Basic energy requirements of Gamma Ray Burst ( GRB ) sources can be easily accounted for by a pair creation process occurring in the “ Dyadosphere ” of a Black Hole endowed with an electromagnetic field ( abbreviated to EMBH for “ electromagnetic Black Hole ” ) .
This includes the recent observations of GRB971214 by Kulkarni et al .
The “ Dyadosphere ” is defined as the region outside the horizon of an EMBH where the electromagnetic field exceeds the critical value for e ^ { + } e ^ { - } pair production .
In a very short time \sim O ( { \hbar \over mc ^ { 2 } } ) , very large numbers of pairs are created there .
Further evolution then leads naturally to a relativistically expanding pair-electromagnetic-pulse ( PEM-pulse ) .
Specific examples of Dyadosphere parameters are given for 10 M _ { \odot } and 10 ^ { 5 } M _ { \odot } EMBH ’ s .
This process does occur for EMBH with charge-to-mass ratio larger than 2.2 \cdot 10 ^ { -5 } and strictly smaller than one .
From a fundamental point of view , this process represents the first mechanism proved capable of extracting large amounts of energy from a Black Hole with an extremely high efficiency ( close to 100 \% ) .