Gravitational waves now serve as a powerful tool for studying physics of compact objects, including black holes and neutron stars. \r\nWhen two compact objects merge, they emit gravitational waves that encode information about their masses, spins, and orbital dynamics. \r\nGround-based detectors capture these signals, allowing us not only to measure the properties of individual mergers but also to characterize the population properties of black holes and neutron stars. In this thesis, I present a collection of works using real and simulated gravitational wave observations of compact binary coalescences to study the physics of black holes and neutron stars, and the implications these observations have on our broader understanding of astrophysics and fundamental physics.
\r\n \r\nThe first part of this thesis is background material reviewing some of the theory behind gravitational waves. The second part focuses on measuring the physical properties of a compact binary coalescence detected in gravitational wave data. This includes the methods and models used in parameter estimation and a presentation of the properties of detections in the fourth Gravitational Wave Transient Catalog (GWTC-4). The third part of this thesis turns to measuring and extracting astrophysical information from the population properties of compact binaries. This features the astrophysical distributions of binary black holes as inferred from GWTC-3 and GWTC-4. I also present studies measuring specific aspects of the binary black hole mass and spin distributions, and the implications these results have for understanding binary black hole formation channels and stellar astrophysics. This section additionally features applications of population inference to studies of large-scale structure and predictions for the gravitational wave stochastic background, as well as technical discussions of the methods and custom libraries used to implement population analyses and potential biases associated with commonly-used methods. The fourth part explores how properties of dense nuclear matter are encoded in observations of neutron stars. This section includes studies using our knowledge of the nuclear equation of state to classify low-mass compact binary mergers, and results from using gravitational waves and electromagnetic observations of neutron stars to measure the equation of state and neutron star population properties.
" }, { "name": "Hourihane, Sophie Rose", "degree": "PhD", "year": "2025", "title": "A Glitch and the Matrix: Advances in Gravitational-Wave Glitch Mitigation and Acceleration of Pulsar Timing Analyses", "advisor": "Chatziioannou, Katerina", "url": "https://resolver.caltech.edu/CaltechTHESIS:04292025-174229134", "creators": [ { "name": { "family": "Hourihane", "given": "Sophie Rose" }, "id": "Hourihane-Sophie-Rose", "orcid": "0000-0002-9152-0719", "display_name": "Hourihane, Sophie Rose" } ], "advisors": [ { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "advisor", "display_name": "Chatziioannou, Katerina" } ], "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": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "member", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Vallisneri", "given": "Michele" }, "id": "Vallisneri-M", "orcid": "0000-0002-4162-0033", "role": "member", "display_name": "Vallisneri, Michele" } ], "option_major": [ "physics" ], "doi": "10.7907/q6k7-hv53", "abstract": "Since the first detection of gravitational-waves in 2015, the field of gravitational-wave astronomy has developed rapidly. Today, there are more than 300 transient gravitational-wave event candidates from stellar-mass sources and we have found evidence for a stochastic background of supermassive black-holes. In this thesis I present work addressing two significant challenges on analyzing these data. The first: mitigating transient, non-Gaussian noise in gravitational-wave detectors, or \"glitches\", that can bias our estimates of physical properties of compact objects. The second: introducing a faster method to analyze pulsar-timing data containing a stochastic background of supermassive black-hole sources. Gravitational-wave astronomy is a data-rich field, and is only becoming more so with upgraded detectors, additional detectors, and longer observing time; we need robust, fast, and unbiased techniques to analyze that data." }, { "name": "Legred, Isaac Norman", "degree": "PhD", "year": "2025", "title": "Neutron Stars: Robust Constraints on Dense Matter from Astrophysics", "advisor": "Chatziioannou, Katerina", "url": "https://resolver.caltech.edu/CaltechTHESIS:06022025-165440282", "creators": [ { "name": { "family": "Legred", "given": "Isaac Norman" }, "id": "Legred-Isaac-Norman", "orcid": "0000-0002-9523-9617", "display_name": "Legred, Isaac Norman" } ], "advisors": [ { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "advisor", "display_name": "Chatziioannou, Katerina" } ], "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": "Kasliwal", "given": "Mansi M." }, "id": "Kasliwal-Mansi-M", "orcid": "0000-0002-5619-4938", "role": "member", "display_name": "Kasliwal, Mansi M." }, { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "member", "display_name": "Chatziioannou, Katerina" } ], "option_major": [ "physics" ], "doi": "10.7907/fzdw-w868", "abstract": "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": "Seymour, Brian Christopher", "degree": "PhD", "year": "2025", "title": "Future Prospects in Gravitational Waves: From Testing\r\nFundamental Physics to Instruments beyond LIGO", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:06032025-041244872", "creators": [ { "name": { "family": "Seymour", "given": "Brian Christopher" }, "id": "Seymour-Brian-Christopher", "orcid": "0000-0002-7865-1052", "display_name": "Seymour, Brian Christopher" } ], "advisors": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "advisor", "display_name": "Chen, Yanbei" } ], "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": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." }, { "name": { "family": "Zurek", "given": "Kathryn M." }, "id": "Zurek-K-M", "orcid": "0000-0002-2629-337X", "role": "member", "display_name": "Zurek, Kathryn M." } ], "option_major": [ "physics" ], "doi": "10.7907/ask9-zk26", "abstract": "In this thesis, we study the prospects for gravitational wave astronomy in the future. We focus on a couple of areas for gravitation waves beyond LIGO: improving measurement techniques of cosmological parameters, developing new waveforms for environmental effects, probing fundamental physics in waveforms, and high frequency gravitational wave detectors.
\r\n\r\nIn the first part of this thesis, we develop two methods to constrain cosmological parameters using gravitational-wave observations. The first approach employs the statistical dark siren method, where the observed distribution of binary black hole events---whose luminosity distances are directly measured---is matched against astrophysical population models. By analyzing the Fisher information in the event distribution, we derive the Cram\\'er-Rao bounds to quantify both statistical uncertainties and potential biases arising from unmodeled features in the merger rate and mass distribution. The second approach leverages the benefits of multiband observations with decihertz detectors, which dramatically improve host galaxy identification by refining source localization. This enhanced capability benefits reduces systematic errors in the measurement of the Hubble constant and other cosmological parameters. Together, these methods pave new pathways for precision cosmography using gravitational waves.
\r\n\r\nIn the second part of the thesis, we investigate gravitational-wave signatures arising from binary black holes merging in the vicinity of supermassive black holes (SMBHs). One study focuses on hierarchical triple systems where the orbital motion around an SMBH imprints striking modulations on the gravitational waveforms. In our work, gravitational lensing is highlighted as a pivotal effect---alongside Doppler shifts and de Sitter precession---that is crucial for breaking parameter degeneracies. A complementary analysis considers eccentric orbits, incorporating orbital pericenter precession alongside Doppler and precession effects to further refine parameter estimation. Together, these investigations demonstrate that dynamic lensing and orbital modulations can be leveraged to probe SMBH properties and their environments with unprecedented precision, underscoring the importance of incorporating these environmental effects into waveform models.
\r\n\r\nIn the third work, we explore inspiral tests of general relativity by examining the phase evolution of gravitational-wave signals from coalescing binary systems. First, we test Giddings' non-violent non-locality proposal, which posits that quantum information is transferred via a non-local interaction that generates metric perturbations around black holes by creating an effective-one-body waveform. We show that this can be captured by parameterized tests of general relativity waveforms. In the second half, we assess the robustness of post-Newtonian coefficients against unmodeled deviations by introducing parameterized tests that exploit the inherent geometry of the waveform. We show that the tests of general relativity are intimately related to the geometry of the signal manifold and propose a new singular value decomposition method to search for deviations for testing the predictions of general relativity and probing potential modifications to gravitational dynamics.
\r\n\r\nIn the fourth part of this thesis, we explore optimizing the GEO600 detector for high-frequency gravitational wave detection. Although GEO600 is less sensitive than LIGO in the conventional 50\u2013400 Hz band, we demonstrate that by detuning the signal-recycling mirror its sensitivity can be enhanced at tens of kHz. Using simulations with Finesse 3.0, we show that the sensitive point can be effectively scanned across various frequencies by adjusting the detuning angle. This tuning enables GEO600 to better target monochromatic sources, such as boson clouds arising from superradiance, thereby opening a promising new window for high-frequency gravitational wave astronomy.
