Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, Texas 78712-0259, USA.
Nature. 2011 Jan 20;469(7330):374-6. doi: 10.1038/nature09694.
The masses of supermassive black holes are known to correlate with the properties of the bulge components of their host galaxies. In contrast, they seem not to correlate with galaxy disks. Disk-grown 'pseudobulges' are intermediate in properties between bulges and disks; it has been unclear whether they do or do not correlate with black holes in the same way that bulges do. At stake in this issue are conclusions about which parts of galaxies coevolve with black holes, possibly by being regulated by energy feedback from black holes. Here we report pseudobulge classifications for galaxies with dynamically detected black holes and combine them with recent measurements of velocity dispersions in the biggest bulgeless galaxies. These data confirm that black holes do not correlate with disks and show that they correlate little or not at all with pseudobulges. We suggest that there are two different modes of black-hole feeding. Black holes in bulges grow rapidly to high masses when mergers drive gas infall that feeds quasar-like events. In contrast, small black holes in bulgeless galaxies and in galaxies with pseudobulges grow as low-level Seyfert galaxies. Growth of the former is driven by global processes, so the biggest black holes coevolve with bulges, but growth of the latter is driven locally and stochastically, and they do not coevolve with disks and pseudobulges.
超大质量黑洞的质量与它们宿主星系的星系晕成分的性质相关。相比之下，它们似乎与星系盘不相关。由星系盘生长而成的“伪星系晕”在性质上介于星系晕和星系盘之间；不清楚它们是否与星系晕以相同的方式与黑洞相关，而星系晕与黑洞的相关性可能是通过黑洞能量反馈来调节的。在这个问题上，关键是要确定星系的哪些部分与黑洞共同演化，这些部分可能是通过黑洞的能量反馈来调节的。在这里，我们报告了具有动态探测到的黑洞的星系的伪星系晕分类，并将其与最近对最大无星系晕星系中速度弥散的测量结果相结合。这些数据证实了黑洞与星系盘不相关，并且表明它们与伪星系晕相关性很小或根本没有。我们认为存在两种不同的黑洞进食模式。当合并驱动气体流入时，星系晕中的黑洞会迅速生长到很高的质量，从而引发类星体活动。相比之下，无星系晕星系和具有伪星系晕星系中的小黑洞则以低水平的塞弗特星系的形式生长。前者的生长是由全局过程驱动的，因此最大的黑洞与星系晕共同演化，但后者的生长是由局部和随机过程驱动的，它们与星系盘和伪星系晕不共同演化。
