Doctor of Philosophy, The Ohio State University, 2015, Physics

The Dark Energy Survey (DES) is an ongoing cosmological survey intended to study the properties of the accelerated expansion of the Universe. In this dissertation, I present work of mine that has advanced the progress of DES. First is an introduction, which explores the physics of the cosmos, as well as how DES intends to probe it. Attention is given to developing the theoretical framework cosmologists use to describe the Universe, and to explaining observational evidence which has furnished our current conception of the cosmos. Emphasis is placed on the dark sector – dark matter and dark energy – the content of the Universe not explained by the Standard Model of particle physics. As its name suggests, the Dark Energy Survey has been specially designed to measure the properties of dark energy. DES will use a combination of galaxy cluster, weak gravitational lensing, angular clustering, and supernovae measurements to derive its state of the art constraints, each of which is discussed in the text. The work described in this dissertation includes science measurements directly related to the first three of these probes. The dissertation presents my contributions to the readout and control system of the Dark Energy Camera (DECam); the name of this software is SISPI. SISPI uses client-server and publish-subscribe communication patterns to coordinate and command actions among the many hardware components of DECam – the survey instrument for DES, a 570 megapixel CCD camera, mounted at prime focus of the Blanco 4-m Telescope. The SISPI work I discuss includes coding applications for DECam's filter changer mechanism and hexapod, as well as developing the Scripts Editor, a GUI application for DECam users to edit and export observing sequence SISPI can load and execute. Next, the dissertation describes the processing of early DES data, which I contributed. This furnished the data products used in the first-completed DES science analysis, and contributed to improving th (open full item for complete abstract)

Committee: Klaus Honscheid (Advisor) Subjects: Astronomy; Astrophysics; Physics

Doctor of Philosophy, Case Western Reserve University, 2007, Physics

This thesis is a report on the research I have done over the last three years. I begin by reviewing the Standard Big Bang cosmology and the theory of inflation. I then describe Island Cosmology, an alternative theory of cosmic origin, which is based on a different hypothesis, and can create the observed universe without requiring an inflationary phase. After fully describing this model, I move on to the subject of computing perturbation spectra. The theory of cosmological perturbations, as it applies to calculating the perturbation spectrum from inflation, is reviewed next. Computing the perturbation spectrum in Island Cosmology involves several challenges, which I then discuss and also review progress made so far in computing the spectrum. In the final part of this thesis I describe my research in gravitational collapse in the presence of a dynamical dark energy component (DDE). I review the very interesting result that in linear regime, the collapsing matter induces the formation of DDE voids, or regions of underdensity. I describe the physics behind the formation of these voids, as well as possible observational consequences.

Committee: Tanmay Vachaspati (Advisor) Subjects: Physics, Astronomy and Astrophysics

Master of Arts (MA), Bowling Green State University, 2024, American Culture Studies

This thesis examines the portrayal of mother-child disconnection and family separation among undocumented African immigrant women in the United States, as depicted in the films Anchor Baby (2010) and Nanny (2022). Through an analysis of these films, the study highlights the socioeconomic challenges faced by these women within the U.S. sociocultural landscape. It investigates how the films depict family separation and mother-child disconnection in relation to the broader issues of socioeconomic hardship, cultural displacement, and housing instability. Additionally, the research explores how African cosmology interprets the immigrant experiences of the female characters in these films. The purpose of this analysis is to contribute to the discourse on the experiences of (un)documented African immigrant women in the United States, promoting further studies in this area. The study focuses specifically on the representations in Anchor Baby and Nanny, rather than attempting to generalize across all African communities. The thesis is structured into three chapters: the first outlines the motivation for the study, the ongoing migration of Africans to the United States, and provides a literature review and an overview of intersectionality as a critical framework. The second chapter offers a detailed analysis of the films, exploring themes of mother-child disconnection, family separation, dreams, survival, disillusionment, fear, uncertainty, hostility, and racism. The final chapter reflects on the key themes addressed in the study.

