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Title: Confronting GRB prompt emission with a model for subphotospheric dissipation

The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. We fit Fermi GRB data with a photospheric emission model which includes dissipation of the jet kinetic energy below the photosphere. The resulting spectra are dominated by Comptonization and contain no significant contribution from synchrotron radiation. In order to fit to the data, we span a physically motivated part of the model's parameter space and create DREAM (Dissipation with Radiative Emission as A table Model), a table model for XSPEC. Here, we show that this model can describe different kinds of GRB spectra, including GRB 090618, representing a typical Band function spectrum, and GRB 100724B, illustrating a double peaked spectrum, previously fitted with a Band+blackbody model, suggesting they originate from a similar scenario. We also suggest that the main difference between these two types of bursts is the optical depth at the dissipation site.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2]
  1. KTH Royal Inst. of Technology, Stockholm (Sweden). Dept. of Physics
  2. Univ. College, Cork (Ireland). Physics Dept.
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society: Letters
Additional Journal Information:
Journal Volume: 454; Journal Issue: 1; Journal ID: ISSN 1745-3925
Publisher:
Royal Astronomical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; radiation mechanisms: thermal; gamma-ray burst: general; gamma-ray burst: individual: GRB 090618; gamma-ray burst: individual: GRB 100724B
OSTI Identifier:
1354921