" }, { "name": "Udall, Rhiannon Pollard", "degree": "PhD", "year": "2025", "title": "Robust Gravitational Wave Analysis at the Catalog Scale", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:05312025-230908742", "creators": [ { "name": { "family": "Udall", "given": "Rhiannon Pollard" }, "id": "Udall-Rhiannon-P", "orcid": "0000-0001-6877-3278", "display_name": "Udall, Rhiannon Pollard" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "chair", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "Reitze", "given": "David H." }, "id": "Reitze-D-H", "orcid": "0000-0002-5756-1111", "role": "member", "display_name": "Reitze, David H." }, { "name": { "family": "McCuller", "given": "Lee P." }, "id": "McCuller-Lee", "orcid": "0000-0003-0851-0593", "role": "member", "display_name": "McCuller, Lee P." }, { "name": { "family": "Hallinan", "given": "Gregg W." }, "id": "Hallinan-G-W", "orcid": "0000-0002-7083-4049", "role": "member", "display_name": "Hallinan, Gregg W." }, { "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" ], "abstract": "The rapid improvement in the sensitivity of ground based gravitational wave detectors has produced a huge variety of technical insights, but has also brought new challenges in gravitational wave data analysis. In this dissertation I address two of those challenges: the rapid increase in the number of detected events, and the need for robust astrophysical inferences in the presence of transient detector glitches. To manage the number of gravitational wave transients now regularly detected, I developed infrastructure for the LIGO-Virgo-KAGRA collaboration which monitors and collates the results of many disparate analyses in order to produce the final transient catalog. I implemented physically informed models for scattered light glitches into standard parameter estimation tools, and so that the potential realizations of these glitches can be marginalized over when performing astrophysical inference. This method was used to better understand GW191109, an event from the third observing run with potentially dynamical formation history. These tools were also applied to better understand the behavior of parameter estimation in the presence of glitches, and to search for statistical tests which can identify if parameter estimation is biased by the presence of a glitch." }, { "name": "Anand, Shreya", "degree": "PhD", "year": "2024", "title": "Cosmic Gold Mining: Hunting for the Astrophysical Sites of r-Process Nucleosynthesis", "advisor": "Kasliwal, Mansi M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06042024-064008692", "creators": [ { "name": { "family": "Anand", "given": "Shreya" }, "id": "Anand-Shreya", "orcid": "0000-0003-3768-7515", "display_name": "Anand, Shreya" } ], "advisors": [ { "name": { "family": "Kasliwal", "given": "Mansi M." }, "id": "Kasliwal-Mansi-M", "orcid": "0000-0002-5619-4938", "role": "advisor", "display_name": "Kasliwal, Mansi M." } ], "committee": [ { "name": { "family": "Fuller", "given": "James" }, "id": "Fuller-J", "orcid": "0000-0002-4544-0750", "role": "chair", "display_name": "Fuller, James" }, { "name": { "family": "Mawet", "given": "Dimitri" }, "id": "Mawet-D", "orcid": "0000-0002-8895-4735", "role": "member", "display_name": "Mawet, Dimitri" }, { "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": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "member", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "Kasliwal", "given": "Mansi M." }, "id": "Kasliwal-Mansi-M", "orcid": "0000-0002-5619-4938", "role": "member", "display_name": "Kasliwal, Mansi M." } ], "option_major": [ "physics" ], "doi": "10.7907/145k-w841", "abstract": "One of the major open questions in astronomy is where the heaviest elements in the Universe are formed. These elements, generated via the rapid neutron-capture process (r-process), require environments abundant with free neutrons, present only in extreme cosmic explosions, which are by nature inherently rare. To date, vivid, direct evidence of heavy element nucleosynthesis has been seen and most extensively studied in the binary neutron star (BNS) merger GW170817. However, neutron star\u2013black hole (NSBH) mergers, some collapsing massive stars (collapsars), and other explosions have also been proposed as alternative sites of r-process production. This thesis explores BNS mergers, NSBH mergers, and collapsars as r-process sites through observational studies. In this work, we first investigate whether r-process signatures are present in the light curves of broadlined type Ic supernovae (SNe Ic-BL) associated with long-duration gamma-ray bursts. For this study, we conduct optical imaging with the Zwicky Transient Facility (ZTF) and near-infrared imaging with the Wide-Field Infrared Camera on the Palomar 200-in Hale telescope of ZTF-discovered SNe Ic-BL. Second, we study the chemical distribution of ejecta in the kilonova (KN)---an optical/near-infrared transient powered by the radioactive decay of r-process elements---counterpart to GW170817, using new state-of-the-art KN models and incorporating precise inclination information on GW170817 into our inference. Third, we describe systematic searches conducted with ZTF for KNe associated with both BNS and NSBH mergers detected by the LIGO Virgo KAGRA detector network during its third and fourth observing runs. Based on our non-detections, we place constraints on the properties of KNe from both BNS and NSBH merger sites. Finally, we summarize the unique insights we have gained on the nature of r-process sites from observations and non-detections. We also discuss prospects for discovering and characterizing these transients with upcoming surveys such as the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope." }, { "name": "Li, Ka Yue Alvin", "degree": "PhD", "year": "2024", "title": "Probing the Higher Redshift Universe by Studying Strong Lensing of Gravitational Waves and Enhancing Search Sensitivity of the GstLAL Search Pipeline", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:05242024-202843732", "creators": [ { "name": { "family": "Li", "given": "Ka Yue Alvin" }, "id": "Li-Ka-Yue-Alvin", "orcid": "0000-0001-6728-6523", "display_name": "Li, Ka Yue Alvin" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "chair", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "Fuller", "given": "James" }, "id": "Fuller-J", "orcid": "0000-0002-4544-0750", "role": "member", "display_name": "Fuller, James" }, { "name": { "family": "Ravi", "given": "Vikram" }, "id": "Ravi-Vikram", "orcid": "0000-0002-7252-5485", "role": "member", "display_name": "Ravi, Vikram" }, { "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/hc11-h960", "abstract": "The LIGO-Virgo-KAGRA (LVK) collaboration first observed gravitational waves in 2015, and more than $90$ gravitational-wave events have been observed, all coming from mergers of compact objects (black holes and neutron stars), known as compact binary coalescences (CBC). Studying and observing gravitational waves opens a new window for us to understand the nature of spacetime and the universe. Strain data from LVK's detectors are analyzed by search pipelines to identify weak gravitational-wave signals in noisy data. To maximize the potential of gravitational waves, it is essential to continue to improve search pipelines' sensitivity to probe GW sources with the broadest range of parameters and from the furthest distances. I will give a detailed overview of the GstLAL pipeline and present related development (ongoing) work for GstLAL to enhance its search effectiveness and efficiency.
\r\n\r\nIn the second part of my thesis, I will focus on gravitational lensing of gravitational waves. As masses can produce curvature in spacetime, gravitational waves, like electromagnetic (EM) waves, are deflected when passing by massive intervening objects before reaching gravitational-wave detectors on Earth, an effect known as gravitational lensing. Observing lensed gravitational waves confirms another prediction in Einstein's general relativity and enables us to conduct cosmography studies, test general relativity, search for dark matter and other exotic phenomena, and deepen our understanding of the universe. I will give a detailed introduction to gravitational lensing of gravitational waves. We then introduce a Targeted subthreshold search for strongly-lensed gravitational wave pipeline called \"TESLA\". The TESLA pipeline is the flagship to look for sub-threshold lensed gravitational waves. Next, we present the results of the LVK collaboration-wide effort to search for lensing signatures in gravitational-wave data from the third observing run O3. Next, we introduce a significant update to the TESLA pipeline, now known as the TESLA-X pipeline, with enhanced search sensitivity towards lensed gravitational waves. We also introduce an alternative ranking statistic implemented into the TESLA-X pipeline that considers the signal's consistency with the assumed lens model. Finally, we end the thesis with a summary and an outline of possible future work.
" }, { "name": "Lo, Ka Lok (Rico)", "degree": "PhD", "year": "2024", "title": "Gravitational Wave Exotica - Advancing the Search for Signatures of Exotic Compact Objects and Gravitational Lensing from Data-Analysis and Theoretical Perspectives", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:08312023-190727801", "creators": [ { "name": { "family": "Lo", "given": "Ka Lok (Rico)" }, "id": "Lo-Ka-Lok-Rico", "orcid": "0000-0003-1561-6716", "display_name": "Lo, Ka Lok (Rico)" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "member", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "Fuller", "given": "James" }, "id": "Fuller-J", "orcid": "0000-0002-4544-0750", "role": "member", "display_name": "Fuller, James" }, { "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/gycj-ch63", "abstract": "In this thesis, I explore two new arenas of gravitational-wave physics and advance them from both data-analysis and theoretical perspectives. I probe the nature of the remnant of a compact binary merger and study the strong gravitational lensing of gravitational waves. For probing the nature of a merger remnant, I first describe recipes of computing radiation emitted by a perturbed Kerr black hole, and in particular using the Generalized Sasaki-Nakamura formalism. Using a modified Kerr black hole spacetime as a model of a generic compact object, I then describe a prescription to compute waveforms of the repeating bursts of gravitational waves, referred to as gravitational-wave echoes, that are theorized to be emitted when a compact object with a reflective surface is formed as the remnant of a merger. Equipped with a waveform model for these echoes, I present a Bayesian model selection approach to look for echoes in data while inferring properties of the potential exotic compact object. I apply this approach to search for echoes in the data covering the first, the second, and the first half of the third observing run of the LIGO-Virgo-KAGRA network. For the strong lensing of gravitational waves, I first develop a Bayesian statistical framework that is capable of computing the probability of a given set of gravitational-wave events being the strongly-lensed counterparts of the same source or simply coming from distinct sources. If they are truly lensed, the framework can also infer the properties of the lensed source in a way unaffected by lensing. I apply this framework to search for signatures of strongly-lensed binary black hole systems in the data covering the third observing run. While we did not find any statistically significant evidence in the search for gravitational-wave echoes and strongly-lensed binary black holes, we can still place limits using the null results. Admittedly the existence of exotic compact objects is speculative and the observing rate of strongly-lensed gravitational waves is rare; however, the scientific impacts that they can bring are profound if they are proven to exist." }, { "name": "Markowitz, Aaron Gregory", "degree": "PhD", "year": "2024", "title": "Interferometric Precision Measurement with Macroscopic Silicon Optomechanics", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:06022024-152003367", "creators": [ { "name": { "family": "Markowitz", "given": "Aaron Gregory" }, "id": "Markowitz-Aaron-Gregory", "orcid": "0000-0003-0223-2342", "display_name": "Markowitz, Aaron Gregory" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "McCuller", "given": "Lee P." }, "id": "McCuller-Lee", "orcid": "0000-0003-0851-0593", "role": "member", "display_name": "McCuller, Lee P." }, { "name": { "family": "Mirhosseini", "given": "Mohammad" }, "id": "Mirhosseini-M", "orcid": "0000-0002-9084-6880", "role": "member", "display_name": "Mirhosseini, Mohammad" }, { "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/wnm8-nb48", "abstract": "Optomechanical sensors provide our most sensitive measurements of spacetime, including observations of gravitational waves by laser interferometric detectors. However, even state of the art detectors like the Advanced Laser Interferometric Gravitational-Wave Observatory (LIGO) are still tens of orders of magnitude away from the measurement limits imposed by Heisenberg uncertainty. This thesis maps out the contours of mechanical and optical losses limiting next generation gravitational wave interferometers, and describes several experiments and analyses to improve those limitations. We review the theory of optomechanical force sensing to understand the influence of optical radiation pressure on the dynamics of mechanical oscillators. We analyze several modified Mach-Zehnder interferometers and show how radiation pressure can be a resource for quantum measurement, including by establishing a surprising optical spring effect in a cavity held on-resonance. The most developed proposal is for a phase-sensitive optomechanical amplifier to avoid the photodetection losses that may limit next-generation gravitational wave interferometers utilizing cryogenic silicon mirrors and \u22482000 nm infrared lasers. The amplifier calls for high quality mechanical oscillators made of single crystal silicon, which we fabricate. We describe our efforts to develop a testbed for cryogenic mechanical loss measurements of silicon oscillators and thin film coatings. And, we show how Bayesian inference can be used to improve our understanding of the physical mechanisms limiting a system\u2019s mechanical loss. Finally, we describe the optical, mechanical, and electronic design of a prototype phase sensitive optomechanical amplifier. The prototype is useful for testing the control system required to implement the full amplifier, and we characterize the current control scheme and the scheme for near-term upgrades. Our latest measurements show a clear path to steadily improving the amplifier\u2019s noise figure with well understood technology." }, { "name": "Gupta, Anchal", "degree": "PhD", "year": "2023", "title": "Next-Generation Technologies for Gravitational Wave Detectors", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:06012023-001004673", "creators": [ { "name": { "family": "Gupta", "given": "Anchal" }, "id": "Anchal-Gupta", "orcid": "0000-0002-1762-9644", "display_name": "Gupta, Anchal" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "member", "display_name": "Golwala, Sunil" }, { "name": { "family": "Hutzler", "given": "Nicholas R." }, "id": "Hutzler-N-R", "orcid": "0000-0002-5203-3635", "role": "member", "display_name": "Hutzler, Nicholas R." }, { "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/cg5p-kr27", "abstract": "Since the first detection of gravitational waves (GW) in 2015, gravitational wave detectors have continually been improved. Now, a compact binary coalescence (CBC) is detected once a week in a full sensitivity observation run of the Advanced Laser Interferometric Gravitational-wave Observatory (LIGO) detectors. This thesis describes research on a collection of projects aimed at developing next-generation of technologies for future gravitational wave detectors. In the first part, I describe my research on directly measuring the coatings Brownian noise of high-reflectivity coatings made out of crystalline AlGaAs. It is a part of the larger effort to reduce the classical noise limit in the 30 Hz to 300 Hz band in the current generation of detectors. The second part describes the Balanced Homodyne Readout (BHR) upgrade that was performed at the 40m prototype at Caltech. This new readout method would be instrumental in reducing excess noise at the lower frequencies in GW detectors. With several future detectors planned with an order of magnitude improvement in sensitivity, the parameter estimation about the merging bodies would be limited by the calibration uncertainty if the calibration method is not updated. In the third part of the thesis, I describe our work on developing a systematic-free absolute calibration of the detector. In this scheme, we refer the calibration to the ultra-stable optical common length mode of the arm cavities in the detectors. In the final part, I describe four new arm length stabilization schemes for the proposed cryogenic upgrade of Advanced LIGO detectors into Voyager." }, { "name": "Li, Xiang", "degree": "PhD", "year": "2023", "title": "Topics in Gravitational Wave Physics: Quantum Theory for Detector Improvement and High-Precision Modeling of Binary Black Hole Ringdown Waveform", "advisor": "Chen, Yanbei", "url": "https://resolver.caltech.edu/CaltechTHESIS:11022022-054918241", "creators": [ { "name": { "family": "Li", "given": "Xiang" }, "id": "Li-Xiang", "orcid": "0000-0002-3780-7735", "display_name": "Li, Xiang" } ], "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": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Chatziioannou", "given": "Katerina" }, "id": "Chatziioannou-K", "orcid": "0000-0002-5833-413X", "role": "member", "display_name": "Chatziioannou, Katerina" }, { "name": { "family": "McCuller", "given": "Lee P." }, "id": "McCuller-Lee", "orcid": "0000-0003-0851-0593", "role": "member", "display_name": "McCuller, Lee P." } ], "option_major": [ "physics" ], "doi": "10.7907/ks5c-zn93", "abstract": "This thesis covers topics in gravitational wave physics, including optomechanical measurement theory, novel detection schemes (PT-symmetric interferometer, matter-wave interferometer), and modeling of binary black hole ringdown waveform.
