标题： 阿塔卡马大型毫米/亚毫米阵列探测变化星系核活动的塞弗特星系Mrk 590中的分子气体储库 显示英文标题

标题： ALMA Probes the Molecular Gas Reservoirs in the Changing-Look Seyfert Galaxy Mrk 590

摘要： 我们研究了马卡良590（Mrk 590）星系核活动星系核（AGN），其中心超大质量黑洞此前一直处于高吸积状态，但现在是否由于缺乏中心气体而关闭。 我们分析了马卡良590的亚角秒分辨 ALMA 对$^{12}$CO(3-2) 谱线和 344 GHz 连续谱辐射的新观测数据。 在内核 150 pc 范围内未检测到$^{12}$CO(3-2) 辐射，约束其中心分子气体质量为$M({\rm H_2}) \lesssim 1.6 \times 10^5\, {M_{\odot}}$，不超过一个典型的巨型分子云，假设 CO 辐射亮度与气体质量转换因子为$\alpha_{\rm CO}\sim 0.8\,{M_{\odot}\,\rm (K \,km\,s^{-1}\,pc^{2}})^{-1}$。 然而，在爱丁顿极限吸积条件下，仍有足够的气体可以维持黑洞活动约$2.6 \times 10^5$年。 因此，我们不能排除该 AGN 可能只是暂时停止供能，未来可能重新开启。 我们在距离 $\sim 1$ 千秒差距处发现了一个环状结构，其中的一个气体团块表现出扰动的动力学特性，位于 AGN 西部 $\sim 200$ 秒差距处，可能正在为星系核心补充气体。 马卡良590在千秒差距尺度上并不比其他附近的AGN宿主星系明显缺少气体，这表明在这个尺度上的气体储层无法直接反映正在进行的 AGN 活动和吸积率。 在中心 150 pc 检测到的连续谱辐射很可能来自温暖的由 AGN 加热的尘埃，尽管不能排除同步辐射和自由-自由辐射的贡献。 显示英文摘要

摘要： We investigate if the active galactic nucleus (AGN) of Mrk 590, whose supermassive black hole was until recently highly accreting, is turning off due to a lack of central gas to fuel it. We analyse new sub-arcsecond resolution ALMA maps of the $^{12}$CO(3-2) line and 344 GHz continuum emission in Mrk 590. We detect no $^{12}$CO(3-2) emission in the inner 150 pc, constraining the central molecular gas mass to $M({\rm H_2}) \lesssim 1.6 \times 10^5\, {M_{\odot}}$, no more than a typical giant molecular gas cloud, for a CO luminosity to gas mass conversion factor of $\alpha_{\rm CO}\sim 0.8\,{M_{\odot}\,\rm (K \,km\,s^{-1}\,pc^{2}})^{-1}$. However, there is still potentially enough gas to fuel the black hole for another $2.6 \times 10^5$ years assuming Eddington-limited accretion. We therefore cannot rule out that the AGN may just be experiencing a temporary feeding break, and may turn on again in the near future. We discover a ring-like structure at a radius of $\sim 1$ kpc, where a gas clump exhibiting disturbed kinematics and located just $\sim 200$ pc west of the AGN, may be refueling the centre. Mrk 590 does not have significantly less gas than other nearby AGN host galaxies at kpc scales, confirming that gas reservoirs at these scales provide no direct indication of on-going AGN activity and accretion rates. Continuum emission detected in the central 150 pc likely originates from warm AGN-heated dust, although contributions from synchrotron and free-free emission cannot be ruled out.