Swift Observations of the X‐Ray–Bright GRB 050315
Vaughan, S. ; Goad, M. R. ; Beardmore, A. P. ; ...Giommi, P. ; et al.
Feb - 2006
ISSN : 0004-637X ;
journal : The Astrophysical Journal
Issue : 2
type: Article Journal
Abstract
This paper discusses Swift observations of the \gamma-ray burst GRB 050315 (z = 1.949) from 80 s to 10 days after the onset of the burst. The X-ray light curve displayed a steep early decay (t-5) for 200 s and several breaks. However, both the prompt hard X-ray/\gamma-ray emission (observed by the BAT) and the first 300 s of X-ray emission (observed by the XRT) can be explained by exponential decays, with similar decay constants. Extrapolating the BAT light curve into the XRT band suggests that the rapidly decaying, early X-ray emission was simply a continuation of the fading prompt emission; this strong similarity between the prompt \gamma-ray and early X-ray emission may be related to the simple temporal and spectral character of this X-ray-rich GRB. The prompt (BAT) spectrum was steep down to 15 keV and appeared to continue through the XRT bandpass, implying a low peak energy, inconsistent with the Amati relation. Following the initial steep decline, the X-ray afterglow did not fade for 1.2 × 104 s, after which time it decayed with a temporal index of \alpha ≈ 0.7, followed by a second break at 2.5 × 105 s to a slope of \alpha 2. The apparent
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