A Possible Explanation for the Radio ``Flare'' in the Early Afterglow of GRB990123

1999/03/01 by Xiangdong Shi, Shi, Xiangdong, Geza Gyuk +1
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph

paper · pdf · doi:10.48550/arxiv.astro-ph/9903023

14 pages including 3 figures, submitted to ApJL

arxiv created 1999/03/01 · arxiv updated 2009/12/01

Abstract

We suggest that the deceleration of the relativistic shock by a denser part of the interstellar medium off line-of-sight produced the observed radio ``flare'' in the early afterglow of GRB990123. We find that this scenario is consistent with observations if the particle number density of this denser part of the medium is between ∼ 200 and ∼ 2× 10⁴ cm^-3. Because of the premature deceleration of part of the shock, the later stage of the afterglow should decay modestly faster than the powerlaw expected from an isotropic shock propagation.

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