Swift observations of the prompt X-ray emission and afterglow from GRB050126 and GRB050219A
| Autor: | M. R. Goad, G. Tagliaferri, K. L. Page, A. Moretti, J. P. Osborne, S. Kobayashi, P. Kumar, P. I. Mészáros, G. Chincarini, T. Sakamoto, B. Zhang, S. D. Barthelmy, A. P. Beardmore, D. N. Burrows, S. Campana, M. Capalbi, L. Cominsky, G. Cusumano, N. Gehrels, P. Giommi, O. Godet, J. E. Hill, J. A. Kennea, H. Krimm, V. La Parola, V. Mangano, T. Mineo, D. C. Morris, K. Mukerjee, J. A. Nousek, P. T. O'Brien, C. Pagani, M. Perri, P. Romano, A. A. Wells |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | Astronomy & Astrophysics. 449:89-100 |
| ISSN: | 1432-0746 0004-6361 |
| Popis: | We report on the temporal and spectral characteristics of the early X-ray emission from the Gamma Ray Bursts GRB050126 and GRB050219A as observed by Swift. The X-ray light-curves of these 2 bursts both show remarkably steep early decays (F(t)\propto t^{-3}), breaking to flatter slopes on timescales of a few hundred seconds. For GRB050126 the burst shows no evidence of spectral evolution in the 20-150 keV band, and the spectral index of the gamma-ray and X-ray afterglows are significantly different suggesting a separate origin. By contrast the BAT spectrum of GRB050219A displays significant spectral evolution, becoming softer at later times, with Gamma evolving toward the XRT photon index seen in the early X-ray afterglow phase. For both bursts, the 0.2-10 keV spectral index pre- and post-break in the X-ray decay light-curve are consistent with no spectral evolution. We suggest that the steep early decline in the X-ray decay light-curve is either the curvature tail of the prompt emission; X-ray flaring activity; or external forward shock emission from a jet with high density regions of small angular size (> Gamma^{-1}). The late slope we associate with the forward external shock. 13 pages, 12 figures, accepted for publication in Astronomy & Astrophysics |
| Databáze: | OpenAIRE |
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