Plasma Expansion in the Geometry of a Collapsing Star

In 1975, following the work on the energetics of black holes, Damour and Ruffini pointed out the existence of the vacuum polarization process à là Sauter–Heisenberg–Euler–Schwinger around black holes endowed with electromagnetic structure (EMBHs), whose electric field strength exceeds the Schwinger critical value Ec = m 2 e c e~ , where c is the speed of light, e and me are electron charge and mass respectively. Damour and Ruffini gave reasons to believe that this process is almost reversible in the sense introduced by Christodoulou and Ruffini and that it extracts the mass energy of an EMBH very efficiently: this have been proved in Ref. 5. The vacuum polarization process around an EMBH offered a natural mechanism for explaining the Gamma Ray Bursts (GRBs), just discovered at the time. Moreover the mechanism had a most peculiar prediction: the characteristic energetics of the burst should be of the order of 10 ergs; while nothing at the time was known about either the distances or the energetics of GRBs. More recently, after the discovery of the afterglow of GRBs and their cosmological distance, the idea by Damour and Ruffini has been reconsidered in Refs. 6–9 where the EMBH model for GRBs is developed. The evidence is now that through the observations of GRBs we are witnessing the formation of an EMBH and therefore are following the process of gravitational collapse in real time. Even more importantly, the tremendous energies involved in the energetics of these sources have their origin in the extractable energy of black holes. Various models have been proposed in order to extract the rotational energy of black holes by processes of relativistic magnetohydrodynamics