The utilization of several tracers of large-scale structure has led to important advancements in our understanding of the history of the Universe, in both characterizing cosmological initial conditions and late-time astrophysics. With the onset of dramatic changes in data volume and quality through existing and near-future experiments, methodologies that harness the information content in imaging and spectroscopic datasets while mitigating systematic effects will have larger impacts than ever before. In this thesis, we present a variety of analysis techniques for galaxy surveys of discrete objects and diffuse light measurements that are demonstrated on both synthetic and real datasets.
\r\n\r\nIn Chapter 2, we develop techniques for measurement of near-infrared extragalactic background light (EBL) anisotropies, focusing on imager data from the Cosmic Infrared Background ExpeRiment (CIBER). Through improvements in methodology and data quality, we present fluctuation measurements in Chapter 3 that are five to ten times more sensitive on several arcminute to degree scales than existing studies, with clear detection of diffuse anisotropies exceeding those from the Poisson noise of individual stars and galaxies. In Chapter 4, we present a new suite of empirically-based galaxy simulations which we use to examine the diversity of galaxies that will be observed with SPHEREx, NASA's upcoming MIDEX mission. We then develop and apply redshift estimation techniques to synthetic SPHEREx observations generated from these simulations, demonstrating the ability to measure the distances to several hundred million galaxies over the full sky. In Chapter 5, we describe a formalism for modeling point-like and diffuse signals in astronomical images, which can be used for robust photometry in the presence of diffuse contaminants, extraction of diffuse signals in the presence of point source contaminants, and more general component separation. In Chapter 6 we apply this modeling framework to Herschel-SPIRE observations of galaxy cluster RX J1347.5-1145, measuring the diffuse thermal Sunyaev-Zel'dovich (tSZ) effect at high significance and using relativistic corrections of the tSZ spectrum to constrain the intra-cluster medium temperature, for which we find consistent estimates with independent X-ray measurements.
", "doi": "10.7907/52md-wx74", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16252", "collection": "thesis", "collection_id": "16252", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11272023-225643701", "primary_object_url": { "basename": "Aralis_Caltech_Thesis.pdf", "content": "final", "filesize": 66683130, "license": "other", "mime_type": "application/pdf", "url": "/16252/1/Aralis_Caltech_Thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "SuperCDMS SNOLAB, HVeV Run 3, and Development of KIPM Detectors", "author": [ { "family_name": "Aralis", "given_name": "Taylor Benjamin", "orcid": "0000-0002-3501-6948", "clpid": "Aralis-Taylor-Benjamin" } ], "thesis_advisor": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" } ], "thesis_committee": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Hitlin", "given_name": "David G.", "orcid": "0000-0003-4028-6982", "clpid": "Hitlin-D-G" }, { "family_name": "Wise", "given_name": "Mark B.", "orcid": "0000-0002-9125-801X", "clpid": "Wise-M-B" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Dark matter is the theorized source of many observed large-scale gravitational effects. It is dark in the sense that it lacks any heretofore measurable direct interaction with the electromagnetic spectrum. Being unable to rely on absorption, reflection, or emission of photons makes studying dark matter particularly challenging. Excluding neutrinos, which fail to explain the observed large-scale effects, dark matter has never been conclusively identified in a local laboratory experiment. There are many proposed models that could explain both our large-scale observations and our lack of local observations while still allowing for the possibility of local observation. Ultra-sensitive direct-detection experiments attempt to make precisely such observations. Confirmed detection of a new stable particle would provide important information for improving our understanding of both dark matter and cosmological models.
\r\n\r\nThe SuperCDMS SNOLAB experiment is a direct-detection experiment designed with an initial focus on particle masses < 10 GeV. The experiment will measure both phonon and ionization signals in kg-scale semiconductor crystals held at cryogenic temperatures. In this thesis, I describe the experiment with emphasis on the ionization readout. I also detail the characterization process I performed on the ionization amplifier's low-power high-electron-mobility transistors (HEMTs).
\r\n\r\nSuperCDMS high-voltage eV-resolution (HVeV) detectors are gram-scale detectors designed to achieve single electron-hole-pair sensitivity. The first HVeV direct-detection search produced world-leading exclusion limits for dark-matter masses down to ~1 MeV. Here, I present my work analyzing the third search using such detectors. Run 3 was the first to include multiple detectors operated simultaneously and achieved an order of magnitude greater exposure than previous runs. I report the resulting exclusion limits for electron-coupled, dark-photon, and axion-like-particle dark matter.
\r\n\r\nLastly, I discuss work performed at Caltech towards the development of kinetic-inductance phonon-mediated (KIPM) dark-matter detectors. KIPM detectors use frequency-multiplexed kinetic inductance detectors (KIDs) and have the potential for excellent event-position reconstruction and background rejection. KIPMs also present a clear path towards sub-eV resolution on event recoil energy. Such detectors could be used as part of a payload upgrade in SuperCDMS SNOLAB. KIPMs could also be used in smaller-scale experiments similar to SuperCDMS HVeV.
", "doi": "10.7907/gxjp-0863", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16452", "collection": "thesis", "collection_id": "16452", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05302024-213502241", "type": "thesis", "title": "Thermal Kinetic Inductance Detector (TKIDs) Camera: A Pathfinder mm-Wave Polarimeter", "author": [ { "family_name": "Minutolo", "given_name": "Lorenzo", "orcid": "0000-0002-4876-112X", "clpid": "Minutolo-Lorenzo" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "O'Brient", "given_name": "Roger", "orcid": "0000-0002-4987-6375", "clpid": "O'Brient-Roger" }, { "family_name": "Chen", "given_name": "Yanbei", "orcid": "0000-0002-9730-9463", "clpid": "Chen-Yanbei" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Thermal kinetic inductance detectors (TKIDs) are novel, superconductive, frequency-multiplexed bolometric detectors that promise the same noise performance as traditional transition-edge superconducting bolometers, but with ease of scalability to large array formats. This research starts with TKIDs being in the early stage of development. Readout hardware and strategies were developed to characterize the first batches of devices, still in the chips form containing a few detectors. The success of the TKIDs chips lead to a more in-depth exploration of the detector physics and the possibility to scale from chips containing tens of detectors to tiles counting hundreds. Novel characterization techniques were developed to deal with the testing of the arrays in a laboratory environment. Finally, the characterization of a science grade tile is detailed.", "doi": "10.7907/pmh8-gy97", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:15061", "collection": "thesis", "collection_id": "15061", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11052022-133519365", "primary_object_url": { "basename": "Understanding_the_Cosmological_Evolution_of_Galaxies_with_Intensity_Mapping.pdf", "content": "final", "filesize": 14263442, "license": "other", "mime_type": "application/pdf", "url": "/15061/1/Understanding_the_Cosmological_Evolution_of_Galaxies_with_Intensity_Mapping.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Understanding the Cosmological Evolution of Galaxies with Intensity Mapping", "author": [ { "family_name": "Sun", "given_name": "Guochao", "orcid": "0000-0003-4070-497X", "clpid": "Sun-Guochao" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Chang", "given_name": "Tzu-Ching", "orcid": "0000-0001-5929-4187", "clpid": "Chang-Tzu-Ching" }, { "family_name": "Furlanetto", "given_name": "Steven R.", "orcid": "0000-0002-0658-1243", "clpid": "Furlanetto-S-R" }, { "family_name": "Hallinan", "given_name": "Gregg W.", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G-W" }, { "family_name": "Hillenbrand", "given_name": "Lynne A.", "orcid": "0000-0001-8638-0320", "clpid": "Hillenbrand-L-A" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The intensity mapping (IM) technique has been proven to be a powerful addition to the toolkit for understanding the cosmology and astrophysics behind cosmic structure formation. From the nearby universe to the epochs of cosmic dawn and reionization, by mapping the large-scale structure traced by a certain intensity field, IM provides an economical and a holistic view of the formation and evolution of galaxies in the cosmological text, in a way that is highly complementary to traditional methods based on individual galaxy detections. In this thesis, I present a number of theoretical perspectives on how the IM technique, especially line intensity mapping (LIM), can help us better understand the cosmological evolution of galaxies --- all the way to the intriguing era of first galaxy formation.
