主要内容:
光球层产生暴本身；内激波的逆康普顿散射产生GeV的辐射。
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文章信息:
- · arXiv e-print (arXiv:1002.2634)
- · References in the Article
- · Citations to the Article (11) (Citation History)
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| Title: |
| A Photosphere-Internal Shock Model of Gamma-Ray Bursts: Implications for the Fermi/LAT Results |
| Authors: |
| Toma, Kenji; Wu, Xue-Feng; Meszaros, Peter |
| Publication: |
| eprint arXiv:1002.2634 |
| Publication Date: |
| 02/2010 |
| Origin: |
| ARXIV |
| Keywords: |
| Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics |
| Comment: |
| 8 pages, 3 figures |
| Bibliographic Code: |
| 2010arXiv1002.2634T |
Abstract
Radially inhomogeneous gamma-ray burst (GRB) jets release variable photospheric emission and can have internal shocks occurring above the photosphere. We argue that the photospheric emission may correspond to the traditional (Band) component at <~1MeV, and the Compton upscattered photospheric (UP) emission off the electrons in the internal shocks may be the distinct high-energy spectral component at >~10MeV, which is observed by Fermi/LAT for some GRBs. We find that a distinct, bright UP emission does not need strong fine tuning of the physical parameters, but the appropriate parameter ranges are limited, which is consistent with the fact that not all the LAT GRBs have a distinct high-energy component. The observed delays of the distinct component behind the Band component which are large compared to the variability times are unlikely to be due to kinematic effects. They may instead be attributed to the temporal evolution of the physical parameters of the jet, and thus the delay timescales could provide a potential tool for investigating the structures of GRB jets themselves and their environments. Based on this idea, we speculate that the difference of the delay timescales of long and short GRBs inferred from the Fermi data could originate from the differences of the progenitors of long and short GRBs. Some other properties of this model are discussed, including temporal correlations among the prompt optical, soft X-ray, and the distinct high-energy component as well as the Band component.
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