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Title: Swift and XMM-Newton observations of the extraordinary gamma-ray burst 060729: More than 125 days of x-ray afterglow
Authors: Grupe, D
Gronwall, C
Wang, X-Y
Roming, PWA
Cummings, J
Zhang, B
Meszaros, P
Trigo, MD
O'Brien, PT
Page, KL
Beardmore, A
Godet, O
vanden Berk DE
Brown, PJ
Koch, S
Morris, D
Stroh, M
Burrows, DN
Nousek, JA
Chester, MM
Immler, S
Mangano, V
Romano, P
Chincarini, G
Osborne, J
Sakamoto, T
Gehrels, N
First Published: 10-Jun-2007
Publisher: American Astronomical Society, IOP Publishing
Citation: Astrophysical Journal, 2007, 662 (1), pp. 443-458
Abstract: We report the results of the Swift andXMM-Newton observations of the Swift -discovered GRB 060729 (T90 = 115 s). The afterglow of this burst was exceptionally bright in X-rays as well as at UV/optical wavelengths, showing an unusually long slow decay phase ( Alpha = 0.14 +/- 0.02), suggesting a larger energy injection phase at early times than in other bursts. The X-ray light curve displays a break at about 60 ks after the burst. The X-ray decay slope after the break is Alpha = 1.29 +/- 0.03. Up to 125 days after the burst we do not detect a jet break, suggesting that the jet opening angle is larger than 28 degrees. We find that the X-ray spectra of the early phase change dramatically and can all be fitted by an absorbed singleYpower-law models or alternatively by a blackbody plus power-law model. The power-law fits show that the X-ray spectrum becomes steeper while the absorption column density decreases. In the blackbody model the temperature decreases from kT = 0.6 to 0.1 keV between 85 and 160 s after the burst in the rest frame. The afterglow was clearly detected up to 9 days after the burst in all six UVOT filters and in UVW1 even for 31 days. A break at about 50 ks is clearly detected in all six UVOT filters from a shallow decay slope of about 0.3 and a steeper decay slope of 1.3.The XMM-Newton observations started about 12 hr after the burst and show a typical afterglow X-ray spectrum with Beta[SUBSCRIPT x] = 1.1 and absorption column density of 1 x 10^21 cm^-2
DOI Link: 10.1086/517868
ISSN: 0004-637X
Type: Journal Article
Rights: Creative Commons “Attribution Non-Commercial No Derivatives” licence CC BY-NC-ND, further details of which can be found via the following link: Archived with reference to SHERPA/RoMEO and publisher website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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