis treats the problem of stationary, spherical, optically thick accretion into black holes. By the phrase \"optically thick\" it is meant that (1) radiative energy transport can be adequately described by the diffusion approximation and (2) the photons are everywhere in local energy equilibrium (LTE) with the accreting gas particles.
\r\n\r\nIn Chapter 1, a general set of equations governing time-independent spherical accretion into black holes is formulated. The equations are fully general relativistic and are applicable to optically thick regions, optically thin regions, and the transition regions which join them. The radiation is treated using frequency-integrated moments. The full, infinite series of moment equations is given, together with the limiting forms the equations take in the optically thick regime.
\r\n\r\nIn Chapter 2, we present the mathematical theory of stationary spherical optically thick accretion. We analyze the integral curves of the differential equations describing the problem. We find a one-parameter family of critical points, where the inflow velocity equals the isothermal sound speed. Physical solutions must pass through one of these critical points. We obtain a complete set of boundary conditions which the solution must satisfy at the horizon of the black hole, and show that these, plus the requirement that the solution pass through a critical point, determine a unique solution to the problem. This analysis leads to a generalization of the well-known Bondi critical point constraint, which arises in the adiabatic accretion problem and which is effective at the point where the inflow velocity equals the adiabatic sound speed. We show that this point can be regarded as a \"diffused critical point\" in our problem. The analysis also yields a simple expression for the diffusive luminosity at radial infinity. Finally, we find a satisfying explanation for the rather peculiar critical point structure of this problem in an analysis of the characteristics and subcharacteristics present in the problem and in a \"hierarchical\" analysis of the waves which propagate along them.
\r\n\r\nIn Chapter 3, we apply the theory of optically thick accretion developed in Chapter 2 to a wide range of physically different accretion regimes. Numerical solutions are presented and their physical properties are discussed. For solutions in which radiation pressure PR dominates gas pressure PG, but in which gas energy density (including its rest-mass) \u03c1G dominates radiation energy density \u03c1R, we pay particular attention to the adabaticity of the flow. Our quantitative results in this regime agree very well with Begelman's (1978) theory. We find the dimensionless number which governs the importance of heat diffusion in our problem and show that it reduces to the idea of \"trapping of photons\" and to the P\u00e9clet number in the appropriate limits. We find that solutions with PR > PG and \u03c1R > \u03c1G are always essentially adiabatic, owing in part to a relativistic suppression of heat flux which becomes important in this regime. The diffusive luminosity at infinity for these solutions is the Eddington limit of the black hole; with the adiabatic accretion rate, \"efficiencies\" of up to order unity are possible. We give preliminary consideration to the question of the stability of our solutions against convection and conclude that the Schwarzschild criterion is applicable, even for our non-static accretion flows. We show that solutions with PR > PG are everywhere stable against convection. On the other hand, solutions which start out at radial infinity with PG > PR are unstable to convection (if the adiabatic index of the gas \u03b3G exceeds 17/12) from radial infinity down to the point where PR ~ PG and the radiation-gas mixture has attained an adiabatic index of 17/12. The diffusive luminosity at infinity for these solutions is reduced from the Eddington limit of the black hole by the factor (\u03b3G - 1)4PR\u221e/\u03b3GPG\u221e; it is further reduced by the ratio of the electron scattering opacity to the actual opacity at infinity, if this differs from unity. In most cases, energy diffusion has a negligible effect on the accretion rate of these solutions.
" }, { "name": "Linfield, Roger Paul", "degree": "PhD", "year": "1981", "title": "Studies of Compact Extragalactic Radio Sources", "advisor": "Readhead, Anthony C. S.; Hall, Marshall", "url": "https://resolver.caltech.edu/CaltechETD:etd-09022008-153247", "creators": [ { "name": { "family": "Linfield", "given": "Roger Paul" }, "id": "Linfield-Roger-Paul", "display_name": "Linfield, Roger Paul" } ], "advisors": [ { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "advisor", "display_name": "Readhead, Anthony C. S." }, { "name": { "family": "Hall", "given": "Marshall" }, "id": "Hall-M", "role": "advisor", "display_name": "Hall, Marshall" } ], "committee": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "chair", "display_name": "Blandford, Roger D." }, { "name": { "family": "Kellerman", "given": "Kenneth I." }, "id": "Kellerman-Kenneth-I", "role": "member", "display_name": "Kellerman, Kenneth I." }, { "name": { "family": "Young", "given": "Peter J." }, "id": "Young-Peter-J", "role": "member", "display_name": "Young, Peter J." }, { "name": { "family": "Readhead", "given": "Anthony C. S." }, "id": "Readhead-A-C-S", "orcid": "0000-0001-9152-961X", "role": "member", "display_name": "Readhead, Anthony C. S." } ], "option_major": [ "astronomy" ], "doi": "10.7907/5cg5-0d24", "abstract": "Three studies of compact, extragalactic radio sources are presented.
\r\n\r\nIn the first, VLBI maps are presented of the nuclear cores of four radio galaxies which have large symmetric radio lobes: 3C 111, 3C 390.3, Cyg A, and 0055+30. Each source contains a nuclear jet having a scale of 1 pc, but no counterjets are seen. The jets in 3C 111 and 0055+30 point directly at the outer radio lobes, but in 3C 390.3 and Cyg A the jets are pointed from 4 to 6 degrees away from the lobes.
\r\n\r\nThe implications of the maps and models of these sources are considered in the second study. It is concluded that in all four cases, the observed asymmetry reflects an intrinsic asymmetry on a msec scale. The minimum pressure in the four jets is calculated, and it is concluded that the jet in Cyg A is very unlikely to be confined by gas pressure.
\r\n\r\nIn the third study, an attempt is made to explain the structure of compact radio sources with a precession-like motion or a relativistic jet. It is found that the curvature of these sources can be readily explained in this way. In addition, the knots which are often revealed by VLBI observations arise naturally in such a model. The main problem with the model is that it cannot by itself explain the arcsecond structure of asymmetric radio sources.
