论文标题
通过电离，中性铁线和伽马射线研究的MEV-TEV宇宙射线侵入分子云中
Intrusion of MeV-TeV Cosmic-Rays into Molecular Clouds Studied by Ionization, the Neutral Iron Line, and Gamma-Rays
论文作者
论文摘要
低能（〜MEV）宇宙射线（CRS）电离分子云，并在6.4 keV处创建中性铁线（Fe IKα）。另一方面，高能量（> 〜GEV）CR与致密的云气体相互作用并产生γ射线。基于一维模型，我们研究气体电离速率，6.4 keV线通量的空间相关性以及来自在相邻的超诺瓦残余物加速的CRS点亮的分子云中的伽马射线排放。我们发现，这三个可观察到的空间分布取决于Crs如何触及云以及云的内部结构。如果侵入以缓慢的扩散表示，则应在电离速率高的云端周围检测到6.4 keV线。另一方面，如果CRS在云中自由流式传输，则应在发射伽马射线的位置观察6.4 keV线。在前者中，负责6.4 KEV线的CR的冷却时间比它们的云越过时间短，而后者则相反。尽管我们将结果与观察结果进行了比较，但我们无法得出结论是否主要实现了扩散或自由流的实现。可以通过Xrism和Athena等未来的X射线任务以及对涵盖更广泛领域的电离率的观察，可以更详细地检查我们的预测。
Low-energy (~MeV) cosmic rays (CRs) ionize molecular clouds and create the neutral iron line (Fe I Kα) at 6.4 keV. On the other hand, high-energy (>~ GeV) CRs interact with the dense cloud gas and produce gamma rays. Based on a one-dimensional model, we study the spatial correlation among ionization rates of gas, 6.4 keV line fluxes, and gamma-ray emissions from a molecular cloud illuminated by CRs accelerated at an adjacent supernova remnant. We find that the spatial distributions of these three observables depend on how CRs intrude the cloud and on the internal structure of the cloud. If the intrusion is represented by slow diffusion, the 6.4 keV line should be detected around the cloud edge where ionization rates are high. On the other hand, if CRs freely stream in the cloud, the 6.4 keV line should be observed where gamma rays are emitted. In the former, the cooling time of the CRs responsible for the 6.4 keV line is shorter than their cloud crossing time, and it is opposite in the latter. Although we compare the results with observations, we cannot conclude whether the diffusion or the free-streaming is dominantly realized. Our predictions can be checked in more detail with future X-ray missions such as XRISM and Athena and by observations of ionization rates that cover wider fields.
