EDP Sciences
Free access
Issue
A&A
Volume 368, Number 2, March III 2001
Page(s) 377 - 390
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20000556


A&A 368, 377-390 (2001)
DOI: 10.1051/0004-6361:20000556

The elementary spike produced by a pure e+e- pair-electromagnetic pulse from a Black Hole: The PEM Pulse

C. L. Bianco, R. Ruffini and S.-S. Xue

I.C.R.A.-International Center for Relativistic Astrophysics and Physics Department, University of Rome "La Sapienza", 00185 Rome, Italy

(Received 21 July 2000 / Accepted 12 December 2000 )

Abstract
In the framework of the model that uses black holes endowed with electromagnetic structure (EMBH) as the energy source, we study how an elementary spike appears to the detectors. We consider the simplest possible case of a pulse produced by a pure e+e- pair-electro-magnetic plasma, the PEM pulse, in the absence of any baryonic matter. The resulting time profiles show a Fast-Rise-Exponential-Decay shape, followed by a power-law tail. This is obtained without any special fitting procedure, but only by fixing the energetics of the process taking place in a given EMBH of selected mass, varying in the range from 10 to 103 $M_\odot$ and considering the relativistic effects to be expected in an electron-positron plasma gradually reaching transparency. Special attention is given to the contributions from all regimes with Lorentz $\gamma$ factor varying from $\gamma=1$ to $\gamma=10^4$ in a few hundreds of the PEM pulse travel time. Although the main goal of this paper is to obtain the elementary spike intensity as a function of the arrival time, and its observed duration, some qualitative considerations are also presented regarding the expected spectrum and on its departure from the thermal one. The results of this paper will be comparable, when data will become available, with a subfamily of particularly short GRBs not followed by any afterglow. They can also be propedeutical to the study of longer bursts in presence of baryonic matter currently observed in GRBs.


Key words: black holes physics -- gamma rays: bursts -- gamma rays: theory -- gamma rays: observations

Offprint request: R. Ruffini, ruffini@icra.it




© ESO 2001