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arXiv 2102.05051astro-ph.GAastro-ph.CO
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在高红移类星体母体中形成大质量种子黑洞

Forming massive seed black holes in high-redshift quasar host progenitors

Alessandro Lupi, Zoltan Haiman, Marta Volonteri

摘要:

当宇宙年龄小于1 Gyr时,质量为$10^9\rm\, M_\odot$量级的大质量黑洞(BH)的存在为明亮的类星体提供了动力,这对它们的形成机制构成了强有力的限制。到目前为止,已经提出了几种方案来解释大规模BH的形成,从第一代恒星的低质量种子BH残留物到大质量气体云快速坍缩产生的大质量种子BH。然而,其中一些场景发生在高Z类星体的祖先内的可能性尚未得到彻底的探索。在这项工作中,我们调查,通过结合暗物质只有N体模拟与半解析框架,是否形成大规模的种子黑洞从同步的原子冷却晕对和/或动态加热的迷你晕的条件得到满足,在过密的地区,一个典型的高红移类星体主机的祖先的形式和演变。我们的分析表明,在这样的地区,即强大的晕集群和高恒星形成率的特殊条件,是至关重要的,以产生一个不可忽略的大量种子BH主机候选人:我们发现$\approx1400$动态加热的无金属的迷你晕,其中包括一个演变成一个同步对,并最终在大规模的类星体主机晕由$z=6$。这表明,高红移类星体宿主晕的祖先可以窝藏早期的大质量种子黑洞。我们的研究结果进一步表明,多个大质量的种子黑洞可能形成在类星体宿主的祖先或附近,可能在较低的红移合并,并产生引力波事件。

英文摘要:

The presence of massive black holes (BHs) with masses of order $10^9\rm\, M_\odot$, powering bright quasars when the Universe was less than 1 Gyr old, poses strong constraints on their formation mechanism. Several scenarios have been proposed to date to explain massive BH formation, from the low-mass seed BH remnants of the first generation of stars to the massive seed BHs resulting from the rapid collapse of massive gas clouds. However, the plausibility of some of these scenarios to occur within the progenitors of high-z quasars has not yet been thoroughly explored. In this work, we investigate, by combining dark-matter only N-body simulations with a semi-analytic framework, whether the conditions for the formation of massive seed BHs from synchronised atomic-cooling halo pairs and/or dynamically-heated mini-haloes are fulfilled in the overdense regions where the progenitors of a typical high-redshift quasar host form and evolve. Our analysis shows that the peculiar conditions in such regions, i.e. strong halo clustering and high star formation rates, are crucial to produce a non-negligible number of massive seed BH host candidates: we find $\approx1400$ dynamically heated metal-free mini-haloes, including one of these which evolves to a synchronised pair and ends up in the massive quasar-host halo by $z=6$. This demonstrates that the progenitors of high-redshift quasar host haloes can harbour early massive seed BHs. Our results further suggest that multiple massive seed BHs may form in or near the quasar host's progenitors, potentially merging at lower redshifts and yielding gravitational wave events.

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