Goad, M. R.M. R.GoadTagliaferri, G.G.TagliaferriPage, K. L.K. L.PageCapalbi, MilviaMilviaCapalbiGiommi, PaoloPaoloGiommiPerri, MatteoMatteoPerri2020-09-172020-09-172006-04-01https://hdl.handle.net/20.500.13025/438Astronomy and Astrophysics, Volume 449, Issue 1, April I 2006, pp.89-100We report on the temporal and spectral characteristics of the early X-ray emission from the Gamma Ray Bursts GRB050126 and GRB050219A as observed by Swift . The X-ray light-curves of these 2 bursts both show remarkably steep early decays (F(t)&prop; t<SUP>-3</SUP>), breaking to flatter slopes on timescales of a few hundred seconds. For GRB050126 the burst shows no evidence of spectral evolution in the 20-150 keV band, and the spectral index of the gamma-ray and X-ray afterglows are significantly different suggesting a separate origin. By contrast the BAT spectrum of GRB050219A displays significant spectral evolution, becoming softer at later times, with Gamma evolving toward the XRT photon index seen in the early X-ray afterglow phase. For both bursts, the 0.2-10 keV spectral index pre- and post-break in the X-ray decay light-curve are consistent with no spectral evolution. We suggest that the steep early decline in the X-ray decay light-curve is either the curvature tail of the prompt emission; X-ray flaring activity; or external forward shock emission from a jet with high density regions of small angular size (>Gamma<SUP>-1</SUP>). The late slope we associate with the forward external shock.gamma rays burstsgamma rays observationsblack hole physics10.1051/0004-6361 20054457http://adsabs.harvard.edu/abs/2006A&A...449...89G2006A&A...449...89G