Physics Commons^™

Classification Of Topological Defects In Cosmological Models, Abigail Swanson

Student Research Submissions

In nature, symmetries play an extremely significant role. Understanding the symmetries of a system can tell us important information and help us make predictions. However, these symmetries can break and form a new type of symmetry in the system. Most notably, this occurs when the system goes through a phase transition. Sometimes, a symmetry can break and produce a tear, known as a topological defect, in the system. These defects cannot be removed through a continuous transformation and can have major consequences on the system as a whole. It is helpful to know what type of defect is produced when …

Reheating Constraints To Palatini Coleman-Weinberg Inflation, Nilay Bostan

Turkish Journal of Physics

In this work, we examine the reheating constraints to symmetry-breaking mechanism, which is associated with Coleman-Weinberg inflation in the early universe. We consider the Coleman-Weinberg inflation potential, where the inflaton has a v ̸= 0 after inflation. Setting Treh = 105 GeV, we first show wreh dependency on ns , r , and N∗ for AV case. Then, we demonstrate the results of ns , r , N∗ , α = dns/d ln k for different reheating temperatures and compare the results with the latest BICEP/Keck data. We also present that ns −r and ns −N∗ planes and the effect …

Buzzard To Cardinal: Improved Mock Catalogs For Large Galaxy Surveys, Chun-Hao To, Joseph Derose, Risa H. Wechsler, Eli Rykoff, Hao-Yi Wu, Susmita Adhikari, Elisabeth Krause, Eduardo Rozo, David H. Weinberg

Physics Faculty Publications and Presentations

We present the Cardinal mock galaxy catalogs, a new version of the Buzzard simulation that has been updated to support ongoing and future cosmological surveys, including the Dark Energy Survey (DES), DESI, and LSST. These catalogs are based on a one-quarter sky simulation populated with galaxies out to a redshift of z = 2.35 to a depth of m_r = 27. Compared to the Buzzard mocks, the Cardinal mocks include an updated subhalo abundance matching model that considers orphan galaxies and includes mass-dependent scatter between galaxy luminosity and halo properties. This model can simultaneously fit galaxy clustering and group–galaxy …

Computing An Image Of Objects Hiding Behind A Black Hole, Shannon Harding

Honors Program Theses and Projects

Gravitational lensing is the bending of light rays around a black hole. The goal of this project was to produce a computer code that would model light rays coming from a grid of objects set behind a rotating black hole. Using these light rays, we produced an image illustrating how this background of objects would appear to an observer on Earth. This was done by creating a MATLAB code to model the paths of multiple light rays at a time. This code was then used to help check and correct a C++ code that produced an image. Over the semester, …

High-Performance Computing In Covariant Loop Quantum Gravity, Pietropaolo Frisoni

Electronic Thesis and Dissertation Repository

This Ph.D. thesis presents a compilation of the scientific papers I published over the last three years during my Ph.D. in loop quantum gravity (LQG). First, we comprehensively introduce spinfoam calculations with a practical pedagogical paper. We highlight LQG's unique features and mathematical formalism and emphasize the computational complexities associated with its calculations. The subsequent articles delve into specific aspects of employing high-performance computing (HPC) in LQG research. We discuss the results obtained by applying numerical methods to studying spinfoams' infrared divergences, or ``bubbles''. This research direction is crucial to define the continuum limit of LQG properly. We investigate the …

Exploring Non-Orientable Topology: Deriving The Poincaré Conjecture And Possibility Of Experimental Vindication With Liquid Crystal, Victor Christianto, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

This review investigates the potential of non-orientable topology as a fundamental framework for understanding the Poincaré conjecture and its implications across various scientific disciplines. Integrating insights from Dokuchaev (2020), Rapoport, Christianto, Chandra, Smarandache (under review), and other pioneering works, this article explores the theoretical foundations linking non-orientable spaces to resolving the Poincaré conjecture and its broader implications in theoretical physics, geology, cosmology, and biology.

