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arXiv 1404.2271astro-ph.GA
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银河系核心GCIRS 3和GCIRS 1 W的红外H3+和PDKEEPAAB研究

Infrared H3+ and CO Studies of the Galactic Core: GCIRS 3 and GCIRS 1W

Miwa Goto, T. R. Geballe, Nick Indriolo, Farhad Yusef-Zadeh, Tomonori Usuda, Thomas Henning, Takeshi Oka

摘要:

我们获得了H3+、R(1,1)l、R(3,3)l和R(2,2)l的关键基本谱线的改进谱,以及CO在朝向红外光源GCIRS 3和GCIRS 1 W的视线上的振转跃迁谱。光谱显示吸收发生在三种气体环境中:(1)与前景螺旋/侧臂相关的冷的稠密和弥漫的气体;(2)温暖和弥漫的气体在很宽的且大多为负的速度范围内吸收,这似乎填充了银河系中央分子区(CMZ)的很大一部分;(3)温暖、致密、致密的云,速度接近+50 km s^-1,可能在中心1-2 pc范围内。前两种云类型对中央星团所有源的反射几乎相同,并且与以前在从Sgr A* 到其以东30 pc的视线上观测到的相似。云类型(3)只在中央星团附近观测到,在GCIRS 3和GCIRS 1 W的视线之间显示出明显的差异,它们在天空中的投影距离仅为0.33pc。我们确定这种材料的一部分,以前已知的HCN映射的Circumnuclear磁盘向内延伸。氢电离率zeta与路径长度L的乘积的下限,对于温暖且弥漫的CMZ气体和核心中温暖且稠密的云,分别为2.3 x 10^5 cm s^-1和1.5 x 10^3 cm s^-1。这些极限表明,这些区域的电离率远高于10^-15 s^-1。

英文摘要:

We have obtained improved spectra of key fundamental band lines of H3+, R(1,1)l, R(3,3)l, and R(2,2)l, and ro-vibrational transitions of CO on sightlines toward the luminous infrared sources GCIRS 3 and GCIRS 1W, each located in the Central Cluster of the Galactic center within several arcseconds of Sgr A*. The spectra reveal absorption occurring in three kinds of gaseous environments: (1) cold dense and diffuse gas associated with foreground spiral/lateral arms; (2) warm and diffuse gas absorbing over a wide and mostly negative velocity range, which appears to fill a significant fraction of the Galaxy's Central Molecular Zone (CMZ); and (3) warm, dense and compact clouds with velocities near +50 km s^-1 probably within 1-2 pc of the center. The absorptions by the first two cloud types are nearly identical for all the sources in the Central Cluster, and are similar to those previously observed on sightlines from Sgr A* to 30 pc east of it. Cloud type (3), which has only been observed toward the Central Cluster, shows distinct differences between the sightlines to GCIRS 3 and GCIRS 1W, which are separated on the sky by only 0.33 pc in projection. We identify this material as part of an inward extension of the Circumnuclear Disk previously known from HCN mapping. Lower limits on the products of the hydrogen ionization rate zeta and the path length L are 2.3 x 10^5 cm s^-1 and 1.5 x 10^3 cm s^-1 for the warm and diffuse CMZ gas and for the warm and dense clouds in the core, respectively. The limits indicate that the ionization rates in these regions are well above 10^-15 s^-1.

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