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Astron. Astrophys. 338, L87-L90 (1998)

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Letter to the Editor

The dyadosphere of black holes and gamma-ray bursts

Giuliano Preparata 1, Remo Ruffini 2 and She-Sheng Xue 3

1 Physics Department, University and INFN-Section of Milan, Via Celoria 16, I-20133 Milan, Italy
2 I.C.R.A.-International Center for Relativistic Astrophysics and Physics Department, University of Rome "La Sapienza", I-00185 Rome, Italy
(e-mail: ruffini@icra.it)
3 I.C.R.A.-International Center for Relativistic Astrophysics c/o Physics Department, University of Rome "La Sapienza", I-00185 Rome, Italy

Received 16 May 1998 / Accepted 12 July 1998


The "dyadosphere" has been defined (Ruffini 1998, Preparata et al. 1998) as the region outside the horizon of a black hole endowed with an electromagnetic field (abbreviated to EMBH for "electromagnetic black hole") where the electromagnetic field exceeds the critical value, predicted by Heisenberg & Euler (1931) for [FORMULA] pair production. In a very short time ([FORMULA]), a very large number of pairs is created there. We here give limits on the EMBH parameters leading to a Dyadosphere for [FORMULA] and [FORMULA] EMBH's, and give as well the pair densities as functions of the radial coordinate. We here assume that the pairs reach thermodynamic equilibrium with a photon gas and estimate the average energy per pair as a function of the EMBH mass. These data give the initial conditions for the analysis of an enormous pair-electromagnetic-pulse or "P.E.M. pulse" which naturally leads to relativistic expansion. Basic energy requirements for gamma ray bursts (GRB), including GRB971214 recently observed at [FORMULA], can be accounted for by processes occurring in the dyadosphere. In this letter we do not address the problem of forming either the EMBH or the dyadosphere: we establish some inequalities which must be satisfied during their formation process.

Key words: black holes – gamma ray bursts

Send offprint requests to: R. Ruffini

© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998