Year: 2006
Type: article
Abstract: We present observations of the early X-ray emission for a sample of 40 gamma-ray bursts (GRBs) obtained using the Swift satellite, for which the narrow-field instruments were pointed at the burst within 10 minutes of the trigger. Using data from the Burst Alert Telescope and the X-Ray Telescope, we show that the X-ray light curve can be well described by an exponential that relaxes into a power law, often with flares superimposed. The transition time between the exponential and the power law provides a physically defined timescale for the burst duration. In most bursts, the power law breaks to a shallower decay within the first hour, and a late emission "hump" is observed, which can last for many hours. In other GRBs the hump is weak or absent. The observed variety in the shape of the early X-ray light curve can be explained as a combination of three components: prompt emission from the central engine, afterglow, and the late hump. In this scenario, afterglow emission begins during or soon after the burst, and the observed shape of the X-ray light curve depends on the relative strengths of the emission due to the central engine and that of the afterglow. There is a strong correlation such that those GRBs with stronger afterglow components have brighter early optical emission. The late emission hump can have a total fluence equivalent to that of the prompt phase. GRBs with the strongest late humps have weak or no X-ray flares.
Source: The Astrophysical Journal
DOI: 10.1086/505457
Authors: P. T. O’Brien, R. Willingale, J. Osborne, M. R. Goad, K. L. Page, S. Vaughan, E. Rol, A. Beardmore, O. Godet, C. P. Hurkett, A. Wells, B. Zhang, S. Kobayashi, D. N. Burrows, J. A. Nousek, J. A. Kennea, A. Falcone, D. Grupe, N. Gehrels, S. Barthelmy, J. Cannizzo, J. Cummings, J. E. Hill, H. Krimm, G. Chincarini, G. Tagliaferri, S. Campana, A. Moretti, P. Giommi, M. Perri, V. Mangano, V. LaParola
Institutions: University of Leicester, University of Nevada, Las Vegas, Liverpool John Moores University, Pennsylvania State University, Goddard Space Flight Center, University of Maryland, Baltimore County, National Academies of Sciences, Engineering, and Medicine, Universities Space Research Association, Brera Astronomical Observatory, University of Milano-Bicocca, National Institute for Astrophysics, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Award: G6193823157
OpenAlex ID: W1986532237