Temporal evolution of radiation from a plasma blob with constant deceleration: application to gamma-ray bursts

Abstract

It has been widely accepted that relativistic effects have to be used for modelling the wide classes of events associated with active galactic nuclei and galactic superluminal sources. Here we propose a simple analytical model of decelerated motion which is able to explain the shape of double-peaked light curves of gamma-ray bursts. We show that the differences between individual bursts of this class may be due to the angle between the line-of-sight and direction of the outflow, and that the duration of the burst is intimately connected with the deceleration parameter. Assuming special relativity formulae and the orientation of the observer with respect to the outflow, we are able to model observed double-peaked light curves and obtain good quality fits. We propose that such smooth double peaked bursts could be produced by new born galactic superluminal sources.