On the Pair Electromagnetic Pulse of a Black Hole with Electromagnetic Structure

摘要

We study the relativistically expanding electron-positron pair plasma formedby the process of vacuum polarization around an electromagnetic black hole(EMBH). Such processes can occur for EMBH's with mass all the way up to $6\cdot10^5M_\odot$. Beginning with a idealized model of a Reissner-Nordstrom EMBHwith charge to mass ratio $\xi=0.1$, numerical hydrodynamic calculations aremade to model the expansion of the pair-electromagnetic pulse (PEM pulse) tothe point that the system is transparent to photons. Three idealized specialrelativistic models have been compared and contrasted with the results of thenumerically integrated general relativistic hydrodynamic equations. One of thethree models has been validated: a PEM pulse of constant thickness in thelaboratory frame is shown to be in excellent agreement with results of thegeneral relativistic hydrodynamic code. It is remarkable that this precisemodel, starting from the fundamental parameters of the EMBH, leads uniquely tothe explicit evaluation of the parameters of the PEM pulse, including theenergy spectrum and the astrophysically unprecedented large Lorentz factors (upto $6\cdot 10^3$ for a $10^3 M_{\odot}$ EMBH). The observed photon energy atthe peak of the photon spectrum at the moment of photon decoupling is shown torange from 0.1 MeV to 4 MeV as a function of the EMBH mass. Correspondingly thetotal energy in photons is in the range of $10^{52}$ to $10^{54}$ ergs,consistent with observed gamma-ray bursts. In these computations we neglect thepresence of baryonic matter which will be the subject of forthcomingpublications.