A compact fireball model of gamma-ray bursts

David Eichler, Amir Levinson

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


It is proposed that the gamma-ray burst (GRB) photons near the peak of the spectrum at several hundred keV are produced on very compact scales, where photon production is limited by blackbody effects and/or the requirement of energetic quanta (E > 2me c2) for efficient further production. The fast variation of order milliseconds in the time profile is then a natural expectation, given the other observed GRB parameters. Analytic calculations are presented to show that the escape of nonthermal, energetic gamma rays can emerge within 1 s of the thermal photons from a gammasphere of below 1012 cm. The minimum asymptotic bulk Lorentz factor in this model is found to be of order several hundred if the photosphere is of order 3 × 1011 cm and greater for larger or smaller photospheric radii. It is suggested that prompt ultra-high-energy gamma rays might provide a new constraint on the asymptotic Lorentz factor of the outflow.

Original languageEnglish
Pages (from-to)146-150
Number of pages5
JournalAstrophysical Journal
Issue number1 PART 1
StatePublished - 20 Jan 2000


  • BL Lacertae objects: general
  • Gamma rays: bursts
  • Radiation mechanisms: thermal

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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