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arXiv 1803.07090astro-ph.GAastro-ph.HEcond-mat.stat-mechgr-qc
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星系核中的黑洞

Black Hole Disks in Galactic Nuclei

Ákos Szölgyén, Bence Kocsis

摘要:

围绕超大质量黑洞运行的物体之间的引力矩驱动着核星团(NSC)中轨道平面的快速重定向,这一过程被称为矢量共振弛豫。在这封信中,我们确定了系统的统计平衡与分布的质量,半长轴,和偏心率。我们平均的相互作用在拱点进动时间,并构建了一个蒙特卡罗马尔可夫链方法抽样的微正则系综的NSC。我们研究的情况下,NSC形成的恒星形成或球状星团的16集。我们发现,大质量恒星和恒星质量的黑洞形成一个扭曲的磁盘,而低质量的恒星类似于一个球形分布与可能的净旋转。这解释了银河系中心顺时针圆盘的起源,并预测了嵌入该结构中的黑洞(BH)的数量。在这样的盘中,大质量恒星之间的合并率、黑洞对大质量恒星的潮汐破坏事件以及BH-BH合并率都大大增加。前两个可能解释了观测到的G1和G2云的起源,后者可能对LIGO和VIRGO的引力波探测很重要。更一般地说,黑洞被认为会在所有致密的球形恒星系统中的圆盘中定居,这些恒星系统是由包括球状星团在内的较小系统合并而成的。

英文摘要:

Gravitational torques among objects orbiting a supermassive black hole drive the rapid reorientation of orbital planes in nuclear star clusters (NSCs), a process known as vector resonant relaxation. In this Letter, we determine the statistical equilibrium of systems with a distribution of masses, semimajor axes, and eccentricities. We average the interaction over the apsidal precession time and construct a Monte Carlo Markov chain method to sample the microcanonical ensemble of the NSC. We examine the case of NSCs formed by 16 episodes of star formation or globular cluster infall. We find that the massive stars and stellar mass black holes form a warped disk, while low mass stars resemble a spherical distribution with a possible net rotation. This explains the origin of the clockwise disk in the Galactic center and predicts a population of black holes (BHs) embedded within this structure. The rate of mergers among massive stars, tidal disruption events of massive stars by BHs, and BH-BH mergers are highly increased in such disks. The first two may explain the origin of the observed G1 and G2 clouds, the latter may be important for gravitational wave detections with LIGO and VIRGO. More generally, black holes are expected to settle in disks in all dense spherical stellar systems assembled by mergers of smaller systems including globular clusters.

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