Ryde 2008 暴本身的黑体成份
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| Title: | Quasi-blackbody component and radiative efficiency of the prompt emission of gamma-ray bursts | |
| Authors: | Ryde, Felix; Pe'er, Asaf | |
| Publication: | eprint arXiv:0811.4135 | |
| Publication Date: | 11/2008 | |
| Origin: | ARXIV | |
| Keywords: | Astrophysics | |
| Comment: | 38 pages, submitted to the Astrophysical Journal | |
| Bibliographic Code: | 2008arXiv0811.4135R |
Abstract
We identify the spectral peak in the prompt emission of gamma-ray bursts (GRBs) with a quasi blackbody component. We show that thermal photons carry a significant fraction (~30 % to more than 50 %) of the prompt emission energy, thereby significantly contributing to the high radiative efficiency. We study a sample of 56 long bursts, all strong enough to allow time-resolved spectroscopy and show that it is possible to model the spectra with a Planck function combined with a single power-law, with the latter describing the non-thermal component in the observed 20-2000 keV range. We analyze the evolution of both the temperature and flux of the thermal component in 49 individual time-resolved pulses, for which the temporal coverage is sufficient, and find a recurring broken power-law behavior: the temperature is nearly constant during the first few seconds, after which it decays as a power law with a sample-averaged index of -0.68. The thermal flux first rises with an averaged index of 0.63 after which it decays with an averaged index of -2. The break times are the same to within errors. The ratio of the observed to the emergent flux typically exhibits a monotoneous power-law increase during the entire pulse and during complex bursts. We show here that the thermal emission can be used to study the properties of the photosphere, hence the physical parameters of the GRB fireball.Bibtex entry for this abstract Preferred format for this abstract (see Preferences)
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