Astrophysics and Astronomy Commons^™

Effects Of Coulomb Collisions On The Structures Of Fast Magnetosonic Shocks, Bo Farnell

Physics and Astronomy Undergraduate Senior Theses

We present fully kinetic particle-in-cell simulations demonstrating qualitative effects of binary Coulomb collisions on fast magnetosonic shocks. We find that with a sufficiently high collisional frequency, shock rippling and reformation can be inhibited, creating stationary, laminar shocks. We see that collisions rapidly bring the reflected population into equilibrium with the upstream population, adding credibility to existing theories that the separation of these two populations create these dynamical behaviors around the shock transition region. We also see that Ohmic heating from Coulomb collisions can suppress instabilities.

Deep Search For Joint Sources Of Gravitational Waves And High-Energy Neutrinos With Icecube During The Third Observing Run Of Ligo And Virgo, R. Abbasi, M. Ackermann, Mario C. Diaz, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

The discovery of joint sources of high-energy neutrinos and gravitational waves has been a primary target for the LIGO, Virgo, KAGRA, and IceCube observatories. The joint detection of high-energy neutrinos and gravitational waves would provide insight into cosmic processes, from the dynamics of compact object mergers and stellar collapses to the mechanisms driving relativistic outflows. The joint detection of multiple cosmic messengers can also elevate the significance of the common observation even when some or all of the constituent messengers are subthreshold, i.e., not significant enough to declare their detection individually. Using data from the LIGO, Virgo, and IceCube observatories, …

Realizing The Long Wavelength Array Swarm, Craig Anthony Taylor

Physics & Astronomy ETDs

Sensitive modern radio interferometers are costly to build and operate at the university level. The `swarm telescope' concept addresses this challenge by enabling the collaborative use of individual telescope systems, overseen by separate institutions, that come together to form a more powerful and manageable facility. This dissertation focuses on demonstrating this concept using the Long Wavelength Array (LWA) by commissioning an aperture synthesis telescope consisting of interconnected LWA stations, called the LWA Swarm. The presented work details building a cost-efficient prototype LWA platform -- the LWA--North Arm station -- to enable synthesis imaging using the 3-element interferometer comprised of LWA1, …

A Multi-Frequency Investigation Of Compact Symmetric Objects, Evan E. Sheldahl

Physics & Astronomy ETDs

Some of the brightest objects in the radio sky are jetted active galactic nuclei (AGN), supermassive black holes in the centers of galaxies that accelerate relativistic electrons into twin radio jets. One of the biggest questions surrounding AGN is how they produce radio jets in the first place. We search for an answer to this question by exploring a class of AGN that have uniquely well-constrained physical properties and are thought to be in an early stage of AGN development: compact symmetric objects (CSOs). Throughout our journey with these remarkable sources, we quantify their efficacy as calibrator sources for radio …

The Yorp Effect In Reboundx, Kaelyn Clement

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect is a radiation-induced torque that can affect the spin and rotational obliquity of small bodies. It has been observed to alter the rotation rate of asteroids in the Solar System (Lowry et al. 2007; Taylor et al. 2007). Under extreme circumstances, YORP can cause a body to fragment, inducing a cascade of fissions. This effect may be important in driving the pollution of white dwarf atmospheres in conjunction with other radiative forces. I developed a YORP calculator for REBOUNDX (Tamayo et al. 2020), an extensional library to the N-body integrator REBOUND (Rein & Liu 2012). I …

The Origins Of Chondrite Families, Isabelle M. Perron

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chondrites, a type of primitive asteroid, are thought to have formed from dust and gas early in the life of our Solar System. These chondrites have remained unchanged since their formation, avoiding being melted or differentiated like other rocky bodies have. Due to this unique characteristic, chondrites can give us useful insight into how asteroids, planetesimals, and even the terrestrial planets formed. In order to study chondrites and their formation, I used code developed by Li et al. (2020), which utilizes thermodynamic code GRAINS (Petaev 2009), to see what conditions the chondrites may have originated from. GRAINS uses a variety …

Relativistic Transients From Compact Objects: Radiation Processes And Geometric Effects, Connery Chen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Relativistic transients from compact objects probe the most extreme regimes of physics, where strong gravity, ultra-relativistic outflows, and high-energy radiation operate simultaneously; understanding the underlying radiation mechanisms and extrinsic geometric and relativistic effects is essential for interpreting observations and constraining source properties. I develop theoretical and computational frameworks to quantify how geometry and relativistic motion shape observed emission from fast radio bursts, gamma-ray bursts, and neutron star mergers. I analyze fast radio bursts from the Galactic magnetar SGR J1935+2154 and show that emission geometry strongly governs burst energetics and detection probability, and influences the link between radio and X-ray emission. …

Fast Radio Bursts And Long Period Radio Transients: Radiation Mechanisms And Propagation Effects, Yuanhong Qu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fast Radio Bursts (FRBs) are bright radio bursts with the highest brightness temperatures in the radio sky. In this thesis, we investigate the trigger mechanisms, radiation mechanisms, and propagation effects of FRBs. Two general classes of coherent radiation mechanisms are considered in two categories: pulsar-like models invoking emission originating within the magnetar magnetosphere, and GRB-like models, which attribute the emission to relativistic magnetized shocks occurring far away from the central engine. We use the general observed properties (polarization features and spectra bandwidths) of repeating FRBs to constrain the physical conditions needed for these two mechanisms. We propose that crust quakes …

Strongly Confined Bismuth Antimonide Quantum Dots, Min Khadka, Rajendra Subedi, Qiaohui Zhou, Xin Lu, Joelin A. Agyei-Mensah, Miguel José-YacamáN, Guillaume Lang, Etienne Herth, Gregory Guisbiers

Faculty Scholarship

Bismuth antimonide (Bi1–xSbx) has emerged as a highly promising material for quantum applications due to its complex band structure. In this study, spherical Bi1–xSbx quantum dots (QDs), with a diameter of around 8 ± 2 nm, were successfully synthesized by pulsed laser ablation in liquids. The energy bandgap was determined at 2.02 ± 0.27 eV, which is significantly higher than the bulk value (∼0.025 eV). The strong confinement nature of the dots was confirmed by the Raman peak shifts. The chemical composition of the Bi1–xSbx QDs was measured to be around 77 ± 2 at. % of Bi and 23 …

Evidence For Environmental Stripping In The Coma Cluster, Richard T. Pomeroy, Juan P. Madrid, Conor R. O’Neill, Alexander T. Gagliano

Physics & Astronomy Faculty Publications

The stability and longevity of globular clusters (GCs) make them effective tracers of the dynamical histories of galaxies in cluster environments. We construct a catalog of 23,351 GC candidates in the Coma Cluster using imaging from the Hubble Space Telescope Advanced Camera for Surveys. We cross-match galaxy data from the SIMBAD, NASA/IPAC Extragalactic Database, and Sloan Digital Sky Survey archives to construct a galaxy sample and model their GC populations using the GC specific frequency. We find several galaxies with significantly smaller GC populations than expected from their luminosities, consistent with either tidal stripping or intrinsically low formation efficiencies. We …

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

Kl Dra As A Benchmark Laboratory For Accretion-Disk Physics: Constraints From Tess And Ground-Based Surveys, Luis E. Salazar Manzano, Liliana E. Rivera Sandoval, Jean-Marie Hameury, Craig O. Heinke, Iwona Kotko, Thomas J. Maccarone, Manuel Pichardo Marcano

Physics & Astronomy Faculty Publications

We present the longest-term optical analysis of the AM CVn system KL Dra using ∼11 yr of monitoring from TESS and wide-field ground-based surveys. The continuous TESS coverage allows us to characterise its frequent outbursts with unprecedented detail, providing the first comprehensive study of an AM CVn during outbursts and enabling detailed modelling of these systems. The superoutbursts in KL Dra generally include a precursor and are followed by a series of rebrightenings after which a sequence of 3–4 large amplitude normal outbursts is observed. We fit parametric profiles to each superoutburst component (precursor, rise to plateau, plateau, and decay), …

Impact Of Intravenous Thrombolysis On Aspiration Thrombectomy Outcomes: An Imperative Trial Subgroup Analysis, Yi-Qian Qian, Yan Wang, Soumya Mohanty, Siyuan Chen

Physics & Astronomy Faculty Publications

Bayesian methods for the detection of continuous gravitational waves (CGWs) in pulsar timing array (PTA) data incur substantial computational costs that grow rapidly due to the number of noise and signal parameters characterizing the fitted model being proportional to the size of the PTA. This computational burden limits the scalability of these methods for large-scale PTAs comprising hundreds of pulsars anticipated from next-generation radio astronomy facilities. In this work, we introduce a computationally efficient frequentist method designed to circumvent this challenge. This is achieved by combining an adaptive spline fitting algorithm that nonparametrically suppresses red noise, thereby eliminating the need …

A Catalogue Of Orbital Periods Of Cataclysmic Variables And Candidates From Tess Observations, Meryem K. Dag, Simone Scaringi, Kieran O’Brien, Martina Veresvarska, Nikita Rawat, Yusuke Tampo, Santiago Hernández-Díaz, Liliana Rivera Sandoval, Wendy Mendoza, Ryan J. Oelkers, Jan Kára

Physics & Astronomy Faculty Publications

We present a systematic analysis of 2544 cataclysmic variable systems and related candidates observed by the Transiting Exoplanet Survey Satellite (TESS), with the aim of compiling a comprehensive catalogue of orbital periods. Using 2-min photometric time-series data, we applied an automated algorithm to generate Lomb–Scargle periodograms and identify the most significant coherent periodic signals, which were subsequently verified through visual inspection. This process yielded a confident sample of 910 sources exhibiting at least one periodic signal, hereafter referred to as the Cataclysmic Variable Confident Catalogue (CCC). For each object, we report the most likely orbital period together with …

Design And Verification Of The Multi-Slit Solar Explorer Camera Field Programmable Gate Arrays, Jordan M. Johnson

All Graduate Reports and Creative Projects, Fall 2023 to Present

The Multi-Slit Solar Explorer, or MUSE, is a NASA mission that will take images of the Sun to study solar flares and the solar corona. The mission will provide insight into the mechanisms behind space weather. The mission consists of two cameras: the Spectrograph (SG), and the Context Imager (CI). The Utah State University Space Dynamics Laboratory is providing both cameras for the mission.

This report describes a part of the design and verification process for a central component on these cameras known as the Field Programmable Gate Arrays (FPGAs). These FPGAs are programmed to acquire, handle, and send images …

Modeling Hot Jupiter Atmospheres For The Classification Of Low Abundance Molecules, Mika Brown

Physics Undergraduate Honors Theses

Transmission spectroscopy is a powerful method for studying exoplanet atmospheres. With the recent launch of the James Webb Space Telescope (JWST), several molecules have been successfully detected in hot Jupiter atmospheres at an unprecedented level of precision with transmission spectroscopy. To better understand current detection capabilities and limitations, this project used machine learning techniques to determine which molecules are currently identifiable at the spectral resolution and wavelength range of JWST’s NIRSpec instrument in PRISM mode. A large synthetic dataset of transmission spectra was first generated using the petitRADTRANS radiative transfer Python package. The resulting spectra were then used to train …

The Trouble Of Energy: Theoretical Foundations Of Loop Quantum Gravity, Hallie Gift

Senior Honors Theses

While general relativity and quantum mechanics have proved to be successful theories with elegant explanations of special cases, an underlying theory is needed to harmonize their copious discrepancies. Popular theories to reconcile the two are broadly termed “quantum gravity,” which refers to theories that introduce a discretized component of gravity either by directly suggesting gravitational quanta or attempting to discretize spacetime geometry. Loop quantum gravity falls under the latter category; it respects the background independence intrinsic to general relativity while attempting to provide an explanation of underlying quantum behavior via Planck-scale-level geometrical discretization. This thesis aims to provide a primer …

Search For Slow-Moving Magnetic Monopoles With An Improved High-Energy Event Removal Algorithm, Reeshi N. Gihosal

Honors Theses

Fermilab’s NOvA (NuMI Off-axis 𝑣𝑒 Appearance) experiment focuses on understanding the behavior of neutrinos and how they affect the cosmos. A sub-focus of the NOvA experiment is the search for magnetic monopoles. These elusive particles have not yet been observed in nature, leaving their behavior to be mysterious. The Far Detector, located in Ash River, MN, is integral in the search for these particles. This project is on simulated magnetic monopoles with speeds thousandths the speed of light, with focus on the role of slicing algorithms in event reconstruction using the NOvA experiment’s reconstruction algorithm. Using sample data, analysis occurred …

Can Methanogens Grow On Asteroids?, Isabella N. Reimer

Biological Sciences Undergraduate Honors Theses

Because of asteroids’ chemical features, they may serve as potential environments for life and are of interest in astrobiology. Dr. Kral’s laboratory studies methanogens, microorganisms in the domain Archaea, as possible life forms on extraterrestrial bodies. Since some methanogens can withstand harsh environmental conditions and produce methane as a waste product, methane production can be used as an indicator of potential microbial activity.  In this study, three methanogen species, Methanothermobacter wolfeii, Methanobacterium formicicum, and Methanosarcina barkeri were tested for growth on asteroid simulants based on the Orgueil (CIE-1) and Murchison (CME-1) meteorites. First, methanogen growth was assessed in the …

The Space In Between, Cailyn Dawson

Theses and Dissertations

This paper asks the question: is it possible for our bodies to hold contradicting identities at the same time?  Through monochromatic self- portraits, the artist creates a link between quantum mechanics and painting, using the principle of superposition to depict these multiple unformed states of being.

Optical Counterparts To X-Ray Sources In Lsst Dp1, Yuankun David Wang, Eric Bellm, Robert I. Hynes, Yue Zhao, Poshak Gandhi, Liliana E. Rivera Sandoval, Sandro Campos, Neven Caplar, Melissa Delucchi, Konstantin Malanchev

Physics & Astronomy Faculty Publications

We present a crossmatch between a combined catalog of X-ray sources and the Vera C. Rubin Observatory Data Preview 1 (DP1) to identify optical counterparts. The six fields targeted as part of DP1 include the Extended Chandra Deep Field South (E-CDF-S), the Euclid Deep Field South, the Fornax Dwarf Spheroidal Galaxy (Fornax dSph), 47 Tucanae (47 Tuc), and science validation fields with low Galactic and ecliptic latitude (SV_95_-25 and SV_38_7, respectively). We find matches to 2314 of 3830 X-ray sources. We also compare our crossmatch to DP1 in the E-CDF-S field to previous efforts to identify optical counterparts. The probability …

X-Raying The Material Surrounding Active Supermassive Black Holes, Isaiah S. Cox

All Dissertations

It is important to understand the nature of the gas and dust immediately surrounding the supermassive black hole (SMBH) in active galactic nuclei (AGN), because this material feeds the accretion disk and couples the activities going on at the AGN scale to the host galaxy. However, there remain large uncertainties on basic properties about this material such as its location and distribution. This is primarily due to the difficulties in resolving spatial information on these scales at extragalactic distances.

AGN emit a tremendous amount of radiation all across the electromagnetic spectrum, including X-rays. The X-rays come from a very small …

Manned Exploration Of Satellites Of The Outer Planets: An Analysis Of Current Technologies And A Discussion Of Advancements Required, Joshua Carson Meador

Theses and Dissertations

The Solar System’s outer planets have many satellites, some of which are known to be the most likely places to find extraterrestrial life in our celestial backyard. Multiple scientific missions have been sent to glean information from these satellites, yet the possibility of a manned expedition has long been exclusive to science fiction stories. This paper intends to collect and analyze the current state of space travel technology to explore the feasibility of such a mission with modern technology and to discuss which future advancements should be the focal point for making such missions a reality. To begin, data on …

Quantifying Noise In Monte Carlo Simulations Of Cosmic Rays In A Shock, Abhro Rahman

Theses and Dissertations

Cosmic rays are a phenomenon known to humankind from the early 1900s, and yet today the details of their physical behavior are not fully settled. While the observed spectral fluxes of cosmic rays follow a power-law trend when plotted against particle energy, the exact mechanisms under which they get to such high energies are still under study. This thesis will undertake a subsection of that task, where the Monte Carlo simulation of particle accelerations is described in Warren (2015), and we aim to identify and quantify the noise inherent in such simulations. This document takes a long path through particle …

Of Dunes And Ice: A Surface-Atmosphere Investigation Of Mars Co2 Sublimation Features And Titan Aeolian Fields, Racine D. Cleveland

