附近赛弗特星系核周盘的高分辨率[CI]（³P₂→³P₁）和CO（J = 7→6）观测
High-Resolution [CI] $({^3\mathrm{P}_2}\rightarrow{^3\mathrm{P}_1})$ and CO $(J=7\rightarrow6)$ Observations of Circumnuclear Disks in Nearby Seyfert Galaxies
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中文总结 AI 辅助
利用阿塔卡马大型毫米波/亚毫米波阵列，对赛弗特星系NGC 613和NGC 1808核周盘进行多波段观测，通过分析[CI]和CO谱线及连续谱，得出分子气体密度、温度、C/CO丰度比等参数，并估计了NGC 613中心超大质量黑洞质量。
中文摘要 AI 辅助
我们利用阿塔卡马大型毫米波/亚毫米波阵列，对赛弗特星系NGC 613和NGC 1808的核周盘进行了[CI]（³P₂ - ³P₁）、CO（J = 7 - 6）以及800 - GHz连续谱观测。图像以0.2''（10 pc）的分辨率揭示了附近星系核中中性气体和尘埃的分布，这在这些频率下是前所未有的。谱线和连续谱在分子环位置均有峰值。通过对[CI]线强度比的分析，得出了分子气体的密度和动力学温度等参数，还通过对[CI]和多条CO线的同时建模，估算了C/CO丰度比和物理条件。基于气体运动学，估计了NGC 613中心超大质量黑洞的质量。
英文摘要
We present [CI] $({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})$, CO $(J=7\mathrm{-}6)$, and 800-GHz continuum observations of the circumnuclear disks (CNDs) in the Seyfert galaxies NGC 613 and NGC 1808 with the Atacama Large Millimeter/submillimeter Array. The images reveal the distributions of neutral gas and dust in nearby galaxy nuclei at a resolution of $0.2''$ (10 pc) which is unprecedented at these frequencies. Both lines and continuum exhibit peaks at the position of molecular tori. The maximum [CI]$({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})/({^3\mathrm{P}_1}\mathrm{-}{^3\mathrm{P}_0})$ integrated-intensity ratio is $\approx1.1$ $(\mathrm{K~km~s}^{-1}$ scale) in the region of the torus, yielding an excitation temperature of $T_\mathrm{ex}\approx60~\mathrm{K}$ under the approximation of local thermodynamic equilibrium (LTE) and optically thin emission. A non-LTE radiative transfer analysis of the [CI] line ratio in the CND constrains the density and kinetic temperature of molecular gas to $n_\mathrm{H_2}>10^3~\mathrm{cm}^{-3}$ and $T_\mathrm{k}>50~\mathrm{K}$, respectively. To estimate the C/CO abundance ratio and physical conditions, we simultaneously modeled the [CI] and multiple CO lines, and obtained solutions with densities and temperatures of $n_\mathrm{H_2}\sim10^{3\mathrm{-}4}~\mathrm{cm}^{-3}$ and $T_\mathrm{k}\sim80\mathrm{-}250~\mathrm{K}$ in the central 63 pc. The C/CO ratios are $\approx2$ in NGC 613 and $\approx0.6$ in NGC 1808. C/CO tends to increase with $T_\mathrm{k}$ and decrease with $n_\mathrm{H_2}$ in the CND, which is consistent with models of photodissociation regions. Based on the kinematics of gas traced by [CI] $({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})$ and CO $(J=7\mathrm{-}6)$, the mass of the supermassive black hole at the center of NGC 613 is estimated to be $\sim2\times10^7~M_\odot$.