\r\n\r\nIn the first part of this thesis, I use the Tomographic Ionized-carbon Mapping Experiment (TIME), a pathfinder for LIM observations of the 158-micron [CII] line emission from the epoch of reionization (EoR), as an example to demonstrate the aspects of high-redshift star-forming galaxies that can be practically studied with LIM. In Chapter 2, I elaborate the science cases of TIME for the investigations of the EoR using the redshifted [CII] line as a star formation rate tracer, and the cosmic molecular gas content near cosmic noon using CO rotational lines redshifted into the same observing bandpass. The results also guide the design of future phases of TIME. In Chapter 3, I introduce and demonstrate an effective masking strategy for the cleaning of line interlopers such as CO from the [CII] data TIME will measure. Using proxies of CO emitters built from stacking analysis of deep, near-infrared selected galaxies, it provides a practical solution to the notoriously challenging line confusion problem for LIM data analysis.
\r\n\r\nThe second part of this thesis focuses on the concept of multi-tracer LIM, namely the synergies among LIM observations of multiple distinct tracers. Forward modeling and inference tools based on semi-analytic models and semi-numerical simulations are developed to explore and showcase the scientific potential of multi-tracer LIM. In Chapter 4, I describe a self-consistent, semi-analytic framework for modeling a variety of LIM signals from the multi-phase interstellar medium (ISM) of galaxies, and use it to illustrate the potential application of LIM to shed light on mean ISM properties of galaxies. In Chapters 5 and 6, I present a new semi-numerical simulation called LIMFAST that is developed for efficiently and self-consistently simulating a plethora of IM signals in the high-redshift universe. The LIMFAST code is particularly tailored for revealing the connection between the EoR and the first galaxy formation with multiple cosmological probes.
\r\n\r\nFinally, in the last part of thesis, I show two example case studies where the IM technique is applied to investigate the astrophysics of star formation in galaxies. In Chapter 7, I present an updated analysis of the contributions from star-forming galaxies at z\u22735 to the observed cosmic near-infrared background. Imprints that reveal the formation histories of first stars, including the prospects for detecting them with the forthcoming space missions, are also studied. In Chapter 8, I describe a novel way to constrain the global star formation law of galaxies using LIM measurements of the baryonic acoustic oscillations.
\r\n\r\nAs an emerging technique in observational cosmology, IM is no doubt still in its early days, promising exciting scientific returns while facing various practical challenges. Studies described in this thesis represent only a tiny fraction of the theoretical efforts from the community, but they pave the way for more follow-up investigations that will eventually turn IM into a truly rewarding endeavor.
", "doi": "10.7907/fzqw-2m61", "publication_date": "2023", "thesis_type": "phd", "thesis_year": "2023" }, { "id": "thesis:15169", "collection": "thesis", "collection_id": "15169", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05142023-053312973", "type": "thesis", "title": "Constraints on the Polarized Dust and the Cosmic Microwave Background Using BICEP / Keck Array Series of Telescopes", "author": [ { "family_name": "Kefeli", "given_name": "Sinan", "orcid": "0000-0002-8604-3516", "clpid": "Kefeli-Sinan" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" }, { "family_name": "Hopkins", "given_name": "Philip F.", "orcid": "0000-0003-3729-1684", "clpid": "Hopkins-P-F" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "BK18 data consists of all the data taken by the Bicep2, Keck Array, and Bicep3 CMB polarization experiments, as well as publicly available WMAP and Planck maps. The Q/U maps reach depths of 2.8, 2.8 and 8.8 \u00b5KCMB arcmin at 95, 150, and 220 GHz respectively over an effective area of ~ 600 square degrees at 95 GHz and ~ 400 square degrees at 150 and 220 GHz. The likelihood analysis yields r < 0.036 at 95% confidence, with unbiased simulations yielding \u03c3(r)=0.009. The multi-component model that is used in the likelihood analysis consists of lensed-\u039bCDM, tensor modes, and polarize dust and synchrotron components. Foreground model consists of thirteen parameters, some of which are estimated in the likelihood analysis with priors derived from larger regions of sky from WMAP and Planck: amplitude, spectral index, and spatial index for dust and sync, as well as their spatial correlation; dust frequency decorrelation and tensor-to-scalar-ratio. Spectral index for dust emission no longer requires a prior taken from measurements on other regions of the sky.
\r\n\r\nIn the BK papers, EE spectra are not used to derive the model, however the spectra agree well with the assumption that EE/BB = 2 for dust. In this thesis we expand on this assumption, sharing the results for the EE/BB estimate for dust when this is a free parameter in the likelihood calculation. We use the map-based and spectral-based band difference approaches to include E-modes in the likelihood analysis. In the BK papers, dust parameters are assumed to be constant over the sky. We will go over the likelihood work on the spatial constraints for the dust spectral index to examine the validity of this assumption.