\r\n\r\nMeasurements are accomplished through the interaction between signal and measurement devices. Identifying the nature of couplings is an important step in designing setups for specific applications. In Chapter II, we develop a general framework based on the system Hamiltonian to unambiguously classify optomechanical couplings. We add the new type, ``coherent coupling'', where the mechanical oscillation couples several non-degenerate optical modes supported in the cavity. We give examples of different couplings, discuss in detail one particular case of the coherent coupling, and demonstrate its benefits in optomechanical experiments. Our general framework allows the design of optomechanical systems in a methodological way, to precisely exploit the strengths of some particular optomechanical couplings.
\r\n\r\nConventional resonant detectors are subject to bandwidth-peak sensitivity trade-off, which can be traced back to the quantum Cramer-Rao Bound. Chapters III and IV in this thesis are devoted to the study of PT-symmetric amplifier, which is a stable quantum amplification scheme enabled by two-mode non-degenerate parametric amplification. In Chapter III, we study stability and sensitivity improvements for laser-interferometric gravitational-wave detectors and microwave cavity axion detectors, under Hamiltonian formalism adopting single-mode and resolved-sideband approximations. In Chapter IV, we go beyond these approximations and consider realistic parameters in the optomechanical realization of PT-symmetric interferometer for gravitational detection. We show that the main conclusion concerning stability remains intact using Nyquist analysis and a detailed time-domain simulation.
\r\n\r\nThe detection method of gravitational waves is developed with linear quantum measurement theory. In Chapter V, we extend the usage of this theory to another kind of measurement device \u2014 matter-wave interferometers, which have been widely discussed as an important platform for many high-precision measurements. This theory allows us to consider fluctuations from both atoms and light and leads to a detailed analysis of back-action (of light back onto the atoms) and its effect on dynamics and measurement noise in atom interferometry. From this analysis, we obtain a Standard Quantum Limit for matter-wave interferometry. We also give a comparison between the LIGO detector and matter-wave interferometer from the perspective of quantum measurement.
\r\n\r\nIn Chapter VI, we switch focus from measurement to gravitational wave sources. Specifically, we study high-frequency gravitational radiation from the ringdown of a binary black hole merger. We study the high-precision modeling on both temporal and spatial features of ringdown wave to propose a more complete test of General Relativity. We show that spin-weighted spheroidal harmonics, rather than spin-weighted spherical harmonics, better represent ringdown angular patterns. We also study the correlation between progenitor binary properties and the excitation of quasinormal modes, including higher-order angular modes, overtones, prograde and retrograde modes. This chapter seeks to provide an analytical strategy and inspire the future development of ringdown tests using data from real gravitational wave events.
" }, { "name": "Xiao, Liting", "degree": "PhD", "year": "2023", "title": "Searching for Gravitational Waves from Compact Binary Coalescences and Stochastic Backgrounds in the LIGO\u2013Virgo Detector Network", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:10202022-200320341", "creators": [ { "name": { "family": "Xiao", "given": "Liting" }, "id": "Xiao-Liting", "orcid": "0000-0003-2703-449X", "display_name": "Xiao, Liting" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "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": "Reitze", "given": "David H." }, "id": "Reitze-D-H", "orcid": "0000-0002-5756-1111", "role": "member", "display_name": "Reitze, David H." }, { "name": { "family": "Bouman", "given": "Katherine L." }, "id": "Bouman-K-L", "orcid": "0000-0003-0077-4367", "role": "member", "display_name": "Bouman, Katherine L." } ], "option_major": [ "physics" ], "doi": "10.7907/zgtx-0582", "abstract": "Gravitational waves (GWs) are ripples in spacetime generated by accelerating masses, carrying away information about the underlying processes. There are four main astrophysical sources detectable in the sensitive band of the LIGO\u2013VIRGO\u2013KAGRA (LVK) GW detector network: compact binary coalescences, burst sources, continuous waves and stochastic gravitational-wave backgrounds. This thesis focuses on the detection methods of two of these categories, coalescing compact binaries and stochastic backgrounds, and their search results across LIGO\u2013Virgo\u2019s first three observing runs spanning from 2015 to 2020.
\r\n\r\nCompact binary coalescences of black holes and/or neutron stars are the only type of GW sources detected so far in the LVK frequency band. Such binary systems lose orbital energy via GW emission and are compact enough to merge within the age of the Universe. PyCBC is a matched-filter, all-sky pipeline for GW signals from compact binary mergers using a bank of modeled gravitational waveform templates. We describe the methods employed in PyCBC and present the developmental updates both in its archival and low-latency configurations for LIGO\u2013Virgo\u2019s third observing run. Using PyCBC to analyze the data from LIGO\u2013Virgo\u2019s first three observing runs, we summarize our results of the searches in gravitational-wave transient catalogs and characterize some exceptional events.
\r\n\r\nA stochastic gravitational-wave background consists of a large number of weak, independent and uncorrelated events of astrophysical or cosmological origin. The GW power on the sky is assumed to contain anisotropies on top of an isotropic component, i.e., the angular monopole. Complementary to the LVK searches, we develop an efficient analysis pipeline to compute the maximum-likelihood anisotropic sky maps in stochastic backgrounds directly in the sky pixel domain using data folded over one sidereal day. We invert the full pixel-pixel correlation matrix in map-making of the GW sky, up to an optimal eigenmode cutoff decided systematically using simulations. In addition to modeled mapping, we implement a model-independent method to probe spectral shapes of stochastic backgrounds. Using data from LIGO\u2013Virgo's first three observing runs, we obtain upper limits on anisotropies as well as the isotropic monopole as a limiting case, consistent with the LVK results. We also set constraints on the spectral shape of the stochastic background using this novel model-independent method.
" }, { "name": "Venugopalan, Gautam", "degree": "PhD", "year": "2022", "title": "Prototype Interferometry in the Era of Gravitational Wave Astronomy", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:06242021-042731868", "creators": [ { "name": { "family": "Venugopalan", "given": "Gautam" }, "id": "Venugopalan-Gautam", "orcid": "0000-0003-4414-9918", "display_name": "Venugopalan, Gautam" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "display_name": "Chen, Yanbei" }, { "name": { "family": "Hutzler", "given": "Nicholas R." }, "id": "Hutzler-N-R", "orcid": "0000-0002-5203-3635", "role": "member", "display_name": "Hutzler, Nicholas R." }, { "name": { "family": "Mawet", "given": "Dimitri" }, "id": "Mawet-D", "orcid": "0000-0002-8895-4735", "role": "member", "display_name": "Mawet, Dimitri" }, { "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/ttwp-1h12", "abstract": "Since the first direct detection of gravitational wave signals from the coalescence of a pair of stella-mass black holes on 14 September 2015, a global network of terrestrial interferometric detectors, with kilometer-scale arms, have opened a new window through which the astrophysical universe can be probed. This success was the result of decades of exploratory work done on smaller-scale prototype interferometers. Even though the detection of astrophysical gravitational wave signals has become almost a routine event, prototype interferometers remain an essential tool in developing technologies for future generations of kilometer-scale detectors. They are unique in that they are large enough to probe physics that cannot be easily investigated on the table-top, but have no obligation to function as an observatory, and so can be readily modified for a wide variety of experiments. This thesis focuses on one direction in which prototype interferometry can be taken, serving as a testbed for testing the laws of quantum mechanics at the macroscopic scale. While this is in itself an interesting experimental program, it can make a direct contribution to the field of gravitational wave astronomy since future generations of terrestrial detectors are expected to be limited in their sensitivity due to measurement limits set by the Heisenberg uncertainty principle. Techniques to evade these limits can be demonstrated on a prototype interferometer, before embarking on an expensive program to implement them at the scale necessary for kilometer-scale observatories.
" }, { "name": "Cahillane, Craig Russell", "degree": "PhD", "year": "2021", "title": "Controlling and Calibrating Interferometric Gravitational Wave Detectors", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:05102021-070729581", "creators": [ { "name": { "family": "Cahillane", "given": "Craig Russell" }, "id": "Cahillane-Craig-Russell", "orcid": "0000-0002-3888-314X", "display_name": "Cahillane, Craig Russell" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "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": "Reitze", "given": "David H." }, "id": "Reitze-D-H", "orcid": "0000-0002-5756-1111", "role": "member", "display_name": "Reitze, David H." }, { "name": { "family": "Kirby", "given": "Evan N." }, "id": "Kirby-E-N", "orcid": "0000-0001-6196-5162", "role": "member", "display_name": "Kirby, Evan N." }, { "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": "10.7907/76jj-mr73", "abstract": "In September 2015, the Advanced LIGO detectors made the first direct detection of gravitational waves from a binary black hole merger [1]. Since then, around fifty total gravitational wave detections have been reported by Advanced LIGO and Advanced Virgo over three dedicated gravitational wave observation times, known as observing runs.
\r\n\r\nObserving run three (O3) ran from April 2019 to March 2020, with higher sensitivity and more stable operation of the Advanced LIGO detectors [2]. In the first half of O3, thirty-nine gravitational wave events were detected [3], as opposed to eleven in all of observing runs one (O1) and two (O2) [4]. The higher rate of detections is due primarily to the increased detector sensitivity to gravitational waves.
\r\n\r\nAlthough the Advanced LIGO detectors are more sensitive to gravitational waves than any detector in history, they have not yet achieved design sensitivity. Work continues to push the detectors to their fundamental limit of sensitivity. The work in this thesis partially covers the effort to improve the sensitivity of the LIGO Hanford detector prior to O3.
\r\n\r\nCalibration of the Advanced LIGO interferometer is the conversion of raw detector data into gravitational wave strain data. This process is crucial to an accurate and precise understanding of astrophysical sources of gravitational waves. The calibration uncertainty pipeline for characterizing the strain uncertainty during O1 and O2 is discussed in detail [5].
\r\n\r\nThis thesis covers topics in long-baseline interferometric gravitational wave detector technology, including an overview of the performance of the detector in O3, commissioning tasks done to increase the sensitivity of the detector for O3, overall calibration uncertainty in the gravitational wave data, and methods for robust estimation of spectral quantities from LIGO data.
" }, { "name": "Callister, Thomas Alfred, III", "degree": "PhD", "year": "2020", "title": "Searching for the Astrophysical Gravitational-Wave Background and Prompt Radio Emission from Compact Binaries", "advisor": "Weinstein, Alan Jay; Hallinan, Gregg W.", "url": "https://resolver.caltech.edu/CaltechTHESIS:05262020-184547015", "creators": [ { "name": { "family": "Callister", "given": "Thomas Alfred, III" }, "id": "Callister-Thomas-Alfred-III", "orcid": "0000-0001-9892-177X", "display_name": "Callister, Thomas Alfred, III" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Hallinan", "given": "Gregg W." }, "id": "Hallinan-G-W", "orcid": "0000-0002-7083-4049", "role": "co-advisor", "display_name": "Hallinan, Gregg W." } ], "committee": [ { "name": { "family": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "chair", "display_name": "Golwala, Sunil" }, { "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": "Hallinan", "given": "Gregg W." }, "id": "Hallinan-G-W", "orcid": "0000-0002-7083-4049", "role": "member", "display_name": "Hallinan, Gregg W." }, { "name": { "family": "Teukolsky", "given": "Saul A." }, "id": "Teukolsky-S-A", "orcid": "0000-0001-9765-4526", "role": "member", "display_name": "Teukolsky, Saul A." } ], "option_major": [ "astrophys" ], "doi": "10.7907/xthf-1p70", "abstract": "Gravitational-wave astronomy is now a reality. During my time at Caltech, the Advanced LIGO and Virgo observatories have detected gravitational waves from dozens of compact binary coalescences. All of these gravitational-wave events occurred in the relatively local Universe. In the first part of this thesis, I will instead look towards the remote Universe, investigating what LIGO and Virgo may be able to learn about cosmologically-distant compact binaries via observation of the stochastic gravitational-wave background. The stochastic gravitational-wave background is composed of the incoherent superposition of all distant, individually-unresolvable gravitational-wave sources. I explore what we learn from study of the gravitational-wave background, both about the astrophysics of compact binaries and the fundamental nature of gravitational waves. Of course, before we can study the gravitational-wave background we must first detect it. I therefore present searches for the gravitational-wave background using data from Advanced LIGO's first two observing runs, obtaining the most stringent upper limits to date on strength of the stochastic background. Finally, I consider how one might validate an apparent detection of the gravitational-wave background, confidently distinguishing a true astrophysical signal from spurious terrestrial artifacts.
\r\n\r\nThe second part of this thesis concerns the search for electromagnetic counterparts to gravitational-wave events. The binary neutron star merger GW170817 was accompanied by a rich set of electromagnetic counterparts spanning nearly the entire electromagnetic spectrum. Beyond these counterparts, compact binaries may additionally generate powerful radio transients at or near their time of merger. First, I consider whether there is a plausible connection between this so-called \"prompt radio emission\" and fast radio bursts \u2014 enigmatic radio transients of unknown origin. Next, I present the first direct search for prompt radio emission from a compact binary merger using the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA). While no plausible candidates are identified, this effort successfully demonstrates the prompt radio follow-up of a gravitational-wave source, providing a blueprint for LIGO and Virgo follow-up in their O3 observing run and beyond.
" }, { "name": "Suter, Bethany Anne", "degree": "Senior Thesis", "year": "2020", "title": "Using Graviton EFT and Massive Gravity to Compute Gravitational Potentials for Black Hole Inspirals", "advisor": "Cheung, Clifford W.", "url": "https://resolver.caltech.edu/CaltechTHESIS:10212021-181920642", "creators": [ { "name": { "family": "Suter", "given": "Bethany Anne" }, "id": "Suter-Bethany-Anne", "orcid": "0000-0002-4503-5771", "display_name": "Suter, Bethany Anne" } ], "advisors": [ { "name": { "family": "Cheung", "given": "Clifford W." }, "id": "Cheung-Clifford", "orcid": "0000-0002-9983-9425", "role": "advisor", "display_name": "Cheung, Clifford W." } ], "committee": [ { "name": { "family": "Cheung", "given": "Clifford W." }, "id": "Cheung-Clifford", "orcid": "0000-0002-9983-9425", "role": "chair", "display_name": "Cheung, Clifford W." }, { "name": { "family": "Politzer", "given": "Hugh David" }, "id": "Politzer-H-D", "orcid": "0000-0002-4983-6621", "role": "member", "display_name": "Politzer, Hugh David" }, { "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/jh6b-bt24", "abstract": "This year, the LIGO detectors entered their third observing run and have been detecting black hole interactions with increasing precision and sensitivity. These detections have opened up a new way to compare the predictions of Einsteinian gravity with more exotic models. One of these models, massive gravity, is a concrete toy to use in testing these predictions. This project uses ideas from EFT and standard techniques from quantum field theory to calculate scattering amplitudes for scalar particles interacting via gravitons. We first calculated amplitudes up to the 1-looplevel assuming the standard massless graviton and then assuming a massive graviton. We then mapped these amplitudes to gravitational potentials for black holes. Future work will include looking at the different predictions of these two theories (massless and massive gravitons), and comparing them to black hole inspiral data to determine if the massive graviton theory could be a legitimate contender as a model for gravity." }, { "name": "Gossan, Sarah Elizabeth", "degree": "PhD", "year": "2019", "title": "Core-Collapse Supernova Physics in the Multi-Messenger Era", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:01312019-123521450", "creators": [ { "name": { "family": "Gossan", "given": "Sarah Elizabeth" }, "id": "Gossan-Sarah-Elizabeth", "orcid": "0000-0002-8138-9198", "display_name": "Gossan, Sarah Elizabeth" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Fuller", "given": "James" }, "id": "Fuller-J", "orcid": "0000-0002-4544-0750", "role": "chair", "display_name": "Fuller, James" }, { "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" }, { "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": "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/ZF1A-6394", "abstract": "Eighty-five years following the historic proposal that core-collapse supernovae accompanied the transition of evolved massive stars to neutron stars [1], the mechanism through which these collapsing stars explode remains uncertain. While supernovae are observed on a daily basis across the electromagnetic spectrum, neutrinos and gravitational waves, emitted from the very heart of the core-collapse supernova central engine, provide a direct glimpse of the dynamics driving the explosion. The joint gravitational wave and electromagnetic observations of a colliding neutron star binary system on 17th August 2017 heralded a new era for multi-messenger astronomy [2]. The next galactic core-collapse supernova presents an unparalleled opportunity to directly probe core-collapse supernova physics and the explosion mechanism.
\r\n\r\nThis thesis explores a number of topics in multi-messenger astronomy and core-collapse supernova physics. First, it tackles the observation problem; detailing an astrophysically motivated search protocol for gravitational waves from core-collapse supernovae triggered by observations of neutrino and/or electromagnetic counterparts. Applying these methods to a number of hypothetical observational scenarios, it presents sensitivity estimates for the second generation of gravitational wave interferometric detectors to both realistic and speculative emission mechanisms associated with core-collapse supernovae. Next, it addresses the prospects for post-detection inference; developing a Bayesian toolkit to interpret gravitational wave observations from core-collapse supernovae and augment current understanding of the explosion mechanism. A proof-of-principle study is also presented, using tailor-made simulations to demonstrate the viability of extracting the angular momentum distribution of nascent millisecond proto-neutron stars from their gravitational wave echoes. Thereafter, it considers the ramifications of failure to accurately capture proto-neutron star hydrodynamics in core-collapse supernova simulations; exploring the influence on the explosion mechanism of gravito-acoustic waves generated by convection in the proto-neutron star mantle. Finally, it ponders the impact of advances in multi-messenger astronomy and source modelling over the next twenty years on the understanding of core-collapse supernova physics.