Graduate Theses and Dissertations

This dissertation investigates a central question: How do planetary boundary layer processes manifest in observable surface geomorphology, and how can planetary imagery be used to quantify those effects? The planetary boundary layer (PBL) governs near-surface exchanges of momentum, heat, and volatiles, yet direct atmospheric measurements remain spatially and temporally limited on most planetary bodies. By analyzing geomorphic features preserved in high-resolution imagery, this work quantifies how boundary-layer processes leave measurable signatures on planetary surfaces. For Mars, high-resolution images from the Mars Reconnaissance Orbiter (MRO) HiRISE instrument were used to map CO2 sublimation features, or Swiss Cheese Features (SCFs), on the …

What Do Black Holes Teach Us About Wigner’S Friend?, Emily Adlam

Mathematics, Physics, and Computer Science Faculty Articles and Research

Recently, Hausmann and Renner have pointed out that several famous paradoxes relating to black holes have a similar character to various Extended Wigner’s Friend paradoxes. In this paper I consider what the connection between these things could teach us about the Wigner’s Friend scenarios. I argue that if we take the analogy between these cases seriously, the black hole paradoxes appear to favour a certain class of response to the Wigner’s Friend scenario - specifically, those which posit intrinsic relationality, rather than effective and emergent relationality, and also those which posit some kind of retrocausality.

Domain Wall Gravitational Waves: Constraints Within Extensions Of The Standard Model, Sophia W. Jensen

Departmental Honors & Graduate Capstone Projects

This work considers an extra-dimensional framework to explain the gravitational wave background (GWB), massive neutrinos, and baryon asymmetry. Through studying all three, restrictions on certain parameters arise and provide bounds on both theories. It is proposed that the GWB is caused by cosmic domain walls, sheet-like topological defects that were theoretically created in the early universe shortly after the Big Bang. A relationship be- tween the energy density of domain walls and the vacuum expectation value of the broken symmetry was defined. Constraints on the parameters, including the already observed fre- quencies of gravitational waves and the current energy content …

Intermediate-Scale Outflow Dynamics Of Eta Carinae, Edmund J. Garcia, Matthew C. Fleenor

Departmental Honors & Graduate Capstone Projects

η Carinae (η Car) is a binary system, with the larger star being an extremely massive, luminous blue variable (LBV) beyond the Eddington Limit. Surrounding the η Car system, numerous multi-wavelength imaging campaigns reveal axisymmetric structures with the expanding bipolar Homunculus Nebula (¡1 pc). In combination with the episodic eruptive history of the η Car system, our initial intermediate-scale imaging revealed further axisym- metric structures (1-5 pc). To gain a more expansive view of how the small scale structure connects to panoramic imaging of the η Car region, we constructed a deep, optical, narrowband mosaic of 189 images utilizing the …

All-Sky Search For Long-Duration Gravitational-Wave Transients In The First Part Of The Fourth Ligo-Virgo-Kagra Observing Run, A. G. Abac, I. Abouelfettouh, F. Acernese, Teviet Creighton, Mario C. Diaz, Raul A. Espinosa, J. Lawrence, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Miriam Ramos Arevalo, Wenhui Wang

Physics & Astronomy Faculty Publications

We present an all-sky search for long-duration gravitational waves (GWs) from the first part of the LIGO-Virgo-KAGRA fourth observing run (O4), called O4a and comprising data taken between May 24, 2023, and January 16, 2024. The GW signals targeted by this search are the so-called “long-duration” ( ≳1  s) transients expected from a variety of astrophysical processes, including nonaxisymmetric deformations in magnetars or eccentric binary coalescences. We make minimal assumptions on the emitted GW waveforms in terms of morphologies and durations. Overall, our search targets signals with durations of ∼1–1000  s and frequency content in the range 16–2048 Hz. In …

The Role Of Human-Centered Artificial Intelligence In Crewed Mars Missions, Jordan Neuman

Student Publications and Presentations

The suggestion of implementing Artificial Intelligence (AI) in crewed missions to the Martian surface can revolutionize mission operations, psychological support, and ethical decision‑making under challenging conditions. This study is a structured, qualitative literature review of current AI research for the future of human space exploration. It uses publicly available peer‑reviewed journal articles and NASA/ESA technical reports on AI for Mars missions. Using Perplexity, the researcher first prompted the AI tool to identify recurring topics across these sources and generate themes. The researcher independently reviewed all sources to confirm and refine those themes. Three themes—mission autonomy, local resource utilization and life‑support, …