" }, { "name": "Wisdom, Jack Leach", "degree": "PhD", "year": "1981", "title": "1. The Origin of the Kirkwood Gaps: A Mapping for Asteroidal Monitor Near the 3/1 Commensurability. 2. The Resonance Overlap Criterion and the Onset of Stochastic Behavior in the Restricted Three-Body Problem", "advisor": "Goldreich, Peter Martin", "url": "https://resolver.caltech.edu/CaltechTHESIS:08282017-145742321", "creators": [ { "name": { "family": "Wisdom", "given": "Jack Leach" }, "id": "Wisdom-Jack-Leach", "display_name": "Wisdom, Jack Leach" } ], "advisors": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" } ], "committee": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "chair", "display_name": "Goldreich, Peter Martin" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Cohen", "given": "Donald S." }, "id": "Cohen-D-S", "role": "member", "display_name": "Cohen, Donald S." }, { "name": { "family": "Zachariasen", "given": "Fredrik" }, "id": "Zachariasen-F", "role": "member", "display_name": "Zachariasen, Fredrik" } ], "option_major": [ "physics" ], "doi": "10.7907/s1r9-ff38", "abstract": "Paper 1:
\r\n\r\nA mapping of the phase space onto itself with the same low order resonance structure as the 3/1 commensurability in the planar elliptic three-body prob\u00adlem is derived. This mapping is approximately one thousand (1000) times faster than the usual method of numerically integrating the averaged equations of motion (as used by Schubart, Froeschl\u00e9 and Scholl in their studies of the asteroid belt). This mapping exhibits some very surprising behavior that might provide the key to the origin of the gaps. A test asteroid placed in the gap may evolve for a million years with low eccentricity (< 0.05) and then suddenly jump to large eccentricity (> 0.3) becoming a Mars crosser. The asteroid can then be removed by a close encounter with Mars. To test this hypothesis a dis\u00adtribution of 300 test asteroids in the neighborhood of the 3/1 commensurability was evolved for two million years. When the Mars crossers are removed the dis\u00adtribution of initial conditions displays a gap at the location of the 3/1 Kirkwood gap. While this is the first real demonstration of the formation of a gap, the gap is too narrow. The planar elliptic mapping is then extended to include the incli\u00adnations and the secular perturbations of Jupiter's orbit. The two million year evolution of the 300 test asteroids is repeated using the full mapping. The resulting gap is somewhat larger yet still too small. Finally the possibility that over longer times more asteroids will become Mars crossers is tested by studying the evolution of one test asteroid near the border of the gap for a much longer time. A jump in its eccentricity occurs after 18 million years indicating that indeed it may simply be a matter of time for the full width of the gap to open.
\r\n\r\nPaper 2:
\r\n\r\nThe resonance overlap criterion for the onset of stochastic behavior is applied to the planar circular-restricted three-body problem with small mass ratio (\u00b5). Its predictions for \u00b5 = 10-3, \u00b5 = 10-4 and \u00b5 = 10-5 are compared to the transitions in the numerically determined Kolmogorov-Sinai entropy and found to be in remarkably good agreement. In addition, an approximate scaling law for the onset of stochastic behavior is derived.
" }, { "name": "K\u00f6nigl, Arieh", "degree": "PhD", "year": "1980", "title": "Relativistic Effects in Extragalactic Radio Sources", "advisor": "Blandford, Roger D.", "url": "https://resolver.caltech.edu/CaltechTHESIS:09252017-141651169", "creators": [ { "name": { "family": "K\u00f6nigl", "given": "Arieh" }, "id": "K\u00f6nigl-Arieh", "orcid": "0000-0002-6827-1005", "display_name": "K\u00f6nigl, Arieh" } ], "advisors": [ { "name": { "family": "Blandford", "given": "Roger D." }, "id": "Blandford-R-D", "role": "advisor", "display_name": "Blandford, Roger D." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/ze0j-3v45", "abstract": "This thesis deals with the interpretation of compact extragalactic radio sources in the context of the twin-beam model with a particular emphasis on the role of special-relativistic kinematical and dynamical effects. Various such effects are investigated, both in a general manner and in application to specific observed phenomena. Among the observed phenomena which are interpreted in this way are:
\r\n\r\ni) Apparent superluminal flux variations, i.e., variations which occur on timescales short compared with the light travel time across the apparent source.\tIt is shown that this and other spectral effects could be attributed to relativistic expansion of the source, and that objections raised against the relativistic interpretation (Terrell 1977) are model-dependent and do not apply in general.
\r\n\r\nii)\tApparent superluminal separation of source components. It\r\nis shown that in a relativistic jet model where the radio emission originates both from the quasi-steady jet itself and from behind shock waves which travel with relativistic speeds in the jet,\r\nthe source could display apparent superluminal expansion in which the moving component (associated with a shock) and the stationary component (associated with the optically-thick core of the jet) would have comparable, Doppler-boosted fluxes.\tThe shocks could either propagate in the jet or arise behind dense clouds which\r\nare accelerated by the supersonic flow.\tThe origin as well as the kinematical and radiative properties of the clouds are discussed, and it is proposed that the bright knots observed in certain jets, such as the jet in M87, could in fact correspond to dense accelerated clouds.
\r\n\r\niii)\tRapid swings in the observed polarization position angle. It is shown that synchrotron sources which accelerate to (or decelerate from) relativistic speeds could display rapid swings in the observed polarization position angle of up to 180\u00b0 as a result of the relativistic aberration effect. This mechanism is suggested for the large swing observed in the BL Lac object AO 0235+164 (Ledden and Aller 1978).
\r\n\r\n\r\nIt is argued that the majority of bright compact sources \r\nare observed along lines of sight making small (\u2272 10\u00b0) angles to the jet velocity. On the basis of this hypothesis, a unified interpretation of compact, variable radio sources and of extended double radio sources is presented. More generally, it is suggest\u00aded that active galactic nuclei may have two types of emission: an isotropic, fairly steady, unpolarized optical continuum, and a beamed, variable, strongly polarized synchrotron component associated with a relativistic jet. The sequence: radio-quiet quasars, radio-loud quasars, and blazars (i.e., optically-violent variable quasars and BL Lac objects) would then correspond to similar sources which are viewed at progressively decreasing angles to their jet axes. Model synchrotron and inverse-Compton spectra for resolved jets and for unresolved inhomogeneous jets are calculated, taking into account the effect of synchrotron - radiation losses, and applied to the interpretation of the spectra of BL Lac objects. The possible contribution of beamed sources to the diffuse x-ray and \u03b3-ray background is also discussed.
\r\n\r\nIn addition, the steady two-dimensional flow of an ideal compressible fluid is studied in the context of special-relativ\u00adistic gas dynamics. The Newtonian equations for potential flow are generalized, and it is found that they can have the same form in the Newtonian and the relativistic regimes if their parameters are defined in the local rest-frame of the fluid. The Mach number thus defined is shown to have the same properties as its Newtonian analog. The Newtonian equations for oblique plane shock waves are similarly generalized in certain cases (which include, in particular, the\u00b7 extreme-relativistic limit). Several applications of these results, particularly to the study of relativistic jets, are suggested.
\r\n\r\n\r\n\r\n\r\n\r\n" }, { "name": "Zimmermann, Mark Edward", "degree": "PhD", "year": "1980", "title": "Studies on Gravitational Waves and Stars with Neutron Cores", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:02172017-144352834", "creators": [ { "name": { "family": "Zimmermann", "given": "Mark Edward" }, "id": "Zimmermann-Mark-Edward", "display_name": "Zimmermann, Mark Edward" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/n4hc-5489", "abstract": "This thesis reports on investigations in two major areas: astrophysics\r\nand relativity. It is divided into six independent chapters.