", "doi": "10.7907/7a55-p606", "publication_date": "2023", "thesis_type": "phd", "thesis_year": "2023" }, { "id": "thesis:15203", "collection": "thesis", "collection_id": "15203", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05232023-174453276", "primary_object_url": { "basename": "AhmedSoliman_Thesis_Final.pdf", "content": "final", "filesize": 32483299, "license": "other", "mime_type": "application/pdf", "url": "/15203/1/AhmedSoliman_Thesis_Final.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "BICEP Array Detectors and Instrumentation at 30/40 GHz: Design, Performance, and Deployment to the South Pole for Constraining Primordial Gravitational Waves", "author": [ { "family_name": "Mohamed Soliman", "given_name": "Ahmed Mohamed", "orcid": "0009-0007-9335-1326", "clpid": "Mohamed-Soliman-Ahmed-Mohamed" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Barish", "given_name": "Barry C.", "orcid": "0000-0001-6386-7371", "clpid": "Barish-B-C" }, { "family_name": "O'Brient", "given_name": "Roger", "orcid": "0000-0002-4987-6375", "clpid": "O'Brient-Roger" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_eng" } ], "abstract": "The discovery of the Cosmic Microwave Background (CMB) in the 1960s has provided strong observational evidence for the Big Bang cosmological model to describe the origin and evolution of the universe. The theory of cosmic inflation was developed in the 1980s to account for the initial density perturbations by a period of exponential expansion in the early Universe to solve the horizon, flatness and monopole problems. Many inflation models predict potentially detectable primordial gravitational-waves (PGWs) background that imprint a B-mode polarization pattern in the CMB. The amplitude of the inflationary B-mode polarization depends on the energy scale of inflation and is parameterized by the tensor-to-scalar ratio r. The detection of a B-mode pattern would open a new window to probe the energy scale at the beginning of time when the universe was a mere fraction of a second old after the Big Bang.
\r\n\r\nThe BICEP/Keck collaboration is building a series of experiments located at the Amundsen-Scott South Pole Station to map the polarization of the CMB at degree angular scales using small-aperture telescopes. Our latest BICEP/Keck publications use data collected through 2018 and report the strongest constraints r0.05 < 0.036 at 95% confidence. The current sensitivity on r is limited by the variance from the gravitational lensing. BICEP/Keck is starting a collaboration with the South Pole Telescope (SPT) team to develop delensing techniques to improve future constraints on r. Characterizing Galactic foregrounds, especially synchrotron emission, remains a priority in order to improve constraints as statistical sensitivity continues to improve. The motivation for this thesis is to develop a highly sensitive receiver at 30 and 40 GHz, at frequencies where the synchrotron foreground dominates. BICEP Array represents the latest phase in the BICEP/Keck experiments, and will map the polarization of the CMB at 30/40, 95, 150, and 220/270 GHz. BICEP Array will search for PGWs with unprecedented sensitivity levels on r by characterizing and removing Galactic synchrotron and dust emission from our maps of the CMB.
\r\n\r\nMy PhD thesis focuses on the technology development for high sensitivity detectors and instrumentation to successfully deploy the first BICEP Array receiver at 30 GHz and 40 GHz to the South Pole in order to constrain the Galactic synchrotron foreground. My dissertation presents the receiver design and performance. I will first explain the engineering design principles, the fabrication and a laboratory demonstration of single-color antenna-coupled Transition Edge Sensor (TES) bolometers. Secondly, I will discuss the design and demonstration of dual-color detectors at 30 and 40 GHz that gain receiver sensitivity by increasing the optical throughput and bandwidth of each pixel. I also developed microstrip diplexer circuits that divide the detector bandwidth into two CMB observing channels. I optimized this approach to design the dual-color bowtie-coupled detector at 90/150 GHz. Thirdly, I will introduce a new wide-band corrugated focal plane module design to minimize the beam mismatch systematic at 30 and 40 GHz bands simultaneously. Our receivers map polarization of the CMB by taking the difference between co-located and orthogonally polarized pair of detectors. Polarized beam difference measurements show a differential beam response due to a shift between the polarization beam centers within a pixel due to an electromagnetic interaction with the focal plane frame. The residual beams leak a temperature to polarization (T-P) in the CMB polarization maps and can produce a false B-mode signal that introduces non-negligible systematic errors for BICEP Array measurements to come with improved sensitivity. The wide-band design reduces this effect and associated systematic errors for 30 and 40 GHz receiver. I also developed a new single-band corrugated focal plane module design for 150 GHz receiver. I performed laboratory measurements of these designs at 30, 40, and 150 GHz to verify the modelled response. The corrugation design will also be extended to the 220/270 GHz receiver. Fourthly, I will show my contributions to the receiver deployment, integration and calibration during the first 2020 observing season. The measurements will include the full optical characterization of the detector camera, in-lab and on-sky sensitivity at the South Pole. I will also describe the tests done to diagnose the challenges during the first season and new upgrades during the second 2022 season to improve the overall sensitivity of the receiver. Improved detector modules have been installed during the 2023 season to further boost the mapping speed for measuring the synchrotron foreground.
\r\n\r\nThe technologies developed for BICEP Array feed into capabilities for the upcoming CMB-S4 program. For example, I used similar methods to design a diplexer for a CMB-S4 dual-color feedhorn-coupled detector design at 90/150 GHz. I will also detail my work on the cryogenic implementation and test of an Adiabatic Demagnetization Refrigerator suitable for demonstrating 100 mK CMB-S4 detector arrays in a prototype 95/150 GHz telescope planned to observe on the BICEP Array.
", "doi": "10.7907/srdx-w019", "publication_date": "2023", "thesis_type": "phd", "thesis_year": "2023" }, { "id": "thesis:15006", "collection": "thesis", "collection_id": "15006", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08222022-081848931", "type": "thesis", "title": "The Development and Performance of the First BICEP Array Receiver at 30 and 40 GHz for Measuring the Polarized Synchrotron Foreground", "author": [ { "family_name": "Zhang", "given_name": "Cheng", "orcid": "0000-0001-8288-5823", "clpid": "Zhang-Cheng" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" }, { "family_name": "Chen", "given_name": "Yanbei", "orcid": "0000-0002-9730-9463", "clpid": "Chen-Yanbei" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The existence of the CMB marks a big success of the lambda cold dark matter standard model, which describes the universe\u2019s evolution with six free parameters. The inflationary theory was added to the picture in the \u201980s to explain the initial conditions of the universe. Scalar perturbations from inflation seeded the formation of the large-scale structure and produced the curl-free E-mode polarization pattern in the CMB. On the other hand, tensor fluctuations sourced primordial gravitational waves (PGW), which could leave unique imprints in the CMB polarization: the gradient-free B-mode pattern. The amplitude of B modes is directly related to the tensor-to-scalar ratio r of the primordial fluctuations, which indicates the energy scale of inflation. The detection of the primordial B modes will be strong supporting evidence of inflation and give us opportunities to study physics at energy scales far beyond what can ever be accessed in laboratory experiments on the Earth.
\r\n\r\nCurrently, the main challenge for the B-mode experiments is to separate the primordial B modes from those sourced by matter between us and the last scattering surface: the galactic foregrounds and the gravitational lensing effect. The two most important foregrounds are thermal dust and synchrotron, which have very different spectral properties from the CMB. Thus the key to foreground cleaning is the high sensitivity data at multiple frequency bands and the accurate modeling of the foregrounds in data analyses and simulations. In this dissertation, I present my work on ISM and dust property studies which enriched our understanding of the foregrounds.
\r\n\r\nThe BICEP/Keck (BK) experiments build a series of polarization-sensitive microwave telescopes targeting degree-scale B-modes from the early universe. The latest publication from the collaboration with data taken through 2018 reported tensor-to-scalar ratio r0.05 < 0.036 at 95% C.L., providing the tightest constraint on the primordial tensor mode.
\r\n\r\nBICEP Array is the latest generation of the series experiments. The final configuration of the BICEP Array has four BICEP3-class receivers spanning six frequency bands, aiming to achieve \u03c3(r) \u227e 0.003. The first receiver of the BICEP Array is at 30 and 40 GHz, constraining the synchrotron foregrounds. In this dissertation, I cover the development of this new receiver focusing on the design and performance of the detectors. I report on the characterizing and diagnosing tests for the receiver during its first few observing seasons.
", "doi": "10.7907/bfsb-6438", "publication_date": "2023", "thesis_type": "phd", "thesis_year": "2023" }, { "id": "thesis:14299", "collection": "thesis", "collection_id": "14299", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:07122021-033018615", "primary_object_url": { "basename": "Thesis_Cheng_Yun_Ting.pdf", "content": "final", "filesize": 6404023, "license": "other", "mime_type": "application/pdf", "url": "/14299/1/Thesis_Cheng_Yun_Ting.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Cosmology and Astrophysics with Intensity Mapping", "author": [ { "family_name": "Cheng", "given_name": "Yun-Ting", "orcid": "0000-0002-5437-0504", "clpid": "Cheng-Yun-Ting" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Steidel", "given_name": "Charles C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" }, { "family_name": "Hopkins", "given_name": "Philip F.", "orcid": "0000-0003-3729-1684", "clpid": "Hopkins-P-F" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" }, { "family_name": "Chang", "given_name": "Tzu-Ching", "orcid": "0000-0001-5929-4187", "clpid": "Chang-Tzu-Ching" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Intensity mapping (IM) has emerged as a promising technique to probe the largescale structures and galaxy formation and evolution across cosmic history. As IM measures the aggregate emission from all sources, it can overcome the limitation of conventional detection-based observations, where the emission from diffuse populations and high-redshift faint galaxies cannot be resolved individually. As several IM experiments will come online in the next decade, demand for IM modeling and data analysis strategies has increased. In this thesis, we present a range of analysis techniques, theoretical modeling, and data analysis results related to IM.
\r\n\r\nIn Chapter 2, we aim to answer the question: When should we use IM? We present a formalism to describe both IM and galaxy detection (GD) approaches, and use it to quantify their individual performance when measuring the large-scale structure (LSS). With this formalism, we can identify the scenarios where each approach is advantageous. We also develop a simple metric for determining the optimal strategy to map the LSS with future experiments.
\r\n\r\nIn Chapters 3 and 4, we interrogate methods for improving the line intensity mapping (LIM) analysis. LIM traces the three-dimensional structure of the universe by probing the emission field from a spectral line. One particular challenge for LIM is to separate the target line signals from interloper lines along the line of sight in order to extract the desired cosmological and astrophysical information. Previously proposed methods of line de-blending, such as masking and cross-correlation, rely on the external galaxy tracers, but sometimes a galaxy catalog with sufficient depth and sky coverage does not exist. Therefore, we develop two new methods for performing line de-confusion that do not require any external information. The first method (Chapter 3) uses the distinct shape of large-scale two-dimensional power spectra of signals and interlopers to distinguish the line emission from different redshifts. The second method (Chapter 4) reconstructs the intensity maps of individual lines from LIM data in the phase space, using multiple lines from the same source to identify the source redshift. We show that both of our methods are able to effectively extract desired line signals from the upcoming LIM experiments.
\r\n\r\nIn Chapter 5, we discuss the application of IM for studying the extragalactic background light (EBL), the integrated light from all sources of emission in the universe. Previous studies on the fluctuations of the EBL indicate that the intra-halo light (IHL) has a significant contribution to the near-infrared EBL. Chapter 5 presents the results on probing the IHL using a stacking analysis of images from the Cosmic Infrared Background Experiment (CIBER). CIBER is a rocket-borne experiment designed to image and perform photometry of the near-infrared EBL. Our results suggest that at z \u223c 0.3 the IHL comprises a large fraction of light associated with \u223c L\u2217 galaxies, implying that the IHL accounts for a non-negligible fraction of the near-infrared cosmic radiation budget.
\r\n\r\nIn Chapter 6, we present a forecast on the EBL constraints with the upcoming SPHEREx mission. We consider cross correlating SPHEREx intensity maps with galaxy catalogs from several current and future surveys. Our model predicts that the EBL spectrum as a function of redshift can be detected from the local universe to the epoch of reionization.
\r\n\r\nThe analysis techniques developed in this thesis can help better extract the information from the IM data; the future IM experiments will extend our current works on investigating the EBL. Therefore, the research in this thesis provides important toolkits and foundations for upcoming IM experiments.
", "doi": "10.7907/p41n-8698", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:13683", "collection": "thesis", "collection_id": "13683", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04272020-121646677", "primary_object_url": { "basename": "thesis-jhunacek-20200427b.pdf", "content": "final", "filesize": 45490715, "license": "other", "mime_type": "application/pdf", "url": "/13683/1/thesis-jhunacek-20200427b.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "TIME: A Millimeter-Wavelength Grating Spectrometer Array for [CII] / CO Intensity Mapping", "author": [ { "family_name": "Hunacek", "given_name": "Jonathon Robert", "orcid": "0000-0001-7066-226X", "clpid": "Hunacek-Jonathon-Robert" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Hopkins", "given_name": "Philip F.", "orcid": "0000-0003-3729-1684", "clpid": "Hopkins-P-F" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "In this thesis I review the design, fabrication, and initial engineering deployment of the TIME (Tomographic Ionized-carbon Mapping Experiment) instrument. TIME seeks to make a first detection of the clustering amplitude of the power spectrum of redshifted [CII] emission from the Epoch of Reionization (z = 5-9). [CII], the 157.7 \u00b5m fine-structure line of singly ionized carbon, traces star formation on large scales, providing a new method for constraining the contribution of star formation to the Reionization process. [CII] intensity mapping complements traditional galaxy surveys by using spatially-broad beams to integrate signal from the many faint sources thought to be responsible for the bulk of the integrated emission from galaxies. TIME covers the 200-300 GHz atmospheric window, which also enables the study of lower-redshift CO emission (z = 0.5-2), a tracer of molecular gas in the period following the peak of cosmic star formation. The full TIME instrument consists of 32 single-polarization grating spectrometers with a resolution R ~ 100. Each spectrometer consists of an input feedhorn coupled to parallel plate waveguide with a curved diffraction grating, which focuses the diffracted light onto an output arc populated by 60 transition-edge sensor (TES) bolometers at 250 mK. The 1920 total detectors couple to the output of the parallel plate waveguide with a direct-absorbing micro-mesh and are organized into buttable arrays covering 4 spatial by either 12 (HF) or 8 (LF) spectral pixels. A partial TIME instrument was field tested in early 2019 on the ARO APA 12m dish at Kitt Peak. We intend to return to Kitt Peak in late 2020 to begin initial science observations.
\r\n", "doi": "10.7907/hp2n-8495", "publication_date": "2020", "thesis_type": "phd", "thesis_year": "2020" }, { "id": "thesis:11125", "collection": "thesis", "collection_id": "11125", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:07182018-144446266", "type": "thesis", "title": "Characterization and Improvement of the Thermal Stability of TES Bolometers", "author": [ { "family_name": "Sonka", "given_name": "Rita Frances", "orcid": "0000-0002-1187-9781", "clpid": "Sonka-Rita-Frances" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Steinbach", "given_name": "Bryan A.", "orcid": "0000-0001-6544-7469", "clpid": "Steinbach-B-A" } ], "thesis_committee": [ { "family_name": "Stone", "given_name": "Edward C.", "orcid": "0000-0002-2010-5462", "clpid": "Stone-E-C" }, { "family_name": "Libbrecht", "given_name": "Kenneth George", "orcid": "0000-0002-8744-3298", "clpid": "Libbrecht-K-G" }, { "family_name": "Frautschi", "given_name": "Steven C.", "clpid": "Frautschi-S-C" }, { "family_name": "Politzer", "given_name": "Hugh David", "orcid": "0000-0002-4983-6621", "clpid": "Politzer-H-D" }, { "family_name": "Refael", "given_name": "Gil", "orcid": "0009-0007-4566-8441", "clpid": "Refael-G" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Steinbach", "given_name": "Bryan A.", "orcid": "0000-0001-6544-7469", "clpid": "Steinbach-B-A" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The successful detection and characterization of the B-modes in the Cosmic Microwave Background (CMB) would dramatically illuminate the physics of the inflationary era. The Observational Cosmology Group is iterating on bolometers in an attempt to detect this signal. The previous detector design became unstable in parts of its transition when adjusted for 220/270 GHz frequencies, limiting its use.
\r\n \r\nWe study the mechanism of instability in these transition edge sensor (TES) bolometers used for ground based observations of the Cosmic Microwave Background (CMB) at 270GHz. The instability limits the range of useful operating resistances of the TES down to \u224850% of the TES normal resistance (R_n), and due to variations in detector properties and optical loading within a column of multiplexed detectors, limits the effective on sky yield to \u224867 %.
\r\n\r\nThrough comparison of 7 new detector thermal capacity designs and measurements of the electrical impedance of the detectors, we show the instability is due to the increased bolometer leg G for higher-frequency detection inducing decoupling of the palladium-gold heat capacity from the thermistor. We demonstrate experimentally that the limiting thermal resistance is due to the small cross sectional area of the silicon nitride bolometer island, and so is easily fixed by layering palladium-gold over an oxide protected TES. The resulting detectors can be biased down to a resistance \u224810% of Rn, improving the effective on-sky yield to \u224893%.
\r\n\r\nWe also investigate a possibly related, unexpected slope in the Aluminum calibration TES transition and determine that it is not due to phase separation, even accounting for the science TES thermal instability.
\r\n", "doi": "10.7907/4v3d-7k67", "publication_date": "2018", "thesis_type": "senior_major", "thesis_year": "2018" }, { "id": "thesis:10838", "collection": "thesis", "collection_id": "10838", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04272018-205538217", "type": "thesis", "title": "Studying the Extragalactic Background Light with the Second Cosmic Infrared Background ExpeRiment, CIBER-2", "author": [ { "family_name": "Lanz", "given_name": "Alicia Elaine", "orcid": "0000-0003-2565-1558", "clpid": "Lanz-Alicia-Elaine" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Harrison", "given_name": "Fiona A.", "orcid": "0000-0003-2992-8024", "clpid": "Harrison-F-A" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Fluctuations in the extragalactic background light trace emission from the entire history of galaxy formation, including emission from early luminous sources prior to the reionization of the universe. The formation of the first luminous objects represents an important transition in the evolution of the universe from its smooth initial state to the clumpy, highly ordered state observable today. However, these objects are faint and diffuse and not well studied; direct observations of their emission are needed to constrain current numerical simulations of the nonlinear evolution of the early universe. A number of recent near-infrared measurements show excess spatial power at large angular scales inconsistent with models of z < 5 emission from galaxies. These measurements have been interpreted as arising from either redshifted emission of early luminous objects, such as stellar and quasar emission from the epoch of reionization, or the combined intra-halo light from stars thrown out of more recent galaxies during merging activity at lower redshifts. Though astrophysically distinct, both interpretations arise from faint, low surface brightness source populations that are difficult to detect except by statistical approaches using careful observations with suitable instruments. The key to determining the source of these background anisotropies will be wide-field imaging measurements spanning multiple bands from the optical to the near-infrared.
\r\n\r\nThe Cosmic Infrared Background ExpeRiment 2 (CIBER-2) will measure spatial anisotropies in the extragalactic infrared background caused by cosmological structure using six broad spectral bands. The experiment uses three 2048 x 2048 Hawaii-2RG near-infrared arrays in three cameras coupled to a single 28.5 cm telescope housed in a reusable sounding rocket-borne payload. A small portion of each array will also be combined with a linear-variable filter to make absolute measurements of the spectrum of the extragalactic background with high spatial resolution for deep subtraction of Galactic starlight. The large field of view and multiple spectral bands make CIBER-2 unique in its sensitivity to fluctuations predicted by models of lower limits on the luminosity of the first stars and galaxies and in its ability to distinguish between primordial and foreground anisotropies. This work encompasses the scientific motivation for CIBER-2 and describes details of the instrument design and verification prior to flight.