Cosmological Vector Fields And Constraining The Neutrino Masses, Avery J. Tishue

Dartmouth College Ph.D Dissertations

In this thesis I explore two main topics: the role and consequences of cosmological vector fields, and new ideas for constraining fundamental physics with state-of-the-art experiments. These topics are disparate in content and technique but unified in their attempt to leverage novel approaches to better understand longstanding questions in cosmology. These questions, such as ``What is causing the universe to accelerate today?'' and ``What are the neutrino masses?'', underpin the modern cosmological paradigm. They play a key role in our understanding of cosmic history, the formation of structure, and the fate of our universe. Answers to or hints about these …

New Physics In The Age Of Precision Cosmology, Vivian I. Sabla

Dartmouth College Ph.D Dissertations

The Lambda-cold dark matter (LCDM) model has become the standard model of cosmology because of its ability to reproduce a vast array of cosmological observations, from the earliest moments of our Universe, to the current period of accelerated expansion, which it does with great accuracy. However, the success of this model only distracts from its inherent flaws and ambiguities. LCDM is purely phenomenological, providing no physical explanation for the nature of dark matter, responsible for the formation and evolution of large-scale structure, and giving an inconclusive explanation for dark energy, which drives the current period of accelerated expansion.

Furthermore, cracks …

The Camels Project: Public Data Release, Francisco Villaescusa-Navarro, Shy Genel, Daniel Anglés-Alcázar, Lucia A. Perez, Pablo Villanueva-Domingo, Digvijay Wadekar, Helen Shao, Faizan G. Mohammad, Sultan Hassan, Emily Moser, Erwin T. Lau, Luis Fernando Machado Poletti Valle, Andrina Nicola, Leander Thiele, Yongseok Jo, Oliver H.E. Philcox, Benjamin D. Oppenheimer, Megan Tillman, Chang Hoon Hahn, Neerav Kaushal, Et Al.

Michigan Tech Publications

The Cosmology and Astrophysics with Machine Learning Simulations (CAMELS) project was developed to combine cosmology with astrophysics through thousands of cosmological hydrodynamic simulations and machine learning. CAMELS contains 4233 cosmological simulations, 2049 N-body simulations, and 2184 state-of-the-art hydrodynamic simulations that sample a vast volume in parameter space. In this paper, we present the CAMELS public data release, describing the characteristics of the CAMELS simulations and a variety of data products generated from them, including halo, subhalo, galaxy, and void catalogs, power spectra, bispectra, Lyα spectra, probability distribution functions, halo radial profiles, and X-rays photon lists. We also release over 1000 …

Systematic Study Of Projection Biases In Weak Lensing Analysis, Prudhvi Raj Varma Chintalapati

Graduate Research Theses & Dissertations

The nature of Dark Energy is possibly one of the most fundamental questions in Physicstoday. Comprising 70% of the energy density of the Universe, and being responsible for the accelerated expansion of the Universe, this mysterious form of energy with negative pressure is challenging our current understanding of the fundamental laws of nature. Cosmological parameters like total relative matter Density Ωm, the normalization of power spectrum σ8 and their combination S8 = σ8 (Ωm/0.3)**0.5 are used to quantify our understanding of the evolution of the large-scale structure in the Universe and shed light on the accelerated expansion, caused by the …

Probability Distributions Of The Scalar Potential, Candace Mathews

Legacy Theses & Dissertations (2009 - 2024)

In the study of cosmological inflation, string theory and supersymmetry have motivated a wide range of possible inflationary models. These models can be parameterized by a scalar potential V, which is a function of N scalar fields, and determines cosmological parameters such as the vacuum stability and energy density. In principle, we can determine V through high energy physics, such as string theory. In practice, though we may not know the details of V we might have clues about a distribution of plausible V’s, which we can build statistics on to further analyze. The purpose of this thesis defense is …

Astrophysics, Cosmology And Particle Phenomenology At The Energy Frontier, Jorge Fernandez Soriano

Dissertations, Theses, and Capstone Projects

This dissertation consists of two parts, treating significantly separated fields. Each part consists on several chapters, each treating a somewhat isolated topic from the rest. In each chapter, I present some of the work developed during my passage through the graduate program, which has mostly been published elsewhere.

