在过去70亿年里，棒在盘状星系AGN燃料中的作用
The role of bars in AGN fueling in disk galaxies over the last seven billion years
摘要：
我们提出的经验约束的影响，恒星酒吧的燃料的活动星系核（AGN）的z=0.84使用的样品的X射线选择的AGN托管在发光的非相互作用的面对和适度倾斜的磁盘星系从钱德拉宇宙调查。使用高分辨率的哈勃太空望远镜成像来识别酒吧，我们发现，酒吧活跃星系的比例显示出类似的行为，不活跃的螺旋，下降与红移从71%在z~0.3，到35%在z~0.8。与活跃的星系通常是大规模的，我们将它们与质量匹配的样本不活跃的螺旋，并表明，虽然在面值的AGN酒吧分数略高，在所有的红移，我们不能排除酒吧分数的活跃和不活跃的星系是相同的。酒吧的存在对活动星系核的强度没有影响，有酒吧和无酒吧的活动星系显示出等效的X射线光度分布。从我们的结果中，我们得出结论，燃料过程的发生和效率是独立的大尺度结构的星系。杆的作用（如果有的话）可以被限制为提供用于BH加燃料发生的合适条件，即，给中央100台电脑补充新的气体。在高红移端，我们发现大约60%的活跃盘星系是无棒星系。我们推测这与已知的动力学状态的磁盘在更高的红移-更多的气体丰富，更容易不稳定性比本地螺旋-这也可能导致气体流入，而不需要酒吧。
英文摘要：
We present empirical constraints on the influence of stellar bars on the fueling of active galactic nuclei (AGNs) out to z=0.84 using a sample of X-ray-selected AGNs hosted in luminous non-interacting face-on and moderately inclined disk galaxies from the Chandra COSMOS survey. Using high-resolution Hubble Space Telescope imaging to identify bars, we find that the fraction of barred active galaxies displays a similar behavior as that of inactive spirals, declining with redshift from 71% at z~0.3, to 35% at z~0.8. With active galaxies being typically massive, we compare them against a mass-matched sample of inactive spirals and show that, while at face value the AGN bar fraction is slightly higher at all redshifts, we cannot rule out that the bar fractions of active and inactive galaxies are the same. The presence of a bar has no influence on the AGN strength, with barred and unbarred active galaxies showing equivalent X-ray luminosity distributions. From our results, we conclude that the occurrence and the efficiency of the fueling process is independent of the large scale structure of a galaxy. The role of bars, if any, may be restricted to providing the suitable conditions for BH fueling to occur, i.e., bring a fresh supply of gas to the central 100 pc. At the high-redshift end, we find that roughly 60% of active disk galaxies are unbarred. We speculate this to be related with the known dynamical state of disks at higher redshifts---more gas-rich and prone to instabilities than local spirals---which could also lead to gas inflows without the need of bars.
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