", "doi": "10.7907/CN9Y-MB61", "publication_date": "2018", "thesis_type": "phd", "thesis_year": "2018" }, { "id": "thesis:11014", "collection": "thesis", "collection_id": "11014", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06042018-002455152", "primary_object_url": { "basename": "Hui_Howard_2018_2.pdf", "content": "final", "filesize": 37313561, "license": "other", "mime_type": "application/pdf", "url": "/11014/7/Hui_Howard_2018_2.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Measuring the Polarization of the Cosmic Microwave Background with BICEP3", "author": [ { "family_name": "Hui", "given_name": "Howard", "orcid": "0000-0001-5812-1903", "clpid": "Hui-Howard" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" }, { "family_name": "Fuller", "given_name": "James", "orcid": "0000-0002-4544-0750", "clpid": "Fuller-J" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Inflation, a period of accelerated expansion in the early Universe, is postulated to answer the horizon, flatness and monopole problems in the standard model of the Universe. This inflationary scenario generically predicts the existence of primordial gravitational waves, which would leave an unique B-mode polarization pattern in the Cosmic Microwave Background. Detection of the primordial B modes at degree angular scales would be a direct evidence for inflation; and the amplitude, parametrized by the tensor-to-scalar ratio r, would allow us to probe the energy scale at 10-35 second after the Big Bang.
\r\n\r\nThe Bicep/Keck Array experiment is a series of telescopes located at the Amundsen-Scott South Pole Station designed to measure the CMB polarization at degree angular scales. The latest result in Bicep/Keck Array, using data collected up to 2015, and combined with other external data, set upper limits on r < 0.06 at 95% confidence. Bicep3 is the latest addition in the experiment, deployed to South Pole in 2015, and started science observation in 2016. It is a 520 mm aperture, compact two-lens refracting telescope at 95 GHz. With 2500 detectors, it achieved instantaneous sensitivity of 9.1μK√s and 7.3μK√s for 2016 and 2017, respectively. After two year of observations, Bicep3 is estimated to reach a map depth of 3.8μK-arcmin. This is the most sensitive polarization measurement at 95 GHz to date.
\r\n\r\nThis dissertation provides an overview of the Bicep3 instrument design. In particular, the performance of the sub-Kelvin focal plane structure, antenna-coupled transition edge sensor and time domain multiplexing SQUID readout system. We discuss various calibration methods used to probe instrument sensitivity and systematics. Finally, we review the analysis pipeline, and some preliminary results from Bicep3.
\r\n", "doi": "10.7907/G8ET-FD62", "publication_date": "2018", "thesis_type": "phd", "thesis_year": "2018" }, { "id": "thesis:11125", "collection": "thesis", "collection_id": "11125", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:07182018-144446266", "type": "thesis", "title": "Characterization and Improvement of the Thermal Stability of TES Bolometers", "author": [ { "family_name": "Sonka", "given_name": "Rita Frances", "orcid": "0000-0002-1187-9781", "clpid": "Sonka-Rita-Frances" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Steinbach", "given_name": "Bryan A.", "orcid": "0000-0001-6544-7469", "clpid": "Steinbach-B-A" } ], "thesis_committee": [ { "family_name": "Stone", "given_name": "Edward C.", "orcid": "0000-0002-2010-5462", "clpid": "Stone-E-C" }, { "family_name": "Libbrecht", "given_name": "Kenneth George", "orcid": "0000-0002-8744-3298", "clpid": "Libbrecht-K-G" }, { "family_name": "Frautschi", "given_name": "Steven C.", "clpid": "Frautschi-S-C" }, { "family_name": "Politzer", "given_name": "Hugh David", "orcid": "0000-0002-4983-6621", "clpid": "Politzer-H-D" }, { "family_name": "Refael", "given_name": "Gil", "orcid": "0009-0007-4566-8441", "clpid": "Refael-G" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Steinbach", "given_name": "Bryan A.", "orcid": "0000-0001-6544-7469", "clpid": "Steinbach-B-A" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The successful detection and characterization of the B-modes in the Cosmic Microwave Background (CMB) would dramatically illuminate the physics of the inflationary era. The Observational Cosmology Group is iterating on bolometers in an attempt to detect this signal. The previous detector design became unstable in parts of its transition when adjusted for 220/270 GHz frequencies, limiting its use.
\r\n \r\nWe study the mechanism of instability in these transition edge sensor (TES) bolometers used for ground based observations of the Cosmic Microwave Background (CMB) at 270GHz. The instability limits the range of useful operating resistances of the TES down to \u224850% of the TES normal resistance (R_n), and due to variations in detector properties and optical loading within a column of multiplexed detectors, limits the effective on sky yield to \u224867 %.
\r\n\r\nThrough comparison of 7 new detector thermal capacity designs and measurements of the electrical impedance of the detectors, we show the instability is due to the increased bolometer leg G for higher-frequency detection inducing decoupling of the palladium-gold heat capacity from the thermistor. We demonstrate experimentally that the limiting thermal resistance is due to the small cross sectional area of the silicon nitride bolometer island, and so is easily fixed by layering palladium-gold over an oxide protected TES. The resulting detectors can be biased down to a resistance \u224810% of Rn, improving the effective on-sky yield to \u224893%.
\r\n\r\nWe also investigate a possibly related, unexpected slope in the Aluminum calibration TES transition and determine that it is not due to phase separation, even accounting for the science TES thermal instability.
\r\n", "doi": "10.7907/4v3d-7k67", "publication_date": "2018", "thesis_type": "senior_major", "thesis_year": "2018" }, { "id": "thesis:10047", "collection": "thesis", "collection_id": "10047", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02062017-171647432", "type": "thesis", "title": "Superconducting Nonlinear Kinetic Inductance Devices", "author": [ { "family_name": "Kher", "given_name": "Aditya Shreyas", "orcid": "0000-0002-5994-428X", "clpid": "Kher-Aditya-Shreyas" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" }, { "family_name": "Schwab", "given_name": "Keith C.", "orcid": "0000-0001-8216-4815", "clpid": "Schwab-K-C" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_eng" } ], "abstract": "We describe a novel class of devices based on the nonlinearity of the kinetic inductance of a superconducting thin film. By placing a current-dependent inductance in a microwave resonator, small currents can be measured through their effect on the resonator\u2019s frequency. By using a high-resistivity material for the film and nanowires as kinetic inductors, we can achieve a large coefficient of nonlinearity to improve device sensitivity. We demonstrate a current sensitivity of 8 pA/√Hz, making this device useful for transition-edge sensor (TES) readout and other cutting-edge applications. An advantage of these devices is their natural ability to be multiplexed in the frequency domain, enabling large detector arrays for TES-based instruments. A traveling-wave version of the device, consisting of a thin-film microwave transmission line, is also sensitive to small currents as they change the phase length of the line due to their effect on its inductance. We demonstrate a current sensitivity of 5 pA/√Hz for this version of the device, making it also suitable for TES readout as well as other current-detection applications. It has the advantage of multi-gigahertz bandwidth and greater dynamic range, offering a different approach to the resonator version of the device. Finally, we also demonstrate a transmission-line resonator version of the device that combines some of the advantages of the nanowire resonator and the traveling-wave device. This version of the device has high dynamic range but can also be easily multiplexed in the frequency domain.