" }, { "name": "Isi Ba\u00f1ales, Maximiliano", "degree": "PhD", "year": "2019", "title": "Fundamental Physics in the Era of Gravitational-Wave Astronomy: The Direct Measurement of Gravitational-Wave Polarizations and Other Topics", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:11042018-161928279", "creators": [ { "name": { "family": "Isi Ba\u00f1ales", "given": "Maximiliano" }, "id": "Isi-Ba\u00f1ales-Maximiliano", "orcid": "0000-0001-8830-8672", "display_name": "Isi Ba\u00f1ales, Maximiliano" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "chair", "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": "Patterson", "given": "Ryan B." }, "id": "Patterson-R-B", "orcid": "0000-0002-5787-9517", "role": "member", "display_name": "Patterson, Ryan B." }, { "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/S15R-3495", "abstract": "In this thesis, I explore several avenues for learning about fundamental physics from gravitational-wave (GW) observations. In particular, I focus on the phenomenological study of basic properties of GWs in ways that require minimal assumptions about the underlying nature of gravity. I place a special emphasis on GW polarizations, but also consider their speed and possible dispersion. To constrain possible modifications to general relativity, I develop data-analysis frameworks to measure these properties with both transient and persistent signals detected by ground-based detectors. This includes, among other results, the analysis of two LIGO and Virgo compact-binary detections, GW170814 and GW170817, to produce the first direct observational statements about the local geometry of GW polarizations. I also present constraints on the potential amplitude of nontensorial monochromatic signals from 200 known pulsars in the Milky Way and describe in detail the methods used to obtain them. Because stochastic signals will be a great resource for studying GW properties, I also carefully review the assumptions that go into standard stochastic analyses and explore their applicability beyond general relativity, concluding that those measurements will have to be interpreted carefully to make meaningful statements about corrections to Einstein\u2019s theory. Besides the properties of the waves themselves, I also study the prospect for using GWs as a means to uncover signatures of new ultralight bosons\u2014an exciting possibility that could bring particle physics into the reach of GW astronomy. I explore the potential of current and future detectors to detect these conjectured particles, concluding that third-generation instruments are certain to place theoretically interesting constraints. Because little can be done in the absence of signals, I also propose data-analysis methods to improve LIGO and Virgo\u2019s chances of detecting both transient and continuous signals. The latter have now been used to diagnose real detection candidates on several occasions.
" }, { "name": "Korth, William Zachary", "degree": "PhD", "year": "2019", "title": "Mitigating Noise in Interferometric Gravitational Wave Detectors", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:05292019-020613259", "creators": [ { "name": { "family": "Korth", "given": "William Zachary" }, "id": "Korth-William-Zachary", "orcid": "0000-0002-4422-1070", "display_name": "Korth, William Zachary" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "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": "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" }, { "name": { "family": "Schwab", "given": "Keith C." }, "id": "Schwab-K-C", "orcid": "0000-0001-8216-4815", "role": "member", "display_name": "Schwab, Keith C." } ], "option_major": [ "physics" ], "doi": "10.7907/4H7V-W213", "abstract": "Gravitational waves, first predicted by Einstein in 1916, eluded detection for nearly a century. These faint ripples in the fabric of spacetime, with typical strain amplitudes at the Earth on the order of |h| \u223c 10\u221222, carry secrets of the universe untold by electromagnetic radiation. Following decades of research and development, a network of terrestrial interferometric detectors succeeded in measuring the passing of a gravitational wave (GW150914) for the first time in 2015. Individual detectors within this network are currently said to be operating in a \u201csecond-generation\u201d configuration; over the next decade, planned upgrades will take these detectors beyond this into a new generation. This thesis concerns the characterization and reduction of noise in one of these second-generation detectors, Advanced LIGO, as well as efforts underway to improve its sensitivity in the coming years.
\r\n\r\nThe first part of this thesis is a detailed overview of gravitational waves, the history of gravitational wave detection, and a reasonably thorough description of the Advanced LIGO detector. Particular attention is paid to a pedagogical motivation of the optical configuration of Advanced LIGO with reference to its forebears. This part ends with an overview of the sources of noise limiting the sensitivity of Advanced LIGO, and an exposition of plans to reduce their influence in the future.
\r\n\r\nThe second part describes the development of a laser gyroscope for use in tilt sensing in Advanced LIGO, starting with a motivation of the work based on limitations in the area of seismic noise sensing and cancellation.
\r\n\r\nThe third part recounts the design, fabrication, testing, installation and commissioning of an important component of the Advanced LIGO detector: the output mode cleaner (OMC).
\r\n\r\nThe fourth part outlines a proposed scheme for reduction of quantum noise in gravitational wave detectors and other experiments. In particular, this scheme allows for the operation of a so-called \u201coptical spring\u201d cavity in such a way as to be largely immune from the deleterious effects of quantum radiation pressure noise.
\r\n\r\nThe fifth and final part describes progress towards a direct measurement of thermal noise in thin silicon ribbons, which is pertinent to the design of suspensions in future cryogenic gravitational wave detectors.
\r\n\r\nThis thesis has the internal LIGO document number P1900035.
" }, { "name": "Quintero, Eric Antonio", "degree": "PhD", "year": "2018", "title": "Improving the Performance and Sensitivity of Gravitational Wave Detectors", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:10162017-190056286", "creators": [ { "name": { "family": "Quintero", "given": "Eric Antonio" }, "id": "Quintero-Eric-Antonio", "orcid": "0000-0002-4269-3445", "display_name": "Quintero, Eric Antonio" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "committee": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "chair", "display_name": "Adhikari, Rana" }, { "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": "Zmuidzinas", "given": "Jonas" }, "id": "Zmuidzinas-J", "role": "member", "display_name": "Zmuidzinas, Jonas" }, { "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/Z9DZ06HS", "abstract": "The field of observational gravitational wave astronomy has begun in earnest, starting with the detection of the strain signal from the binary black hole merger GW150914 by the Laser Interferometer Gravitational-wave Observatory (LIGO) in 2015. The current incarnation of the LIGO observatories, known as Advanced LIGO, has achieved strain sensitivities on the order of 10\u221223/\u221aHz in the hundreds of Hz region, which has enabled unambiguous detection of astrophysical gravitational wave signals. Nevertheless, the scientific output from the LIGO observatories is constrained by the instrumental performance and sensitivity, as there remain many more distant and exotic sources to be observed.
\r\n\r\nThis thesis describes a few topics in experimental gravitational physics, broadly unified by the desire to improve the performance and sensitivity of gravitational wave interferometers. First, it describes an experimental effort to search for a novel form of nonlinear mechanical noise that may be relevant for the ultimate performance of the mirror sus- pension systems used throughout the instrument. Next, it summarizes work done at the CalTech 40m LIGO controls prototype to realize its fully operational state, and a novel automated controls algorithm developed and tested there that may be useful in simplifying the control of current and future interferometers. Finally, it describes work done on a system to identify and subtract unwanted noise couplings out of recorded aLIGO strain data in an automated fashion. The noise subtraction system applied to GW150914 is demonstrated to reduce the uncertainties of the black hole mass parameters by about 10%.
" }, { "name": "Hall, Evan Drew", "degree": "PhD", "year": "2017", "title": "Long-Baseline Laser Interferometry for the Detection of Binary Black-Hole Mergers", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:01302017-113507797", "creators": [ { "name": { "family": "Hall", "given": "Evan Drew" }, "id": "Hall-Evan-Drew", "orcid": "0000-0001-9018-666X", "display_name": "Hall, Evan Drew" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "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": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "member", "display_name": "Golwala, Sunil" }, { "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/Z9PG1PQ9", "abstract": "Late in 2015, gravitational physics reached a watershed moment with the first direct detections of gravitational waves. Two events, each from the coalescence of a binary black hole system, were detected by the Laser Interferometer Gravitational-wave Observatory (LIGO). At present, LIGO comprises two 4 km laser interferometers, one in Washington and the other in Louisiana; a third detector is planned to be installed in India. These interferometers, known as Advanced LIGO, belong to the so-called \u201csecond generation\u201d of gravitational-wave detectors. Compared to the first-generation LIGO detectors (Initial and Enhanced LIGO), these instruments use multi-stage active seismic isolation, heavier and higher-quality mirrors, and more laser power to achieve an unprecedented sensitivity to gravitational waves. In 2015, both Advanced LIGO detectors achieved a strain sensitivity better than 10-23/Hz1/2 at a few hundred hertz; ultimately, these detectors are designed to achieve a sensitivity of a few parts in 10-24/Hz1/2 at a few hundred hertz.
\r\n\r\nThis thesis covers several topics in gravitational physics and laser interferometry. First, it presents the design, control scheme, and noise performance of the Advanced LIGO detector in Washington during the first observing run (O1). Second, it discusses some issues relating to interferometer calibration, and the impact of calibration errors on astrophysical parameter estimation. Third, it discusses the prospects for using terrestrial and space-based laser interferometers as dark matter detectors.
\r\n\r\nThis thesis has the internal LIGO document number P1600295.
" }, { "name": "Driggers, Jennifer Clair", "degree": "PhD", "year": "2015", "title": "Noise Cancellation for Gravitational Wave Detectors", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:06052015-123753277", "creators": [ { "name": { "family": "Driggers", "given": "Jennifer Clair" }, "id": "Driggers-Jennifer-Clair", "orcid": "0000-0002-6134-7628", "display_name": "Driggers, Jennifer Clair" } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "committee": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "chair", "display_name": "Adhikari, Rana" }, { "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": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Murray", "given": "Richard M." }, "id": "Murray-R-M", "orcid": "0000-0002-5785-7481", "role": "member", "display_name": "Murray, Richard M." } ], "option_major": [ "physics" ], "doi": "10.7907/Z94F1NNP", "abstract": "The LIGO gravitational wave detectors are on the brink of making the first direct detections of gravi- tational waves. Noise cancellation techniques are described, in order to simplify the commissioning of these detectors as well as significantly improve their sensitivity to astrophysical sources. Future upgrades to the ground based detectors will require further cancellation of Newtonian gravitational noise in order to make the transition from detectors striving to make the first direct detection of gravitational waves, to observatories extracting physics from many, many detections. Techniques for this noise cancellation are described, as well as the work remaining in this realm." }, { "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": "Martynov, Denis V.", "degree": "PhD", "year": "2015", "title": "Lock Acquisition and Sensitivity Analysis of Advanced LIGO Interferometers", "advisor": "Adhikari, Rana", "url": "https://resolver.caltech.edu/CaltechTHESIS:05282015-142013480", "creators": [ { "name": { "family": "Martynov", "given": "Denis V." }, "id": "Martinov-Denis-V", "display_name": "Martynov, Denis V." } ], "advisors": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "advisor", "display_name": "Adhikari, Rana" } ], "committee": [ { "name": { "family": "Adhikari", "given": "Rana" }, "id": "Adhikari-R", "orcid": "0000-0002-5731-5076", "role": "chair", "display_name": "Adhikari, Rana" }, { "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": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "orcid": "0000-0002-9730-9463", "role": "member", "display_name": "Chen, Yanbei" }, { "name": { "family": "Murray", "given": "Richard M." }, "id": "Murray-R-M", "orcid": "0000-0002-5785-7481", "role": "member", "display_name": "Murray, Richard M." } ], "option_major": [ "physics" ], "doi": "10.7907/Z9Q81B1F", "abstract": "Laser interferometer gravitational wave observatory (LIGO) consists of two complex large-scale laser interferometers designed for direct detection of gravitational waves from distant astrophysical sources in the frequency range 10Hz - 5kHz. Direct detection of space-time ripples will support Einstein's general theory of relativity and provide invaluable information and new insight into physics of the Universe.
