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Speaker |
Zhang, Bing |
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Coauthors |
Wei Deng, He Gao |
| Talk Title |
The role of photosphere emission in GRBs |
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Abstract |
I will discuss the role of photosphere emission in the observed GRB spectra. I argue that the data are consistent with the hypothesis that the photosphere emission is quasi-thermal, and it has different degrees of dominance in GRB spectra among different bursts. In a small fraction of GRBs (e.g. GRB 090902B) whose jet composition is matter dominated, it plays a dominant role. In most other GRBs, the photosphere emission is either sub-dominant or completely suppressed. In these GRBs, the jet composition is likely hybrid, but with a significant fraction contained in Poynting flux. I show that a quasi-thermal photosphere emission component has difficulty to interpret the main Band function component in the GRB spectra, which is likely of an origin of synchrotron radiation in the optically thin region. The combination of a quasi-thermal photosphere emission and a non-thermal synchrotron component at large radii can reproduce a variety of observed GRB spectra, given that GRBs have a diverse jet composition. |
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