A&A 430, 465-470 (2005)
Decay properties of the X-ray afterglows of gamma-ray burstsB. Gendre1 and M. Boër2
1 Istituto di Astrofisica Spaziale e Fisica Cosmica, Via Fosso del Cavaliere 100, 00133 Roma, Italy
2 Observatoire de Haute-Provence, 04870 St. Michel l'Observatoire, France
(Received 20 September 2004 / Accepted 2 November 2004 )
We present a set of seventeen Gamma-Ray Bursts (GRBs) with known redshifts and X-ray afterglow emission. We apply cosmological corrections in order to compare their fluxes normalized at a redshift of 1. Two classes of GRB can be defined using their X-ray afterglow light curves. We show that the brightest afterglows seem to decay faster than the dimmer ones. We also point out evidence for a possible flux limit of the X-ray afterglow depending on the time elapsed since the burst. We try to interpret these observations in the framework of the canonical fireball model of GRB afterglow emission.
Key words: gamma rays: bursts -- X-rays: general
© ESO 2005