Ubiquitous argonium (ArH+) in the diffuse interstellar medium: molecular tracer of almost purely atomic gas
Ubiquitous argonium (ArH+) in the diffuse interstellar medium: molecular tracer of almost purely atomic gas
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DOI：
10.1051/0004-6361/201423727
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发表时间：
2014-06-01
影响因子：
6.5
通讯作者：
Falgarone, E.
中科院分区：
文献类型：
--
作者：
Schilke, P.;Neufeld, D. A.;Falgarone, E.
目标。我们描述了一个以前未识别的星际吸收线ArH+的分配，并讨论其相关性的背景下，氢化物吸收扩散气体中的低H-2分数。分配给ArH+的置信度进行了讨论，并确定对几个视线的列密度。然后讨论的化学模型的框架内的结果，目的是解释所观察到的柱密度。我们拟合的谱线与多个速度分量，并确定列密度从线连续比。ArH+的柱密度进行了比较，其他物种，跟踪星际介质（ISM）的组件与不同的H-2丰度。我们建立了考虑紫外辐射和宇宙射线电离的化学模型。由于检测到两种同位素，（ArH+）-Ar-36和（ArH+）-Ar-38，我们有信心的载体分配给NeH+。在[NeH+]/[ArH+] 99.9%原子限度下未检出。
Aims. We describe the assignment of a previously unidentified interstellar absorption line to ArH+ and discuss its relevance in the context of hydride absorption in diffuse gas with a low H-2 fraction. The confidence of the assignment to ArH+ is discussed, and the column densities are determined toward several lines of sight. The results are then discussed in the framework of chemical models, with the aim of explaining the observed column densities.Methods. We fitted the spectral lines with multiple velocity components, and determined column densities from the line-to-continuum ratio. The column densities of ArH+ were compared to those of other species, tracing interstellar medium (ISM) components with different H-2 abundances. We constructed chemical models that take UV radiation and cosmic ray ionization into account.Results. Thanks to the detection of two isotopologues, (ArH+)-Ar-36 and (ArH+)-Ar-38, we are confident about the carrier assignment to NeH+. is not detected with a limit of [NeH+]/[ArH+] 99.9% atomic.