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On the Mechanism of Gamma-Ray Burst Afterglows

Z. Lucas Uhm·Andrei M. Beloborodov
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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 10^3-10^4 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 (Beloborodov, Uhm 2006); we use it in our calculations.

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Z. Lucas Uhm, Andrei M. Beloborodov. 2007-08-11. On the Mechanism of Gamma-Ray Burst Afterglows. https://doi.org/10.1086/519837

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