Astrophysics and Astronomy Commons^™

Helioseismic Diagnostics Of Active Regions And Their Magnetic Fields, John T. Stefan

Dissertations

While two and a half decades of nearly constant observation by the Solar and Heliospheric Observatory (SOHO) and the Solar Dynamics Observatory (SDO) spacecraft have yielded key insights into the structure and dynamics of active regions, it is still unclear if active regions can be identified before emerging on the solar surface and, once emerged, whether the subsurface structure of an active region’s magnetic field can be measured. Regarding the dynamical processes associated with active regions, the height and mechanism of sunquake excitation remains poorly understood. To answer these questions, a comprehensive survey of active region magnetic fields and their …

Core-Collapse Supernova Simulations With Spectral Two-Moment Neutrino Transport, Ran Chu

Doctoral Dissertations

The primary focus of this dissertation is to develop a next-generation, state-of-the-art neutrino kinetics capability that will be used in the context of the next-generation, state-of-the-art core-collapse supernova (CCSN) simulation frameworks \thornado\ and \FLASH.\index{CCSN} \thornado\ is a \textbf{t}oolkit for \textbf{h}igh-\textbf{or}der \textbf{n}eutrino-r\textbf{ad}iation hydr\textbf{o}dynamics, which is a collection of modules that can be incorporated into a simulation code/framework, such as \FLASH, together with a nuclear equation of state (EOS)\index{EOS} library, such as the \WeakLib\ EOS tables. The first part of this work extends the \WeakLib\ code to compute neutrino interaction rates from~\cite{Bruenn_1985} and produce corresponding opacity tables.\index{Bruenn 1985} The processes of emission, …

Chasing Transients: Constructing Local Galaxy Catalogs For Electromagnetic Follow-Up Of Gravitational Wave Events, Chaoran Zhang

Theses and Dissertations

Gravitational waves (GWs) provide a new window for observing the universe which is not possible using traditional electromagnetic (EM) wave astronomy. The coalescence of compact object binaries, such as black holes (BHs) and neutron stars (NSs) generates “loud" GW signals that are detectable by the LIGO-Virgo-KAGRA (LVK) GW Observa- tory. If the binary contains at least one NS, there is a possibility that an observable EM counterpart will be launched during and/or after the merger. The first joint detection of GW radiation (GW170817) and its EM counterpart (AT 2017gfo) greatly extended our understanding of the universe in many fields, such …

First-Principles Study Of Doping Effects On Ferroelectricity And On Rashba Spin Splitting, Zegnet Yimer Muhammed

Graduate Theses and Dissertations

In this dissertation, we have thoroughly studied the effect of chemical and charge dopingon ferroelectrics (PbTiO3 and BaTiO3) and Rashba type semiconductor (BiTeI). In the first project, We investigate the polar instability and soft modes in electron-doped PbTiO3 using linear-response density functional calculations. Because, metallicity and ferroelectric-like polar distortion are mutually non-compatible, and their coexistence in the same system is an intriguing subject of fundamental interest in the field of structure phase transition. However, it is unclear what mechanism may extend the limit of metallicity that allows polar distortion. We find that ferroelectric instability can remarkably sustain up to an …

Day ‘N’ Nite: Habitability Of Tidally Locked Planets With Sporadic Rotation, Cody James Shakespeare

UNLV Theses, Dissertations, Professional Papers, and Capstones

Tidally locked worlds provide a unique opportunity for constraining the climates of detected exoplanets. They are unique in that few exoplanet spin and obliquity states are known or will be determined in the near future. The TRAPPIST-1 exoplanet system has multiple habitable zone planets that, in the past, have been presumed to be tidally locked. However, a recent study shows the dynamical conditions present in the TRAPPIST-1 system make rotation and large librations possible spin states for these planets. I confirm the tendency for these planets to sporadically transition from tidally locked libration to slow rotation using N-body simulations independent …

A Method For Exploring The Habitability Of Earth-Like Exoplanets: Applications To Tess Objects Of Interest 203 B, 256 B, And 700 D, Paul Bonney

