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Optical flashes and radio flares in GRB afterglows: Numerical study

Kobayashi, Shiho and Sari, Re'em (2000) Optical flashes and radio flares in GRB afterglows: Numerical study. In: Gamma Ray Bursts: 5th Huntsville Symposium, Huntsville, AL, 18-22 October 1999. American Institute of Physics Conference Proceedings. No.526. American Institute of Physics , Melville, NY, pp. 550-554. ISBN 1-56396-947-5.

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We numerically study the evolution of an adiabatic relativistic fireball interacting with an ambient uniform medium, both in the initial energy transfer stage and in its late evolution. It is shown that the Blandford-McKee solution adequately describes the evolution of the shocked ejecta quite early on and for as long as the fire-ball material has relativistic temperatures. In the case where the reverse shock is only mildly relativistic, the shocked ejecta becomes cold almost immediately and the evolution deviates from the Blandford-McKee solution. We derive analytical expressions for the ejecta evolution in its cold regime. This solution gives a good approximation to the numerical results. We estimate the radiation from the fireball ejecta using the numerical hydrodynamic evolution in both cases: cold and hot ejecta. Surprisingly, we find that both evolutions give rather similar light curves, decaying approximately as t^–2 in the optical and peaking after about one day in the radio, even though the hydrodynamics is different.

Item Type:Book Section
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Sari, Re'em0000-0002-1084-3656
Additional Information:©2000 American Institute of Physics. Issue Date: September 8, 2000.
Subject Keywords:cosmology, stellar winds, gamma-ray sources (astronomical), supernovae, afterglows, plasma shock waves, black holes, plasma magnetohydrodynamics, X-ray sources (astronomical)
Series Name:American Institute of Physics Conference Proceedings
Issue or Number:526
Record Number:CaltechAUTHORS:KOBaipcp00
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9388
Deposited By: Archive Administrator
Deposited On:17 Dec 2007
Last Modified:08 Nov 2021 20:58

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