Formation of massive black holes through runaway collisions in dense young star clusters
Formation of massive black holes through runaway collisions in dense young star clusters
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DOI：
10.1038/nature02448
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发表时间：
2004-02
期刊：
影响因子：
64.8
通讯作者：
S. Zwart;H. Baumgardt;P. Hut;J. Makino;S. McMillan
中科院分区：
文献类型：
--
作者：
S. Zwart;H. Baumgardt;P. Hut;J. Makino;S. McMillan
一个发光的 X 射线源与 MGG 11 相关，MGG 11 是一组年轻恒星，距星暴星系 M 82 中心约 200 pc（参考文献 , ）。这个来源的特性可以通过一个质量至少为 350 个太阳质量 (350M⊙) 的黑洞来最好地解释，该黑洞介于恒星质量和超大质量黑洞之间。附近但质量稍大的星团（MGG 9）没有显示出这种中等质量黑洞的证据，这就提出了一个问题：星团的哪些物理特征可以解释这种差异。在这里，我们报告了星团内恒星演化和运动的数值模拟，其中恒星可以相互合并。我们发现，对于 MGG 11，动态摩擦会导致大质量恒星迅速下沉到星团中心，并在那里参与失控碰撞。这会产生一颗 800-3,000M⊙ 的恒星，最终坍缩成中等质量的黑洞。 MGG 9 星团中不会发生这种失控，因为较大的星团半径导致质量分离时间尺度比 MGG 11 长五倍。
A luminous X-ray source is associated with MGG 11—a cluster of young stars ∼200 pc from the centre of the starburst galaxy M 82 (refs , ). The properties of this source are best explained,by invoking a black hole with a mass of at least 350 solar masses (350M⊙), which is intermediate between stellar-mass and supermassive black holes. A nearby but somewhat more massive cluster (MGG 9) shows no evidence of such an intermediate-mass black hole,, raising the issue of just what physical characteristics of the clusters can account for this difference. Here we report numerical simulations of the evolution and motion of stars within the clusters, where stars are allowed to merge with each other. We find that for MGG 11 dynamical friction leads to the massive stars sinking rapidly to the centre of the cluster, where they participate in a runaway collision. This produces a star of 800–3,000M⊙, which ultimately collapses to a black hole of intermediate mass. No such runaway occurs in the cluster MGG 9, because the larger cluster radius leads to a mass segregation timescale a factor of five longer than for MGG 11.