A Circumnuclear Disk (CND) of molecular gas occupies the central few parsecs of the Galactic Center. It is likely subject to turbulent disruptions from violent events in its surrounding environment, but the effect of such perturbations has not yet been investigated in detail. Here we perform 3D, N-body/smoothed particle hydrodynamic (SPH) simulations with an adapted general turbulence driving method to investigate the CND's structural evolution, in particular its reaction to varied scales of injected turbulence. We find that, because of shear flow in the disk, transient arcs of gas (streams) naturally arise when turbulence is driven on large scales (up to ~4 pc), as might occur when a supernova blast wave encounters the CND. Because energetic events arise naturally and often in the central parsecs of our Galaxy, this result suggests that the transient structures that characterize the CND do not imply that the CND itself is a transient structure. We also note that features similar to the density concentrations, or "clumps", detailed in literature emerge when we account for the observed orientation of the disk and for the spatial resolution of observations. As such, clumps could be an artifact of observational limitations.
We numerically study the origin of the multi-armed spiral structure observed in the circumnuclear gaseous mini-disks of nearby galaxies. We show that the presence of dust in such disks and its interaction with the gravitationally stable gaseous component leads to the development of a multi-armed spiral structure. As a particular example, we study the formation of the multi-armed spiral pattern in the mini-disk of the galaxy NGC 4736, for which the observational data for the rotation and the density distribution are available. We find that the multi-armed spiral structure grows in the stable ga…
The cold molecular gas in the circumnuclear disk (CND) of radio galaxies provides critical information for understanding the mass accretion onto active galactic nuclei. We present the first detection and maps of HCN J=1-0 and HCO+ J=1-0 emission lines from the circumnuclear region of a nearby radio galaxy, NGC 4261, using the Northern Extended Millimeter Array. Both molecular lines are detected at a radial velocity of +-700 km/s relative to the systemic velocity of the galaxy, and they arise from a CND with an outer radius of 100 pc. The velocity fields of HCN and HCO+ are fitted with a Kepler…
Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations found a positive correlation between the mass of dense molecular gas in the circumnuclear disks (CNDs) and accretion rate to the active galactic nuclei (AGNs). This indicates that star formation activity in the CNDs is essential for triggering the accretion of mass to AGNs. Although the starburst-driven turbulence is a key mechanism for the transfer of angular momentum and the resultant mass accretion from the CND scale to the inner radius, the observational evidence is lacking. We report the very-long-baseline-interferome…
Active galactic nuclei play a key role in the evolution of galaxies, but their inner workings and physical connection to the host are poorly understood due to a lack of angular resolution. Infrared interferometry makes it possible to resolve the circumnuclear dust in the nearby Seyfert 2 galaxy, Circinus. Previous observations have revealed complex structures and polar dust emission but interpretation was limited to simple models. MATISSE makes it possible to image these structures for the first time. We observed the Circinus Galaxy with VLTI/MATISSE, producing 150 correlated flux spectra and …
Rotation and stability of the circumnuclear gas disk in the Galactic Center potential by the ALMA CMZ Exploration Survey (ACES)
Institute of Astronomy, The University of Tokyo(东京大学天文研究所);Astrophysics Research Institute, Liverpool John Moores University(利物浦约翰摩尔大学天体物理研究所);CCosmic Origins Of Life (COOL)(宇宙生命起源研究(COOL));Department of Astronomy, University of Florida(佛罗里达大学天文学系);Max Planck Institute for Astronomy(马克斯·普朗克天文学研究所);Center for Astrophysics and Space Astronomy(科罗拉多大学博尔德分校天体物理与行星科学系空间天体物理研究中心);Department of Astrophysical and Planetary Sciences(欧洲南方天文台);University of Colorado, Boulder(康涅狄格大学物理系);European Southern Observatory (ESO)(西班牙国家航空航天技术研究所/西班牙高等科学研究委员会天体生物学中心);Department of Physics, University of Connecticut;Centro de Astrobiología (CAB), CSIC-INTA
