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arXiv 1810.01985astro-ph.GAastro-ph.HEastro-ph.SR
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第一星团中由潮汐破裂事件引起的中等质量黑洞的增长

Growth of intermediate mass black holes by tidal disruption events in the first star clusters

Yuya Sakurai, Naoki Yoshida, Michiko S. Fujii

摘要:

研究了逃逸恒星碰撞形成中等质量黑洞后第一个星团的恒星动力学。我们使用Sakurai et al.(2017)的宇宙学模拟结果来跟踪星团在活动暗物质(DM)晕中的演化。星团内的质量分离促使大质量恒星偶尔被中央IMBH捕获,导致潮汐破裂事件(TDE)。我们发现TDE率与IMBH质量成比例,为$\dot{N}_{\rm TDE}\sim0.3\,{\rm Myr}^{-1}(M_{\rm IMBH}/1000\,{\rm M}_{\odot})^2$。DM分量通过从外部剥离恒星来影响星团演化。当星团内DM密度增加时,恒星的速度色散增加,TDE率减小。到了TDE,中央的IMBH在1500万年内增长到与$700-2500\,{\rm M}_{\odot}$一样大。IMBH可能是在$z\gtrsim 6-7$观测到的超大质量黑洞形成的种子,如果通过星系合并和/或大规模气体吸积提供了大量的气体,或者它们可能从早期时代到现在的宇宙仍然是IMBH。

英文摘要:

We study the stellar dynamics of the first star clusters after intermediate-mass black holes (IMBHs) are formed via runaway stellar collisions. We use the outputs of cosmological simulations of Sakurai et al. (2017) to follow the star cluster evolution in a live dark matter (DM) halo. Mass segregation within a cluster promotes massive stars to be captured by the central IMBH occasionally, causing tidal disruption events (TDEs). We find that the TDE rate scales with the IMBH mass as $\dot{N}_{\rm TDE}\sim0.3\,{\rm Myr}^{-1}(M_{\rm IMBH}/1000\,{\rm M}_{\odot})^2$. The DM component affects the star cluster evolution by stripping stars from the outer part. When the DM density within the cluster increases, the velocity dispersion of the stars increases, and then the TDE rate decreases. By the TDEs, the central IMBHs grow to as massive as $700-2500\,{\rm M}_{\odot}$ in 15 million years. The IMBHs are possible seeds for the formation of supermassive BHs observed at $z\gtrsim 6-7$, if a large amount of gas is supplied through galaxy mergers and/or large-scale gas accretion, or they might remain as IMBHs from the early epochs to the present-day Universe.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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