EDP Sciences
Free access
Volume 430, Number 2, February I 2005
Page(s) 465 - 470
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20042031

A&A 430, 465-470 (2005)
DOI: 10.1051/0004-6361:20042031

Decay properties of the X-ray afterglows of gamma-ray bursts

B. Gendre1 and M. Boër2

1  Istituto di Astrofisica Spaziale e Fisica Cosmica, Via Fosso del Cavaliere 100, 00133 Roma, Italy
    e-mail: gendre@rm.iasf.cnr.it
2  Observatoire de Haute-Provence, 04870 St. Michel l'Observatoire, France
    e-mail: Michel.Boer@oamp.fr

(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

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