\r\n\r\nChapter I contains estimates of the astrophysically-likely amplitude\r\nof gravitational radiation emitted by the Crab and Vela pulsars. For\r\nmy analysis, I model the pulsars as rapidly-rotating, freely-precessing,\r\nrigid or elastic solid bodies. I find that the Crab is likely to produce\r\ngravitational waves at Earth with dimensionless amplitude 10-27\u00b12, and\r\nthat Vela is likely to give waves one or two orders of magnitude larger.
\r\n\r\nChapters II and III study the gravitational radiation produced by\r\nan idealized rotating and freely-precessing rigid body in the weak-field,\r\nslow-motion, small-stresses, quadrupole-moment formalism. Chapter II gives\r\nthe results for axisymmetric objects and for arbitrarily shaped objects\r\nundergoing small-angle precession. In that chapter, I also discuss the\r\napplication of my results to neutron stars in nature, and I describe in\r\ndetail how to analyze the incoming waves and extract information about\r\ntheir source. Chapter III extends the analysis of Chapter II to the\r\ngeneral case of an arbitrary rigid body undergoing large-angle precession.
\r\n\r\nChapter IV considers all astrophysically-reasonable sources of\r\ngravitational waves. Based on a minimal set of \"cherished beliefs\" about\r\nthe universe and about gravitation, I give general upper limits to the\r\nexpected intensity of gravitational radiation at the earth, at various\r\nfrequencies and from a variety of sources.
\r\n\r\nChapter V examines a \"natural\" coordinate system which might be set\r\nup by a rotating and accelerating observer. I expand the metric through\r\nsecond-order terms in distance from the origin of the coordinates; from\r\nthe metric, I derive the equations of motion for test particles. I\r\nidentify many forces and pseudoforces in the equations of motion, and\r\nI discuss how my results may be used to analyze some laboratory gravitational\r\nexperiments.
\r\n\r\nChapter VI of this thesis is a report on my results in studying nucleo-synthesis\r\nin stars with neutron-star cores. I was not able to generate\r\nany self-consistent models with a total mass of 16 M\u2299, core mass of 1 M\u2299,\r\n\r\nand core radius of 10 km; nuclear reactions fell short of producing the\r\nneeded luminosity by a factor of 25 or more. I describe in detail my\r\nmodeling procedures and the reasons for the failure of nucleosynthesis,\r\nand I point out extensions and modifications of my models which may be\r\nmore successful.
\r\n\r\n" }, { "name": "Caves, Carlton Morris", "degree": "PhD", "year": "1979", "title": "Theoretical Investigations of Experimental Gravitation", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:03152016-161054898", "creators": [ { "name": { "family": "Caves", "given": "Carlton Morris" }, "id": "Caves-Carlton-Morris", "orcid": "0000-0001-8876-1186", "display_name": "Caves, Carlton Morris" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/H3T8-FQ06", "abstract": "This thesis has two basic themes: the investigation of new experiments\r\nwhich can be used to test relativistic gravity, and the investigation of new\r\ntechnologies and new experimental techniques which can be applied to make\r\ngravitational wave astronomy a reality.
\r\n\r\nAdvancing technology will soon make possible a new class of gravitation\r\nexperiments: pure laboratory experiments with laboratory sources of non-Newtonian\r\ngravity and laboratory detectors. The key advance in techno1ogy\r\nis the development of resonant sensing systems with very low levels of dissipation.\r\nChapter 1 considers three such systems (torque balances, dielectric\r\nmonocrystals, and superconducting microwave resonators), and it proposes\r\neight laboratory experiments which use these systems as detectors. For each\r\nexperiment it describes the dominant sources of noise and the technology\r\nrequired.
\r\n\r\nThe coupled electro-mechanical system consisting of a microwave cavity\r\nand its walls can serve as a gravitational radiation detector. A gravitational \r\nwave interacts with the walls, and the resulting motion induces\r\ntransitions from a highly excited cavity mode to a nearly unexcited mode.\r\nChapter 2 describes briefly a formalism for analyzing such a detector, and\r\nit proposes a particular design.
\r\n\r\nThe monitoring of a quantum mechanical harmonic oscillator on which a\r\nclassical force acts is important in a variety of high-precision experiments,\r\nsuch as the attempt to detect gravitational radiation. Chapter 3 reviews\r\nthe standard techniques for monitoring the oscillator; and it introduces a\r\nnew technique which, in principle, can determine the details of the force\r\nwith arbitrary accuracy, despite the quantum properties of the oscillator.
\r\n\r\nThe standard method for monitoring the oscillator is the \"amplitude-\r\nand-phase\" method (position or momentum transducer with output fed through\r\na linear amplifier). The accuracy obtainable by this method is limited by\r\nthe uncertainty principle. To do better requires a measurement of the type\r\nwhich Braginsky has called \"quantum nondemolition.\" A well-known quantum\r\nnondemolition technique is \"quantum counting,\" which can detect an arbitrarily\r\nweak force, but which cannot provide good accuracy in determining\r\nits precise time-dependence. Chapter 3 considers extensively a new type\r\nof quantum nondemolition measurement - a \"back-action-evading\" measurement\r\nof the real part X1 (or the imaginary part X2) of the oscillator's complex\r\namplitude. In principle X1 can be measured arbitrarily quickly and arbitrarily\r\naccurately, and a sequence of such measurements can lead to an\r\narbitrarily accurate monitoring of the classical force.
\r\n\r\nChapter 3 describes explicit gedanken experiments which demonstrate that\r\nX1 can be measured arbitrarily quickly and arbitrarily accurately, it considers\r\napproximate back-action-evading measurements, and it develops a theory\r\nof quantum nondemolition measurement for arbitrary quantum mechanical systems.
\r\n\r\nIn Rosen's \"bimetric\" theory of gravity the (local) speed of gravitational\r\nradiation vg is determined by the combined effects of cosmological\r\nboundary values and nearby concentrations of matter. It is possible for vg\r\nto be less than the speed of light. Chapter 4 shows that emission of gravitational\r\nradiation prevents particles of nonzero rest mass from exceeding the\r\nspeed of gravitational radiation. Observations of relativistic particles\r\nplace limits on vg and the cosmological boundary values today, and observations\r\nof synchrotron radiation from compact radio sources place limits on\r\nthe cosmological boundary values in the past.
" }, { "name": "De Logi, Walter K.", "degree": "PhD", "year": "1978", "title": "Electromagnetic Wave Generation and Propagation in Gravitational Fields", "advisor": "Papas, Charles Herach", "url": "https://resolver.caltech.edu/CaltechTHESIS:08312017-150019175", "creators": [ { "name": { "family": "De Logi", "given": "Walter K." }, "id": "De-Logi-Walter-K", "display_name": "De Logi, Walter K." } ], "advisors": [ { "name": { "family": "Papas", "given": "Charles Herach" }, "id": "Papas-C-H", "role": "advisor", "display_name": "Papas, Charles Herach" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "eleceng" ], "doi": "10.7907/es3k-qv56", "abstract": "We use Feynman perturbation techniques to analyze some aspects\r\nof electromagnetic wave generation and propagation in weak gravitational\r\nfields.
