Gamma-ray bursts and their afterglows: toward a unified model

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Title: Gamma-ray bursts and their afterglows: toward a unified model
Author: McMahon, Erin Malia, 1980-
Abstract: Although much progress has been made in our understanding of gamma -ray bursts (GRBs ) and their afterglows in the last few decades , some critical questions remain unanswered . One of these questions regards the form in which energy is transported from the explosion to the site at which the gamma -rays are produced - - i .e . is the energy carried in the kinetic energy of electrons and /or protons , or is much of it stored in a magnetic field ? This dissertation documents a series of attempts to more clearly understand the nature of GRB outflows . First , we explore the possibility that the GRB is produced by an external shock , created when a baryonic outflow is decelerated by the surrounding medium . Next , emission from the external reverse shock is used to try to determine if the GRB ejecta is pair enriched . We then use data from several interesting , Swift -detected GRBs pin down the GRB emission radius , bulk Lorentz factor , magnetic field strength , and electron energy . We end by describing our nearly model independent method of modeling the GRB radiation as a combination of synchrontron and synchrontron self -Compton . We find that the GRB is likely to be produced by the syncrontron self -Compton radiation mechanism and predict that the accompanying prompt optical emission should be very high . If bright optical radiation during the GRB is not found , we think that this is good evidence that the acceleration of electrons is taking place repeatedly on a short timescale , effectively ruling out shock -based acceleration models .
URI: http : / /hdl .handle .net /2152 /3790
Date: 2008-08-29


Gamma-ray bursts and their afterglows: toward a unified model. Doctoral dissertation, The University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /3790 .

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