Signatures of a Maxwellian component in shock-accelerated electrons in GRBs
Signatures of a Maxwellian component in shock-accelerated electrons in GRBs
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DOI：
10.1111/j.1365-2966.2009.15454.x
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发表时间：
2009-05
影响因子：
4.8
通讯作者：
D. Giannios;A. Spitkovsky
中科院分区：
文献类型：
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作者：
D. Giannios;A. Spitkovsky
最近的细胞内粒子模拟表明，在相对论性激波中耗散的能量的很大一部分被沉积到与高能幂律尾部相连的麦克斯韦电子分布中。在这里，我们探讨了这种混合热-非热粒子分布对伽马射线暴的余辉和瞬发辐射的观测意义。当麦克斯韦分量在能量收支中占主导地位时，当特征同步加速器频率穿过观测波段时，余辉光曲线呈现出非常陡峭的衰减阶段，随后衰减幅度更小。在爆发后约100秒的x射线中出现陡峭的衰减，并伴随着在大量早期余辉中观察到的特征的硬-软-硬光谱演化。如果内部激波产生类似的混合电子分布，则在同步加速器谱峰处预计会出现碰撞。
Recent particle-in-cell simulations suggest that a large f raction of the energy dissipated in a relativistic shock is deposited into a Maxwellian distribu tion of electrons that is connected to the high-energy power-law tail. Here, we explore the observational implications of such a mixed thermal-nonthermal particle distribution for the a fterglow and prompt emission of gamma-ray bursts. When the Maxwellian component dominates the energy budget, the afterglow lightcurves show a very steep decline phase followed by a more shallow decay when the characteristic synchrotron frequency crosses the observe d band. The steep decay appears in the X-rays at∼100 sec after the burst and is accompanied by a characteristi c hard-soft-hard spectral evolution that has been observed in a large number of early afterglows. If internal shocks produce a similar mixed electron distribution, a bump is expected at the synchrotron peak of theν fν spectrum.