Part I – Cosmic Rays and Particle Physics

• Chapter 1: In this chapter we present an introduction to the topic of cosmic ray physics, with an special focus on the so-called ultra high energy cosmic rays: their potential origins, effects during their propagation between their sources and Earth, the different techniques used …

Einstein's Equations, Lagrangians For General Relativity, And Adm Formalism, Timothy Corbett

Student Research Submissions

Einstein’s equations describe the relation of spacetime curvature and present matter. We will consider the case of a Lorentzian manifold diffeomorphic to ℝ × Σ, where time t ∈ ℝ and the three-dimensional manifold Σ represents space. In a homogeneous and isotropic universe, the three-dimensional manifold Σ of the Lorentzian manifold has Riemann curvature tensor ⁽³⁾R = KI, where K is a constant and I is the 3 × 3 identity matrix. Space is flat when K = 0, spherical when K is positive, and hyperbolic when K is negative. In this paper, we will show models agreeing with …

Perturbative Unitarity And Nec Violation In Genesis Cosmology, Yong Cai, Ji Xu, Shuai Zhao, Siyi Zhou

Physics Faculty Publications

Explorations of the violation of null energy condition (NEC) in cosmology could enrich our understanding of the very early universe and the related gravity theories. Although a fully stable NEC violation can be realized in the “beyond Horndeski” theory, it remains an open question whether a violation of the NEC is allowed by some fundamental properties of UV-complete theories or the consistency requirements of effective field theory (EFT). We investigate the tree-level perturbative unitarity for stable NEC violations in the contexts of both Galileon and “beyond Horndeski” genesis cosmology, in which the universe is asymptotically Minkowskian in the past. We …

Wavelet Packet Power Spectrum Of The Sdss Lyman-Alpha Forest: A Tool For Large-Scale Structure Detection, Jason Pero

College of Science and Health Theses and Dissertations

One of the goals of astrophysics is to obtain a full understanding how the Universe is organized on large scales and how structure evolved. In this thesis we develop a method of detecting structure on Mpc scales by measuring the one-dimensional power spectrum of the transmitted ux in the Lyman- forest. The method is based on the wavelet packet transform (WPT), which has several advantages over the Fourier transform. This includes reduced noise, resulting in less data manipulation and scrubbing in the early stages of analysis. Another advantage is localization of outliers in the data, which allows the general trend …

Gravitational Wave Timing Residual Models For Pulsar Timing Experiments, Casey Mcgrath

Theses and Dissertations

The ability to detect gravitational waves now gives scientists and astronomers a new way in which they can study the universe. So far, the scientific collaboration LIGO has been successful in detecting binary black hole and binary neutron star mergers. These types of sources produce gravitational waves with frequencies of the order hertz to millihertz. But there do exist other theoretical sources which would produce gravitational waves in different parts of the frequency spectrum. Of these are the theoretical mergers of supermassive black hole binaries (SMBHBs), which could occur upon the merging of two galaxies with supermassive black holes at …

Effective Computational Cosmology, Eva Nesbit

Dissertations - ALL

Effective Field Theories (EFTs) provide a unique framework in which to attempt to answer outstanding questions in cosmology (and all field of physics, for that matter). This work investigates how the use of both EFTs and computational tools can help us to advance our knowledge of how the universe evolved and formed over time. Specifically, we review the successful EFT of Inflation, the EFT of Dark Energy (EFTDE), and introduce the EFT of Reheating as a generalized model of particle formation after inflation. In this way, we show how effective EFTs are at quantifying physical phenomenology at many different energy …

Searching For The Global 21 Cm Cosmic Dawn Absorption Signal With The Long Wavelength Array, Christopher Dilullo

Physics & Astronomy ETDs

The redshifted 21 cm signal from neutral hydrogen offers one of the best observational probes of Cosmic Dawn and the Epoch of Reionization. This dissertation presents an effort to detect the redshifted 21 cm signal using the Long Wavelength Array station located on the Sevilleta National Wildlife Refuge in New Mexico, USA (LWA-SV). The major goal is to validate the potential detection reported by the EDGES collaboration. This measurement requires a dynamic range on the order of 10⁵ in order to disentangle the cosmological signal from the Galactic foregrounds. The beamforming capability of LWA-SV is novel to this search. …