\r\n\r\nInitial phase of LIGO started in 2002, and since then data was collected during six science runs. Instrument sensitivity was improving from run to run due to the effort of commissioning team. Initial LIGO has reached designed sensitivity during the last science run, which ended in October 2010.
\r\n\r\nIn parallel with commissioning and data analysis with the initial detector, LIGO group worked on research and development of the next generation detectors. Major instrument upgrade from initial to advanced LIGO started in 2010 and lasted till 2014.
\r\n\r\nThis thesis describes results of commissioning work done at LIGO Livingston site from 2013 until 2015 in parallel with and after the installation of the instrument. This thesis also discusses new techniques and tools developed at the 40m prototype including adaptive filtering, estimation of quantization noise in digital filters and design of isolation kits for ground seismometers.
\r\n\r\nThe first part of this thesis is devoted to the description of methods for bringing interferometer to the linear regime when collection of data becomes possible. States of longitudinal and angular controls of interferometer degrees of freedom during lock acquisition process and in low noise configuration are discussed in details.
\r\n\r\nOnce interferometer is locked and transitioned to low noise regime, instrument produces astrophysics data that should be calibrated to units of meters or strain. The second part of this thesis describes online calibration technique set up in both observatories to monitor the quality of the collected data in real time. Sensitivity analysis was done to understand and eliminate noise sources of the instrument.
\r\n\r\nCoupling of noise sources to gravitational wave channel can be reduced if robust feedforward and optimal feedback control loops are implemented. The last part of this thesis describes static and adaptive feedforward noise cancellation techniques applied to Advanced LIGO interferometers and tested at the 40m prototype. Applications of optimal time domain feedback control techniques and estimators to aLIGO control loops are also discussed.
\r\n\r\nCommissioning work is still ongoing at the sites. First science run of advanced LIGO is planned for September 2015 and will last for 3-4 months. This run will be followed by a set of small instrument upgrades that will be installed on a time scale of few months. Second science run will start in spring 2016 and last for about 6 months. Since current sensitivity of advanced LIGO is already more than factor of 3 higher compared to initial detectors and keeps improving on a monthly basis, upcoming science runs have a good chance for the first direct detection of gravitational waves.
\r\n" }, { "name": "Singer, Leo Pound", "degree": "PhD", "year": "2015", "title": "The Needle in the 100 deg\u00b2 Haystack: The Hunt for Binary Neutron Star Mergers with LIGO and Palomar Transient Factory", "advisor": "Weinstein, Alan Jay; Kulkarni, Shrinivas R.", "url": "https://resolver.caltech.edu/CaltechTHESIS:12102014-223122387", "creators": [ { "name": { "family": "Singer", "given": "Leo Pound" }, "id": "Singer-Leo-Pound", "orcid": "0000-0001-9898-5597", "display_name": "Singer, Leo Pound" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Kulkarni", "given": "Shrinivas R." }, "id": "Kulkarni-S-R", "orcid": "0000-0001-5390-8563", "role": "co-advisor", "display_name": "Kulkarni, Shrinivas R." } ], "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": "Kulkarni", "given": "Shrinivas R." }, "id": "Kulkarni-S-R", "orcid": "0000-0001-5390-8563", "role": "member", "display_name": "Kulkarni, Shrinivas R." }, { "name": { "family": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "member", "display_name": "Ott, Christian D." }, { "name": { "family": "Reitze", "given": "David H." }, "id": "Reitze-D-H", "orcid": "0000-0002-5756-1111", "role": "member", "display_name": "Reitze, David H." } ], "option_major": [ "physics" ], "doi": "10.7907/Z9ZP442V", "abstract": "The Advanced LIGO and Virgo experiments are poised to detect gravitational waves (GWs) directly for the first time this decade. The ultimate prize will be joint observation of a compact binary merger in both gravitational and electromagnetic channels. However, GW sky locations that are uncertain by hundreds of square degrees will pose a challenge. I describe a real-time detection pipeline and a rapid Bayesian parameter estimation code that will make it possible to search promptly for optical counterparts in Advanced LIGO. Having analyzed a comprehensive population of simulated GW sources, we describe the sky localization accuracy that the GW detector network will achieve as each detector comes online and progresses toward design sensitivity. Next, in preparation for the optical search with the intermediate Palomar Transient Factory (iPTF), we have developed a unique capability to detect optical afterglows of gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Burst Monitor (GBM). Its comparable error regions offer a close parallel to the Advanced LIGO problem, but Fermi's unique access to MeV-GeV photons and its near all-sky coverage may allow us to look at optical afterglows in a relatively unexplored part of the GRB parameter space. We present the discovery and broadband follow-up observations (X-ray, UV, optical, millimeter, and radio) of eight GBM-IPTF afterglows. Two of the bursts (GRB 130702A / iPTF13bxl and GRB 140606B / iPTF14bfu) are at low redshift (z=0.145 and z = 0.384, respectively), are sub-luminous with respect to \"standard\" cosmological bursts, and have spectroscopically confirmed broad-line type Ic supernovae. These two bursts are possibly consistent with mildly relativistic shocks breaking out from the progenitor envelopes rather than the standard mechanism of internal shocks within an ultra-relativistic jet. On a technical level, the GBM--IPTF effort is a prototype for locating and observing optical counterparts of GW events in Advanced LIGO with the Zwicky Transient Facility." }, { "name": "Hodge, Kari Alison", "degree": "PhD", "year": "2014", "title": "The Search for Gravitational Waves from the Coalescence of Black Hole Binary Systems in Data from the LIGO and Virgo Detectors. Or: A Dark Walk through a Random Forest", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:06022014-104457554", "creators": [ { "name": { "family": "Hodge", "given": "Kari Alison" }, "id": "Hodge-Kari-Alison", "orcid": "0000-0002-1025-0420", "display_name": "Hodge, Kari Alison" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "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": "Golwala", "given": "Sunil" }, "id": "Golwala-S-R", "orcid": "0000-0002-1098-7174", "role": "member", "display_name": "Golwala, Sunil" }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "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/HY26-2059", "abstract": "The LIGO and Virgo gravitational-wave observatories are complex and extremely sensitive strain detectors that can be used to search for a wide variety of gravitational waves from astrophysical and cosmological sources. In this thesis, I motivate the search for the gravitational wave signals from coalescing black hole binary systems with total mass between 25 and 100 solar masses. The mechanisms for formation of such systems are not well-understood, and we do not have many observational constraints on the parameters that guide the formation scenarios. Detection of gravitational waves from such systems \u2014 or, in the absence of detection, the tightening of upper limits on the rate of such coalescences \u2014 will provide valuable information that can inform the astrophysics of the formation of these systems. I review the search for these systems and place upper limits on the rate of black hole binary coalescences with total mass between 25 and 100 solar masses. I then show how the sensitivity of this search can be improved by up to 40% by the the application of the multivariate statistical classifier known as a random forest of bagged decision trees to more effectively discriminate between signal and non-Gaussian instrumental noise. I also discuss the use of this classifier in the search for the ringdown signal from the merger of two black holes with total mass between 50 and 450 solar masses and present upper limits. I also apply multivariate statistical classifiers to the problem of quantifying the non-Gaussianity of LIGO data. Despite these improvements, no gravitational-wave signals have been detected in LIGO data so far. However, the use of multivariate statistical classification can significantly improve the sensitivity of the Advanced LIGO detectors to such signals." }, { "name": "Privitera, Stephen M.", "degree": "PhD", "year": "2014", "title": "The Importance of Spin for Observing Gravitational Waves from Coalescing Compact Binaries with LIGO and Virgo", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:05282014-160218103", "creators": [ { "name": { "family": "Privitera", "given": "Stephen M." }, "id": "Privitera-Stephen-M", "display_name": "Privitera, Stephen M." } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "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": "Ott", "given": "Christian D." }, "id": "Ott-C-D", "orcid": "0000-0003-4993-2055", "role": "member", "display_name": "Ott, Christian D." }, { "name": { "family": "Prince", "given": "Thomas A." }, "id": "Prince-T-A", "orcid": "0000-0002-8850-3627", "role": "member", "display_name": "Prince, Thomas A." }, { "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/Q6KC-1957", "abstract": "General Relativity predicts the existence of gravitational waves, which carry information about the physical and dynamical properties of their source. One of the many promising sources of gravitational waves observable by ground-based instruments, such as in LIGO and Virgo, is the coalescence of two compact objects (neutron star or black hole). Black holes and neutron stars sometimes form binaries with short orbital periods, radiating so strongly in gravitational waves that they coalesce on astrophysically short timescales. General Relativity gives precise predictions for the form of the signal emitted by these systems. The most recent searches for theses events used waveform models that neglected the effects of black hole and neutron star spin. However, real astrophysical compact objects, especially black holes, are expected to have large spins. We demonstrate here a data analysis infrastructure which achieves an improved sensitivity to spinning compact binaries by the inclusion of spin effects in the template waveforms. This infrastructure is designed for scalable, low-latency data analysis, ideal for rapid electromagnetic followup of gravitational wave events." }, { "name": "Patel, Pinkesh Kiritbhai", "degree": "PhD", "year": "2011", "title": "Search for Gravitational Waves from a Nearby Neutron Star Using Barycentric Resampling", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:09142010-170958877", "creators": [ { "name": { "family": "Patel", "given": "Pinkesh Kiritbhai" }, "id": "Patel-Pinkesh-Kiritbhai", "display_name": "Patel, Pinkesh Kiritbhai" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "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": "Hirata", "given": "Christopher M." }, "id": "Hirata-C-M", "orcid": "0000-0002-2951-4932", "role": "member", "display_name": "Hirata, Christopher M." }, { "name": { "family": "Hitlin", "given": "David G." }, "id": "Hitlin-D-G", "orcid": "0000-0003-4028-6982", "role": "member", "display_name": "Hitlin, David G." }, { "name": { "family": "Siemens", "given": "Xavier" }, "id": "Siemens-X", "orcid": "0000-0002-7778-2990", "role": "member", "display_name": "Siemens, Xavier" }, { "name": { "family": "Cutler", "given": "Curt J." }, "id": "Cutler-C-J", "orcid": "0000-0002-2080-1468", "role": "member", "display_name": "Cutler, Curt J." } ], "option_major": [ "physics" ], "doi": "10.7907/00AG-ZF69", "abstract": "Rapidly spinning neutron stars in our Galactic neighborhood are promising sources of quasi-monochromatic continuous gravitational waves observable by the current LIGO detectors. I describe a search done on the LIGO S5 data, looking for an isolated neutron star hypothesized to be at a distance of about 100 parsecs. This kind of search is computationally bound and is made possible by the implementation of barycentric resampling, which is described here as well. I also describe the work done at the Hanford LIGO site, while taking data for the Astrowatch program." }, { "name": "Ward, Robert Lawrence", "degree": "PhD", "year": "2010", "title": "Length Sensing and Control of a Prototype Advanced Interferometric Gravitational Wave Detector", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechTHESIS:05252010-134621351", "creators": [ { "name": { "family": "Ward", "given": "Robert Lawrence" }, "id": "Ward-Robert-Lawrence", "display_name": "Ward, Robert Lawrence" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "orcid": "0000-0002-0928-6784", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "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": "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" }, { "name": { "family": "Schwab", "given": "Keith C." }, "id": "Schwab-K-C", "orcid": "0000-0001-8216-4815", "role": "member", "display_name": "Schwab, Keith C." } ], "option_major": [ "physics" ], "doi": "10.7907/20SX-2935", "abstract": "There is a worldwide effort to directly detect gravitational radiation. The Laser Interferometer Gravitational Wave Observatory (LIGO) operates three kilometer-scale interferometric gravitational wave detectors at two sites: two in Hanford, WA and one in Livingston, LA. A significant upgrade, called Advanced LIGO, is planned for these detectors. The core work of this thesis involves using a 40m prototype interferometer on the Caltech campus to study length and sensing and control techniques for Advanced LIGO. The principal results are the development of a lock acquisition protocol for an advanced detector and a comparison of noise couplings between two gravitational wave signal extraction techniques, called RF and DC readout.
