MG14 - Talk detail |
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Participant |
Zhang, Bing | |||||||
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Institution |
University of Nevada Las Vegas - 4505 Maryland Parkway, Box 454002 - United States - NV - USA | |||||||
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Session |
GB2 |
Accepted |
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Order |
Time |
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Talk |
Oral abstract |
Title |
Physical mechanism of GRB prompt emission | |||||
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Abstract |
I will discuss some recent progress in understanding GRB prompt emission mechanism in our group. Analyses of GRB prompt emission spectra suggest that GRB jet composition is diverse, with most of the bursts carry a significant fraction of energy in Poynting flux. The emission mechanism of the main "Band" function spectral component is likely synchrotron, with emission region far (e.g. beyond 10^15 cm) from the central engine. The energy dissipation mechanism of at least some GRBs is likely internal collision-induced magnetic reconnection and turbulence (ICMART). Several major ingredients of the ICMART model are recently confirmed from numerical simulations. |
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Pdf file |
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Session |
GB4 |
Accepted |
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Time |
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Talk |
Oral abstract |
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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Pdf file |
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Session |
GB1 |
Accepted |
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Order |
Time |
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Talk |
Oral abstract |
Title |
Possible electromagnetic counterparts of FRBs and cosmological implications | |||||
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Abstract |
I discuss two topics on FRBs. First, some FRBs may have EM counterparts in other wavelengths. I discuss a possible association of a small fraction of FRBs with GRBs, and more generic FRB afterglow emission regardless of their origin. Second, assuming that the redshifts of a good sample of FRBs are measured (through GRB associations or by other means), I will discuss how to apply FRBs to constrain cosmological parameters and dark energy equation of state. |
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Pdf file |
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