On the Mechanism of Gamma-Ray Burst Afterglows
Abstract
The standard model of afterglow production by the forward shock wave is not supported by recent observations. We propose a model in which the forward shock is invisible and afterglow is emitted by a long-lived reverse shock in the burst ejecta. It explains observed optical and X-ray light curves, including the plateau at 103-104 s with a peculiar chromatic break, and the second break that was previously associated with a beaming angle of the explosion. The plateau forms following a temporary drop of the reverse-shock pressure much below the forward-shock pressure. A simplest formalism that can describe such blast waves is the ``mechanical'' model; we use it in our calculations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2007
- DOI:
- 10.1086/519837
- arXiv:
- arXiv:astro-ph/0701205
- Bibcode:
- 2007ApJ...665L..93U
- Keywords:
-
- Gamma Rays: Bursts;
- Hydrodynamics;
- Radiation Mechanisms: Nonthermal;
- Relativity;
- Shock Waves;
- Astrophysics
- E-Print:
- 11 pages, 3 figures, accepted to ApJ Letters