High Spectral and Spatial Resolution Observations of Shocked Molecular Hydrogen at the Galactic Center
High Spectral and Spatial Resolution Observations of Shocked Molecular Hydrogen at the Galactic Center
复制标题
银河系中心震动氢分子的高光谱和空间分辨率观测
DOI：
10.1086/322496
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
M. Ashley
中科院分区：
文献类型：
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作者：
F. Yusef;S. Stolovy;M. Burton;M. Wardle;M. Ashley
OH （1720 MHz）脉泽的存在和1665/1667 MHz对应脉泽的缺失已被证明是与银河系超新星遗迹相关的激波分子气体的明确诊断。这表明激波分子气体应该与在银河系中心的环核盘（CND）和Sgr A东探测到的OH （1720 MHz）脉泽有关。为了验证这一假设，我们利用哈勃太空望远镜（HST）上的NICMOS和英澳望远镜（AAT）上的新南威尔士大学红外法布里-佩罗（unswif）标准子观测了H2 -0 S(1)和Brγ谱线，这些线位于CND和Sgr A East中探测到OH （1720 MHz）微波激射的区域附近。研究结果表明，H2分布在华北盆地的南北裂片和Sgr A东部。几乎所有在银河系中心探测到的脉泽斑都伴随着H2的发射。特别地，我们在CND西北附近发现了一个引人注目的丝状结构，并有证据表明，激波分子气体与银河系中心70公里s-1分子云有关。我们认为，CND的发射可能发生在由碰撞引起的团块随机运动耗散或在更均匀的介质中湍流耗散加热的气体中。此外，在靠近Sgr A东壳的东部边缘，检测到高度红移的气体高达140 km s-1。这些观测结合了OH （1720 MHz）的结果表明，Sgr A东膨胀到50和70 km s-1云以及进入CND的叶状体时，H2气体受到了冲击和加速。
The presence of OH (1720 MHz) masers and the absence of counterparts at 1665/1667 MHz has proved to be a clear diagnostic of shocked molecular gas associated with Galactic supernova remnants. This suggests that shocked molecular gas should be associated with the OH (1720 MHz) masers that have been detected in the circumnuclear disk (CND) and Sgr A East at the Galactic center. In order to test this hypothesis, we observed the H2 1-0 S(1) and Brγ lines using NICMOS on the Hubble Space Telescope (HST) and the University of New South Wales Infrared Fabry-Perot (UNSWIRF) etalon at the Anglo-Australian Telescope (AAT), near the regions where OH (1720 MHz) masers are detected in the CND and Sgr A East. We present the distribution of H2 in the north and south lobes of the CND and in Sgr A East. H2 emission accompanies almost all the maser spots detected at the Galactic center. In particular, we find a striking filamentary structure near the northwest of the CND and evidence that shocked molecular gas is associated with the 70 km s-1 molecular cloud at the Galactic center. We argue that the emission from the CND could arise in gas heated by the dissipation of the random motion of clumps by collisions or the dissipation of turbulence in a more homogeneous medium. In addition, highly redshifted gas of up to 140 km s-1 close to the eastern edge of the Sgr A East shell is detected. These observations combined with OH (1720 MHz) results suggest that the H2 gas is shocked and accelerated by the expansion of Sgr A East into the 50 and the 70 km s-1 clouds and into the lobes of the CND.