From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs
From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs
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从银河系中心的环核盘到活动星系核厚而模糊的环面
DOI：
10.1051/0004-6361/202141684
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发表时间：
2022
影响因子：
6.5
通讯作者：
Le Petit F.
中科院分区：
文献类型：
--
作者：
Vollmer B.;Davies R. I.;Gratier P.;Lizee Th.;Imanishi M.;Gallimore J. F.;Impellizzeri C. M. V.;Garcia-Burillo S.;Le Petit F.
为星系中的中央黑洞提供燃料所需的高吸积率可以通过厚盘和厚环中的粘性扭矩来实现，这可以通过活动星系NGC1068的内部∼20PC内的毫米干涉测量来解决，该测量可以在类似的尺度上进行，并且对银河系中心的环核圆盘的单盘观测具有敏感性。为了解释对这些区域的观测并确定其气体分布的物理性质，我们提出了一个包括以下内容的模拟工作：(I)涉及盘状气体云之间部分非弹性碰撞的简单动力学模拟；(Ii)由动力学模型和观测标定的湍流块状气盘的分析模型；(Iii)通过H2O、H2和CO发射的局域湍流和宇宙射线气体加热和冷却；以及(Iv)分子丰度的确定。我们还考虑了光解离区(PDR)，在那里气体被中央引擎直接照亮。我们将由此得到的CO、HCN、HCO+和CS亮度温度的模型数据立方体与现有的观测数据进行了比较。在这两种情况下，运动学都可以通过一个或两个云与先前存在的环的碰撞来解释，对于CND来说是顺行的，对于NGC1068来说是逆行的。而且，只有密集的盘状云，线通量可以复制到大约2倍的范围内。为了避免云间介质的自吸收，在最大尺度上的湍流加热必须减少50-200倍。我们的模型表明，湍流机械能输入是厚气体盘内主要的气体加热机制。湍流是通过径向气体吸积获得的势能来维持的，而径向气体吸积本身又被流入的云的碰撞所增强。在NGC1068中，我们不能排除云间气体对分子线发射的显著贡献。在这个天体中，当活动星系核的大部分X射线辐射被尘埃升华半径内的一层康普顿厚的气体吸收时，光学和紫外线辐射可以使气环内缘光解离区的分子线发射增加50%∼。红外泵浦还可以使整个气环上的HCN(3−2)管路通量增加约两倍。我们的模型支持气云坠落到星系中心原有气环上的情景，它是可行的，并与银河系中心CND和NGC1068内部20个PC内的致密气体分布的现有观测结果相一致。
The high accretion rates needed to fuel the central black hole in a galaxy can be achieved via viscous torques in thick disks and rings, which can be resolved by millimeter interferometry within the inner ∼20 pc of the active galaxy NGC 1068 at comparable scales and sensitivity to single dish observations of the Circumnuclear Disk (CND) in the Galactic Center. To interpret observations of these regions and determine the physical properties of their gas distribution, we present a modeling effort that includes the following: (i) simple dynamical simulations involving partially inelastic collisions between disk gas clouds; (ii) an analytical model of a turbulent clumpy gas disk calibrated by the dynamical model and observations; (iii) local turbulent and cosmic ray gas heating and cooling via H2O, H2, and CO emission; and (iv) determination of the molecular abundances. We also consider photodissociation regions (PDRs) where gas is directly illuminated by the central engine. We compare the resulting model datacubes of the CO, HCN, HCO+, and CS brightness temperatures to available observations. In both cases the kinematics can be explained by one or two clouds colliding with a preexisting ring, in a prograde sense for the CND and retrograde for NGC 1068. And, with only dense disk clouds, the line fluxes can be reproduced to within a factor of about two. To avoid self-absorption of the intercloud medium, turbulent heating at the largest scales, comparable to the disk height, has to be decreased by a factor of 50–200. Our models indicate that turbulent mechanical energy input is the dominant gas-heating mechanism within the thick gas disks. Turbulence is maintained by the gain of potential energy via radial gas accretion, which is itself enhanced by the collision of the infalling cloud. In NGC 1068, we cannot exclude that intercloud gas significantly contributes to the molecular line emission. In this object, while the bulk of the X-ray radiation of the active galactic nucleus is absorbed in a layer of Compton-thick gas inside the dust sublimation radius, the optical and UV radiation may enhance the molecular line emission from photodissociation regions by ∼50% at the inner edge of the gas ring. Infrared pumping may also increase the HCN(3−2) line flux throughout the gas ring by about a factor of two. Our models support the scenario of infalling gas clouds onto preexisting gas rings in galactic centers, and it is viable and consistent with available observations of the CND in the Galactic Center and the dense gas distribution within the inner 20 pc of NGC 1068.
块状吸积盘中的湍流粘度 - II。
影响因子：
6.5
作者：
Bernd Vollmer;T. Beckert
通讯作者：
T. Beckert
SGR A West 的远红外线观测
DOI：
10.1007/978-94-011-0752-5_33
发表时间：
1994
期刊：
--
影响因子：
--
作者：
E. Erickson;S. Colgan;J. Simpson;R. Rubin;M. Haas
通讯作者：
M. Haas
早期型塞弗特星系的发射线成像巡天。
DOI：
10.1086/177595
发表时间：
1996
期刊：
The Astrophysical Journal
影响因子：
--
作者：
J. Mulchaey;A. Wilson;Z. Tsvetanov
通讯作者：
Z. Tsvetanov