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arXiv 0905.2417astro-ph.HE
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费米卫星探测到的伽马射线暴产生高能光子

On the generation of high energy photons detected by the Fermi Satellite from gamma-ray bursts

Pawan Kumar, Rodolfo Barniol Duran

摘要:

费米卫星对伽马射线暴的观测,能够探测到能量范围很宽的光子:8 keV到> 300 GeV,为研究这些神秘的爆炸打开了一个新的窗口。人们普遍认为,能量大于100 MeV的光子是由产生较低能量光子的同一个源产生的-至少在光谱形状是能带函数的情况下。本文报道了一个令人惊讶的发现--GRB 080916 C的费米数据明确地表明,高能光子(>= 100 MeV)是通过同步加速器过程在外激波中产生的,而低能光子则有明显不同的来源。高能光子产生区(以及余辉发射区)的磁场与星周介质的激波压缩磁场一致。这一结果揭示了伽马射线暴余辉所需的磁场的起源这一重要问题。高能辐射的外部冲击模型做出了可靠的预测,可以用现有和未来的观测进行检验。

英文摘要:

Observations of gamma-ray bursts by the Fermi satellite, capable of detecting photons in a very broad energy band: 8keV to >300GeV, have opened a new window for the study of these enigmatic explosions. It is widely assumed that photons of energy larger than 100 MeV are produced by the same source that generated lower energy photons -- at least whenever the shape of the spectrum is a Band function. We report here a surprising discovery -- the Fermi data for a bright burst, GRB 080916C, unambiguously shows that the high energy photons (>= 100MeV) were generated in the external shock via the synchrotron process, and the lower energy photons had a distinctly different source. The magnetic field in the region where high energy photons were produced (and also the late time afterglow emission region) is found to be consistent with shock compressed magnetic field of the circum-stellar medium. This result sheds light on the important question of the origin of magnetic fields required for gamma-ray burst afterglows. The external shock model for high energy radiation makes a firm prediction that can be tested with existing and future observations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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