Early Optical Polarization of a Gamma Ray Burst Afterglow
Astrophysics
2009-11-13 v1
Abstract
We report the optical polarization of a gamma ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2-sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.
Cite
@article{arxiv.astro-ph/0703654,
title = {Early Optical Polarization of a Gamma Ray Burst Afterglow},
author = {Carole G. Mundell and Iain A. Steele and Robert J. Smith and Shiho Kobayashi and Andrea Melandri and Cristiano Guidorzi and Andreja Gomboc and Chris J. Mottram and David Clarke and Alessandro Monfardini and David Carter and David Bersier and .},
journal= {arXiv preprint arXiv:astro-ph/0703654},
year = {2009}
}
Comments
8 pages including 1 figure. Accepted for publication in Science; published online 15 March 2007; 10.1126/science.1138484