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arXiv 0709.4568astro-ph
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内激波的伽马射线暴高能辐射

Gamma-Ray Burst high energy emission from Internal Shocks

A. Galli, D. Guetta

摘要:

本文研究了伽马射线暴(GRB)瞬发和X射线耀斑阶段内激波(IS)的同步辐射和同步辐射自康普顿(SSC)辐射。其目的是测试的IS模型的耀斑排放和伽玛暴是否可以GeV源。我们确定的参数,IS模型可以解释所观察到的提示和X射线耀斑发射,并研究了高能量SSC发射的AGILE和GLAST卫星的探测能力。我们发现,在伽玛暴的即时阶段的SSC发射的可探测性提高火球洛伦兹因子和时间的变化的较高的值。如果IS是耀斑产生的机制,并且产生耀斑的壳层的洛伦兹因子为100的量级,则耀斑光变曲线将呈现出时间变化为10-100 ms的亚结构,其时间变化远小于耀斑的平均持续时间,与伽玛暴瞬发相观测到的时间变化相似。如果假设较低的洛伦兹因子,例如10-25,那么40 s的较大时间变率也可以解释观测到的耀斑特性。然而,在这种情况下,我们预测X射线耀斑在非常高的能量(MeV-GeV)下没有对应物。对X射线耀斑光变曲线的子结构的研究,以及同时进行的X射线和高能观测,将使我们能够证实晚IS是X射线耀斑的原因的假设。

英文摘要:

In this paper we study synchrotron and synchrotron self Compton (SSC) emission from internal shocks (IS) during the prompt and X-ray flare phases of Gamma-Ray Bursts (GRBs). The aim is to test the IS model for the flare emission and for whether GRBs can be GeV sources. We determine the parameters for which the IS model can account for the observed prompt and X-ray flares emission, and study the detectability of the high energy SSC emission by the AGILE and GLAST satellites. We find that the detectability of the SSC emission during the prompt phase of GRBs improves for higher values of the fireball Lorentz factor and of the temporal variability. If IS is the mechanism responsible of the flare emission, and the Lorentz factor of the shells producing the flare is of the order of 100, the flare light curves are expected to present some substructures with temporal variability of 10-100 ms which are much smaller than the average duration of flares, and similar to those observed during the prompt phase of GRBs. If one assumes lower Lorentz factors, such as 10-25, then a larger temporal variaibility of 40 s can also account for the observed flare properties. However in this case we predict that X-ray flares do not have a counterpart at very high energies (MeV-GeV). An investigation on the substructures of the X-ray flares light curves, and simultaneous X-ray and high energy observations, will allow us to corroborate the hypothesis that late IS are responsible of the X-ray flares.

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