主要内容:
认为暴本身的辐射是多温度的黑体辐射，高能部分是同步辐射、SSC和暴本身辐射的IC的混合。
精彩摘抄:
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| GRB 090902B的谱 |
文章信息:
- · arXiv e-print (arXiv:1007.2228)
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Abstract
Photospheric (thermal) emission is inherent to the gamma-ray burst (GRB) "fireball" model. We show here, that inclusion of this component in the analysis of the GRB prompt emission phase naturally explains some of the prompt GRB spectra seen by the Fermi satellite over its entire energy band. The sub-MeV peak is explained as multi-color black body emission, and the high energy tail, extending up to the GeV band, results from roughly similar contributions of synchrotron emission, synchrotron self Compton (SSC) and Comptonization of the thermal photons by energetic electrons originating after dissipation of the kinetic energy above the photosphere. We show how this analysis method results in a complete, self consistent picture of the physical conditions at both emission sites of the thermal and non-thermal radiation. We study the connection between the thermal and non-thermal parts of the spectrum, and show how the values of the free model parameters are deduced from the data. We demonstrate our analysis method on GRB090902B: We deduce a Lorentz factor in the range 780 <= \eta <= 1000, photospheric radius r_{ph} ~ 6.1 - 7.8*10^{11} cm and dissipation radius r_\gamma >= 3.8 - 5.0*10^{15} cm. By comparison to afterglow data, we deduce that a large fraction, \epsilon_d ~ 85% - 95% of the kinetic energy is dissipated, and that large fraction, ~equipartition of this energy is carried by the electrons and the magnetic field. This high value of \epsilon_d questions the "internal shock" scenario as the main energy dissipation mechanism for this GRB.
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