%0 Journal Article
%T Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir
%A D. A. Frail
%A S. R. Kulkarni
%A R. Sari
%A S. G. Djorgovski
%A J. S. Bloom
%A T. J. Galama
%A D. E. Reichart
%A E. Berger
%A F. A. Harrison
%A P. A. Price
%A S. A. Yost
%A A. Diercks
%A R. W. Goodrich
%A F. Chaffee
%J Physics
%D 2001
%I arXiv
%R 10.1086/338119
%X Gamma-ray bursts (GRBs) are the most brilliant objects in the Universe but efforts to estimate the total energy released in the explosion -- a crucial physical quantity -- have been stymied by their unknown geometry: spheres or cones. We report on a comprehensive analysis of GRB afterglows and derive their conical opening angles. We find that the gamma-ray energy release, corrected for geometry, is narrowly clustered around 5x10**50 erg. We draw three conclusions. First, the central engines of GRBs release energies that are comparable to ordinary supernovae, suggesting a connection. Second, the wide variation in fluence and luminosity of GRBs is due entirely to a distribution of opening angles. Third, only a small fraction of GRBs are visible to a given observer and the true GRB rate is at least a factor of 500 times larger than the observed rate.
%U http://arxiv.org/abs/astro-ph/0102282v1