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arXiv 2006.05893astro-ph.HE
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短伽马射线暴中的反向冲击--GRB 160821 B事例及其作为引力波对应物的前景

Reverse Shocks in Short Gamma-Ray Bursts -- The case of GRB 160821B and prospects as gravitational-wave counterparts

Gavin P Lamb

摘要:

产生伽玛暴余辉的激波系统由一个正激波和一个反向激波组成。对于短伽玛暴,观测到的反向激波的证据很少,然而,伽玛暴160821 B的余辉需要在早期的反向激波来解释射电观测。此外,GRB 160821 B还伴随着最佳采样的macronova,没有引力波探测,以及一个有趣的晚期X射线余辉行为,表明了一个刷新冲击。在轴上短伽玛暴中观测到的反向激波的存在意味着反向激波应该被认为是引力波探测到的合并的潜在对应物。作为引力波的对应物,离轴伽玛射线暴喷流的余辉可以揭示喷流结构--在这些结构化喷流系统中将存在反向激波,如果观察到这些反向激波的特征,则可以指示出流中的磁化程度。在这里,我们展示了GRB 160821 B的情况,以及如何在离轴观测者的结构射流中出现反向激波。

英文摘要:

The shock system that produces the afterglow to GRBs consists of a forward- and a reverse-shock. For short GRBs, observational evidence for a reverse-shock has been sparse, however, the afterglow to GRB 160821B requires a reverse-shock at early times to explain the radio observations. GRB 160821B is additionally accompanied by the best-sampled macronova without a gravitational-wave detection, and an interesting late-time X-ray afterglow behaviour indicative of a refreshed-shock. The presence of an observed reverse-shock in an on-axis short GRB means that the reverse-shock should be considered as a potential counterpart to gravitational-wave detected mergers. As a gravitational-wave counterpart, the afterglow to an off-axis GRB jet can reveal the jet structure -- a reverse-shock will exist in these structured jet systems and the signature of these reverse-shocks, if observed, can indicate the degree of magnetisation in the outflow. Here we show the case of GRB 160821B, and how a reverse-shock will appear for an off-axis observer to a structured jet.

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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