Expanding The Frontiers Of Supernova Cosmology In Preparation For Next Generation Telescopes, Justin Roberts-Pierel

Theses and Dissertations

Supernova (SN) research has been the source of many astronomical discoveries over the past several decades, most prominently the accelerated expansion of the universe by so-called “dark energy” in 1998. Next generation surveys like the Vera C. Rubin Observatory and the Nancy G. Roman Space Telescope, in large part through traditional luminosity distance measurements with Type Ia supernovae (SNe Ia), are set to reveal more about the nature of dark energy this decade than at any time in history. The enormous SN Ia samples from Roman and Rubin mean cosmological inferences will no longer be limited by statistical uncertainties, …

All-Sky Search In Early O3 Ligo Data For Continuous Gravitational-Wave Signals From Unknown Neutron Stars In Binary Systems, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, K. E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

Rapidly spinning neutron stars are promising sources of continuous gravitational waves. Detecting such a signal would allow probing of the physical properties of matter under extreme conditions. A significant fraction of the known pulsar population belongs to binary systems. Searching for unknown neutron stars in binary systems requires specialized algorithms to address unknown orbital frequency modulations. We present a search for continuous gravitational waves emitted by neutron stars in binary systems in early data from the third observing run of the Advanced LIGO and Advanced Virgo detectors using the semicoherent, GPU-accelerated, BinarySkyHough pipeline. The search analyzes the most sensitive frequency …

The First Three Seconds: A Review Of Possible Expansion Histories Of The Early Universe, R. Allahverdi, M. A. Amin, A. Berlin, N. Bernal, C. T. Byrnes, M. S. Delos, A. L. Erickcek, M. Escudero, D. G. Figueroa, K. Freese, T. Harada, D. Hooper, D. I. Kaiser, T. Karwal, K. Kohri, G. Krnjaic, M. Lewicki, K. D. Lozanov, V. Poulin, K. Sinha, Tristan L. Smith, T. Takahashi, T. Tenkanen, J. Unwin, V. Vaskonen, S. Watson

Physics & Astronomy Faculty Works

It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial …

Magnetic Structure And Radiative Captures Of Few-Nucleon Systems: Status And Prospects, Laura Elisa Marcucci, Rocco Schiavilla, Alex Gnech, Michele Viviani

Physics Faculty Publications

We review the main ingredients for an ab-initio study of few-nucleon reactions of astrophysical interest within the chiral effective field theory approach, with particular attention to radiative captures relevant for Big Bang Nucleosynthesis and stellar evolution. We conclude with an outlook for ongoing and future work.

Dark Matter Production Beyond The Thermal Wimp Paradigm: An Exploration Of Early Matter Domination Scenarios, Jacek Ksawery Osinski

Physics & Astronomy ETDs

In the standard thermal history of the Universe, the energy density is dominated by radiation throughout the postinflationary era, until matter-radiation equality after big bang nucleosynthesis (BBN). However, we currently do not have any observational probes of the pre-BBN period, and radiation domination (RD) is therefore an assumption. Generic early Universe models predict the presence of additional components in the postinflationary Universe which can lead to periods of nonstandard evolution before the onset of BBN. A prominent example of such a period is a phase of early matter domination (EMD) in which the Universe undergoes matter-dominated expansion for a time, …

Stability Of A Regular Black Holes Thin-Shell Wormhole In Reissner-Nordstrom - De Sitter Space-Time, A. Eid

Applications and Applied Mathematics: An International Journal (AAM)

The dynamics regular black holes thin shell wormhole with a phantom energy equation of state in Reissner-Nordstrom - De sitter space-time is studied using the Darmois-Israel formalism. A mechanical stability analysis is carried out by using the standard perturbation method. The stable and unstable static solution depends on the suitable value of parameters.

