On the existence of a reverse shock in magnetized GRB ejecta

Details On the existence of a reverse shock in magnetized GRB ejecta On the existence of a reverse shock in magnetized GRB ejecta

2007-11-13

arxiv.org/abs/0711.1980v2

Astronomy and Astrophysics

Astrophysics

8 pages, 1 figure, A&A in press, small changes to match the accepted version

Scientific paper

10.1051/0004-6361:20078931

The role of magnetic fields in gamma-ray burst (GRB) flows remains controversial. The study of the early afterglow phases and, in particular, of the reverse shock dynamics and associated emission offers a promising probe of the magnetization of the ejecta. In this paper, we derive the conditions for the existence of a reverse shock in arbitrarily magnetized ejecta that decelerate and interact with the circumburst medium. Both constant and wind-like density profiles are considered. We show, in contrast to previous estimates, that ejecta with magnetization larger than unity are not crossed by a reverse shock for a large fraction of the parameter space relevant to GRB flows. Allowing for shell spreading, there is always a relativistic or mildly relativistic reverse shock forming in sigma_o < 0.3 ejecta. From this, we conclude that the paucity of optical flashes, believed to be a distinctive signature of a reverse shock, may be explained by the existence of dynamically important magnetic fields in the ejecta.

Affiliated with

Also associated with

No associations

Rating

On the existence of a reverse shock in magnetized GRB ejecta does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On the existence of a reverse shock in magnetized GRB ejecta, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the existence of a reverse shock in magnetized GRB ejecta will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-270523