Query : 2008A&A...478..747G

2008A&A...478..747G - Astronomy and Astrophysics, volume 478, 747-753 (2008/2-2)

On the existence of a reverse shock in magnetized gamma-ray burst ejecta.


Abstract (from CDS):

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 σ0>1 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 σ0≲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.

Abstract Copyright:

Journal keyword(s): gamma rays: bursts - magnetohydrodynamics (MHD) - shock waves

Simbad objects: 3

goto Full paper

goto View the references in ADS

Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 SN 2002lt SN* 08 08 59.858 +06 43 37.52           SNIc: 347 1
2 GRB 990123 gB 15 25 29 +44 45.0     8.95     ~ 980 1
3 GRB 060418 gB 15 45 42.600 -03 38 20.00 15.73 16.19 14.98     ~ 352 0

To bookmark this query, right click on this link: simbad:objects in 2008A&A...478..747G and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact