Are there MeV gamma-ray bursts?
- 1 January 1996
- proceedings article
- Published by AIP Publishing in AIP Conference Proceedings
- Vol. 384 (1) , 233-237
- https://doi.org/10.1063/1.51671
Abstract
It is often stated that gamma-ray bursts (GRBs) have typical energies of several hundred keV, where the typical energy may be characterized by the hardness H, the photon energy corresponding to the peak of νF ν . Among the 54 BATSE bursts analyzed by Band et al. more than half have 100 keV <H<400 keV . Is the narrow range of H a real feature of GRBs or is it due to an observational bias? We consider the possibility that bursts of a given bolometric luminosity occur with a distribution: p(H)d log H∝H γ d log H. We model the detection efficiency of BATSE as a function of H and calculate the expected distribution of H in the observed sample for various values of γ. The Band sample shows a paucity of soft (X-ray) bursts, which may be real. However, because the detection efficiency of BATSE falls steeply with increasing H, the paucity of hard bursts need not be real. We find that the observed sample is consistent with a distribution above H=100 keV with γ≈0 (constant numbers of GRBs per decade of hardness) or even γ=0.5 (increasing numbers with increasing hardness). Thus, we suggest that a large population of unobserved hard gamma-ray bursts may exist. It is important to extend the present analysis to a larger sample of BATSE bursts and to include the OSSE and COMPTEL limits. If the full sample is consistent with γ≳0, then it would be interesting to look for MeV bursts in the future.Keywords
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