The Astrophysics Of Nanohertz Gravitational Waves, S. Burke-Spolaor, S. R. Taylor, M. Charisi, T. Dolch, J. S. Hazboun, A. M. Holgado, L. Z. Kelley, T. J. W. Lazio, D. R. Madison, N. Mcmann, C. M. F. Mingarelli, A. Rasskazov, X. Siemens, J. J. Simon, Tristan L. Smith

Physics & Astronomy Faculty Works

Pulsar timing array (PTA) collaborations in North America, Australia, and Europe, have been exploiting the exquisite timing precision of millisecond pulsars over decades of observations to search for correlated timing deviations induced by gravitational waves (GWs). PTAs are sensitive to the frequency band ranging just below 1 nanohertz to a few tens of microhertz. The discovery space of this band is potentially rich with populations of inspiraling supermassive black hole binaries, decaying cosmic string networks, relic post-inflation GWs, and even non-GW imprints of axionic dark matter. This article aims to provide an understanding of the exciting open science questions in …

The Discovery Of A Gravitationally Lensed Supernova Ia At Redshift 2.22, David Rubin, Brian Hayden, Xiaosheng Huang, Greg Aldering, R Amanullah, K Barbary, K Boone, M Brodwin, S E. Deustua, S Dixon, P Eisenhardt, A S. Fruchter, A H. Gonzalez, A Goobar, R R. Gupta, I Hook, M. James Jee, A G. Kim, M Kowalski, C Lidman, E V. Linder, K Luther, J Nordin, R Pain, Saul Perlmutter, Z Raha, M Rigault, P Ruiz-Lapuente, C Saunders, C Sofiatti, A L. Spadafora, S A. Stanford, D Stern, N Suzuki, S C. Williams

Physics and Astronomy

We present the discovery and measurements of a gravitationally lensed supernova (SN) behind the galaxy cluster MOO J1014+0038. Based on multi-band Hubble Space Telescope and Very Large Telescope (VLT) photometry of the supernova, and VLT spectroscopy of the host galaxy, we find a 97.5% probability that this SN is a SN Ia, and a 2.5% chance of a CC SN. Our typing algorithm combines the shape and color of the light curve with the expected rates of each SN type in the host galaxy. With a redshift of 2.2216, this is the highest redshift SN Ia discovered with a spectroscopic …

Studies In Gravitational-Wave Astronomy And Tests Of General Relativity, Hong Qi

Theses and Dissertations

Modern astronomical data sets provide the opportunity to test our physical theories of the Universe at unprecedented levels of accuracy. This dissertation examines approaches to testing gravitational theories using a) observations of stars orbiting the center of the Milky Way; b) observations of the pulsations of Cepheid variable stars in dwarf galaxies; and c) gravitational-wave observations of compact binary mergers.

Observations of stars orbiting the center of the Milky Way have been used to infer the mass of the putative black hole that exists there. I discuss how well present and future measurements of stellar orbits can constrain the black …

Thermodynamics Of Cosmological Models With Generalized $G$ And $\Lambda $, M Saratchandra Singh, Sanasam Surendra Singh

Turkish Journal of Physics

Here we investigate spatially flat Friedmann-Robertson-Walker space-time models of the universe to study the thermodynamic behaviors in light of variables $G$ and $\Lambda $. A particular method to find the solutions of Einstein's field equations and mathematical expressions for temperature and entropy of the perfect fluid cosmological models is introduced by using both the equation of state and the assumption $G=G_{0} \,a^{n}$. It is observed that the phantom field of ($\omega

Nature Of Entropy In A Scalar-Tensor Theory Of Gravity, Onur Siğinç, Mustafa Salti, Hi̇lmi̇ Yanar, Oktay Aydoğdu

Turkish Journal of Physics

This work is devoted to studying the generalized nature of the entropy function in a specific form of the scalar-tensor-vector (STeVe) theory of gravity for the Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime in the state of thermal equilibrium. For this purpose, we define an equilibrium picture of thermodynamics by making use of a suitable set of the dark energy density and dark pressure descriptions, which defines an energy-momentum tensor obeying the local energy conservation law. Furthermore, we also discuss our results numerically in order to get additional implications.

On The Time Variation Of Dust Extinction And Gas Absorption For Type Ia Supernovae Observed Through A Nonuniform Interstellar Medium, Xiaosheng Huang, G Aldering, M. Biederman, B. Herger

Physics and Astronomy

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures () will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent …