Gomboc 2006 早期光学闪

主要内容:
认为正反激波可能产生的只是在射电波段。而磁场耗散产生的是光学闪

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文章信息:

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Title:
Optical flashes, reverse shocks and magnetization
Authors:
Gomboc, Andreja; Kobayashi, Shiho; Mundell, Carole G.; Guidorzi, Cristiano; Melandri, Andrea; Steele, Iain A.; Smith, Robert J.; Bersier, David; Carter, David; Bode, Michael F.
Publication:
eprint arXiv:0902.1830
Publication Date:
02/2009
Origin:
ARXIV
Keywords:
Astrophysics - High Energy Astrophysical Phenomena
Comment:
6 pages, 2 figures. Submitted to the proceedings of the 6th Huntsville GRB Symposium 2008
Bibliographic Code:
2009arXiv0902.1830G
AbstractDespite the pre-Swift expectation that bright optical flashes from reverse shocks would be prevalent in early-time afterglow emission, rapid response observations show this not to be the case. Although very bright at early times, some GRBs such as GRB 061007 and GRB 060418, lack the short-lived optical flash from the reverse shock within minutes after the GRB. In contrast, other optical afterglows, such as those of GRB 990123, GRB 021211, GRB 060111B, GRB 060117, GRB 061126, and recently GRB 080319B, show a steep-to-flat transition within first 10^3 s typical of a rapidly evolving reverse + forward shock combination. We review the presence and absence of the reverse shock components in optical afterglows and discuss the implications for the standard model and the magnetization of the fireball. We show that the previously predicted optical flashes are likely to occur at lower wavelengths, perhaps as low as radio wavelengths and, by using the case of GRB 061126 we show that the magnetic energy density in the ejecta, expressed as a fraction of the equipartion value, is a key physical parameter.
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