Committee: Timothy Messer-Kruse PhD (Committee Chair); Alberto Gonzalez PhD (Committee Member) Subjects: African Literature; African Studies; American Studies

Doctor of Philosophy (PhD), Ohio University, 2024, Physics and Astronomy (Arts and Sciences)

As more wide-angle, large-scale, all-sky surveys become available so do opportunities for significant advancements into our understanding of the Universe through the study of formation and evolution of structure and testing cosmological models. It is important to address the systematic errors of weak lensing measurements as statistical errors improve, especially those that are planned as part of an automated process such as pipelines for the Vera Rubin Observatory's Legacy Survey of Space and Time. I obtained and analyzed images from 14 Hubble Space Telescope Advanced Camera for Surveys Wide Field Camera galaxy clusters spanning redshifts from 0.4 to 0.9 to identify potential galaxy cluster centroids and determine the optimal centroid usage based on observable indicators. I utilized the Principal Component Analysis method on individual exposures to describe the point spread function and the KSB+ method to correct the galaxy shapes and measure the shear. I then performed a bootstrap resampling analysis to identify the weak lensing centroid for each cluster. I compared this centroid with the brightest cluster galaxy (BCG), light and X-ray centroids to determine which centroid was optimal. I also searched for observable markers indicating when it is beneficial to use which centroid. My analysis of the survey suggests the BCG as the better choice of center compared to light or X-ray centroids, but is still offset from the mass centroid at a statistically significant level in a number of the clusters. I found no clear indicator within my research of an ideal centroid choice.

Committee: Douglas Clowe (Advisor); Joseph Shields (Committee Member); Ryan Fogt (Committee Member); David Drabold (Committee Member); Eric Stinaff (Committee Member) Subjects: Astronomy; Astrophysics; Physics

Master of Fine Arts (MFA), Bowling Green State University, 2024, Creative Writing/Poetry

This manuscript is the best representation of where I am currently at as a writer of poetry. I chose the title Animal Lessons because there seems to be either an animal or human truth I am searching for when I write. I'm drawn to settings that are close to me & remind me of home—wherever that happens to be. I was inspired by various language and lore related to precious stones. There are poems inspired formally by obituaries, the Fibonacci sequence, a single carmina figurata and ekphrasis. The first section is somewhat optimistic but at the same time hints at certain truths lurking underneath the surface. This truth can relate to the animalistic or human nature. The second section is inspired mostly by history—either history I am removed from or history related to my family. Running throughout this section are themes of being fractured or being separated; the love poems are related to love ending. There are poems that explore grief and the reality that this loss entails. The third section is in celebration of the infinite. What stays when we are gone or what aspects we might outlive. Some things fade and others endure but I do feel like I have concluded through crafting this work that we, as we understand ourselves to be, are also infinite.

Committee: Sharona Muir Ph.D. (Committee Chair); Amorak Huey M.F.A. (Committee Member); Abigail Cloud M.F.A. (Committee Member); Larissa Szporluk Celli M.F.A. (Committee Member) Subjects: Fine Arts

Doctor of Philosophy, The Ohio State University, 2023, Physics

The Dark Energy Spectroscopic Instrument (DESI) is a purpose built instrument on the Mayall 4-meter telescope in Kitt Peak, Arizona. It is undertaking an ambitious, 5 year survey of the same name to measure the redshifts of 40 million galaxies and quasars. At the time of writing DESI is about 2 years into its 5 year survey. With the vast new dataset collected by DESI, the DESI collaboration will produce novel constraints on cosmology and in particular the nature of dark energy using techniques such as Baryon Acoustic Oscillations and Redshift Space Distortions. In this work I detail some of my contributions to the success of DESI as a survey. These include in particular the design and writing of software for the Focal Plane System and its novel robotic fiber positioners as well as the commissioning of the Focal Plane system and continued support in the early survey. This does not include earlier work on testing and verifying positioner robots off of the production line. This document will also cover an exploration into a new method to account for systematics in clustering measurements resulting from the DESI instrument. The chapters will proceed as follows. The first chapter will provide a brief introduction to our cosmological universe, concluding with its statistical fluctuations and how we measure the fluctuations. The second chapter will introduce the DESI instrument, the survey it is undertaking and its key operational loop. The third chapter will cover the development of the focal plane software used through commissioning, its structure, and will conclude with some performance statistics. The fourth chapter will cover the commissioning of the focal plane, challenges encountered and key moments. The fifth and final chapter will discuss the imputation of galaxies into DESI clustering catalogs, this is an exploration into a potential new way to account for systematics resulting from the design of DESI and its survey.

