AAS 197, January 2001
Session 25. Gamma Ray Bursts: Localization and Identification
Oral, Monday, January 8, 2001, 1:30-3:00pm, Golden Ballroom

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[25.06] Cosmological and Intrinsic Properties of Gamma-Ray Bursts.

N.M. Lloyd (Stanford University Department of Physics)

This talk will summarize the work done in my thesis on the cosmological and intrinsic properties of Gamma-Ray Bursts. I will highlight a few of the main results from my past work published in collaboration with my thesis advisor, Vahe' Petrosian. In particular, I will discuss our work on: 1) The distribution of, and correlations between the spectral characteristics of GRBs, 2) The cosmological evolution of GRBs (as inferred from our studies in item 1), 3) Emission mechanisms in GRB internal shocks. Item 3 will emphasize our recent work involving the time resolved spectral properties of GRBs. We show that time resolved spectral fits are consistent with synchrotron emission from internal shocks, when realistic synchrotron models are used, and we present the time evolution of the physical GRB parameters for some representative bursts. We focus in particular on the large number (~35 %) of bursts that fall above the so-called synchrotron ``line of death''. We show that some of these bursts can be explained by synchrotron self-absorption, but that most are due to optically thin emission from electrons with small pitch angles. We discuss the implications this has on particle acceleration in GRBs.

The author(s) of this abstract have provided an email address for comments about the abstract: nicole@urania.stanford.edu

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