ALMA 200 pc Imaging of a z ∼ 7 Quasar Reveals a Compact, Disk-like Host Galaxy
ALMA 200 pc Imaging of a z ∼ 7 Quasar Reveals a Compact, Disk-like Host Galaxy
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DOI：
10.3847/1538-4357/ac49e8
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发表时间：
2022-01
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通讯作者：
F. Walter;M. Neeleman;R. Decarli;B. Venemans;R. Meyer;A. Weiss;E. Bañados;S. Bosman;C. Carilli;Xiaohui Fan;D. Riechers;H. Rix;T. Thompson
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作者：
F. Walter;M. Neeleman;R. Decarli;B. Venemans;R. Meyer;A. Weiss;E. Bañados;S. Bosman;C. Carilli;Xiaohui Fan;D. Riechers;H. Rix;T. Thompson
我们给出了z = 6.9类星体J234833.34-305410.0的158 μm [C ii]谱线和下面的尘埃连续体的0.″035分辨率（10200 pc）成像。阿塔卡马大型毫米/亚毫米波阵列18小时的观测揭示了极其紧凑的发射（直径为1.1kpc），这与一个简单的，几乎面对面的，旋转支持的圆盘一致，其速度色散为1.160 km s−1。仅在中心200 pc的气体质量是104 × 109 M <$，大约是中心超大质量黑洞的两倍。因此，我们没有解决黑洞的影响范围，也没有发现中心超大质量黑洞的运动学特征。[C ii]线的运动学建模表明，大半径处的动力学质量与气体质量一致，几乎没有为恒星和/或暗物质的显着质量贡献留下空间。托姆雷-Q参数在整个盘面上都小于1，因此有利于星星的形成，这与系统的高红外光度相一致。在中心区域的尘埃是光学厚，在温度>132 K。使用标准的尘埃加热与星星形成的比例关系，这意味着一个前所未有的高星星形成率密度>104 M yr−1 kpc−2。在某些假设下，这样高的数字仍然可以用星星形成的爱丁顿极限来解释，但也可能意味着中心超大质量黑洞有助于加热中心200 pc的尘埃。
We present 0.″035 resolution (∼200 pc) imaging of the 158 μm [C ii] line and the underlying dust continuum of the z = 6.9 quasar J234833.34–305410.0. The 18 hour Atacama Large Millimeter/submillimeter Array observations reveal extremely compact emission (diameter ∼1 kpc) that is consistent with a simple, almost face-on, rotation–supported disk with a significant velocity dispersion of ∼160 km s−1. The gas mass in just the central 200 pc is ∼4 × 109 M ⊙, about a factor of two higher than that of the central supermassive black hole. Consequently we do not resolve the black hole’s sphere of influence, and find no kinematic signature of the central supermassive black hole. Kinematic modeling of the [C ii] line shows that the dynamical mass at large radii is consistent with the gas mass, leaving little room for a significant mass contribution by stars and/or dark matter. The Toomre–Q parameter is less than unity throughout the disk, and thus is conducive to star formation, consistent with the high-infrared luminosity of the system. The dust in the central region is optically thick, at a temperature >132 K. Using standard scaling relations of dust heating by star formation, this implies an unprecedented high star formation rate density of >104 M ⊙ yr−1 kpc−2. Such a high number can still be explained with the Eddington limit for star formation under certain assumptions, but could also imply that the central supermassive black hole contributes to the heating of the dust in the central 200 pc.