Committee: Klaus Honscheid (Advisor); Paul Martini (Committee Member); Christopher Hirata (Committee Member); Richard Furnstahl (Committee Member) Subjects: Astrophysics; Physics

Doctor of Philosophy, The Ohio State University, 2023, Physics

Correlations in and with the flux transmission of the Lyman-alpha (LyA) forest in the spectra of high-redshift quasars are powerful cosmological tools, yet these measurements can be compromised if the intrinsic quasar continuum is significantly uncertain. One particularly problematic case is broad absorption line (BAL) quasars, which exhibit blueshifted absorption associated with many spectral features that are consistent with outflows of up to ~0.1c. As these absorption features can both fall in the forest region and be difficult to distinguish from LyA absorption, cosmological analyses eliminate the ~12 - 16% of quasars that exhibit BALs. This work explores an alternate approach that includes BALs in the LyA auto correlation function, with the exception of the expected locations of the BAL absorption troughs. This procedure is tested on both the SDSS DR14 and DESI Year 1 LyA catalogs, using the reduction of error on the autocorrelations as a metric for success. The masking procedure returns over 95% of the pathlength that is lost by the exclusion of BALs, as well as increases the density of sightlines. It shows that including BAL quasars reduces the fractional uncertainty in the covariance matrix and correlation function by 12% on SDSS DR14 and 20% on DESI Year 1. Furthermore, it does not significantly change the shape of the correlation function relative to analyses that exclude BAL quasars. It also evaluates different definitions of BALs, masking strategies, and potential differences in the quasar continuum in the forest region for BALs with different amounts of absorption.

Committee: Paul Martini (Advisor); Linda Carpenter (Committee Member); Chris Hirata (Committee Member); Klaus Honscheid (Advisor) Subjects: Astronomy; Physics

Master of Science (MS), Ohio University, 2023, Physics and Astronomy (Arts and Sciences)

Baryon Acoustic Oscillations (BAO) are sound waves in the photon-baryon fluid that was the early universe, frozen at the surface of last scattering as the universe expanded and cooled. The signatures of these waves show up in the Cosmic Microwave Background as well as large-scale galaxy distribution, and because of this they have a known scale length. Thus, BAO can be used to determine the expansion history of the universe, with the ultimate goal of constraining the density of dark energy as a means of revealing its nature. The Nancy Grace Roman Space Telescope (Roman) is a telescope set to launch in 2027. It will be performing a large spectroscopic survey, mock catalogs of which are now available. This work uses these mock catalogs to examine the BAO signature present in the 2-point correlation function of galaxy distribution in order to predict how well the BAO peak can be recovered from the survey's galaxy redshift data. We tested different expected survey conditions, finding that the BAO feature in the correlation function can be recovered to within one standard deviation in comparison to a reference cosmological model, and is a worthwhile goal for the Roman telescope galaxy survey.

Committee: Hee-Jong Seo (Advisor); Christian Drischler (Committee Member); Douglas Clowe (Committee Chair) Subjects: Astronomy

Master of Sciences, Case Western Reserve University, 2023, Physics

Future Stage IV ground based CMB telescopes will be more sensitive than ever due to the increase in number of detectors and advancements in detector technology. These detectors will improve the precision and sensitivity of CMB measurements that continue to provide data on the early Universe and structure of the cosmos. Despite the increase in detector sensitivity, noise will continue to remain a problem in data extraction due to various environmental factors. Many ground based CMB experimental sites reside in high elevation, cold areas as they reduce the noise in the atmosphere that the photons travel through. In this thesis we will be looking at the best projected frequency band center and edge locations for Stage III CMB experiments at these sites, as well as deciding what changes may be made to bandwidth and edge placement in future Stage IV instruments.

