标题： 通过超临界吸积恒星质量种子来增长大质量黑洞 显示英文标题

标题： Growing massive black holes through super-critical accretion of stellar-mass seeds

摘要： 驱动在$z \sim 6-7$观测到的明亮类星体的巨大黑洞的快速聚集仍然是一个谜题。 已经提出了各种直接坍缩模型，以从初始种子质量为$\sim 10^5\,\rm M_\odot$的黑洞开始生长，这些种子质量随后可以在爱丁顿极限下吸积时达到十亿倍太阳质量。 在这里，我们提出了一种替代情景，基于预期存在于高红移星系核心中的气体核区盘（CND）中嵌入的恒星质量黑洞的辐射低效超临界吸积。 我们的亚秒差距分辨率流体动力学模拟显示，恒星质量黑洞在 CND 中心 100 秒差距内的轨道上会与来自周围气体碎裂产生的极高密度气体团块结合。 由于有大量的密集冷气体供应，根据“薄盘”解允许以超爱丁顿速率增长的恒星质量黑洞可以在几百万年内将其质量增加三个数量级。 这些发现得到了两种不同流体动力学代码运行的模拟的支持，RAMSES 基于自适应网格细化技术，GIZMO 基于新的拉格朗日 Godunov 方法，并且具有相似但不完全相同的子网格配方用于恒星形成、超新星反馈、黑洞吸积和反馈。 超临界吸积流的低辐射效率对于我们的黑洞的快速质量增长至关重要，因为这意味着周围核环境的辐射加热适度。 显示英文摘要

摘要： The rapid assembly of the massive black holes that power the luminous quasars observed at $z \sim 6-7$ remains a puzzle. Various direct collapse models have been proposed to head-start black hole growth from initial seeds with masses $\sim 10^5\,\rm M_\odot$, which can then reach a billion solar mass while accreting at the Eddington limit. Here we propose an alternative scenario based on radiatively inefficient super-critical accretion of stellar-mass holes embedded in the gaseous circum-nuclear discs (CNDs) expected to exist in the cores of high redshift galaxies. Our sub-pc resolution hydrodynamical simulations show that stellar-mass holes orbiting within the central 100 pc of the CND bind to very high density gas clumps that arise from the fragmentation of the surrounding gas. Owing to the large reservoir of dense cold gas available, a stellar-mass black hole allowed to grow at super-Eddington rates according to the "slim disc" solution can increase its mass by 3 orders of magnitudes within a few million years. These findings are supported by simulations run with two different hydro codes, RAMSES based on the Adaptive Mesh Refinement technique and GIZMO based on a new Lagrangian Godunov-type method, and with similar, but not identical, sub-grid recipes for star formation, supernova feedback, black hole accretion and feedback. The low radiative efficiency of super-critical accretion flows are instrumental to the rapid mass growth of our black holes, as they imply modest radiative heating of the surrounding nuclear environment.