Possible detection of hard X-ray afterglows of short γ-ray bursts
Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK e-mail: firstname.lastname@example.org
2 Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy e-mail: email@example.com
Corresponding author: D. Lazzati, firstname.lastname@example.org
Accepted: 10 October 2001
We report the discovery of a transient and fading hard X-ray emission in the BATSE lightcurves of a sample of short γ-ray bursts. We have summed each of the four channel BATSE light curves of 76 short bursts to uncover the average overall temporal and spectral evolution of a possible transient signal following the prompt flux. We found an excess emission peaking ~30 s after the prompt one, detectable for ≈ 100 s. The soft power-law spectrum and the time-evolution of this transient signal suggest that it is produced by the deceleration of a relativistic expanding source, as predicted by the afterglow model.
Key words: gamma rays: bursts / radiation mechanisms: non-thermal
© ESO, 2001