Committee: John Ruhl (Advisor); Corbin Covault (Committee Member); Benjamin Monreal (Committee Member) Subjects: Astronomy; Astrophysics; Physics

Doctor of Philosophy, Case Western Reserve University, 2023, Physics

SPT-3G is a new camera on the South Pole Telescope, currently being used to observe the sky in the millimeter-wavelength and make maps of the Cosmic Microwave Background (CMB). The CMB can be used to probe the origins of the universe and understand its subsequent evolution and the growth of structure. Clusters of galaxies, the largest gravitationally bound objects in the universe, trace out the distribution of matter across the universe. Observations of the CMB can be used to detect and characterize galaxy clusters via the Sunyaev Zel'dovich effect, wherein CMB photons are inverse Compton scattered off of hot gas within galaxy clusters. This effect can be used to measure the temperature evolution of the CMB as the universe expanded. In this thesis I give background on cosmology, describe the SPT-3G instrument and my role in its development, describe the software pipeline I wrote to detect galaxy clusters using SPT-3G, and give the new constraint on CMB temperature evolution that we have made using the 2019 and 2020 SPT-3G observations.

Committee: John Ruhl (Advisor); Aviva Rothman (Committee Member); Idit Zehavi (Committee Member); Benjamin Monreal (Committee Member) Subjects: Astrophysics; Physics

Doctor of Philosophy, The Ohio State University, 2022, Physics

This work presents the development and applications of a new image simulation tool, Obiwan, which which can be used to determine the selection function of a galaxy redshift survey and calculate 3-dimensional (3D) clustering statistics. This is a forward model of the process by which images of the night sky are transformed into a 3D large–scale structure catalog. The photometric pipeline automatically detects and models galaxies and then generates a catalog of such galaxies with detailed information for each one of them, including their location, redshift and so on. Systematic biases in the imaging data are therefore imparted into the catalogs and must be accounted for in any scientific analysis of their information content. Obiwan simulates this process for samples selected from the DESI Legacy Surveys imaging data. This imaging data will be used to select target samples for the next-generation Dark Energy Spectroscopic Instrument (DESI) experiment. We discuss the design of the Obiwan software and show an application on a portion of the SDSS-IV extend Baryon Oscillation Spectroscopic Survey Emission Line Galaxies (ELG) sample. Systematic biases in the data are clearly identified and removed. We compare the 3D clustering results to those obtained by the map–based approach applied to the full eBOSS sample. We find the results are consistent, thereby validating the eBOSS ELG catalogs. We also show how Obiwan can be used with the DESI sample of large red galaxies (LRG).

Committee: Klaus Honscheid (Advisor); Christopher Hirata (Committee Member); Amy Connelly (Committee Member); Samir Mathur (Committee Member); Theodore Allen (Committee Chair) Subjects: Astronomy; Astrophysics; Physics

