Gamma-ray bursts from evaporating primordial black holes (original) (raw)

GAMMA-RAY BURSTS FROM EVAPORATING PRIMORDIAL BLACK HOLES A. A. Belyanin, V. V. Kocharovsky, and V1. V. Kocharovsky UDC 524.7 It is believed that the detection of gamma-my bursts from evaporating primordial black holes is highly improbable in the near .future since the ezpected photon fluz, consisting mainly of photons with energies ~ 1 Ge V, is too low. Contrary to this point of view, we show that a large fraction of the black hole power at the final stage of evaporation (the last 103 s) can be liberated as a burst of soft 7-ray emission of duration 10-1-103 s and luminosity 102s-103: erg/s in the energy range O. I-1 Me V. According to our calculations of the black hole evaporation rate (within the Standard Model of elementary particles), when the black hole temperature ezceeds approzimately I0 Ge V, the charged particle outflow from a black hole forms a well-defined plasma and can be described in the hydrodynamic approzimation. In this case more than half of the rest energy of a black hole can be converted into soft gamma-rays due to the presence of the magnetic field with energy density comparable to that of charged particles. We consider various mechanisms leading to such transformation and estimate their e~ciency. It is shown that, at least, some of the 9aroma-ray bursts detected by BATSE can be associated with evaporating black holes.