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arXiv 2102.05679astro-ph.GA
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z ~ 6类星体宿主星系的动力学

The Kinematics of z ~ 6 Quasar Host Galaxies

Marcel Neeleman, Mladen Novak, Bram P. Venemans, Fabian Walter, Roberto Decarli, Melanie Kaasinen, Jan-Torge Schindler, Eduardo Banados, Chris L. Carilli, Alyss… 展开作者

Marcel Neeleman, Mladen Novak, Bram P. Venemans, Fabian Walter, Roberto Decarli, Melanie Kaasinen, Jan-Torge Schindler, Eduardo Banados, Chris L. Carilli, Alyssa B. Drake, Xiaohui Fan, Hans-Walter Rix

摘要:

利用阿塔卡玛大型毫米/亚毫米阵列在[CII]-158微米([CII])辐射下观测到的27个z~6类星体宿主星系的运动学,分辨率为~ 0.25“。我们发现,9个星系显示干扰[CII]发射,无论是由于一个密切的同伴星系或最近的合并。十个星系有平滑的速度梯度,与气体盘的辐射一致。剩下的八个类星体宿主星系没有显示出速度梯度,这表明这些系统中的气体是分散主导的。所有星系都显示出高速色散,平均速度为129+-10 km/s。为了提供一个估计的动态质量的两倍半光半径的类星体宿主星系,我们使用我们公开的运动学拟合代码,qubefit的[CII]发射线的运动学模型。这导致平均动力学质量为5.0+-0.8(+-3.5)x 10^10 Msun。将动力学质量与超大质量黑洞的质量进行比较,发现在2.4sigma显著性上,该样本低于局部导出的核球质量-黑洞质量关系.即使我们考虑了大的系统不确定性,这个结果也是稳健的。利用几种不同的分子质量估算方法,我们估计气体质量分数> 10%,表明气体在z~6类星体宿主星系的重子质量中占很大比例。最后,我们推测,在[CII]运动学的大变化是一个迹象,气体吸积到z~6超大质量黑洞不是由一个单一的沉淀因素。

英文摘要:

We explore the kinematics of 27 z~6 quasar host galaxies observed in [CII]-158 micron ([CII]) emission with the Atacama Large Millimeter/sub-millimeter Array at a resolution of ~0.25''. We find that nine of the galaxies show disturbed [CII] emission, either due to a close companion galaxy or recent merger. Ten galaxies have smooth velocity gradients consistent with the emission arising from a gaseous disk. The remaining eight quasar host galaxies show no velocity gradient, suggesting that the gas in these systems is dispersion-dominated. All galaxies show high velocity dispersions with a mean of 129+-10 km/s. To provide an estimate of the dynamical mass within twice the half-light radius of the quasar host galaxy, we model the kinematics of the [CII] emission line using our publicly available kinematic fitting code, qubefit. This results in a mean dynamical mass of 5.0+-0.8(+-3.5) x 10^10 Msun. Comparison between the dynamical mass and the mass of the supermassive black hole reveals that the sample falls above the locally derived bulge mass--black hole mass relation at 2.4sigma significance. This result is robust even if we account for the large systematic uncertainties. Using several different estimators for the molecular mass, we estimate a gas mass fraction of >10%, indicating gas makes up a large fraction of the baryonic mass of z~6 quasar host galaxies. Finally, we speculate that the large variety in [CII] kinematics is an indication that gas accretion onto z~6 super massive black holes is not caused by a single precipitating factor.

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