Doctor of Philosophy, The Ohio State University, 2022, Astronomy

The composition and evolution of galaxies have been an elemental but long-standing mystery in Astronomy. In the last century, the advent of telescopes across the electromagnetic spectrum has revolutionized our perception of galaxies from a mere assembly of stars to a complex ecosystem. Both observational and theoretical studies have pointed towards the existence of a gaseous medium beyond the stellar component of galaxies, aka, the circumgalactic medium (CGM). The CGM is a multi-phase gas surrounding the stellar disk of a galaxy, filling up its dark-matter halo. The CGM is simultaneously the fuel tank, waste dump, and recycle hub of galaxies. It is expected to harbor the baryons, metals, and feedback that are missing from the stellar disk. I have studied the two extreme phases of the CGM to investigate how the feeding (accretion) and the feedback (outflow) at the galactic scale govern the evolution of the Milky Way and similar nearby galaxies. The ≥106 K hot CGM, despite being challenging to detect, is a treasure trove of galaxy evolution. By probing the hot CGM of the Milky Way (MW) using X-ray absorption lines of multiple metal ions, I have discovered a super-virial 107 K phase coexisting with the well-known virialized 106 K phase, featuring non-solar abundance ratios of light elements, α-enhancement, and non-thermal line broadening. I have also detected this super-virial phase of MW CGM in X-ray emission analyses. Detection of these surprising properties of the CGM along multiple directions in the sky suggests a strong connection between the hot CGM and past Galactic outflow(s). Observations of MW-like galaxies complement our observations of the Milky Way. I have discovered the hot CGM emission of an MW-mass galaxy NGC 3221 that is extended (~150-200 kpc) and is massive enough to account for its missing baryons. The CGM is not isothermal, with the CGM within 100 kpc of NGC 3221 being super-virial, and fainter along the minor axis than the global a (open full item for complete abstract)

Committee: Smita Mathur (Advisor); Paul Martini (Committee Member); Annika Peter (Committee Member); Adam Leroy (Committee Member) Subjects: Astronomy; Astrophysics

Doctor of Philosophy, The Ohio State University, 2022, Astronomy

While wide-field optical imaging surveys have revealed much about the Universe on the largest scales, numerous questions remain on scales too small for these programs to address. Addressing these questions requires a synthesis of galaxy evolution theory and cosmology. For example, recent observational programs have discovered dwarf satellite galaxies of low-mass hosts that are gas-deficient and have signs of quenched star formation. This is not predicted in traditional galaxy evolution theory, and if this environmental quenching is a general trend it will have repercussions for cosmological studies that seek to use these dwarf satellite galaxies. I combine observational and theoretical methods to show that starvation, or the cessation of cold gas inflows, is the most likely explanation for this quenching; this is the first time this mechanism has been suggested to be effective at this mass scale. If confirmed with a larger sample of dwarf satellite galaxies, it highlights a need for revised models of the circumgalactic media of low-mass galaxies. I next conduct an optical imaging survey for such dwarf satellite galaxies around six nearby, low-mass hosts, developing new observational methods and a new theoretical framework to interpret the survey results. These novel methods are computationally efficient and easily applicable to next-generation surveys which promise extreme data volumes. I use my new, probabilistic theoretical framework to show that the survey results are consistent with the canonical LCDM cosmology.

Committee: Annika Peter (Advisor); Jennifer Cheavens (Committee Member); Adam Leroy (Committee Member); Christopher Kochanek (Committee Member) Subjects: Astronomy; Astrophysics

Doctor of Philosophy, The Ohio State University, 2021, Astronomy

The standard Λ Cold Dark Matter (ΛCDM) model assumes that our Universe is geometrically flat and expanding, governed by General Relativity, and made up of three main constituents at present: baryonic matter, dark matter, and dark energy. Within the last decade the parameters governing ΛCDM have been tightly constrained by a variety of cosmological measurements including those of the cosmic microwave background (CMB), baryon acoustic oscillations (BAO), galaxy clustering, weak gravitational lensing, and redshift space distortions (RSD). Despite the impressive ability of ΛCDM to describe these varied observations substantial challenges to the model remain. In particular there remains a 5-10% tension between predictions of matter clustering from CMB data and other, late-time cosmological probes. The resolution of this tension may ultimately lie in new physics, such as complex dark energy or dark matter, or a deviation from General Relativity on cosmological scales. Establishing or refuting the reality of this tension is therefore one of the highest priority challenges of observational cosmology today. In this dissertation I present research on a variety of topics within cosmology related to meeting this challenge. The primary focus of my research is to derive robust and precise constraints on ΛCDM using novel combinations of cosmological observables that utilize galaxy clusters. I also present research on halo and galaxy assembly bias. Both of these phenomena are related to my primary research focus because they can potentially bias cosmological constraints. Finally I present work on modeling and forecasting the combination of galaxy-galaxy lensing and galaxy clustering in the final data release of the Dark Energy Survey. Much of the technical development in this work will be applicable to my primary research focus in the future. Beginning in Chapter 1 we study halo assembly bias for haloes in the mass range 3.7 × 1011 h-1 Msun - 5.0 ×1013 h-1 Msun. Using the Lar (open full item for complete abstract)

