主要内容:
说是外激波余辉。
精彩摘抄:
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| 大于2秒的可以，小于的应该是暴本身的。 |
文章信息:
- · arXiv e-print (arXiv:1009.1432)
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- · Citations to the Article (1) (Citation History)
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Abstract
Long-lived high-energy (>100 MeV) emission, a common feature of most Fermi-LAT detected Gamma-ray burst, is detected up to ~10^2 s in the short GRB 090510. We study the origin of this long-lived high-energy emission of GRB 090510, using broad-band observations including X-ray and optical data. We confirm that the late > 100 MeV, X-ray and optical emission can be naturally explained via synchrotron emission from an adiabatic forward shock propagating in a homogeneous ambient medium with low number density. The Klein-Nishina effects are found to be significant, and effects due to jet spreading and magnetic field amplification in the shock appear to be required. Under the constraints from the low-energy observations, the adiabatic forward shock synchrotron emission is consistent with the later-time (t > 2 s) high-energy emission, but falls below the early-time (t<2 s) high energy emission. Thus we argue that an extra high energy component is needed at early times, which accounts for the initial steep decay of the light curve. We consider several possible origins for the extra component, most of which can be excluded. Based on the high initial temporal variability and the coincident emerging bumps in the LAT and BAT light curves at t~1-3 s, we suggest that the duration of the prompt emission is T~2 s. Thus, we attribute the early part of the high-energy emission (t<2 s) to the prompt component, and the long-lived high energy emission (t>2 s) to the adiabatic forward shock synchrotron afterglow radiation. This avoids the requirement for an extremely high initial Lorentz factor.
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