Cosmic-Ray主导区域（CRDR）中的化学
Chemistry in Cosmic-Ray Dominated Regions (CRDRs)
摘要：
分子线观测可以作为诊断宇宙射线质子的数量密度的程度，具有10秒至100秒的MeV的能量，在星暴星系和活跃的核星系中增强。给出了使用UCL\_PDR代码获得的分子丰度分数与宇宙射线诱导电离率$ζ$的函数关系的结果。其目的不是模拟任何特定的外部星系。相反，它是为了确定分子丰度对$ζ$的依赖性的特征，部分是为了能够为宇宙射线主导区域（CRDRs）制定合适的观测方案，然后刺激详细的建模。对于$10^4$ cm $^{-3}$的氢核数密度，以及高的可见消光，一些物种的丰度分数随着$ζ$增加到$10^{-14}$ s $^{-1}$而增加，但是对于高得多的$ζ$值，所有分子物种的丰度分数都显著低于它们的峰值。我们特别表明，OH，H $_{2}$ O，H $_{3}^{+}$，H $_{3}$ O $^{+}$和OH $^{+}$达到大的分数丰度（$\geqslant 10^{-8}$）的$ζ$一样大的$10^{-12}$的$^{-1}$。当$ζ> 10^{-13}$是$^{-1}$时，HCO $^{+}$是CRDRs的不良示踪剂。含硫物质可能是CRDRs气体的有用示踪剂，其中$ζ\sim 10^{-16}$是$^{-1}$。氨在$ζ\leqslant 10^{-16}$ s $^{-1}$中的丰度分数很高，含氯化萘物种中的氮含量随着$ζ$的增加而显著增加，甚至高达$\sim 10^{-14}$ s $^{-1}$。在本文中，我们还讨论了我们的模型预测，比较他们最近在银河系和河外源的检测。我们表明，他们同意以及，第一近似，与观测约束。
英文摘要：
Molecular line observations may serve as diagnostics of the degree to which the number density of cosmic ray protons, having energies of 10s to 100s of MeVs each, is enhanced in starburst galaxies and galaxies with active nuclei. Results, obtained with the UCL\_PDR code, for the fractional abundances of molecules as functions of the cosmic-ray induced ionisation rate, $ζ$, are presented. The aim is not to model any particular external galaxies. Rather, it is to identify characteristics of the dependencies of molecular abundances on $ζ$, in part to enable the development of suitable observational programmes for cosmic ray dominated regions (CRDRs) which will then stimulate detailed modelling. For a number density of hydrogen nuclei of of $10^4$ cm$^{-3}$, and high visual extinction, the fractional abundances of some species increase as $ζ$ increases to $10^{-14}$ s$^{-1}$, but for much higher values of $ζ$ the fractional abundances of all molecular species are significantly below their peak values. We show in particular that OH, H$_{2}$O, H$_{3}^{+}$, H$_{3}$O$^{+}$ and OH$^{+}$ attain large fractional abundances ($\geqslant 10^{-8}$) for $ζ$ as large as $10^{-12}$ s$^{-1}$. HCO$^{+}$ is a poor tracer of CRDRs when $ζ> 10^{-13}$ s$^{-1}$. Sulphur-bearing species may be useful tracers of CRDRs gas in which $ζ\sim 10^{-16}$ s$^{-1}$. Ammonia has a large fractional abundance for $ζ\leqslant 10^{-16}$ s$^{-1}$ and nitrogen appears in CN-bearing species at significant levels as $ζ$ increases, even up to $\sim 10^{-14}$ s$^{-1}$. In this paper, we also discuss our model predictions, comparing them to recent detections in both galactic and extragalactic sources. We show that they agree well, to a first approximation, with the observational constraints.
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