\r\n\r\nA lumped-element resonator similar to the first device can be placed in a loop configuration to make it sensitive to magnetic fields. We demonstrate an example of such a device whose sensitivity could ultimately reach levels similar to those of state-of-the-art DC SQUIDs, making it potentially useful for many magnetometry applications given its ease of multiplexing. Finally, a similar microwave resonator is shown to exhibit parametric gain of up to 29 dB in the presence of a strong pump tone. The noise performance of this parametric amplifier approaches the quantum limit, making it useful for applications in quantum information and metrology.
", "doi": "10.7907/Z9JQ0Z1F", "publication_date": "2017", "thesis_type": "phd", "thesis_year": "2017" }, { "id": "thesis:9139", "collection": "thesis", "collection_id": "9139", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09042015-035149228", "type": "thesis", "title": "The Astrophysics of Strongly Interacting Systems", "author": [ { "family_name": "Nerella", "given_name": "Tejaswi Venumadhav", "orcid": "0000-0002-1661-2138", "clpid": "Nerella-Tejaswi-Venumadhav" } ], "thesis_advisor": [ { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" } ], "thesis_committee": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Ott", "given_name": "Christian D.", "orcid": "0000-0003-4993-2055", "clpid": "Ott-C-D" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "div_pma" } ], "abstract": "This thesis presents investigations in four areas of theoretical astrophysics: the production of sterile neutrino dark matter in the early Universe, the evolution of small-scale baryon perturbations during the epoch of cosmological recombination, the effect of primordial magnetic fields on the redshifted 21-cm emission from the pre-reionization era, and the nonlinear stability of tidally deformed neutron stars.
\r\n\r\nIn the first part of the thesis, we study the asymmetry-driven resonant production of 7 keV-scale sterile neutrino dark matter in the primordial Universe at temperatures T >~ 100 MeV. We report final DM phase space densities that are robust to uncertainties in the nature of the quark-hadron transition. We give transfer functions for cosmological density fluctuations that are useful for N-body simulations. We also provide a public code for the production calculation.
\r\n\r\nIn the second part of the thesis, we study the instability of small-scale baryon pressure sound waves during cosmological recombination. We show that for relevant wavenumbers, inhomogenous recombination is driven by the transport of ionizing continuum and Lyman-alpha photons. We find a maximum growth factor less than ≈ 1.2 in 107 random realizations of initial conditions. The low growth factors are due to the relatively short duration of the recombination epoch.
\r\n\r\nIn the third part of the thesis, we propose a method of measuring weak magnetic fields, of order 10-19 G (or 10-21 G if scaled to the present day), with large coherence lengths in the inter galactic medium prior to and during the epoch of cosmic reionization. The method utilizes the Larmor precession of spin-polarized neutral hydrogen in the triplet state of the hyperfine transition. We perform detailed calculations of the microphysics behind this effect, and take into account all the processes that affect the hyperfine transition, including radiative decays, collisions, and optical pumping by Lyman-alpha photons.
\r\n\r\nIn the final part of the thesis, we study the non-linear effects of tidal deformations of neutron stars (NS) in a compact binary. We compute the largest three- and four-mode couplings among the tidal mode and high-order p- and g-modes of similar radial wavenumber. We demonstrate the near-exact cancellation of their effects, and resolve the question of the stability of the tidally deformed NS to leading order. This result is significant for the extraction of binary parameters from gravitational wave observations.
\r\n", "doi": "10.7907/Z900001N", "publication_date": "2016", "thesis_type": "phd", "thesis_year": "2016" }, { "id": "thesis:8958", "collection": "thesis", "collection_id": "8958", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06012015-163200704", "primary_object_url": { "basename": "teply_grant_2015_thesis.pdf", "content": "final", "filesize": 15369733, "license": "other", "mime_type": "application/pdf", "url": "/8958/1/teply_grant_2015_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Measurement of the Polarization of the Cosmic Microwave Background with the BICEP2 and Keck Array Telescopes", "author": [ { "family_name": "Teply", "given_name": "Grant Paul", "clpid": "Teply-Grant-Paul" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Spiropulu", "given_name": "Maria", "orcid": "0000-0001-8172-7081", "clpid": "Spiropulu-M" }, { "family_name": "Dor\u00e9", "given_name": "Olivier P.", "orcid": "0000-0001-7432-2932", "clpid": "Dor\u00e9-O" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Precision polarimetry of the cosmic microwave background (CMB) has become a mainstay of observational cosmology. The \u039bCDM model predicts a polarization of the CMB at the level of a few \u03bcK, with a characteristic E-mode pattern. On small angular scales, a B-mode pattern arises from the gravitational lensing of E-mode power by the large scale structure of the universe. Inflationary gravitational waves (IGW) may be a source of B-mode power on large angular scales, and their relative contribution to primordial fluctuations is parameterized by a tensor-to-scalar ratio r. BICEP2 and Keck Array are a pair of CMB polarimeters at the South Pole designed and built for optimal sensitivity to the primordial B-mode peak around multipole l ~ 100. The BICEP2/Keck Array program intends to achieve a sensitivity to r \u2265 0.02. Auxiliary science goals include the study of gravitational lensing of E-mode into B-mode signal at medium angular scales and a high precision survey of Galactic polarization. These goals require low noise and tight control of systematics. We describe the design and calibration of the instrument. We also describe the analysis of the first three years of science data. BICEP2 observes a significant B-mode signal at 150 GHz in excess of the level predicted by the lensed-\u039bCDM model, and Keck Array confirms the excess signal at > 5\u03c3. We combine the maps from the two experiments to produce 150 GHz Q and U maps which have a depth of 57 nK deg (3.4 \u03bcK arcmin) over an effective area of 400 deg2 for an equivalent survey weight of 248000 \u03bcK2. We also show preliminary Keck Array 95 GHz maps. A joint analysis with the Planck collaboration reveals that much of BICEP2/Keck Array's observed 150 GHz signal at low l is more likely a Galactic dust foreground than a measurement of r. Marginalizing over dust and r, lensing B-modes are detected at 7.0\u03c3 significance.", "doi": "10.7907/Z9XP72WM", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:7866", "collection": "thesis", "collection_id": "7866", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06072013-113004037", "type": "thesis", "title": "Testing Inflationary Cosmology with the BICEP1 and BICEP2 Experiments", "author": [ { "family_name": "Aikin", "given_name": "Randol Wallace", "clpid": "Aikin-Randol-Wallace" } ], "thesis_advisor": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Filippone", "given_name": "Bradley W.", "orcid": "0000-0002-2618-2688", "clpid": "Filippone-B-W" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Recent observations of the temperature anisotropies of the cosmic microwave background (CMB) favor an inflationary paradigm in which the scale factor of the universe inflated by many orders of magnitude at some very early time. Such a scenario would produce the observed large-scale isotropy and homogeneity of the universe, as well as the scale-invariant perturbations responsible for the observed (10 parts per million) anisotropies in the CMB. An inflationary epoch is also theorized to produce a background of gravitational waves (or tensor perturbations), the effects of which can be observed in the polarization of the CMB. The E-mode (or parity even) polarization of the CMB, which is produced by scalar perturbations, has now been measured with high significance. Con- trastingly, today the B-mode (or parity odd) polarization, which is sourced by tensor perturbations, has yet to be observed. A detection of the B-mode polarization of the CMB would provide strong evidence for an inflationary epoch early in the universe\u2019s history.
