The Distribution of Burst Energy and Shock Parameters for Gamma-Ray Bursts
Author(s) -
Pawan Kumar
Publication year - 2000
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/312821
Subject(s) - afterglow , physics , gamma ray burst , astrophysics , luminosity , interstellar medium , full width at half maximum , optics , galaxy
We calculate the statistical distribution of observed afterglow flux, in somefixed observed frequency band, and at some fixed observer time after theexplosion ($t_{obs}$) in two models - one where the explosion takes place in auniform density medium and the other where the surrounding medium has apower-law stratification such as is expected for a stellar wind. For photonenergies greater than about 500 electron-volt and $t_{obs}\gta 10^3$ sec theafterglow flux distribution functions for the uniform ISM and the wind modelsare nearly identical. We compare the width of the theoretical distribution withthe observed x-ray afterglow flux and find that the FWHM of the distributionfor energy in explosion and the fractional energy in electrons ($\epsilon_e$)are each less than about one order of magnitude and the FWHM for the electronenergy index is 0.6 or less.Comment: 12 pages & 3 figure, submitted to ApJ on 12/20/199
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