\r\n\r\nIn addition, a search in LIGO data was carried out for broadband, long-duration stochastic gravitational waves emitted from point sources. The results of this search are presented.
" }, { "name": "Keppel, Drew Garvin", "degree": "PhD", "year": "2009", "title": "Signatures and Dynamics of Compact Binary Coalescences and a Search in LIGO\u2019s S5 Data", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechETD:etd-05202009-115750", "creators": [ { "name": { "family": "Keppel", "given": "Drew Garvin" }, "id": "Keppel-Drew-Garvin", "display_name": "Keppel, Drew Garvin" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "role": "chair", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." }, { "name": { "family": "Prince", "given": "Thomas A." }, "id": "Prince-T-A", "role": "member", "display_name": "Prince, Thomas A." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/03MS-2W96", "abstract": "In this thesis, we probe several aspects of compact binary environments, focusing on results of orbits and collisions of compact objects. First, we describe a search for low-mass compact-binary-coalescence gravitational-wave signals in data from the LIGO detectors' most sensitive, longest-running science run to date (S5). We also go into detail on the interpretation of the results including its development. We then investigate the bounds on the mass of the graviton that could be achieved from the detection gravitational waves from a binary black hole merger. Last, we study the flow of momentum in compact binaries using the Landau-Lifshitz formalism.\r\n" }, { "name": "Goggin, Lisa Maria", "degree": "PhD", "year": "2008", "title": "A Search for Gravitational Waves from Perturbed Black Hole Ringdowns in LIGO Data", "advisor": "Weinstein, Alan Jay", "url": "https://resolver.caltech.edu/CaltechETD:etd-05232008-125947", "creators": [ { "name": { "family": "Goggin", "given": "Lisa Maria" }, "id": "Goggin-Lisa-Maria", "display_name": "Goggin, Lisa Maria" } ], "advisors": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "role": "advisor", "display_name": "Weinstein, Alan Jay" } ], "committee": [ { "name": { "family": "Weinstein", "given": "Alan Jay" }, "id": "Weinstein-Alan-J-Physics", "role": "chair", "display_name": "Weinstein, Alan Jay" }, { "name": { "family": "Lange", "given": "Andrew E." }, "id": "Lange-A-E", "role": "member", "display_name": "Lange, Andrew E." }, { "name": { "family": "Porter", "given": "Frank C." }, "id": "Porter-F-C", "role": "member", "display_name": "Porter, Frank C." }, { "name": { "family": "Chen", "given": "Yanbei" }, "id": "Chen-Yanbei", "role": "member", "display_name": "Chen, Yanbei" } ], "option_major": [ "physics" ], "doi": "10.7907/VKN2-K456", "abstract": "According to General Relativity a perturbed black hole will return to a stable configuration by the emission of gravitational radiation in a superposition of quasi-normal modes. Such a perturbation will occur due to the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform, which we refer to as a ringdown, is expected to be dominated by a single mode. As the waveform is well-known the method of matched filtering can be implemented to search for this signal using LIGO data. LIGO is sensitive to the dominant mode of perturbed black holes with masses between 10 and 500 Msun, the regime of intermediate-mass black holes, to a distance of up to 300 Mpc. We present a search for gravitational waves from black hole ringdowns using data from the fourth LIGO science run. We implement a blind analysis of the data. We use Monte Carlo simulations of the expected waveform, and an estimation of the background from timeslides to tune the search. We present an analysis of the waveform parameter estimation and estimate the efficiency of the search. As there were no gravitational wave candidates found, we place an upper limit on the rate of black hole ringdowns in the local universe." }, { "name": "Savov, Pavlin", "degree": "PhD", "year": "2008", "title": "Topics in Gravitational-Wave Physics", "advisor": "Thorne, Kip S.", "url": "https://resolver.caltech.edu/CaltechTHESIS:07152021-205059459", "creators": [ { "name": { "family": "Savov", "given": "Pavlin" }, "id": "Savov-Pavlin", "display_name": "Savov, Pavlin" } ], "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." } ], "option_major": [ "physics" ], "doi": "10.7907/72z7-n083", "abstract": "While the astrophysics community is on the brink of detecting the first gravitational-wave signal [1, 2, 3], efforts continue to improve the existing detectors and develop new technologies for future-generation detectors. In parallel, the need is rapidly growing for improved analyzes and interpretations of the science data that comes from the detectors. This thesis contributes to these issues with research results related to (i) the design of possible upgrades for the Advanced detectors for the ground-based Laser Interferometer Gravitational-wave Observatory (AdvLIGO) [4, 5, 6, 7] (i.e. for improved versions of the initial LIGO detectors [9, 10]), and (ii) future data analysis techniques for the Laser Interferometer Space Antenna (LISA) [11, 12] (a planned space-based gravitational-wave mission). More specifically:
\r\n\r\nCurrently, an international array of first-generation ground-based, laser-interferometer gravitational-wave detectors (consisting of LIGO, VIRGO [13, 14], GEO600 [15, 16] and TAMA300 [17]) is actively searching for gravitational waves in the frequency band (10 Hz { 10 kHz), with peak sensitivity at a few hundred Hertz. On September the 30th, 2007, the initial LIGO interferometers finished their Science Run 5 (S5) [18], which collected one year of triple coincidence data at the interferometers' design sensitivity. The next version of LIGO's interferometers, called Enhanced LIGO [19], with amplitude sensitivity improved by a factor about 2 (event rate increased by a factor 2\u00b3\u224310), is being implemented and will\r\ncollect data in science mode in 2009-10. Advanced LIGO is expected to begin operations around 2013. At the end of commissioning, it will have a factor ten better amplitude sensitivity than initial LIGO, which translates to a thousand-fold increase in event rate. Therefore, just a few hours of observations by AdvLIGO will be worth the entire lifetime of initial LIGO. Another significant advantage of the Advanced LIGO design is that it will allow tuning of the sensitivity as a function of frequency, so as to optimize searches for specific astrophysical sources with specific expected spectra.
\r\n\r\nLISA, the first system of space-based gravitational-wave interferometers, is planned for launch and science operation in 2018 or perhaps somewhat later, depending on political developments. It will operate with peak sensitivity around a few milliHertz and should detect galore of signals simultaneously. The lifetime of the mission is expected to be around five years.
\r\n\r\nThis thesis consists of four chapters: this introductory chapter, two chapters (2 and 3) dealing with research relevant to the technology for a possible upgrade of Advanced LIGO, and one chapter (4) relevant to data analysis for LISA. Specifically: Chapter 2 elucidates the influence of the shape (power profile) of an interferometer's arm-cavity light beams on a tilt instability, in which the tilt of an arm cavity mirror is driven by light pressure. Chapter 3 proves a duality relation between arm cavities with almost at mirrors (as originally planned for AdvLIGO) and cavities with almost concentric spherical mirrors (a design change that has been made, to control the tilt instability). I discovered and used this duality relation numerically in the research reported in Chapter 2, but only later, in collaboration with others, did I prove the duality relation analytically (Chapter 3). Chapter 4 reports details of and results from a Mock LISA Data Challenge in which gravitational wave signals from\r\n(mock) supermassive black-hole binaries were sought and found in simulated LISA data.
" }, { "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": "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": "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": "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": "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": "Rao, Shanti Raja", "degree": "PhD", "year": "2003", "title": "Mirror Thermal Noise in Interferometric Gravitational Wave Detectors", "advisor": "Libbrecht, Kenneth George", "url": "https://resolver.caltech.edu/CaltechETD:etd-05092003-153759", "creators": [ { "name": { "family": "Rao", "given": "Shanti Raja" }, "id": "Rao-Shanti-Raja", "display_name": "Rao, Shanti Raja" } ], "advisors": [ { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "role": "advisor", "display_name": "Libbrecht, Kenneth George" } ], "committee": [ { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "role": "chair", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Barish", "given": "Barry C." }, "id": "Barish-B-C", "role": "member", "display_name": "Barish, Barry C." }, { "name": { "family": "Mabuchi", "given": "Hideo" }, "id": "Mabuchi-H", "role": "member", "display_name": "Mabuchi, Hideo" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "display_name": "Thorne, Kip S." } ], "option_major": [ "physics" ], "doi": "10.7907/5W0V-QB90", "abstract": "The LIGO (Laser Interferometer Gravitational-wave Observatory) project has begun its search for gravitational waves, and efforts are being made to improve its ability to detect these. The LIGO observatories are long, Fabry-Perot-Michelson interferometers, where the interferometer mirrors are also the gravitational wave test masses. LIGO is designed to detect the ripples in spacetime caused by cataclysmic astrophysical events, with a target gravitational wave minimum strain sensitivity of 4 x 10^-22 around 100 Hz. The Advanced LIGO concept calls for an order of magnitude improvement in strain sensitivity, with a better signal to noise ratio to increase the rate of detection of events. Some of Advanced LIGO's major requirements are improvements over the LIGO design for thermal noise in the test mass substrates and reflective coatings.