\r\n\r\nIn the first part of this report we calculate differential \r\ncross sections d\u03c3/d\u03a9 for the scattering of plane electromagnetic\r\nwaves by weakly gravitating and rotating bodies in the long-wavelength \r\nlimit (wavelength of incident radiation >> radius of scatterer >> mass \r\nof scatterer). We find that the polarization of right (or left) \r\ncircularly polarized electromagnetic waves is unaffected by the \r\nscattering process (i.e., helicity is conserved), and that the two \r\nhelicity states of the photon are scattered differently by a rotating \r\nbody. This coupling between the photon helicity and the angular \r\nmomentum of the scatterer also leads to a partial polarization of \r\nunpolarized incident light.
\r\n\r\n\r\nFor the sake of comparison, we also compute the differential \r\ncross sections for the gravitational scattering of scalar and gravi\u00adtational \r\nwaves. For the latter there is neither helicity conservation \r\nnor helicity-dependent scattering; and the angular momentum has no \r\npolarizing effect on incident, unpolarized gravitational waves.
\r\n\r\nIn the second part of this report, we analyze the conversion \r\nof gravitational waves into electromagnetic waves (and vice versa) \r\nunder the \"catalytic\" action of a static electromagnetic background \r\nfield. Closed-form differential cross sections are presented for \r\nconversion in the Coulomb field of a point charge, electric and \r\nmagnetic dipole fields, and uniform electrostatic and magnetostatic \r\nfields. Using the model calculation of conversion in a Coulomb field, \r\nwe discuss the problems that we must face when calculating non-gauge\u00ad-invariant \r\ntransition amplitudes, as is frequently done in the litera\u00adture.
\r\n\r\n\r\nWe conclude this report by pointing out how charged-particle \r\nbeams may be used (in principle) as direction-sensitive gravitational\u00ad-wave detectors.
\r\n \r\n\r\n\r\n" }, { "name": "Kov\u00e1cs, S\u00e1ndor J\u00e1nos, Jr.", "degree": "PhD", "year": "1977", "title": "The Generation of Gravitational Waves", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08252017-093756825", "creators": [ { "name": { "family": "Kov\u00e1cs", "given": "S\u00e1ndor J\u00e1nos, Jr." }, "id": "Kov\u00e1cs-S\u00e1ndor-J\u00e1nos-Jr.", "display_name": "Kov\u00e1cs, S\u00e1ndor J\u00e1nos, Jr." } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/VHQW-W277", "abstract": "This dissertation is written in three tracks. Track 1, (Pages ii-vi)\r\nis intended for those many many people who don't know any physics but who\r\ndo know how to read English and a bit of Hungarian perhaps.
\r\n\r\nTrack 2 is intended for those one hundred or so people in the whole\r\nworld who do know classical physics and have serious interests in, or\r\nare experts in relativity theory. Papers 1, 2 and 3 dealing with \r\nrelativity are entirely Track 2.
\r\n\r\nThe remaining paper is Track 3 and is for the benefit of even fewer\r\npeople who have a simultaneous interest in relativity and quantum field\r\ntheory.
\r\n\r\nI will not discuss the abstracts of the individual papers here -\r\nsince each paper is preceded by its own abstract. Suffice it to say that this\r\ndissertation is a collection of papers dealing with the theoretical\r\naspects of how gravitational waves may (or may not) be generated\r\nby gravitational bremsstrahlung, and in Paper 4 Walter and I try to\r\nshow that some classical relativity problems may be solved with much\r\ngreater ease via a quantum approach.
" }, { "name": "Page, Don Nelson", "degree": "PhD", "year": "1976", "title": "Accretion Into and Emission from Black Holes", "advisor": "Thorne, Kip S.; Hawking, Stephen W.", "url": "https://resolver.caltech.edu/CaltechTHESIS:07192012-091529776", "creators": [ { "name": { "family": "Page", "given": "Don Nelson" }, "id": "Page-Don-Nelson", "display_name": "Page, Don Nelson" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." }, { "name": { "family": "Hawking", "given": "Stephen W." }, "id": "Hawking-S-W", "orcid": "0000-0002-9079-593X", "role": "advisor", "display_name": "Hawking, Stephen W." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/RAEC-8822", "abstract": "Analyses are given of various processes involving matter falling\r\ninto or coming out of black holes.
\r\n\r\nA significant amount of matter may fall into a black hole in a\r\ngalactic nucleus or in a binary system. There gas with relatively high\r\nangular momentum is expected to form an accretion disk flowing into the\r\nhole. In this thesis the conservation laws of rest mass, energy, and\r\nangular momentum are used to calculate the radial structure of such a\r\ndisk. The averaged torque in the disk and flux of radiation from the\r\ndisk are expressed as explicit, algebraic functions of radius.
\r\n\r\nMatter may be created and come out of the gravitational field of\r\na black hole in a quantum-mechanical process recently discovered by\r\nHawking. In this thesis the emission rates of massless particles by\r\nHawking's process are computed numerically. The resulting power spectra\r\nof neutrinos, photons, and gravitons emitted by a nonrotating hole are\r\ngiven. For rotating holes, the rates of emission of energy and angular\r\nmomentum are calculated for various values of the rotation parameter.\r\nThe evolution of a rotating hole is followed as energy and angular\r\nmomentum are given up to the emitted particles. It is found that angular\r\nmomentum is lost considerably faster than energy, so that a black\r\nhole spins down to a nearly nonrotating configuration before it loses a\r\nlarge fraction of its mass. The implications are discussed for the lifetimes and possible present configurations of primordial black\r\nholes (the only holes small enough for the emission to be significant\r\nwithin the present age of the universe.
\r\n\r\nAs an astrophysical application, a calculation is given of the\r\ngamma-ray spectrum today from the emission by an assumed distribution\r\nof primordial black holes during the history of the universe. Comparison\r\nwith the observed isotropic gamma-ray flux above about 100 MeV yields\r\nan upper limit of approximately 10^4 pc^(-3) for the average number density\r\nof holes around 5 x 10^(14)g. (This is the initial mass of a nonrotating\r\nblack hole that would just decay away in the age of the universe.) The\r\nprospects are discussed for observing the final, explosive decay of an\r\nindividual primordial black hole. Such an observation could test the\r\ncombined predictions of general relativity and quantum mechanics and\r\nalso could provide information about inhomogeneities in the early universe\r\nand about the nature of strong interactions at high temperatures.
