Journal Article

An external-shock origin of the relation for gamma-ray bursts

A. Panaitescu

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 393, issue 3, pages 1010-1015
Published in print March 2009 | ISSN: 0035-8711
Published online February 2009 | e-ISSN: 1365-2966 | DOI:
An external-shock origin of the  relation for gamma-ray bursts

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We investigate the possibility that the relation between the peak energy Ep of the νFν spectrum and energy output for long-duration gamma-ray bursts (GRBs) arises from the external shock produced by the interaction of a relativistic outflow with the ambient medium. To that aim, we take into account the dependence of all parameters which determine Ep and on the radial distribution of the ambient medium density and find that the relation can be explained if the medium around GRBs has a universal radial stratification. For various combinations of GRB radiative process (synchrotron or inverse-Compton) and dissipation mechanism (reverse or forward shock), we find that the circumburst medium must have a particle density with a radial distribution different than the R−2 expected for the stellar wind corresponding to a constant mass-loss rate and terminal speed.

Keywords: radiation mechanisms: non-thermal; shock waves; gamma-rays: bursts

Journal Article.  5463 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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