Optical flashes, reverse shocks and magnetization

Andreja Gomboc, Shiho Kobayashi, Carole G. Mundell, Cristiano Guidorzi, Andrea Melandri, Iain A. Steele, Robert J. Smith, David Bersier, David Carter, Michael F. Bode

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding

21 Citations (SciVal)


Despite 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 103 s typical of a rapidly evolving reverse forwad 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.

Original languageEnglish
Title of host publicationGamma-Ray Burst - 6th Huntsville Symposium
Number of pages6
Publication statusPublished - 27 Nov 2009
Event6th Huntsville Symposium on Gamma-Ray Bursts - Huntsville, AL, USA United States
Duration: 20 Oct 200823 Oct 2008


Conference6th Huntsville Symposium on Gamma-Ray Bursts
Country/TerritoryUSA United States
CityHuntsville, AL


  • Gamma-ray bursts
  • Gamma-ray sources

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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