| Gamma-Ray Burst (GRB) prompt emission spectra contain a wealth of information about the unresolved creation mechanism and source environment. A detailed spectral study of GRBs is, therefore, crucial to unveiling their nature. Previous spectral studies have shown compelling evidence that the Synchrotron Shock Model (SSM) cannot entirely account for observed spectra in terms of the spectral parameters. However, spectral parameters often depend on photon models employed and integration timescales of the spectra. The primary purpose of this dissertation is to explore model-unbiased spectral properties of GRB prompt emission in great detail with the best available statistics.; First, I present a systematic spectral analysis of 350 bright BATSE GRBs (30 keV--2 MeV) with high energy and time resolution. To obtain unbiased spectral parameters, various photon models were used to fit each spectrum, and internal characteristics of each model were also investigated. A thorough analysis was performed on 342 time-integrated and 8459 time-resolved burst spectra, and the effects of integration times in determining the spectral parameters were explored. Typical spectra are described as a broken power law with various break curvatures: very sharp to very smooth. The analysis was then extended to broadband spectra of high-energy GRBs observed with BATSE and EGRET (30 keV--200 MeV). One event was identified to have a very high peak energy in the power density spectrum, Epeak > 167 MeV, and two events indicated high-energy excess.; Finally, the well-constrained, model-unbiased spectral parameters were used to examine some of the existing GRB emission models. I show, with good statistical confidence, that a considerable number of spectra are inconsistent with the SSM, while the jitter-synchrotron model can account for the spectral behavior of most GRBs in our sample.; The analysis of GRB prompt emission spectra presented in this dissertation is derived from the most sensitive and largest database to date. Therefore, these results provide exceptional statistics to set a standard for spectral properties of GRB prompt emission, and will be a pivotal reference for both theorists and observers, for the upcoming GLAST era and for defining science criteria for future missions. |
