The Ecology of Star Clusters and Intermediate-Mass Black Holes in the Galactic Bulge
The Ecology of Star Clusters and Intermediate-Mass Black Holes in the Galactic Bulge
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DOI：
10.1086/500361
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发表时间：
2005-11
期刊：
影响因子：
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通讯作者：
S. P. Portegies Zwart;H. Baumgardt;S. McMillan;J. Makino;P. Hut;T. Ebisuzaki
中科院分区：
文献类型：
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作者：
S. P. Portegies Zwart;H. Baumgardt;S. McMillan;J. Makino;P. Hut;T. Ebisuzaki
我们模拟了银河系内部的100pc，研究了星团和中质量黑洞（IMBHs）的形成和演化。在这项研究中，我们对位于凸起的星团和银河系中心超大质量黑洞的内部十分之一秒差进行了广泛的直接n体模拟。在我们的n体模拟中，通过半解析解考虑了星团在凸起潮汐场中的动态摩擦。n体计算被用来校准一个半解析模型的形成和演化的隆起。我们发现，在银河系中心100pc以内诞生的星团中，有10%的星团在向内迁移过程中经历了核心坍缩，并通过逃逸恒星合并形成了IMBHs。在星团解散后，这些IMBHs继续向内漂移，携带着一些质量最大的恒星。我们预测，在超大质量黑洞（SMBH）的~ 10%范围内，有~50个质量为~1000 M☉的IMBHs。其中几颗恒星预计仍将伴随着该星团中一些质量最大的恒星。我们还发现，在SMBH的几毫秒差距内，有几个imbh的稳定种群。这一人口推动了imbh和SMBH之间的合并率，其速度约为每10兆当量1个，足以形成SMBH的累积大部分质量。在整个宇宙中，大质量黑洞和大质量黑洞的合并可以被LISA以大约每周两次的速度探测到。
We simulate the inner 100 pc of the Milky Way to study the formation and evolution of the population of star clusters and intermediate-mass black holes (IMBHs). For this study we perform extensive direct N-body simulations of the star clusters that reside in the bulge, and of the inner few tenth of parsecs of the supermassive black hole in the Galactic center. In our N-body simulations the dynamical friction of the star cluster in the tidal field of the bulge are taken into account via semianalytic solutions. The N-body calculations are used to calibrate a semianalytic model of the formation and evolution of the bulge. We find that ~10% of the clusters born within ~100 pc of the Galactic center undergo core collapse during their inward migration and form IMBHs via runaway stellar merging. After the clusters dissolve, these IMBHs continue their inward drift, carrying a few of the most massive stars with them. We predict that a region within ~10 pc of the supermassive black hole (SMBH) is populated by ~50 IMBHs of ~1000 M☉. Several of these are still expected to be accompanied by some of the most massive stars from the star cluster. We also find that within a few milliparsecs of the SMBH there is a steady population of several IMBHs. This population drives the merger rate between IMBHs and the SMBH at a rate of about one per 10 Myr, sufficient to build the accumulated majority of mass of the SMBH. Mergers of IMBHs with SMBHs throughout the universe are detectable by LISA at a rate of about two per week.