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journal id: "astrophysicalxjournal"
| Authors | T.W. Giblin, J.A. van Paradijs, C. Kouveliotou, V. Connaughton, R.A.M.J. Wijers, M.S. Briggs, R.D. Preece, G.J. Fishman | | Title | Evidence for an early high-energy afterglow observed with BATSE from GRB 980923 |
| Journal | Astrophysical Journal |
| Volume | 524 |
| Year | 1999 |
| Issue | 1 |
| Pages | L47-L50 |
| ISSN | 0004637X |
| Faculty | Faculty of Science |
| Institute/dept. | FNWI: Astronomical Institute Anton Pannekoek (IAP) |
| Keywords | Gamma ray bursts |
| Abstract | In this Letter, we present the first evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a gamma-ray burst, GRB 980923. The event consists of rapid variability lasting ~40 s followed by a smooth power-law emission tail lasting ~400 s. An abrupt change in spectral shape is found when the tail becomes noticeable. Our analysis reveals that the spectral evolution in the tail of the burst mimics that of a cooling synchrotron spectrum, similar to the spectral evolution of the low-energy afterglows for gamma-ray bursts. This evidence for a separate emission component is consistent with the internal-external shock scenario in the relativistic fireball picture. In particular, it illustrates that the external shocks can be generated during the gamma-ray emission phase, as in the case of GRB 990123. |
| Note | ©1999 American Astronomical Society |
| Document type | Article |
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