\r\n\r\nThermal noise in the interferometer mirrors is a significant challenge in LIGO's development. This thesis reviews the theory of test mass thermal noise and reports on several experiments conducted to understand this theory.v\r\n\r\n
Experiments to measure the thermal expansion of mirror substrates and coatings use the photothermal effect in a cross-polarized Fabry-Perot interferometer, with displacement sensitivity of 10^-15 m/rHz. Data are presented from 10 Hz to 4kHz on solid aluminum, and on sapphire, BK7, and fused silica, with and without commercial TiO2/SiO2 dielectric mirror coatings. The substrate contribution to thermal expansion is compared to theories by Cerdonio et al. and Braginsky, Vyatchanin, and Gorodetsky. New theoretical models are presented for estimating the coating contribution to the thermal expansion. These results can also provide insight into how heat flows between coatings and substrates relevant to predicting coating thermoelastic noise.
\r\n\r\nThe Thermal Noise Interferometer (TNI) project is a interferometer built specifically to study thermal noise, and this thesis describes its construction and commissioning. Using LIGO-like designs, components, and processes, the TNI has a minimum length noise in each of two arm cavities of 5 x 10^-18 m/rHz around 1 kHz.
" }, { "name": "Evans, Matthew John", "degree": "PhD", "year": "2002", "title": "Lock Acquisition in Resonant Optical Interferometers", "advisor": "Barish, Barry C.", "url": "https://resolver.caltech.edu/CaltechETD:etd-12062004-115632", "creators": [ { "name": { "family": "Evans", "given": "Matthew John" }, "id": "Evans-Matthew-John", "display_name": "Evans, Matthew John" } ], "advisors": [ { "name": { "family": "Barish", "given": "Barry C." }, "id": "Barish-B-C", "role": "advisor", "display_name": "Barish, Barry C." } ], "committee": [ { "name": { "family": "Barish", "given": "Barry C." }, "id": "Barish-B-C", "role": "chair", "display_name": "Barish, Barry C." }, { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "member", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "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" } ], "option_major": [ "physics" ], "doi": "10.7907/N1J2-M098", "abstract": "The LIGO (Laser Interferometric Gravitational-wave Observatory) project, and other projects around the world, are currently planning to use long-baseline (> 1 km) interferometers to directly detect gravitational radiation from astrophysical sources. In this work we present a framework for lock acquisition, the process by which an initially uncontrolled resonant interferometer is brought to its operating point. Our approach begins with the identification of a path which takes the detector from the uncontrolled state to the operational state. The properties of the detector's outputs along this path, embodied in the sensing matrix, must be determined and parameterized in terms of measureables. Finally, a control system which can compute the inverse of the sensing matrix, apply it to the incoming signals, and make the resulting signals available for feedback is needed to close the control loop. This formalism was developed and explored extensively in simulation and was subsequently applied to the LIGO interferometers. Results were in agreement with expectation within error, typically \u00b120% on the sensing matrix elements, and the method proved capable of bringing a high-finesse power-recycled Fabry-Perot-Michelson interferometer (a LIGO detector) to its operating point." }, { "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": "Mason, James Edward", "degree": "PhD", "year": "2001", "title": "Signal Extraction and Optical Design for an Advanced Gravitational Wave Interferometer", "advisor": "Vogt, Rochus E.; Porter, Frank C.", "url": "https://resolver.caltech.edu/CaltechTHESIS:04302012-152752095", "creators": [ { "name": { "family": "Mason", "given": "James Edward" }, "id": "Mason-James-Edward", "display_name": "Mason, James Edward" } ], "advisors": [ { "name": { "family": "Vogt", "given": "Rochus E." }, "id": "Vogt-R-E", "role": "advisor", "display_name": "Vogt, Rochus E." }, { "name": { "family": "Porter", "given": "Frank C." }, "id": "Porter-F-C", "orcid": "0000-0003-1948-8889", "role": "advisor", "display_name": "Porter, Frank C." } ], "committee": [ { "name": { "family": "Libbrecht", "given": "Kenneth George" }, "id": "Libbrecht-K-G", "orcid": "0000-0002-8744-3298", "role": "chair", "display_name": "Libbrecht, Kenneth George" }, { "name": { "family": "Mabuchi", "given": "Hideo" }, "id": "Mabuchi-H", "role": "member", "display_name": "Mabuchi, Hideo" }, { "name": { "family": "Thorne", "given": "Kip S." }, "id": "Thorne-K-S", "role": "member", "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": "Porter", "given": "Frank C." }, "id": "Porter-F-C", "orcid": "0000-0003-1948-8889", "role": "member", "display_name": "Porter, Frank C." }, { "name": { "family": "Vogt", "given": "Rochus E." }, "id": "Vogt-R-E", "role": "member", "display_name": "Vogt, Rochus E." } ], "option_major": [ "physics" ], "doi": "10.7907/amrv-a028", "abstract": "The LIGO project is two 4 km baseline interferometers which are currently being\r\nconstructed in the quest to directly detect gravitational radiation. Concurrent with\r\nthis effort is research aimed at increasing the strain sensitivity of the initial interferometers to 2.5 x 10^(-23)/\u221aHz. The optical configuration, which defines the detector gain and bandwidth, is one such area of research. Resonant sideband extraction (RSE) is the configuration which is proposed for advanced LIGO. RSE allows for much more freedom in the optimization of the detector response compared to the\r\ninitial configuration.
\r\n\r\nThe principle of RSE is examined in the context of a three mirror coupled cavity.\r\nThe effect of optical losses on the design of an RSE interferometer is discussed. Two\r\nmodel optimizations of the interferometer design are done: one for binary inspiral\r\nsources and one for periodic sources at 1 kHz.
\r\n\r\nAn optical heterodyne signal extraction scheme is proposed to sense the deviation\r\nof the mirrors away from their nominal positions, and to read out the gravitational\r\nwave signal. The scheme is applied to the two model interferometers previously\r\ndesigned, and its performance is analyzed for each case. Allowable residual deviations of the common mode degrees of freedom are also derived.
\r\n\r\nA tabletop prototype of an RSE interferometer has been constructed to demonstrate\r\nboth the viability of the proposed signal extraction scheme and the tunability\r\nof the RSE interferometer. Good agreement on both counts is found between the\r\nmeasured experimental data and the modeled predictions.
\r\n\r\nThe coupling of laser frequency and amplitude noise into the gravitational wave\r\nreadout port is analyzed for the RSE configuration assuming the proposed gravitational\r\nwave signal readout scheme. Specifications for the allowable laser frequency\r\nand amplitude noise, as well as allowable residual deviations of the differential mode\r\ndegrees of freedom, are derived for the two model interferometers.
\r\n" }, { "name": "Zucker, Michael Edward", "degree": "PhD", "year": "1989", "title": "Experiments with a Laser Interferometric Gravitational Wave Antenna", "advisor": "Drever, Ronald W. P.", "url": "https://resolver.caltech.edu/CaltechTHESIS:10252013-143448203", "creators": [ { "name": { "family": "Zucker", "given": "Michael Edward" }, "id": "Zucker-Michael-Edward", "display_name": "Zucker, Michael Edward" } ], "advisors": [ { "name": { "family": "Drever", "given": "Ronald W. P." }, "id": "Drever-R-W-P", "role": "advisor", "display_name": "Drever, Ronald W. P." } ], "committee": [ { "name": { "family": "Drever", "given": "Ronald W. P." }, "id": "Drever-R-W-P", "role": "chair", "display_name": "Drever, Ronald W. 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": "Prince", "given": "Thomas A." }, "id": "Prince-T-A", "orcid": "0000-0002-8850-3627", "role": "member", "display_name": "Prince, Thomas A." }, { "name": { "family": "Gomez", "given": "Ricardo" }, "id": "Gomez-R", "role": "member", "display_name": "Gomez, Ricardo" } ], "option_major": [ "physics" ], "doi": "10.7907/T5D0-4N31", "abstract": "Sources and effects of astrophysical gravitational radiation are explained briefly to motivate discussion of the Caltech 40 meter antenna, which employs laser interferometry to monitor proper distances between inertial test masses. Practical considerations in construction of the apparatus are described. Redesign of test mass systems has resulted in a reduction of noise from internal mass vibrations by up to two orders of magnitude at some frequencies. A laser frequency stabilization system was developed which corrects the frequency of an argon ion laser to a residual fluctuation level bounded by the spectral density \u221as\u03bd(f) \u2264 60 \u00b5Hz/\u221aHz, at fluctuation frequencies near 1.2 kHz. These and other improvements have contributed to reducing the spectral density of equivalent gravitational wave strain noise to \u221aSh(f) \u2248 10\u207b\u00b9\u2079/\u221a Hz at these frequencies.
\r\n\r\nFinally, observations made with the antenna in February and March of 1987 are described. Kilohertz-band gravitational waves produced by the remnant of the recent supernova are shown to be theoretically unlikely at the strength required for confident detection in this antenna (then operating at poorer sensitivity than that quoted above). A search for periodic waves in the recorded data, comprising Fourier analysis of four 105-second samples of the antenna strain signal, was used to place new upper limits on periodic gravitational radiation at frequencies between 305 Hz and 5 kHz. In particular, continuous waves of any polarization are ruled out above strain amplitudes of 1.2 x 10\u207b\u00b9\u2078 R.M.S. for waves emanating from the direction of the supernova, and 6.2 x 10\u207b\u00b9\u2079 R.M.S. for waves emanating from the galactic center, between 1.5 and 4 kilohertz. Between 305 Hz and 5kHz no strains greater than 1.2 x 10\u207b\u00b9\u2077 R.M.S. were detected from either direction. Limitations of the analysis and potential improvements are discussed, as are prospects for future searches.
" } ]