Graduate Theses and Dissertations

The Transiting Exoplanet Survey Satellite (TESS) has and is continuing to discover a multitude of potentially habitable planet candidates. As more planets are detected and confirmed, it becomes increasingly important to strategically search for signs of habitability with which to differentiate and prioritize them for further observation, in particular with the James Webb Space Telescope (JWST). To facilitate this, I have created a method for prioritizing TESS planet candidates based on parameters derived from their light curves and have applied the method to the TESS Candidate Target List (CTL). This data set uses preliminary fits to transit modeling which can …

Orbit Propagation And Determination Algorithms For Satellite Ground Stations, Shamma Esmaeel Jamali

Theses

The satellite orbital parameters are essential for satellite operations. With these parameters, it is possible to estimate the satellite position in the recent past and near future, which is essential to effectively plan satellite operations and associate satellite telemetry with geographical locations.
However, for small or medium satellite operators who do not possess the infrastructure required to track their satellites, the problem of determining the satellite orbit is problematic. To access the orbit for their satellites, these organizations have to rely on third parties such as Celestrak. These entities provide the service free of charge but do not provide orbital …

Kinetic Modeling Of Ionospheric Outflows Observed By The Visions-1 Sounding Rocket, Robert M. Albarran Ii

Doctoral Dissertations and Master's Theses

Plasma escape from the high-latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. The VISIONS-1 (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of nightside ion outflow at altitudes where it is initiated, below 1000 km. Energetic ion data from the VISIONS-1 polar cap boundary crossing …

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 …

Diagnostics Of Energy Release In Solar Flares With Radio Dynamic Imaging Spectroscopy, Yingjie Luo

Dissertations

Studies of the magnetic energy release and conversion process lie at the core of solar flare physics. Radio observations serve as a unique diagnostic method. In this dissertation, taking advantage of broadband radio dynamic imaging spectroscopy observations made by the Karl G. Jansky Very Large Array (VLA), studies are carried out on the flare energy release processes using different types of radio emissions.

The VLA is a general-purpose radio observatory located in New Mexico, which provides high-quality radio dynamic imaging spectroscopic observations with an ultra-fast time cadence. In the first study, stochastic decimetric radio spike bursts are observed by the …

Distance Estimates To Evolved Stars Using Infrared Emission And Verification And Validation Of The Plasma Code Empire, Brandon M. Medina

Physics & Astronomy ETDs

Gaining insight into the structure and dynamics of the Milky Way is important for understanding the universe on a large scale. Evolved stars on the Asymptotic Giant Branch are useful for studying the Milky Way because their emission is peaked in the infrared, where interstellar extinction effects are not as dominant. To further understand the physical properties of these objects like luminosity and investigate the Galaxy's structure, we need distance estimates. Obtaining distance estimates for these evolved stars via trigonometric parallax measurements is time-consuming, so infrared surveys studying Asymptotic Giant Branch stars can benefit from other distance estimate methods. In …

Searching For Gravitational Wave Associations With High-Energy Astrophysical Transients, Brandon Joseph Piotrzkowski

Theses and Dissertations

Gravitational waves (GW) have become an invaluable tool in modern astronomy, especiallyin conjunction with other astronomical observations. GWs are created in highly dynamical systems such as compact binary coalescences (CBC) which are comprised of black holes and/or neutron stars. The Laser Interferometer Gravitational Wave Observatory (LIGO), Virgo Observatory, and KAGRA have now collectively identified almost a hundred of these events. GWs have also been predicted to come from core collapse supernovae. Both of these types of systems have been shown to produce other detectable transients, such as gamma- ray bursts (GRB) and neutrino bursts. Observations of the same astrophysical system …

The Cosmic History Of X-Ray Binary Evolution, Woodrow Gilbertson

Graduate Theses and Dissertations

The Chandra Deep Fields provide an extraordinary window into the high-energy history of the cosmos. Observations of non-active galaxies within the deep fields can be leveraged to extract information about the formation and evolution of X-ray binaries (XRBs). Previous studies have suggested that the evolution of XRB luminosity can be expressed a function of physical parameters such as star formation rate, stellar mass, stellar age, and metallicity. The goal of this work is to develop and implement a complete physical parameterization for the luminosity of XRB populations, which can be utilized for a variety of further studies.

Chapter 1 provides …

Data-Driven Population Inference From Gravitational-Wave Sources And Electromagnetic Counterparts, Siddharth Mohite

Theses and Dissertations

Gravitational-wave (GW) astronomy has presented an unprecedented way to view the universe and study populations of astrophysical objects such as merging compact binaries containing black holes (BHs) and neutron stars (NSs). With the latest catalog of observations detected by the Advanced LIGO-Virgo detector network, recent analyses are placing interesting constraints on the population of BHs and NSs in these binaries. In particular, we are learning a great deal about how these binaries are distributed as a function of their masses. Another aspect of GW astronomy that has the potential to provide insights into fundamental physics is the multi-messenger follow up …

Surpassing The Standard Quantum Limit Using An Optical Spring, Torrey Cullen

LSU Doctoral Dissertations

In 1916, Albert Einstein predicted the existence of gravitational waves based on his new theory of general relativity. He predicted an accelerating mass with a non-zero quadrupole moment would emit energy in the form of gravitational waves. Often referred to as ripples in space-time, gravitational waves are extremely small by the time reach Earth, potentially having traveled hundreds of megaparsecs. It is common for these ripples in space-time to stretch and squeeze matter 1000 times smaller than the width of a proton.
Laser interferometer observatories were first built in the 1990s in the US and Europe, and as sensitivity improvements …

Resource Estimation For Quantum Simulation Algorithms, Changhao Yi

Physics & Astronomy ETDs

A major application of quantum computers is simulating other quantum systems that are intractable to simulate classically. The broad family of algorithms for this problem go by the name of quantum simulation. Product formulas provide resource efficient and practical methods to simulate Hamiltonian dynamics. In this thesis, we study the resource estimation of quantum simulation by product formula from two aspects. First, we provide a detailed analysis of the algorithm itself. Using the effective Hamiltonian perspective, we successfully reduce the circuit complexity of quantum phase estimation and digital adiabatic simulation. Second, we analyze the performance of dynamical decoupling, a widely-used …

Calibration Of The Lux-Zeplin Dual-Phase Xenon Time Projection Chamber With Internally Injected Radioisotopes, Christopher D. Nedlik

Doctoral Dissertations

Self-shielding in ton-scale liquid xenon (LXe) detectors presents a unique challenge for calibrating detector response to interactions in the detector's innermost volume. Calibration radioisotopes must be injected directly into the LXe to reach the central volume, where they must either decay away with a short half life or be purified out. We present an overview of, and results from, the prototype source injection system (SIS) developed at the University of Massachusetts Amherst for the LUX-ZEPLIN experiment (LZ). The SIS is designed to refine techniques for the injection and removal of precise activities of various calibration radioisotopes that are useful in …

Investigating The Thermodynamics And Seismic Profile Of The Europan Hydrosphere Through Pure-Water Modeling And Saltwater Experiments, Samantha Rosenfeld

Honors Theses

We explore the properties of the hydrosphere on Europa involving both a modeling technique and experimental methods. We perform a computational analysis of the thermodynamic properties for an ideal, pure-water Europan ice shell using a Python programming framework called SeaFreeze. We create four models assuming surface temperatures of either 50 K or 140 K and ice shell thicknesses of either 3 km or 30 km. We observe mostly linear trends for the density and seismic wave velocities with respect to depth and find that surface temperature has the greatest effect on the models. Simultaneously, we experimentally investigate the phase diagram …

Waves And Oscillations In A Sunspot: Observations And Modeling Of Noaa Ar 12470, Yi Chai

Dissertations

Waves and oscillations are important solar phenomena not only because they can propagate and dissipate energy in the chromosphere, but also because they carry information about the structure of the atmosphere in which they propagate. Among these phenomena, the one of the most interesting ones occurs in the sunspot umbra. In this area, continuously propagating magnetohydrodynamic (MHD) waves generated from below the photosphere create the famous 3-minute sunspot umbral oscillations that affect the line profile of spectral lines due to temperature, density, and velocity changes of the plasma in the region. In the past decades, numerous observations and models have …

Emergent Spectra Of Young X-Ray Emitting Populations Across Environments, Alex Siebenmorgen

Physics Undergraduate Honors Theses

We construct reasonably accurate models of the X-Ray spectra of a multitude of sources in M51. We construct both average and individual models for the sources, which are split into 16 groups as the counts per source increases. Then, we create a plot to show how the model-predicted values of column density (nH) and photon index (gamma) change with luminosity. These models will be used to create an accurate X-Ray stellar energy distribution (SED) for M51, and to better understand how the SED changes with environmental factors like metallicity and star formation rate (SFR).

Dust-Gas Dynamics Driven By The Streaming Instability With Various Pressure Gradients, Stanley Antedio Baronett

UNLV Theses, Dissertations, Professional Papers, and Capstones

The radial pressure gradient (RPG), along the midplane of gaseous protoplanetary disks (PPD) – planetary nurseries – poses a severe obstacle to planet formation. Micron-sized dust grains, embedded in the disc, must quickly grow to kilometer-sized planetesimals – the building blocks of planets – before fatally drifting inwards, by RPG-induced gas drag, into a central host star. However, the RPG simultaneously powers one of the most robust processes to overcome this radial-drift barrier: the streaming instability (SI). Spontaneously triggered, the SI aerodynamically concentrates drifting dust via drag-induced, coupled interactions and feedback with the surrounding gas. In particular, the non-linear phase …

Signal Yields And Detector Modeling In Xenon Time Projection Chambers, And Results Of An Effective Field Theory Dark Matter Search Using Lux Data, Gregory Ransford Carl Rischbieter

Legacy Theses & Dissertations (2009 - 2024)

The nature of dark matter continues to be one of the biggest remaining mysteries in physics. Astrophysical measurements indicate that dark matter makes up more than a quarter of the Universe's total energy density, and it is well-motivated that dark matter is comprised of Weakly Interacting Massive Particles (WIMPs). Direct detection techniques utilizing liquid and gaseous noble elements have become the primary method of probing the potential non-gravitational interactions between WIMPs and Standard Model matter, with the leading technology being the dual-phase Time Projection Chamber (TPC). The Large Underground Xenon (LUX) and its second-generation successor, LUX-ZEPLIN (LZ), are two xenon …

Investigation Of Tertiary Impact Cratering And Relation To Impact Physics Theory, Mikayla Huffman

Undergraduate Honors Theses

Extraterrestrial impact crater formation is important in many subfields of planetary science, including geochronology, planetary formation, and dynamic fragmentation theory. Current dynamic fragmentation theory lacks scale dependence and relies heavily on terrestrial data. Exploring a range of impact and ejecta velocities as is produced by cratering events on the Moon may bridge the gap between heavily terrestrial-based theory and planetary data. The secondary craters of secondary craters deemed “tertiary craters,” have been theorized, but planetary images have not been of sufficient resolution to effectively search for them until recently. Tertiary craters are formed by relatively low-velocity fragments ejected by nearby …

Chandra Spectral Constraints Of The Low-Metallicity Collision Ring Cartwheel Galaxy, Chloë Benton

Physics Undergraduate Honors Theses

With the sophistication of the Chandra X-Ray Observatory, many observations of the behaviors of binary systems have been researched and studied. As an excellent example, for the low metallicity Cartwheel Galaxy, some fraction of the X-ray photons emitted from X-ray binaries have been intercepted by the detectors on the telescope and have been compiled into “events file.” When modeled properly, this data can produce insight into the behavior of the stellar populations in this object. The primary goal of this project is to use these events files to measure the X-ray properties of the X-ray binaries in the Cartwheel Galaxy …

