ALMA Reveals an Inhomogeneous Compact Rotating Dense Molecular Torus at the NGC 1068 Nucleus
ALMA Reveals an Inhomogeneous Compact Rotating Dense Molecular Torus at the NGC 1068 Nucleus
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DOI：
10.3847/2041-8213/aaa8df
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发表时间：
2018-01
期刊：
影响因子：
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通讯作者：
M. Imanishi;K. Nakanishi;T. Izumi;Keiichi Wada Naoj;Kagoshima University
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文献类型：
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作者：
M. Imanishi;K. Nakanishi;T. Izumi;Keiichi Wada Naoj;Kagoshima University
本文介绍了我们在阿尔马第4周期高空间分辨率（0.04-0.07”）观测的结果，在HCN J=3-2和HCO+ J=3-2线上，对NGC 1068的核进行了观测，它是附近的典型的第2型活动星系核（AGN）。我们以前的阿尔马观测确定了这些线在质量吸积超大质量黑洞周围的环面的假定位置的紧凑发射。我们现在报告说，我们已经检测到这种紧凑的发射旋转，东部和西部的红移和蓝移，分别。与先前报道的CO J=6-5发射不同，HCN J=3-2和HCO+ J=3-2发射的形态学和动力学排列都大致沿沿着东西方向排列（即，预期的环面方向），这表明这些分子线是环面中旋转致密分子气体成分的更好探针。环的西部比东部具有更大的速度色散和更强的HCN J=3-2和HCO+ J=3-2线发射，揭示了高度不均匀的分子环。在距活动星系核沿着环面方向0.5-2.0”处，发现环面中的致密分子气体和宿主星系的致密分子气体是反向旋转的，这表明NGC 1068核过去曾发生过外部过程。
We present the results of our ALMA Cycle 4 high-spatial-resolution (0.04-0.07") observations, at HCN J=3-2 and HCO+ J=3-2 lines, of the nucleus of NGC 1068, the nearby prototypical type 2 active galactic nucleus (AGN). Our previous ALMA observations identified the compact emission of these lines at the putative location of the torus around a mass-accreting supermassive black hole. We now report that we have detected the rotation of this compact emission, with the eastern and western sides being redshifted and blueshifted, respectively. Unlike the previously reported CO J=6-5 emission, both the morphological and dynamical alignments of the HCN J=3-2 and HCO+ J=3-2 emission are roughly aligned along the east-west direction (i.e., the expected torus direction), suggesting that these molecular lines are better probes of a rotating dense molecular gas component in the torus. The western part of the torus exhibits larger velocity dispersion and stronger emission in the HCN J=3-2 and HCO+ J=3-2 lines than the eastern part, revealing a highly inhomogeneous molecular torus. The dense molecular gas in the torus and that of the host galaxy at 0.5-2.0" from the AGN along the torus direction are found to be counter-rotating, suggesting an external process happened in the past at the NGC 1068 nucleus.