The 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 millimetre interferometry within the inner ~20pc of the active galaxy NGC1068 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 modelling effort that includes (i) a simple dynamical simulations involving partially inelastic collisions between disk gas…
We perform the first three-dimensional radiation hydrodynamical simulations that investigate the growth of intermediate-mass BHs (IMBHs) embedded in massive self-gravitating, dusty nuclear accretion disks. We explore the dependence of mass accretion efficiency on the gas metallicity $Z$ and mass injection at super-Eddington accretion rates from the outer galactic disk $\dot{M}_{\rm in}$, and find that the central BH can be fed at rates exceeding the Eddington rate only when the dusty disk becomes sufficiently optically thick to ionizing radiation. In this case, mass outflows from the disk owin…
The Galactic Center black hole and the nuclear star cluster are surrounded by a clumpy ring of gas and dust (the circumnuclear disk, CND) that rotates about them at a standoff distance of ~1.5 pc. The mass and density of individual clumps in the CND are disputed. We seek to use H$_2$ to characterize the clump size distribution and to investigate the morphology and dynamics of the interface between the ionized interior layer of the CND and the molecular reservoir lying further out (corresponding to the inner rim of the CND, illuminated in ultraviolet light by the central star cluster). We have …
Molecules in the Circumnuclear Disk of the Galactic Center
在中央黑洞Sgr A* 周围的几个秒差距内,环核盘(CND)的致密分子云材料中的化学物质可能受到许多高能现象的影响,例如来自大质量中央星团的高紫外线通量,来自Sgr A* 的X射线,冲击波和增强的宇宙射线通量。最近,用IRAM 30米和APEX 12米望远镜对80- 500千兆赫频率范围的相当大一部分进行了光谱调查,并对CND内和附近的选定位置进行了调查。这些数据集包含来自分子HCN、HCO $^+$、HNC、CS、SO、SiO、CN、H $_2$ CO、HC $_3$ N、N $_2$ H $^+$、H $_3$ O $^+$等的线。我们进行大速度梯度分析,以获得柱密度和总氢密度,$n$,为每个物种的分子云位于西南瓣的CND。上述分子的数据表明10 $^5\,$ cm $^{-3} \lesssim n <10^6\,$ cm $^{-3}$,这表明CND是潮汐不稳定的。导出的化学成分进行比较,使用UCL\_CHEM代码,包括气体和粮食反应,冲击波的影响计算的化学模型。模型运行不同的冲击波速度,宇宙射线电离率,和数密度。由此产生的化学成分最适合一个非常高的宇宙射线电离率值$ζ\sim 10^{-14}\,$ s $^{-1}$,3个数量级高于正常的银河系分子云的值,如果前冲击密度为$n=10^5\,$ cm $^{-3}$。
The Pairing of Accreting Massive Black Holes in Multiphase Circumnuclear Disks: the Interplay between Radiative Cooling, Star Formation, and Feedback Processes
Utilizing the Atacama Large Millimeter/submillimeter Array (ALMA), we present CS line maps in five rotational lines ($J_{\rm u}=7, 5, 4, 3, 2$) toward the circumnuclear disk (CND) and streamers of the Galactic Center. Our primary goal is to resolve the compact structures within the CND and the streamers, in order to understand the stability conditions of molecular cores in the vicinity of the supermassive black hole (SMBH) Sgr A*. Our data provide the first homogeneous high-resolution ($1.3'' = 0.05$ pc) observations aiming at resolving density and temperature structures. The CS clouds have si…
Modeling the Milky Way Circumnuclear Disk: Rosettes and Rings
Northwestern University(西北大学);Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)(天体物理学跨学科探索与研究中心);Department of Physics and Astronomy, Northwestern University(西北大学物理与天文系);School of Natural Sciences, Institute for Advanced Study(高等研究院自然科学学院)
We studied the magnetic field structures and dynamics of magnetized multiphase gas on parsec scales around supermassive black holes by using global 3D magnetohydrodynamics (MHD) simulations. We considered the effect of radiative cooling and X-ray heating due to active galactic nuclei (AGNs). The gas disk consists of a multiphase gas with (1) cold ($\leq 10^3$ K) and thin, and (2) warm ($\sim 10^4$ K) and thick components with a wide range of number densities. The turbulent magnetic energy at maximum is comparable to the thermal and turbulent kinetic energies in the turbulent motion. We confirm…
The molecular circumnuclear disk (CND) in Centaurus A: A multi-transition CO and [CI] survey with Herschel, APEX, JCMT, and SEST
我们介绍了赫歇尔空间天文台以及SEST、JCMT和APEX对NGC 128(Centaurus~A)中心致密环核盘的新CO和C^o线测量结果。Cen A中心的CO阶梯与星暴星系或活动星系核的CO阶梯有很大的不同。此外,Cen A [CI]中心发射线的相对强度也比其它星系的强得多。在同一视线范围内,致密的环核盘(CND)的CO表面亮度明显高于伸展得多的薄盘(ETD)。我们的LVG和PDR/XDR模型表明,如果通过紫外光子加热,则大部分CND气体相对较冷(25 - 80 K)且密度不高(~ 300 cm^{-3}),尽管在CND和ETD中都存在一些密度高得多的气体,其密度约为30 000 cm^{-3}。最后,在CND中也有高激发、高密度相(但在ETD中没有),要么是极端PDR的形式,但更可能是XDR的形式。Cen A CND的总气体质量为8.4 x 10^{7} M(太阳),不确定系数为2。CO-H2转换系数为4 x 10^{20} K km/s,也在2倍以内。
