Please use this identifier to cite or link to this item:
|Title:||Spectral evolution and the onset of the X-ray GRB afterglow|
|Authors:||Evans, P. A.|
Osborne, J. P.
O'Brien, P. T.
|Publisher:||American Institute of Physics (AIP)|
|Citation:||GAMMA RAY BURSTS 2010, 2011, 1358, 117|
|Abstract:||Based on light curves from the Swift Burst Analyser, we investigate whether a ‘dip’ feature commonly seen in the early‐time hardness ratios of Swift‐XRT data could arise from the juxtaposition of the decaying prompt emission and rising afterglow. We are able to model the dip as such a feature, assuming the afterglow rises as predicted by Sari and Piran . Using this model we measure the initial bulk Lorentz factor of the fireball. For a sample of 23 GRBs we find a median value of Γ[subscript: 0] = 225, assuming a constant‐density circumburst medium; or Γ[subscript: 0] = 93 if we assume a wind‐like medium.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
Files in This Item:
There are no files associated with this item.
Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.