Open AccessGamma‐ray bursts: post‐burst evolution of fireballs
Author(s) -
Huang Y. F.,
Dai Z. G.,
Wei D. M.,
Lu T.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01632.x
Subject(s) - physics , gamma ray burst , adiabatic process , astrophysics , synchrotron radiation , flux (metallurgy) , interstellar medium , afterglow , radiation , relativistic beaming , astronomy , active galactic nucleus , galaxy , optics , quantum mechanics , materials science , metallurgy
The post‐burst evolution of fireballs that produce γ‐ray bursts (GRBs) is studied, assuming the expansion of fireballs to be adiabatic and relativistic. Numerical results as well as an approximate analytic solution for the evolution are presented. Owing to the adoption of a new relation between t R and γ, our results differ markedly from previous studies. Synchrotron radiation from the shocked interstellar medium is carefully calculated, using a conventional set of equations. The observed X‐ray flux of GRB afterglows can be reproduced easily. Although the optical afterglows seem much more complicated, our results can still present a rather satisfactory agreement with observations. We also find that the expansion will no longer be highly relativistic about 4 d after the main GRB. We thus suggest that the marginally relativistic phase of the expansion should be investigated so as to check the afterglows observed a week or more later.