We present the line observations in our ALMA imaging spectral scan toward three deeply buried nuclei in NGC 4418 and Arp 220. We cover 67 GHz in $f_{\rm rest}$=215-697 GHz at about 0.2$"$ (30, 80 pc) resolution. All the nuclei show dense line forests; we report our initial line identification using 55 species. The line velocities generally indicate gas rotation around each nucleus, tracing nuclear disks of $\sim$100 pc sizes. We confirmed the counter-rotation of the nuclear disks in Arp 220 and that of the nuclear disk and the galactic disk in NGC 4418. While the brightest lines exceed 100 K, …
Chemical Features in the Circumnuclear Disk of the Galactic Center
银河系中心的环核盘(CND)暴露于来自超大质量黑洞Sgr A* 和恒星活动的许多高能现象。这些高能活动可以通过与UV光子、宇宙射线、X射线和冲击波的相互作用影响CND中的化学成分。我们的目标是约束的物理条件存在于CND的化学建模所观察到的分子物种检测到的对it.We分析了一组选定的分子线数据采取对一个位置在西南瓣的CND与IRAM 30米和APEX 12米望远镜和推导出的柱密度的每个分子使用大速度梯度(LVG)分析。确定的化学成分进行比较与时间相关的气体颗粒化学模型的基础上UCL\_CHEM代码,包括冲击波的影响,不同的物理参数。检测CO、HCN、HCO $^+$、HNC、CS、SO、SiO、NO、CN、H $_2$ CO、HC $_3$ N、N $_2$ H $^+$和H $_3$ O $^+$等分子,并获得它们的柱密度。从LVG分析获得的总氢密度范围在$2 \times 10^4$和$1 \times 10^6\,$ cm $^{-3}$之间,并且大多数物种指示大约几个$\times 10^5\,$ cm $^{-3}$的值,其低于对应于罗氏极限的值,这表明CND是潮汐不稳定的。在密度为$\sim10^4\,$ cm $^{-3}$、宇宙射线电离率高、速度为$>10^{-15} \,$ s $^{-1}$或速度为$> 40\,$ km s $^{-1}$的激波的情况下,化学模型…
We present an analysis of the 4-2600 $μ$m spectral energy distributions (SEDs) of the west and east nuclei and the diffuse infrared (IR) region of the merger-driven starburst Arp 220. We examine several possible source morphologies and dust temperature distributions using a mixture of silicate and carbonaceous grains. From fits to the SEDs we derive dust masses, temperatures, luminosities, and dust inferred gas masses. We show that the west and east nuclei are powered by central sources deeply enshrouded behind $\sim 10^{26}$ cm$^{-2}$ column densities of hydrogen with an exponential density d…
MICONIC: The multiphase circumnuclear region of Centaurus A as seen with JWST/MIRI MRS observations. I. Spectral inventory and properties of the warm molecular disk
Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris(索邦大学,法国国家科学研究中心,UMR 7095,巴黎天文台);SRON Netherlands Institute for Space Research(荷兰空间研究所);Leiden Observatory, Leiden University(莱顿天文台,莱顿大学);Observatoire de Paris, PSL University, Sorbonne Université, LUX(巴黎天文台,PSL大学,索邦大学,LUX);Centro de Astrobiología (CAB), CSIC-INTA(天体生物学中心(CAB),西班牙国家研究委员会-国家航空航天技术研究所);Department of Physics and Astronomy, Universiteit Gent(根特大学物理与天文学系);Telespazio UK for the European Space Agency (ESA)(欧洲航天局(ESA)旗下泰雷兹阿莱尼亚太空英国分公司);European Space Agency, c/o Space Telescope Science Institute(欧洲航天局,代管于太空望远镜科学研究所)
In the nearby (D=14 Mpc) AGN-starburst composite galaxy NGC 1068, it has been found that the molecular gas in the Circum-nuclear Disk (CND) is outflowing, which is a manifestation of ongoing AGN feedback. The outflowing gas has a large spread of velocities, which likely drive different shock chemistry signatures at different locations in the CND. We perform a multi-line molecular study using two shock tracers, SiO and HNCO, with the aim to determine the gas properties traced by these two species, and explore the possibility of reconstructing the shock history in the CND. Five SiO transitions a…
The circumnuclear region of M31, consisting of multiphase interstellar medium, provides a close-up view of the interaction of the central supermassive black hole and surrounding materials. Far-infrared (FIR) line structure lines and their flux ratios can be used as diagnostics of physical properties of the neutral gas in this region. Here we present the first FIR spectroscopic mapping of the circumnuclear region of M31 in [C ii] 158 um, [O i] 63 um and [O iii] 88 um lines with the Herschel Space Observatory, covering a ~500 x 500 pc (2' x 2') field. Significant emissions of all three lines are…
We used the Atacama Large Millimeter/Submillimeter Array (ALMA) to map the CO(3-2) and [CI](1-0) lines, as well as their underlying continuum emission, from the central $\sim 200$ pc region of the Circinus galaxy that hosts the nearest type 2 Seyfert-class active galactic nucleus (AGN), with a spatial resolution of $\sim 6-15$ pc. The lines and continuum-emitting regions consist of a circumnuclear disk (CND; 74 pc $\times$ 34 pc) and spiral arms. The distribution of the continuum emission revealed a temperature-dependent dust geometry and possibly polar dust elongation in the torus region. The…
Multiphase Gas Structure in the Circumnuclear Region of NGC 5506 Observed with ALMA
International Christian University(国际基督教大学);National Astronomical Observatory of Japan(日本国立天文台);The Graduate University for Advanced Studies, SOKENDAI(高级研究院);National Institute of Technology, Kure College(国立高等专门学校吴工业高等专门学校);Kagoshima University(鹿儿岛大学);Kogakuin University of Technology & Engineering(工學館大學)