\r\n" }, { "name": "Lee, David Li", "degree": "PhD", "year": "1974", "title": "Frameworks for Analyzing and Testing Theories of Gravity", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-04092004-111803", "creators": [ { "name": { "family": "Lee", "given": "David Li" }, "id": "Lee-David-Li", "display_name": "Lee, David Li" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/KC8C-MS78", "abstract": "This thesis presents theoretical frameworks for the analysis and testing of gravitation theories - both metric and non-metric. For non-metric theories, the high-precision Eotvos-Dicke-Braginskii (EDB) experiments are demonstrated to be powerful tests of their gravitational coupling to electromagnetic interactions. All known non-metric theories are ruled out to within the precision of the EDB experiments. We present a new metric theory of gravity that cannot be distinguished from general relativity in all current and planned solar system experiments. However, this theory has very different gravitational-wave properties. Hence, we point out the need for further tests of metric theories beyond the Parametrized Post-Newtonian formalism, and emphasize the importance of the observation of gravitational waves as a tool for testing relativistic gravity in the future. A theory-independent formalism delineating the properties of weak, plane gravitational waves in metric theories is set up.\r\n\r\nGeneral conservation laws that follow from variational principles in metric theories of gravity are investigated." }, { "name": "Lightman, Alan Paige", "degree": "PhD", "year": "1974", "title": "I. Time-Dependent Accretion Disks Around Compact Objects and II. Theoretical Frameworks for Analyzing and Testing Gravitation Theories", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-11112003-091837", "creators": [ { "name": { "family": "Lightman", "given": "Alan Paige" }, "id": "Lightman-Alan-Paige", "display_name": "Lightman, Alan Paige" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/1QYN-CQ82", "abstract": "Part I.\r\n\r\nThe theory of time-independent accretion disks around compact objects is developed, generalizing the stationary models of various authors to allow time dependence on the radial-flow time scale. Equations are derived for the time evolution of matter surface density [Sigma] and for implicit expressions of relevant disk variables in terms of [Sigma]. Analytic and numerical studies of these equations yield numerical models of mass accretion from a disk onto a compact object and a discovery of the unstable nature of the \"inner region\" of the disk, causing a breakdown of current accretion disk models.\r\n\r\nPart II.\r\n\r\nTheoretical frameworks for analyzing and testing gravitation theories are developed for both nonmetric and metric theories. Highly precise experimental confirmation of the Weak Equivalence Principle is shown to be deadly if not fatal evidence for ruling out all nonmetric theories of gravity. For the class of metric theories we demonstrate the necessity for going beyond current frameworks of analysis (e.g.,the PPN framework) by constructing a new theory of gravity identical to GRT in the Post-Newtonian limit. As a first step in transcending current frameworks, we develop a formalism for delineating and testing all metric theories of gravity on the basis of their gravitational-wave properties and thereby emphasize gravitational-wave observations as a future tool for testing gravitation theories. We also investigate conservation laws and some common properties of Lagrangian-based metric theories of gravity." }, { "name": "Teukolsky, Saul Arno", "degree": "PhD", "year": "1974", "title": "Perturbations of a Rotating Black Hole", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-08022006-094950", "creators": [ { "name": { "family": "Teukolsky", "given": "Saul Arno" }, "id": "Teukolsky-Saul-Arno", "orcid": "0000-0001-9765-4526", "display_name": "Teukolsky, Saul Arno" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/N3AW-PV92", "abstract": "Decoupled, separable equations describing perturbations of a Kerr black hole are derived. These equations can be used to study black-hole processes involving scalar, electromagnetic, neutrino or gravitational fields. A number of astrophysical applications are made: Misner's idea that gravitational synchrotron radiation might explain Weber's observations is shown to be untenable; rotating black holes are shown to be stable against small perturbations; energy amplification by \"superradiant scattering\" of waves off a rotating black hole is computed; the \"spin down\" (loss of angular momentum) of a rotating black hole caused by a stationary non-axisymmetric perturbation is calculated." }, { "name": "Dykla, John Joseph", "degree": "PhD", "year": "1973", "title": "Conserved Quantities and the Formation of Black Holes in the Brans-Dicke Theory of Gravitation", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06022015-082916942", "creators": [ { "name": { "family": "Dykla", "given": "John Joseph" }, "id": "Dykla-John-Joseph", "display_name": "Dykla, John Joseph" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/h455-hg42", "abstract": "In Part I, we construct a symmetric stress-energy-momentum\r\npseudo-tensor for the gravitational fields of Brans-Dicke theory, and use this to establish rigorously conserved integral expressions for energy-momentum Pi and angular momentum Jik. Application of the two-dimensional surface integrals to the exact static spherical vacuum solution of Brans leads to an identification of our conserved mass with the active gravitational mass. Application to the distant fields of an arbitrary stationary source reveals that Pi and Jik have the same physical interpretation as in general relativity. For gravitational waves whose wavelength is small on the scale of the background radius of curvature, averaging over several wavelengths in the Brill-Hartle-Isaacson manner produces a stress-energy-momentum tensor for gravitational radiation which may be used to calculate the changes in Pi and Jik of their source.
\r\n\r\nIn Part II, we develop strong evidence in favor of a conjecture by Penrose--that, in the Brans-Dicke theory, relativistic gravitational collapse in three dimensions produce black holes identical to those of general relativity. After pointing out that any black hole solution of general relativity also satisfies Brans-Dicke theory, we establish the Schwarzschild and Kerr geometries as the only possible spherical and axially symmetric black hole exteriors, respectively. Also, we show that a Schwarzschild geometry is necessarily formed in the collapse of an uncharged sphere.
\r\n\r\nAppendices discuss relationships among relativistic gravity theories and an example of a theory in which black holes do not exist.
\r\n" }, { "name": "Kwan, John Ying-Kuen", "degree": "PhD", "year": "1973", "title": "Polarization Properties of Astrophysical Masers", "advisor": "Goldreich, Peter Martin", "url": "https://resolver.caltech.edu/CaltechTHESIS:08252017-145131867", "creators": [ { "name": { "family": "Kwan", "given": "John Ying-Kuen" }, "id": "Kwan-John-Ying-Kuen", "display_name": "Kwan, John Ying-Kuen" } ], "advisors": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/906J-2N21", "abstract": "Observed interstellar OH and H2O maser lines at 18 cm and\r\n1.35 cm exhibit unusual polarization properties. The OH emitters with the\r\nhighest brightness temperatures, usually associated with H II regions, almost\r\nalways show a high degree of circular polarization. The H2O maser line,\r\non the other hand, is rarely polarized, and then only linearly polarized.
\r\n\r\nThe preference for circular polarization in the brightest OH\r\nsources was attributed by Litvak to the mechanism of parametric down-conversion.\r\nIn this process the higher-frequency components of a Zeeman\r\nsplit maser line are down-converted to lower-frequency components and to\r\nan electron cyclotron wave. This mechanism is shown to be too weak to be\r\nof importance in astrophysical masers.
\r\n\r\nThe polarization properties of the OH and H2O masers are related \r\nto the physical conditions in the maser clouds. It is found that the magnetic\r\nfield, the plasma, and trapped infrared lines in maser sources play an\r\nimportant role in determining the polarization on the emitted radiation.
