Issue |
A&A
Volume 471, Number 1, August III 2007
|
|
---|---|---|
Page(s) | 1 - 5 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20066160 | |
Published online | 06 June 2007 |
The rise of the afterglow in GRB 050820a
Institut d'Astrophysique de Paris – UMR 7095 CNRS et Université Pierre et Marie Curie, 98 bis boulevard Arago, 75014 Paris, France e-mail: genet@iap.fr
Received:
1
August
2006
Accepted:
4
April
2007
Context.The early optical afterglow of GRB 050820a recorded by the RAPTOR telescope shows both a contribution from the prompt emission and the initial rise of the afterglow.
Aims.It is therefore well-suited for the study of the dynamical evolution of the GRB ejecta when it first undergoes the decelerating effect of the environment. This is a complex phase where the internal, reverse, and forward shocks can all be present simultaneously.
Methods.We have developed a simplified model that can follow these different shocks in an approximate, but self-consistent way. It is applied to the case of GRB 050820a to obtain the prompt and afterglow light curves.
Results.We show that the rise of the afterglow during the course of the prompt emission has some important consequences. The reverse shock propagates back into the ejecta before internal shocks are completed, which affects the shape of the gamma-ray profile.
Conclusions.We get the best results when the external medium has a uniform density, but obtaining a simultaneous fit of the prompt and afterglow emission is not easy. We discuss a few possibilities that could help to improve this situation.
Key words: gamma rays: bursts / shock waves / radiation mechanisms: non-thermal
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.