Mundell 2007 GRB 060418早期余辉的偏振观测

主要内容:
得到不大于8%的偏振度，排除了大尺度磁场的可能性。

精彩摘抄:


文章信息:
Early Optical Polarization of a Gamma Ray Burst Afterglow

Authors: Carole G. Mundell (1), Iain A. Steele (1), Robert J. Smith (1), Shiho Kobayashi (1) Andrea Melandri (1), Cristiano Guidorzi (1,2,3), Andreja Gomboc (4) Chris J. Mottram (1), David Clarke (5), Alessandro Monfardini (1,6), David Carter (1), David Bersier (1).

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.

Comments:

8 pages including 1 figure. Accepted for publication in Science; published online 15 March 2007; 10.1126/science.1138484

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:astro-ph/0703654v1