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arXiv 0907.1086astro-ph.GAastro-ph.CO
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黑洞的生长:来自暗活动星系的见解

The Growth of Black Holes: Insights From Obscured Active Galaxies

Jenny E. Greene, Nadia L. Zakamska, Xin Liu, Aaron J. Barth, Luis C. Ho

摘要:

昏暗的或窄线的活动星系提供了一个在明亮和强烈吸积的黑洞存在下的类星体环境的通畅视图。我们利用斯隆数字巡天在红移0.1 < z < 0.45处光学选择的发光窄线活动星系的大型新样本,结合麦哲伦低色散巡天摄谱仪(LDSS 3)的后续观测,研究这些极端物体中黑洞质量和宿主星系性质的分布。我们发现整个样品的黑洞质量(<log M_BH/M_sun> = 8.0 +/- 0.7)和爱丁顿比(<log L/L_Edd> = -0.7 +/- 0.7)的范围很窄,与可比的宽线系统惊人地相似。相比之下,我们推断出广泛的恒星形成的性质和主机形态的样本,从磁盘为主的椭圆星系。近四分之一的公司有高度不安的形态,表明正在进行的合并。与明显正在经历显著增长的黑洞不同,这些星系似乎是在前一个时代形成了它们的大部分恒星。另一方面,从这些系统中气体和恒星速度色散之间缺乏相关性可以清楚地看出,宿主星系星际介质与恒星远未处于维里平衡。虽然我们的研究结果对在高光度活跃星系中用气体代替恒星弥散的可靠性提出了强烈的质疑,但它们确实提供了直接的证据,表明发光吸积黑洞在整个星系范围内影响着它们的周围环境。

英文摘要:

Obscured or narrow-line active galaxies offer an unobstructed view of the quasar environment in the presence of a luminous and vigorously accreting black hole. We exploit the large new sample of optically selected luminous narrow-line active galaxies from the Sloan Digital Sky Survey at redshifts 0.1 < z < 0.45, in conjunction with follow-up observations with the Low Dispersion Survey Spectrograph (LDSS3) at Magellan, to study the distributions of black hole mass and host galaxy properties in these extreme objects. We find a narrow range in black hole mass (<log M_BH/M_sun> = 8.0 +/- 0.7) and Eddington ratio (<log L/L_Edd> = -0.7 +/- 0.7) for the sample as a whole, surprisingly similar to comparable broad-line systems. In contrast, we infer a wide range in star formation properties and host morphologies for the sample, from disk-dominated to elliptical galaxies. Nearly one-quarter have highly disturbed morphologies indicative of ongoing mergers. Unlike the black holes, which are apparently experiencing significant growth, the galaxies appear to have formed the bulk of their stars at a previous epoch. On the other hand, it is clear from the lack of correlation between gaseous and stellar velocity dispersions in these systems that the host galaxy interstellar medium is far from being in virial equilibrium with the stars. While our findings cast strong doubt on the reliability of substituting gas for stellar dispersions in high luminosity active galaxies, they do provide direct evidence that luminous accreting black holes influence their surroundings on a galaxy-wide scale.

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