Committee: Christopher Kochanek (Committee Member); Christopher Hirata (Committee Member); David Weinberg (Advisor) Subjects: Astronomy; Astrophysics

PhD, University of Cincinnati, 2021, Arts and Sciences: Physics

The Cosmic Microwave Background (CMB) has provided a wealth of information since its discovery in the 1960s. The blackbody nature and the temperature anisotropies of the CMB have helped form the current cosmological paradigm of a hot Big Bang and the ?CDM model of the Universe. We are now looking to the polarization field of the CMB for answers about the early Universe. The theory of Cosmic Inflation postulates that the Universe went through a period of exponential expansion in the earliest moments. This theory generally predicts a stochastic background of primordial gravitational waves which would leave a faint B-mode pattern in the polarization of the CMB. The BICEP/Keck Array telescopes are small aperture multi-frequency microwave polarimeters at the Amundsen–Scott South Pole Station. These telescopes continuously observe a ~1% patch of the Southern sky targeting degree angular scales where the amplitude of the primordial gravitational waves is predicted to peak. The multi-frequency observation allows for the disentanglement of galactic foreground signals from the CMB signal. To date, these experiments provide the tightest constraints on the tensor-to-scalar ratio at r < 0.07 at 95% confidence. The discussion of this thesis is split into two parts. In the first part, it will discuss the design, development, and performance of the BICEP Array Housekeeping system. The Housekeeping system is an electronics data acquisition system designed to read out the thermistors of the cryogenically cooled receivers and provide temperature control. The second part of the thesis will discuss high level data analysis using a multi-component model of the bandpower data. In particular, there will be discussion of a novel minimum variance quadratic estimator used as an alternative to the maximum likelihood estimator.

Committee: Colin Bischoff Ph.D. (Committee Chair); Matthew Bayliss Ph.D. (Committee Member); Alexandre Sousa Ph.D. (Committee Member); Hans-Peter Wagner Ph.D. (Committee Member) Subjects: Physics

Doctor of Philosophy (PhD), Ohio University, 2021, Physics and Astronomy (Arts and Sciences)

Large-scale structure (LSS) of the Universe traced by galaxies is one of the essential probes of dark energy, dark matter, neutrino masses, nature of gravity, and statistical properties of primordial fluctuations. The clustering of primordial fluctuations from the cosmic microwave background to LSS provides a standard ruler test to study the dynamics of the cosmic expansion and the mysterious dark energy. Additionally, LSS can be utilized to reconstruct the primordial features and the statistical properties of the initial conditions of the Universe. Future galaxy redshift surveys are designed to extend aggressively to higher redshifts to reach a greater cosmic volume for improved precision as well as for studying the dynamics of dark energy further back in time. For instance, the Dark Energy Spectroscopic Instrument (DESI) will observe millions of galaxies and quasars, producing a three–dimensional map probing the Universe across 10 billion light-years or out to the redshift of 3.5. With enormous data volume, we can address fundamental cosmological problems with higher statistical precision, but such analyses demand more advanced methods and theoretical modeling of systematics. Emmission line galaxies (ELGs) are star-forming galaxies that populate the high redshift universe and therefore are promising tracers for LSS that will be targeted in future galaxy surveys. Quasi-stellar objects or quasars (QSOs) are distant galaxies that host massive black holes and the accreting black holes make these objects bright enough to be used as targets for high redshift galaxy surveys. However, the measurements of such targets are subject to various observational systematic effects that are still largely unknown. Mitigating such effects is crucial for deriving unbiased and precise cosmological constraints. This dissertation addresses the challenge of observational systematics by comparing the results of various approaches. My dissertation consists of three parts: In the first part, (open full item for complete abstract)