Terrestrial Planet Formation In M-Dwarf And Binary Star Systems, Anna C. Childs

UNLV Theses, Dissertations, Professional Papers, and Capstones

I examine circumbinary terrestrial planet formation in a gas free environment around various binary systems and terrestrial planet formation in a gaseous environment around M-dwarfs. While terrestrial cirumbinary planets have yet to be observed, this is likely due to observational bias. Motivated by recent observations of highly misaligned circumbinary gas disks, I perform a suite of n-body studies to understand the properties of terrestrial planets around various binary systems. In a polar alignment, a circumbinary disk is inclined by 90 degrees relative to the binary orbital plane. I find that terrestrial planet formation in a polar configuration may be as …

Exploring The Glow Of The Universe In Gamma-Rays And Hunting Distant Agn, Changam Meenakshi Rajagopal

All Dissertations

The entirety of the γ-ray radiation permeating our Universe is encoded in the extragalactic γ-ray background. This is a superposition of resolved sources, mostly powerful relativistic jets powered by supermassive black holes, i.e., blazars, and an unresolved isotropic component, aka, the diffuse isotropic gamma-ray background (IGRB). Studying the IGRB can help unveil its composition, as well as unearth multi-messenger relationships between the intensities of PeV neutrinos, ultra high energy cosmic rays (> 1018 eV), and sub-TeV γ-rays. The comparable energy budgets of these three phenomena (neutrinos, UHECR, and γ-rays) indicates a physical connection or a common source amongst them. On …

Nano-Fabricated Atomic Waveguides For Inertial Measurements, Adrian S. Orozco

Physics & Astronomy ETDs

Atom-based inertial measurement systems can measure acceleration and rotation very precisely in the laboratory. The central element of these systems is atom interferometry where the phase shifts are sensitive to inertial forces experienced by the atom. This phenomenon has been used to make atom-based gravimeters, gradiometers, and gyroscopes. Recent effort has been made to make these systems more compact which require small size, light weight, and low power (SWaP). Nano-fabricated waveguides, such as photonic waveguides or optical nanofibers, offer a promising avenue to meet these goals. They have dimensions comparable to the guided light’s wavelength producing a mode that not …

Reliability Of Quantum Simulation On Nisq-Era Devices, Karthik R. Chinni

Physics & Astronomy ETDs

We study the reliability of quantum simulation on Noisy intermediate-scale quantum (NISQ)-era devices in the presence of errors and imperfections, with a focus on exploring the relationship between the properties of the system being simulated and the errors in the output of the simulator. We first consider simulation of the Lipkin-Meshkov-Glick (LMG) model, which becomes chaotic in the presence of a background time-dependent perturbation. Here we show that the quantities that depend on the global structure of the phase space are robust, while other quantities that depend on the local trajectories are fragile and cannot be reliably extracted from the …

Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice

Doctoral Dissertations and Master's Theses

The detailed mechanisms coupling the solar wind to Earth's magnetosphere are not yet fully understood. Solar wind plasma is heated non-adiabatically as it penetrates the magnetosphere, and this process must span scale sizes. Reconnection alone is not able to account for the observed heating; other mechanisms must be at work. One potential process is the Kelvin-Helmholtz instability (KHI). The KHI is a convective instability which operates at the fluid scale in plasmas, but is capable of driving secondary process at smaller scales. Previous work has shown evidence of magnetic reconnection, various ion scale wave modes, mode conversion, and turbulence associated …

Characterizing Agn Influence On The Calculated Metallicities Of Adjacent Star-Forming Spaxels, Aidan Khelil

Honors Papers

In this thesis, I introduce a method to identify and characterize the effects of active galactic nuclei (AGN) on the spectra of nearby star-forming regions. I analyze spatially-resolved areas of galaxies called “spaxels” within Data Release 15 of the Sloan Digital Sky Survey (SDSS) with the goal of locating those which are physically close to AGN. I find those spaxels with calculated metallicities which lie adjacent to AGN-flagged spaxels and characterize their metallicity values relative to the spaxels which are not adjacent to AGN-flagged spaxels, using a total of 11 separate metallicity calibrations. I find that the current methods to …