Modeling and Analysis of Gamma-Ray Burst Dynamics and Emission
Open AccessGamma-Ray Bursts (GRBs) are bright flashes of gamma rays that outshine the rest of the gamma-ray sky, emitting the sun's entire life-time energy over the span of tens of seconds or, occasionally, in a fraction of a second. Their extreme conditions, such as their intense magnetic fields and high particle energies, allow us to study physics in conditions not reproducible here on Earth. In this dissertation, I summarize the observational and theoretical considerations of GRBs, followed by a description of the modeling and data analysis work I have completed.I discuss the semi-analytic model I have developed to simulate the dynamical evolution of GRB outflows from their launch to deceleration. I describe how the model calculates emission from both the prompt and afterglow phases, a unique capability with respect to other GRB models. I demonstrate how the spectra and light curves generated by the model compare to observations. I discuss how the model has revealed that the external shock may play a larger role in GRB prompt emission than previously expected and how the flux variability witnessed in the optical afterglow of GRB030329 may be produced via a set of refreshed shocks.Finally, I discuss the instrumental bias imparted on prompt emission duration measurements for GRBs observed by the \textit{Neil Gehrels Swift Observatory} Burst Alert Telescope (Swift/BAT). Traditionally, the duration of the prompt emission is used to infer the nature of the GBR's progenitor, but duration measurements are affected by instrument bias. The “tip-of-the-iceberg” effect describes how the source signal can become hidden by background noise and, consequently, lead to duration measurements shorter than the intrinsic duration. I demonstrate how duration measurements made for Swift/BAT GRBs can be highly sensitive to observing conditions, in some cases being significantly shorter than the true burst duration.
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