\r\n\r\nIn this work, we explore experimental techniques and analysis methods used to probe the B- mode polarization of the CMB. These experimental techniques have been used to build the Bicep2 telescope, which was deployed to the South Pole in 2009. After three years of observations, Bicep2 has acquired one of the deepest observations of the degree-scale polarization of the CMB to date. Similarly, this work describes analysis methods developed for the Bicep1 three-year data analysis, which includes the full data set acquired by Bicep1. This analysis has produced the tightest constraint on the B-mode polarization of the CMB to date, corresponding to a tensor-to-scalar ratio estimate of r = 0.04\u00b10.32, or a Bayesian 95% credible interval of r < 0.70. These analysis methods, in addition to producing this new constraint, are directly applicable to future analyses of Bicep2 data. Taken together, the experimental techniques and analysis methods described herein promise to open a new observational window into the inflationary epoch and the initial conditions of our universe.
", "doi": "10.7907/z9vx0df2", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7094", "collection": "thesis", "collection_id": "7094", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05302012-095444014", "type": "thesis", "title": "Searching for Primordial Gravitational Waves at Degree Scales from the South Pole", "author": [ { "family_name": "Brevik", "given_name": "Justus Albert", "orcid": "0000-0002-8058-5197", "clpid": "Brevik-Justus-Albert" } ], "thesis_advisor": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Adhikari", "given_name": "Rana", "orcid": "0000-0002-5731-5076", "clpid": "Adhikari-R" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We report on the preliminary performance of the Bicep2 mm-wave polarimeter, deployed in 2009 to the South Pole and will observe through 2012. Bicep2 is currently imaging the polarization of the cosmic microwave background at 150 GHz using an array of 512 antenna-coupled superconducting bolometers. It has been designed for high sensitivity and low systematics in order to pursue the primordial B-mode polarization signal. The instrument and its characterization are presented in this thesis, with particular attention to the detectors and readout system. The instrument sensitivity, mapping speed are discussed along with the expected constraint on the scalar-to-tensor ratio that should be made from one year of data.", "doi": "10.7907/E6Z2-CV94", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:5995", "collection": "thesis", "collection_id": "5995", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08172010-183547836", "primary_object_url": { "basename": "Sullivan_thesis_(FINAL).pdf", "content": "final", "filesize": 34555058, "license": "other", "mime_type": "application/pdf", "url": "/5995/1/Sullivan_thesis_(FINAL).pdf", "version": "v4.0.0" }, "type": "thesis", "title": "CIBER: A Near-Infrared Probe of the Epoch of Reionization", "author": [ { "family_name": "Sullivan", "given_name": "Ian Sorensen", "clpid": "Sullivan-Ian-Sorensen" } ], "thesis_advisor": [ { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Bock", "given_name": "James J.", "orcid": "0000-0002-5710-5212", "clpid": "Bock-J-J" }, { "family_name": "Cooray", "given_name": "Asantha", "orcid": "0000-0002-3892-0190", "clpid": "Cooray-A" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The Cosmic Infrared Background Experiment (CIBER) is a NASA sounding rocket payload that was first launched in February 2009. CIBER consists of four co-aligned instruments designed to study the near-Infrared background by measuring fluctuations and the absolute spectrum. The platform of a sounding rocket enables observations of the near-Infrared background outside of narrow atmospheric windows that are uncontaminated by airglow.\r\n \r\nCIBER uses two spectrometers to measure the absolute brightness spectrum of the extragalactic near-Infrared background. One, a high-resolution Fabry-Perot spectometer, is tuned to the 854.5 nm CaII line of the solar spectrum, and is designed to measure the absolute brightness of the Zodiacal Light directly, which is the source of greatest uncertainty in the near-Infrared background spectrum. The second spectrometer measures the near-Infrared background spectrum from 700 nm to 1800 nm, spanning the wavelength range where a Lyman limit cutoff feature from reionization could appear. \r\n\r\nCIBER also houses two Infrared imaging telescopes, which have identical optics that give 2 x 2 degree field of views with 7 arcsecond pixels, but have different band defining filters. The first imager has a wide band centered at 1600 nm, and images the background at the expected peak of the spectrum. The imagers\u2019 wide field of view allows them to measure the distinctive power spectrum of first-light galaxy fluctuations peaking at 10 arcminutes. The second imager has a wide band centered at 1000 nm that is intended to image at wavelengths shorter than the Lyman cutoff, and provides a powerful systematic test for any detection made at 1600 nm. First-light fluctuations should have a distinctive spatial power spectrum with very red 1600 nm / 1000 nm color, distinctly redder than the approximately solar color of any residual fluctuations arising from Zodiacal light, Galactic starlight, or moderate-redshift galaxies.\r\n\r\nThis work describes the design and characterization of the instruments for the first launch, and the modifications and further characterization that have led to a second flight in July 2010 that successfully eliminated the most serious instrumental problems identified in the first flight.\r\n", "doi": "10.7907/EFS6-PJ64", "publication_date": "2011", "thesis_type": "phd", "thesis_year": "2011" } ]