SEARCH OF THE ENERGETIC GAMMA-RAY EXPERIMENT TELESCOPE (EGRET) DATA FOR HIGH-ENERGY GAMMA-RAY MICROSECOND BURSTS

Hawking (1974) and Page & Hawking (1976) investigated theoretically th e possibility of detecting high-energy gamma rays produced by the quan tum-mechanical decay of a small black hole created in the early univer se. They concluded that, at the very end of the life of the small blac k hole, it would radiate a burst of gamma rays peaked near 250 MeV wit h a total energy of about 10(34) ergs in the order of a microsecond or less. The characteristics of a black hole are determined by laws of p hysics beyond the range of current particle accelerators; hence, the s earch for these short bursts of high-energy gamma rays provides at lea st the possibility of being the first test of this region of physics. The Compton Observatory EGRET has the capability of detecting directly the gamma rays from such bursts at a much fainter level than SAS 2, a nd a search of the EGRET data has led to an upper limit of 5 x 10(-2) black hole decays per pc3 yr-1, placing constraints on this and other theories predicting microsecond high-energy gamma-ray bursts.