Award Date

5-14-2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Astronomy

Department

Physics and Astronomy

First Committee Member

Bing Zhang

Second Committee Member

Daniel Proga

Third Committee Member

Stephen Lepp

Fourth Committee Member

Pengtao Sun

Number of Pages

155

Abstract

The prompt emission of Gamma-Ray Bursts (GRBs) has been detected over 40 years, but the mechanism of the prompt emission is still a mystery. The problem can be summarized as several debatable questions: What is the energy composition of the jets/outflows? What is the energy dissipation mechanism? How are the particles accelerated during the energy dissipation process? What is the radiation mechanism to produce the observed prompt emission? In order to solve these problems, several theoretical models have been proposed, including the classical "internal shock (IS)" model, the "dissipative photosphere" model, the "magnetic dissipation" model, and so on. Different models have different strengths and weaknesses. Observations also show a diversity of GRB emission properties, and different GRBs may favor different models. Statistically, a small fraction of GRBs, show an obvious feature of the thermal origin; in contrast, the majority of GRBs, with the so called "Band-function" spectra, favor the non-thermal origin. A promising magnetic dissipation model proposed by Zhang & Yan (2011) dubbed "the Internal-Collision-induced MAgnetic Reconnection and Turbulence (ICMART)" model shows great potential to overcome the weaknesses in other models and interpret the observations of the majority of GRBs. However, since some important ingredients of this model are still of a speculative nature, the follow-up detailed numerical simulation works are definitely needed to give a solid footing to this model.

Keywords

Electromagnetic fields; Energy dissipation; Gamma ray bursts; prompt emission; photosphere; Spectrum analysis

Disciplines

Astrophysics and Astronomy

Language

English


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