Committee: Hee-Jong Seo Prof. (Advisor) Subjects: Astronomy; Physics

BA, Oberlin College, 2021, East Asian Studies

This thesis examines two Japanese board games, both called sugoroku 双六, from a religious studies perspective. Although bearing the same name, ban-sugoroku 盤双六 and e-sugoroku 絵双六 have long been studied separately because of their different origins, eras, layouts and rules. However, an examination of visual and textual evidence such as illustrated handscrolls and encyclopedic sources demonstrates that the two games are strikingly similar: both games carry cosmological meanings, and their religious functions are closely tied to the process of playing. I propose that the inextricable nature of ritual and play exhibited in both games enabled them to serve for laypersons as accessible alternatives to mandalas and other contemporaneous religious objects that were often used by Buddhist priests. I argue that the games served as portable liminal space that enabled exchanges between the supernatural realm and the ordinary world, therefore making highly specialized religious knowledge and practices tangible to the laypeople. Although scholars have begun to recognize important similarities between ritual and play, few have studied specific games through the lens of religious rituals. Challenging the widely held misconception that play is for children and rituals are for adults, my thesis on sugoroku redefines the boundaries between ritual and play and the sacred and the secular. 盤双六も絵双六も日本の盤上遊戯である。どちらも「双六」と呼ばれているにもかかわらず、両者を分けて研究される傾向がある。盤双六と絵双六は、起源をはじめ、小道具や材料、ルール、流行していた時代など、異なる点が多いということは異論を挟む余地がない。ただし、絵巻、古記録、古辞典などの史料によると、盤双六と絵双六は宇宙論的な意味を持っており、それらの宗教的な役割は遊ぶことと密接に関連している点で共通している。本稿では、両方のゲームで示された儀礼と遊びの不可分な性質により、同時期の儀礼で僧侶によってよく使用された物の代用として在家の者が使われたと指摘する。両方とも境界的(liminal)な空間として異界とのコミュニケーションを可能にさせ、仏教儀礼の専門知識を在家の者に使用できるようになったと推測している。先行研究では、儀礼と遊びは近似していることが明らかになっている。しかし、具体的な宗教の儀礼と特定の遊戯を比べた研究はほとんどない。本稿では、遊びは子供向けであり、儀礼は大人向けだという広く受け入れられている考え方に疑問を投げかけ、儀礼と遊ぶこと、また宗教と世俗の境界を再定義する。

Committee: Andrew Macomber (Advisor); Hsiu-Chuang Deppman (Committee Member); Bonnie Cheng (Committee Member); Sheila Miyoshi Jager (Committee Chair) Subjects: Asian Studies

Doctor of Philosophy, The Ohio State University, 2020, Astronomy

Dark energy, the hypothesized cause of the universe's accelerating expansion, is the mystery that drives modern cosmology. To gain insight into the physical causes of acceleration, upcoming large-scale imaging surveys will provide statistical constraints on the standard cosmological model. Weak gravitational lensing, an essential probe of large-scale structure, is a key phenomenon whose observation comprises a vital part of these missions. Exquisite precision is required to take full advantage of weak lensing in the coming decades. This dissertation presents two new weak-lensing methods for achieving such precision, while also opening the door to advances in galaxy formation/evolution and other areas of astrophysics. Galaxy-galaxy lensing is an essential tool for probing dark matter halos and constraining cosmological parameters. While galaxy-galaxy lensing measurements usually rely on shear, weak-lensing magnification contains additional constraining information. Using the fundamental plane (FP) of elliptical galaxies to anchor the size distribution of a background population is one method that has been proposed for performing a magnification measurement. In the first part of this dissertation, I present a formalism for using the FP residuals of elliptical galaxies to jointly estimate the foreground mass and background redshift errors for a stacked lens scenario. The FP residuals include information about weak-lensing magnification κ, and therefore foreground mass, since to first order, nonzero κ affects galaxy size but not other FP properties. I also present a modular, extensible code that implements the formalism using emulated galaxy catalogs of a photometric galaxy survey. I find that combining FP information with observed number counts of the source galaxies constrains mass and photo-z error parameters significantly better than an estimator that includes number counts only. In particular, the constraint on the mass is 17.0% if FP residuals are included, as (open full item for complete abstract)

