Ultraefficient internal shocks

Shiho Kobayashi*, Re'em Sari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


Gamma-ray bursts are believed to originate from internal shocks that arise in an irregular relativistic wind. The process has been thought to be inefficient, converting only a few percent of the kinetic energy into gamma rays. We define ultraefficient internal shocks as those in which the fraction of emitted energy is larger than the fraction of energy given to the radiating electrons at each collision. We show that such a scenario is possible and even plausible. In our model, colliding shells that do not emit all their internal energy are reflected from each other, causing subsequent collisions and thereby allowing more energy to be emitted. As an example, we obtain about 60% overall efficiency even if the fraction of energy that goes to electrons is ∈e = 0.1, provided that the shells' Lorentz factor varies between 10 and 104. The numerical temporal profile reflects well the activity of the source that ejects the shells, though numerous collisions take place in this model.

Original languageAmerican English
Pages (from-to)934-939
Number of pages6
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - 20 Apr 2001
Externally publishedYes


  • Gamma rays: bursts
  • Relativity
  • Shock waves


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