Gamma-rays from molecular clouds illuminated by cosmic rays escaping from interacting supernova remnants
Gamma-rays from molecular clouds illuminated by cosmic rays escaping from interacting supernova remnants
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DOI：
10.1111/j.1365-2966.2010.17539.x
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发表时间：
2010-07
影响因子：
4.8
通讯作者：
Y. Ohira;K. Murase;R. Yamazaki
中科院分区：
文献类型：
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作者：
Y. Ohira;K. Murase;R. Yamazaki
最近，伽马射线望远镜 AGILE 和费米观测到了几个与分子云相互作用的中年超新星遗迹（SNR）。它们的伽马射线很可能是由宇宙射线（CR）和核子之间的非弹性碰撞产生的中性π介子衰变产生的，这表明SNR构成了银河CR的大部分。在本文中，我们提供了逃离有限尺寸区域的 CR 分布的解析解，这自然地解释了观察到的中年 SNR 的破坏幂律谱。此外，伽马射线谱断裂能的典型值1-10 GeV，可以自然地从恒星风动力学显示分子云与爆炸中心之间约10 pc 之间的分离这一事实来解释。我们发现与分子云相互作用的四个中年SNR（W51C、W28、W44和IC 443）的失控CR谱可能是相同的，尽管它导致不同的伽马射线谱。这一结果与最近关于银河CR传播的研究结果一致，并支持SNR确实是银河CR的来源。
Recently, the gamma-ray telescopes AGILE and Fermi observed several middle-aged supernova remnants (SNRs) interacting with molecular clouds. It is likely that their gamma-rays arise from the decay of neutral pions produced by the inelastic collision between cosmic rays (CRs) and nucleons, which suggests that SNRs make the bulk of Galactic CRs. In this paper, we provide the analytical solution of the distribution of CRs that have escaped from a finite-size region, which naturally explains observed broken power-law spectra of the middle-aged SNRs. In addition, the typical value of the break energy of the gamma-ray spectrum, 1–10 GeV, is naturally explained from the fact that the stellar wind dynamics shows a separation between the molecular clouds and the explosion centre of about 10 pc. We find that the runaway-CR spectrum of the four middle-aged SNRs (W51C, W28, W44 and IC 443) interacting with molecular clouds could be the same, even though it leads to different gamma-ray spectra. This result is consistent with that of recent studies of Galactic CR propagation, and supports that SNRs are indeed the sources of Galactic CRs.