Committee: Christopher Hirata (Advisor); David Weinberg (Committee Member); Adam Leroy (Committee Member) Subjects: Astronomy; Astrophysics

Doctor of Philosophy, Case Western Reserve University, 2020, Physics

The Cosmic Microwave Background (CMB) temperature anisotropies have been mapped with increasing precision in the last 30 years. Although the measurements have been found to be in excellent agreement with statistical predictions of ΛCDM, several large-scale features of CMB temperature were observed to be anomalous, with p-values in the per mille to per cent level. Among those features is the lack of correlation on the largest angles (S1/2 anomaly) and the lack of variance in the ecliptic north. Although well-established results, they remain unexplained. To test the hypothesis that these anomalies are merely statistical fluctuations, we explore simulations of CMB maps constrained by current temperature data. We look at the contribution of the integrated Sachs-Wolfe effect to S1/2 and show how correlations from early-time and late-time physical effects contribute to its value. In anticipation of future polarization experiments, we generate realizations of polarization maps and predict the distribution of the hemispherical variance in polarization, considering different sky-coverage scenarios. We find that the low northern-hemisphere variance seen in temperature is not expected in polarization. We also study how the variance of polarization depends on current measurements of ΛCDM parameters and find that it is noticeably sensitive to present uncertainties in the reionization optical depth (τ). We explore how current improvements in the measurement of τ result in a tighter constraint on polarization-variance expectations, and how future τ measurements can further reduce the uncertainty in the polarization-variance distribution, thus improving our ability to test for the variance anomaly with upcoming polarization data.

Committee: Glenn Starkman (Advisor); Craig Copi (Committee Member); John Ruhl (Committee Member); Stacy McGaugh (Committee Member) Subjects: Astrophysics; Physics; Theoretical Physics

Doctor of Philosophy, The Ohio State University, 2019, Physics

Cosmic acceleration is the most surprising discovery in modern history. While the phenomenon has been proven by a plethora of cosmological observations, the underlying mechanism is still a mystery. There have been various attempts to understand the driver of cosmic acceleration in a form of "dark energy" or "modified gravity", but none of these has compelling evidence. This thesis contains my PhD research projects dedicated to find the origin of cosmic acceleration. In Chapter 2, I describe the DES-CMASS (DMASS) galaxy sample constructed from images taken from the Dark Energy Survey (DES). The sample is designed for a joint analysis of the existing BAO and RSD measurements from BOSS using the CMASS galaxy sample and a galaxy-galaxy lensing measurement from DES. We show that DMASS successfully replicates CMASS in many ways, such as by comparing galaxy bias, angular correlation functions, and redshifts. Chapter 3 describes the DES Y1 analysis for extended cosmological models focusing on modified gravity (MG), which I contributed. DES Y1 shear measurement significantly improves the existing MG constraints. We show that the resulting MG constraints are consistent with general relativity. In the latter part of the chapter, I forecast the detection of MG parameters for DMASS to demonstrate the capability of DMASS to achieve tighter constraints by cancelling galaxy bias. Finally, in Chapter 4, we study the information content of the three-dimensional galaxy correlation function and power spectrum when realistic scale cuts are applied. We find that two estimators are complementary to each other and combining the two yields small improvement for joint constraints.

Committee: Klaus Honscheid Professor (Advisor); Christopher M. Hirata Professor (Committee Member); Samir Mathur Professor (Committee Member); Richard J. Furnstahl Professor (Committee Member) Subjects: Astrophysics; Physics