" }, { "name": "Ni, Wei-Tou", "degree": "PhD", "year": "1973", "title": "Metric Theories of Gravity and their Astrophysical Implications", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:08282017-154628547", "creators": [ { "name": { "family": "Ni", "given": "Wei-Tou" }, "id": "Ni-Wei-Tou", "display_name": "Ni, Wei-Tou" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/MCQM-3M81", "abstract": "The increasing importance of relativistic gravity in astrophysics has led to the need for a detailed analysis of theories of gravity and their viability. Accordingly, in this thesis, metric theories of gravity are compiled, and are classified into four groups: (i) general relativity\r\n(ii) scalar-tensor theories (iii) conformally flat theories and (iv) stratified theories. The post-Newtonian limit of each theory is constructed and its Parametrized Post-Newtonian (PPN) values are obtained. These results, when combined with experimental data and with recent work by Nordtvedt and Will, show that, of all theories thus far examined by our group, the only currently viable ones are (i) general relativity, (ii) the Bergmann-Wagoner scalar-tensor theory and its special cases (Nordtvedt; Brans-Dicke-Jordan, (iii) recent, (as yet unpublished ) vector-tensor theory by Nordtvedt, Hellings,\r\nand Will, and (iv) a new stratified theory by the author, which is presented for the first time in this thesis.
\r\n\r\n\r\nThe PPN formalism is used to analyze stellar stability in any metric theory of gravity. This analysis enables one to infer, for any given gravitation theory, the extent to which post-Newtonian effects induce instabilities in white dwarfs, in neutron stars, and in supermassive stars. It also reveals the extent to which our current empirical knowledge of post-Newtonian gravity (based on solar-system experiments) actually guarantees that relativistic instabilities exist. In particular, it shows that for \"conservative theories of gravity\", current solar-system experiments gua\u00adrantee that relativistic corrections do induce \r\ndynamical instabilities in stars with adiabatic indices slightly greater than 4/3, while for \"non-conservative theories\", current experiments do not permit any firm conclusion.\r\n
" }, { "name": "Press, William Henry", "degree": "PhD", "year": "1973", "title": "Applications of Black-Hole Perturbation Techniques", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-08252008-111253", "creators": [ { "name": { "family": "Press", "given": "William Henry" }, "id": "Press-William-Henry", "display_name": "Press, William Henry" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/0HKZ-DJ23", "abstract": "Separable, decoupled differential equations which describe gravitational, electromagnetic, and scalar perturbations of nonrotating (Schwarzschild) and rotating (Kerr) black holes have recently become available. Fortuitously, many interesting astrophysical processes near black holes can accurately be studied with these perturbation equations. A number of such processes are here investigated (as well as some matters of principle in pure relativity): \"vibrations\" of black holes, and the long wave-trains of gravitational waves which such vibrations may generate; the spectrum and intensity of gravitational radiation from a particle falling radially into a Schwarzschild hole; the physical significance of the Newman-Penrose conserved quantities, the result that they are never physically measurable and do not always exist; the time evolution of a rotating black hole immersed in a static scalar field, a quantitative calculation of the hole's \"spin-down\" and \"alignment\"; scalar-field calculations of superradiant wave scattering from a rotating black hole, and of the possibility of \"floating orbits\" \u2014 these are both wave processes which extract a hole's rotational energy. Included is a discussion of how these scalar-field results can be extended to the electromagnetic and gravitational cases. The most important perturbation problem yet to be solved is the question of whether rotating black holes are stable (against processes which would spontaneously emit gravitational waves). The astrophysical implications of instabilities are discussed, and a method for deciding the stability question (on which work is in progress) is outlined in detail. An appendix includes additional work on peripherally related matters. Several papers included in this thesis are extended from their published form by a more detailed discussion of numerical methods.\r\n" }, { "name": "Schutz, Bernard Frederick, Jr.", "degree": "PhD", "year": "1972", "title": "Relativistic Velocity: Potential Hydrodynamics and Stellar Stability", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:03212016-112353716", "creators": [ { "name": { "family": "Schutz", "given": "Bernard Frederick, Jr." }, "id": "Schutz-Bernard-Frederick", "display_name": "Schutz, Bernard Frederick, Jr." } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/05NX-9C06", "abstract": "The equations of relativistic, perfect-fluid hydrodynamics are cast in Eulerian form using six scalar \"velocity-potential\" fields, each of which has an equation of evolution. These equations determine the motion of the fluid through the equation
\r\n\r\nU\u028b=\u00b5-1 (\u00f8,\u028b + \u03b1\u03b2,\u028b + \u019fS,\u028b).
\r\n\r\nEinstein's equations and the velocity-potential hydrodynamical equations\r\nfollow from a variational principle whose action is
\r\n\r\nI = (R + 16\u03c0 p) (-g)1/2 d4x,
\r\n\r\nwhere R is the scalar curvature of spacetime and p is the pressure of the fluid. These equations are also cast into Hamiltonian form, with Hamiltonian density \u2013T00 (-goo)-1/2.
\r\n\r\nThe second variation of the action is used as the Lagrangian governing the evolution of small perturbations of differentially rotating stellar models. In Newtonian gravity this leads to linear dynamical stability criteria already known. In general relativity it leads to a new sufficient condition for the stability of such models against arbitrary perturbations.
\r\n\r\nBy introducing three scalar fields defined by
\r\n\r\n\u03c1 \u1d74 = \u2207\u03bb + \u2207x(xi + \u2207x\u0263i)
\r\n\r\n(where \u1d74 is the vector displacement of the perturbed fluid element, \u03c1 is the mass-density, and i, is an arbitrary vector), the Newtonian stability criteria are greatly simplified for the purpose of practical applications. The relativistic stability criterion is not yet in a form that permits practical calculations, but ways to place it in such a form are discussed.
