Award Date

5-15-2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Committee Member

Bing Zhang

Second Committee Member

Ali Kheirandish

Third Committee Member

Zhaohuan Zhu

Fourth Committee Member

Monika Neda

Number of Pages

233

Abstract

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. I present PromptX, a computational toolkit for modeling X-ray counterparts to neutron star mergers. PromptX computes observer-frame light curves and spectra, enabling rapid characterization of multimessenger events. In tandem with GRB afterglow modeling toolkits such as VegasAfterglow, these frameworks provide predictive, low-latency diagnostics to inform and optimize broadband follow-up campaigns. Applying PromptX to the growing population of luminous, spectrally soft fast X-ray transients detected by the Einstein Probe, I show that geometry alone cannot explain their observed energetics. Interpreting these events requires understanding the distinct radiation mechanisms, outflow dynamics, and progenitor properties that power them. These results demonstrate that geometric effects and radiation processes are inseparable in interpreting transient emission from compact objects and provide self-consistent modeling frameworks that integrate theoretical models with high-energy astrophysical observations.

Keywords

Compact objects; High-energy astrophysics; Multimessenger astrophysics; Numerical modeling; Radiation processes; Relativistic transients

Disciplines

Astrophysics and Astronomy | Physical Sciences and Mathematics | Physics

File Format

PDF

File Size

7700 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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