发表机构
Carnegie Mellon University; UCLA; University of Virginia; Universidade de Santiago de Compostela; University of North Carolina at Chapel Hill; Northwestern University; University of Florida（卡内基梅隆大学; 加州大学洛杉矶分校; 弗吉尼亚大学; 圣地亚哥德孔波斯特拉大学; 北卡罗来纳大学教堂山分校; 西北大学; 佛罗里达大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究提出基于星团失控碰撞的MBH种子模型，应用于5σ过密区模拟，提升MBH并合率与LISA事件率，改善低质量星系MBH标度关系，加速早期MBH增长。
AI 中文摘要
詹姆斯·韦布空间望远镜（JWST）已在红移z≳6处发现大质量星团，这些星团为大质量黑洞（MBH）种子的形成提供了极具潜力的环境。我们提出了一种新的适用于宇宙学模拟的MBH种子模型，其物理机制基于星团中的失控碰撞。我们根据局部星际介质（ISM）生成亚网格星团，并通过恒星演化与两体弛豫过程对其进行演化。通过失控碰撞形成的MBH种子质量由其宿主星团的属性决定，其中包含金属丰度依赖的恒星风效应。我们还对演化星团中的潮汐瓦解事件（TDEs）进行追踪，这类事件在MBH双星中会增强，并且考虑了MBH并合后的引力波（GW）反冲效应。我们将该模型应用于一个5σ过密区的约束模拟中，在星团质量满足10⁴≤m_SC≤10⁸M⊙的情况下，形成了质量范围为10³-10⁵.⁶M⊙的种子。由于种子的数量与质量均与局部环境直接相关，我们得到了适用于低质量星系（M_galaxy~10⁶⁻⁹M⊙）的更符合物理规律的M_BH-M_galaxy标度关系，而这一区域是此前种子模型难以准确描述的。单个暗物质晕内自然允许原位形成多个MBH，从而产生空间上成团的种群，与其他种子模型相比，这将MBH并合率提高了约100倍，显著提升了预期的激光干涉空间天线（LISA）事件率。TDEs可主导10³⁻⁴M⊙MBH的增长，并产生峰值光度L_peak~10⁴²⁻⁴³erg·s⁻¹的明亮耀斑，提高了低质量种子的可观测性。该种子方案加速了z≳8时早期MBH的增长，而后续自调节气体吸积过程会使不同种子模型下的中心MBH在z=6时均演化至约10⁸.⁶M⊙的相近质量。
英文摘要
JWST has revealed massive star clusters at $z\gtrsim 6$, which provide promising environments for massive black hole (MBH) seed formation. We introduce a new MBH seeding model for cosmological simulations, physically motivated by the runaway collisions in star clusters. Subgrid star clusters are generated according to the local ISM and evolved through stellar evolution and two-body relaxation. The masses of MBH seeds formed through runaway collisions are determined by the properties of their host clusters, including the effects of metallicity-dependent stellar winds. We further follow tidal disruption events (TDEs) with the evolving clusters, which can be enhanced in MBH binaries, and account for gravitational-wave (GW) recoil following MBH mergers. We implement this model in a constrained simulation of a 5$σ$ overdense region, where seeds of $10^{3}-10^{5.6}\,M_\odot$ form in clusters with $10^{4}\leq m_{\rm SC}\leq 10^{8}\,M_\odot$. Because both the seed abundance and mass are directly connected to the local environment, we have a more physical $M_{\rm BH}\!-\!M_{\rm galaxy}$ scaling for low-mass galaxies ($M_{\rm galaxy}\sim10^{6-9}\,M_\odot$), a regime poorly described by previous seeding models. Multiple MBHs are naturally allowed to form in-situ within individual halos, producing a spatially clustered population. This increases the MBH merger rate by $\sim100$ relative to other seeding models, significantly enhancing the expected LISA event rate. TDEs can dominate the growth of $10^{3-4}\,M_\odot$ MBHs and produce luminous flares of $L_{\rm peak}\sim 10^{42-43}\,{\rm erg\,s^{-1}}$, increasing the observability of low-mass seeds. This seeding prescription accelerates early MBH growth at $z\gtrsim 8$, while subsequent self-regulated gas accretion drives the central MBH toward similar masses $\sim10^{8.6}\, M_\odot$ by $z=6$ across different seeding models.
Comments32 pages, 24 figures. Comments are welcome!