\r\n\r\n" }, { "name": "Price, Richard Henry", "degree": "PhD", "year": "1971", "title": "Nonspherical Perturbation of Relativistic Gravitational Collapse", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:01192010-090920179", "creators": [ { "name": { "family": "Price", "given": "Richard Henry" }, "id": "Price-Richard-Henry", "display_name": "Price, Richard Henry" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/1EGC-Y160", "abstract": "It is known that there can be no gravitational, electromagnetic, or scalar field perturbations (except angular momentum) of a Schwarzschild black hole. A gravitationally collapsing star with nonspherical perturbations must therefore radiate away its perturbations or halt its collapse. The results of computations in comoving coordinates are presented to show that the scalar field in a collapsing star neither disappears nor halts the collapse, as the star passes inside its gravitational radius.\r\n\r\nOn the star's surface, near the event horizon, the scalar field varies as a_1 + a_2 exp (-t/2M) due to time dilation. The dynamics of the field outside the star can be analyzed with a simple wave equation containing a spacetime-curvature induced potential. This potential is impenetrable to zero-frequency waves and thus a_1, the final value of the field on the stellar surface, is not manifested in the exterior; the field vanishes. The monopole perturbation falls off as t^(-2); higher \u2113-poles fall off as \u2113n t/t^(2\u2113+3).\r\n\r\nThe analysis of scalar-field perturbations works as well for electromagnetic and gravitational perturbations and also for zero-restmass perturbation fields of arbitrary integer spin. All these perturbation fields obey wave equations with curvature potentials that differ little from one field to another. For all fields, radiatable multipoles (\u2113 \u2265 spin of the field) fall off as \u2113nt/t^(2\u2113+3).\r\n" }, { "name": "Will, Clifford Martin", "degree": "PhD", "year": "1971", "title": "Theoretical Frameworks for Testing Relativistic Gravity. The Parametrized Post-Newtonian Formalism", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-09302005-113319", "creators": [ { "name": { "family": "Will", "given": "Clifford Martin" }, "id": "Will-Clifford-Martin", "display_name": "Will, Clifford Martin" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/NQNB-RK02", "abstract": "Increasing sophistication and precision of experimental tests of relativistic gravitation theories has led to the need for a detailed theoretical framework for analysing and interpreting these experiments. Such a framework is the Parametrized Post-Newtonian (PPN) formalism, which treats the post-Newtonian limit of arbitrary metric theories of gravity in terms of nine metric parameters, whose values vary from theory to theory. The theoretical and experimental foundations of the PPN formalism are laid out and discussed, and the detailed definitions and equations for the formalism are given. It is shown that some metric theories of gravity predict that a massive, self-gravitating body's passive gravitational mass should not be equal to its inertial mass, but should be an anisotropic tensor which depends on the body's self-gravitational energy (violation of the \"principle of equivalence\"). Two theorems are presented which probe the theoretical structure of the PPN formalism. They state that (i) a metric theory of gravity possesses post-Newtonian integral conservation laws if and only if its nine PP parameters have values which satisfy a set of seven constraint equations, and (ii) a metric theory of gravity is invariant under asymptotic Lorentz transformations if and only if its PPN parameters satisfy a set of three constraint equations. Some theories of gravity (including Whitehead's theory and theories which violate one of the \"Lorentz-invariance\" parameter constraints) are shown to predict an anisotropy in the Newtonian gravitational constant. Gravimeter data on the tides of the solid Earth are used to put an upper limit on the magnitude of the predicted anisotropy, and thence to rule out such theories." }, { "name": "Defouw, Richard John", "degree": "PhD", "year": "1970", "title": "Thermal Instability and the Convective Stability of Stellar Chromospheres", "advisor": "Goldreich, Peter Martin", "url": "https://resolver.caltech.edu/CaltechETD:etd-05012008-103453", "creators": [ { "name": { "family": "Defouw", "given": "Richard John" }, "id": "Defouw-Richard-John", "display_name": "Defouw, Richard John" } ], "advisors": [ { "name": { "family": "Goldreich", "given": "Peter Martin" }, "id": "Goldreich-P-M", "role": "advisor", "display_name": "Goldreich, Peter Martin" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "astronomy" ], "doi": "10.7907/QDN8-FH95", "abstract": "It is generally believed that stellar chromospheres are stable against convection since the Schwarzschild criterion indicates stability when temperature increases with height. It is shown, however, that the Schwarzschild criterion does not apply to chromospheres because it ignores the possibility of thermal instability. In the absence of a magnetic field, thermally unstable regions of a chromosphere will be overstable if the temperature inversion is sufficiently steep. This overstability may explain the origin of a certain class of oscillations in the solar chromosphere. Thermally unstable regions containing magnetic fields are monotonically unstable for all values of the temperature gradient. It is suggested that this monotonic instability of magnetic regions is responsible for spicule formation in the solar chromosphere. Elementary considerations of thermal balance predict that the temperature gradient should diverge at levels of marginal stability. The chromospheric region of spicule formation should therefore be bounded below by an abrupt temperature jump.
\r\n\r\nThe above results are derived by analyzing the stability of a simple model chromosphere in which all neutral hydrogen atoms are assumed to be in the ground state. Although the model chromosphere emits only free-bound radiation, its thermal instability is caused by the same ionization effects which lead to instability in plasmas emitting line radiation. Thermally unstable regions of a stellar chromosphere, although not represented in detail by the model, should behave in a similar fashion.
\r\n" }, { "name": "Burke, William Lionel", "degree": "PhD", "year": "1969", "title": "The Coupling of Gravitational Radiation to Nonrelativistic Sources", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-10152002-090530", "creators": [ { "name": { "family": "Burke", "given": "William Lionel" }, "id": "Burke-William-Lionel", "display_name": "Burke, William Lionel" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/89HA-6J10", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThis thesis examines the problem of the coupling of gravitational radiation to its sources in the limit of weak fields and slowly-moving sources; it shows in detail how the irreversibility caused by the escape of radiation can be included in the formalism.\r\n\r\nThe usual slow-motion expansions of General Relativity (EIH and post-Newtonian) have the difficulty that they are not uniformly valid for large distances - distances where radiation becomes important and where the outgoing wave-boundary condition must be imposed. This difficulty is eliminated by using the method of matched asymptotic expansions. A second asymptotic expansion, in the same slowness parameter as enters in the near zone, is used to represent the radiation. This outer expansion provides matching conditions on the inner expansion that generate radiative corrections to the inner expansion.\r\n\r\nUsing this technique we show that the escape of radiation leads to an extraction of energy from the sources, without ever having to define the energy carried in the gravitational waves. The damping is found by calculating the work done by the fields that react back on the source. Explicit expressions are given for these fields, and these can be used to calculate, in lowest order, all the irreversible effects caused by radiation.