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C. Pagani (OAB/PSU), D. C. Morris (PSU), S. Kobayashi (U. Liverpool), T. Sakamoto (GSFC), A. D. Falcone, D. Grupe (PSU), A. Moretti (OAB), J. A. Kennea, D. N. Burrows, A. Retter (PSU), K. Page (U. Leicester), S. Campana (OAB), J. E. Hill, S. Barthelmy (GSFC), G. Chincarini, G. Tagliaferri (OAB), A. Wells (U. Leicester), P. Giommi (ASI), J. A. Nousek (PSU), N. Gehrels (GSFC)
The fast and autonomous response of the Swift satellite to newly detected Gamma-Ray Bursts (GRBs) has provided a new view on their X-ray and optical afterglows. We present here the X-ray Telescope (XRT) observations of GRB 050607 discovered by the Swift Burst Alert Telescope on June 7th 2005. The striking feature of the X-ray emission is the intense flaring activity during the early afterglow phase, indicative of central engine activity extended to several hundred seconds after the burst detection. The flares have very rapid timing variations and asymmetric shapes, similar to the FREDs that are frequently observed in the prompt GRB emission. Some indication of short timescale activity was also present during the brightest flare decay. After the flares, the X-ray lightcurve entered a phase of slow decay during which the forward shocks were probably being refreshed, followed by a late steepening consistent with the standard external shock model. Analysis of the X-ray emission showed spectral variations during the flares, with a harder spectrum at the flares onset and a softer component that lingered longer, dominating the flares' decay.
This work is supported at Penn State by NASA contract NAS5-00136; at the University of Leicester by the Particle Physics and Astronomy Research Council on grant numbers PPA/G/S/00524 and PPA/Z/S/2003/00507; and at OAB by funding from ASI on grant number I/R/039/04.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.