Possible detection of hard X-ray afterglows of short gamma-ray bursts

We report the discovery of a transient and fading hard X-ray emission in th e BATSE lightcurves of a sample of short gamma -ray bursts. We have summed each of the four channel BATSE light curves of 76 short bursts to uncover t he average overall temporal and spectral evolution of a possible transient signal following the prompt flux. We found an excess emission peaking simil ar to 30 s after the prompt one, detectable for approximate to 100 s. The s oft power-law spectrum and the time-evolution of this transient signal sugg est that it is produced by the deceleration of a relativistic expanding sou rce, as predicted by the afterglow model.