\r\n\r\nIn this thesis the problem of calculating radiation reaction for bodies with very weak gravitational fields (U/c[superscript 2] << v[superscript 2]/c[superscript 2] << 1) is solved definitely. The case of gravitationally bound systems (U/c[superscript 2] [...] v[superscript 2/c[superscript 2] << 1) is discussed and a program for dealing with this case is set up, but the calculations for this case have not yet been done." }, { "name": "Ipser, James Reid", "degree": "PhD", "year": "1969", "title": "The Stability of Relativistic, Spherically Symmetric Star Clusters", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-10152002-160828", "creators": [ { "name": { "family": "Ipser", "given": "James Reid" }, "id": "Ipser-James-Reid", "display_name": "Ipser, James Reid" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/GF6C-JN05", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nIt has been suggested that very dense star clusters might play important roles in quasi-stellar sources and in the nuclei of certain galaxies, where violent events occur. Such star clusters should become unstable against relativistic gravitational collapse when, in the course of evolution, they contract down to a certain critical density. In this thesis the study of the relativistic instability which triggers such collapse is initiated: The theory of the stability of a spherically symmetric star cluster against small radial perturbations is developed within the framework of general relativity. Collisions between stars in the cluster are neglected, since in realistic situations the time scale for collisions should be much greater than the time scale for the growth of the relativistic instability. The equation of motion governing the small radial perturbations of a spherical cluster is derived and is shown to be self-conjugate. Associated with the equation of motion is a dynamically conserved quantity, and a multidimensional variational principle for the normal modes of radial pulsation. The variational principle provides a necessary and sufficient criterion for the stability of the cluster. Also derived are much simpler, one-dimensional, sufficient (but not necessary) criteria for stability. The most important sufficient criterion is this: A relativistic, spherical cluster is stable against radial perturbations if the gas sphere with the same distributions of density and pressure is stable against radial perturbations with adiabatic index [Gamma][subscript 1] = ([rho] + p)p[subscript -1](dp/dr) (d[rho]/dr)[superscript -1].\r\n\r\nThe stability criteria are used to diagnose numerically the stability of (i) clusters of identical stars with heavily-truncated Maxwell-Boltzmann velocity distributions, and (ii) clusters whose densities and isotropic pressures obey polytropic laws of index 2 or 3. The calculations show that a cluster of either type is unstable against collapse if the redshift of a photon emitted from its center and received at infinity is z[subscript c][...] 0.5. The cluster is stable if z[subscript c][...]0.5.\r\n\r\nFor purposes of motivation, two new theorems on the theory of the stability of highly relativistic stars (not star clusters!) are also presented in this thesis. The first theorem states that a highly relativistic, spherical star is stable if and only if its adiabatic index (assumed to be constant in the interior regions) is greater than a certain critical value, [gamma][subscript crit], which depends in a specified way on the high-density equation of state. Because of relativistic effects this critical value is somewhat larger than the Newtonian value [gamma][subscript crit] = 4/3. The second theorem shows that, at high central densities, the curves of - (binding energy) versus radius for certain hot, isentropic sequences of stellar models must exhibit damped clockwise spirals. This spiraling reflects the onset of instability in one radial mode of pulsation after another as the central density increases along the sequence.\r\n\r\n" }, { "name": "Jacobs, Kenneth Charles", "degree": "PhD", "year": "1969", "title": "Bianchi Type I Cosmological Models", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechETD:etd-10162002-080822", "creators": [ { "name": { "family": "Jacobs", "given": "Kenneth Charles" }, "id": "Jacobs-Kenneth-Charles", "display_name": "Jacobs, Kenneth Charles" } ], "advisors": [ { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "advisor", "display_name": "Thorne, Kip S." } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/KSSQ-R708", "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThis thesis begins with a brief review of observations of cosmological interest and with a sketch of the \"standard\" spatially homogeneous and isotropic cosmological models of our Universe that are currently in vogue. Following this introduction we investigate in great detail anisotropic cosmologies and cosmological models of Bianchi Type I. Our primary goal is to understand the consequences of expansion anisotropies in the general relativistic, hot big-bang theory of cosmology.\r\n\r\nWe use the Einstein field equations with vanishing cosmological constant, and Maxwell's equations, to study the temporal evolution of anisotropic Bianchi Type I cosmologies. These cosmologies are spatially homogeneous, but anisotropic; and they have no rotation. We consider only cosmologies with the \"flat\", diagonal, Bianchi Type I metric ds[superscript 2] - dt[superscript2] - A[superscript 2](t)dx[superscript 2] - B[superscript 2](t)dy[superscript 2] - C[superscript 2](t)dz[superscript 2].\r\n\r\nWe begin by studying the general properties of Bianchi Type I cosmologies. Then we consider the stress-energy tensor for massless-particle gases (either degenerate or non-degenerate) which decouple from thermal equilibrium and become freely-propagating in our diagonal Bianchi Type I metric. We investigate the dynamical effects of anisotropic neutrino stresses, and we show how neutrino viscosity damps out most of the existing expansion anisotropies when neutrinos decouple.\r\n\r\nFinally, we elucidate the structure and properties of the Einstein field equations for anisotropic Bianchi Type I cosmologies by deriving a large number of analytical and numerical solutions to these equations. Our stress-energy tensor consists, in general, of perfect-fluid matter with the barotropic equation of state p[subscript m] = [gamma] [rho][subscript m] (0 [<=] [gamma] [<=] 1), and a uniform comoving magnetic field, with energy-density [rho][subscript b], aligned along the z-axis. We first consider the PERFECT-FLUID case where [rho][subscript b] = 0. We find the general analytical solution (for all [gamma]), and construct semi-realistic cosmological models of our Universe using this solution. Then we consider the PERFECT-FLUID-MAGNETIC case where [rho][subscript b] [is not equal to] 0. We derive several analytical solutions, find the behavior near the initial physical singularity for the remaining cases, and study those remaining cases by numerical integration of the field equations. We then consider semi-realistic PERFECT-FLUID-MAGNETIC cosmological models of our Universe.\r\n\r\nIn our semi-realistic cosmological models we study the possible effects of expansion anisotropies and of a uniform primordial magnetic field upon the following: (a) the type of initial physical singularity, (b) the thermal history and temporal evolution of our Universe, (c) primordial element formation, (d) the time when expansion anisotropies become small, and (e) the temperature isotropy of the observed 2.7[degrees]K cosmic microwave radiation.\r\n" }, { "name": "Kinnersley, William Morris, III", "degree": "PhD", "year": "1969", "title": "Type D Gravitational Fields", "advisor": "Mathews, Jon", "url": "https://resolver.caltech.edu/CaltechETD:etd-04272006-094112", "creators": [ { "name": { "family": "Kinnersley", "given": "William Morris, III" }, "id": "Kinnersley-William-Morris-III", "display_name": "Kinnersley, William Morris, III" } ], "advisors": [ { "name": { "family": "Mathews", "given": "Jon" }, "id": "Mathews-J", "role": "advisor", "display_name": "Mathews, Jon" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "physics" ], "doi": "10.7907/9TE3-F842", "abstract": "The Newman-Penrose tetrad equations are set up for the principal tetrad of a Type D gravitational field in vacuum. With no further assumptions, the equations are integrated, yielding an exhaustive list of Type D vacuum metrics. The solutions all possess two commuting Killing vectors and depend on from one to four arbitrary constants. The Type D fields with expanding rays are six closely related versions of Kerr-NUT space, the EhlersKundt \"C\" metric, and a new generalization of the \"C\" metric possessing rotation. For zero expansion we find the three EhlersKundt \"B\" metrics, plus rotating generalizations of each.\r\n\r\nThe six Kerr-NUT metrics are interpreted as spinning particles with timelike, lightlike, or spacelike momentum and angular momentum vectors occurring in all possible combinations. The \"C\" metric is tentatively identified as a gravitational analog of the runaway solutions encountered in electrodynamics, i. e. , a point mass executing hyperbolic motion.\r\n\r\nNext we consider Type D fields with electromagnetism present. We find that all of the above vacuum metrics can be readily \"charged\" by adding a non-null electromagnetic field whose principal null vectors coincide with the gravitational ones. We also discuss some interesting generalizations of the Schwarzschild and \"C\" metrics containing the geometrical optics limit of a null electromagnetic field which propagates along one principal null congruence. In the Schwarzschild case they generalize Vaidya's \"shining star\" metric, to include the field of a particle traveling along an arbitrarily accelerated world-line.\r\n" } ]