[论文解读] The Noctua Suite of Simulations -- The Difficulty of Growing Massive Black Holes in Low-Mass Dwarf Galaxies

Jonathan Petersson, Michaela Hirschmann+7 more|ArXiv.org|Apr 10, 2025

Relativity and Gravitational Theory被引用 3

一句话总结

论文提出高分辨率辐射流体动力学模拟（Noctua）以量化星系反馈如何在孤立的低质量矮星系中调控气体向大质量黑洞的吸积，探索初始MBH质量与人工气 inflows 的依赖性。

ABSTRACT

Aims. We study the individual and cumulative impact of stellar feedback processes on massive black hole (MBH) growth in a simulated low-mass dwarf galaxy. Methods. A suite of high-resolution radiation-hydrodynamic simulations called Noctua is performed, using the ArepoNoctua numerical framework for BHs in galaxy simulations. The chemical evolution of the gas is explicitly modelled in a time-dependent non-equilibrium way. Two types of stellar feedback are considered: individually-traced type II supernova (SNII) explosions, and radiatively transferred (on-the-fly) ionising stellar radiation (ISR) from OB stars. As part of the numerical framework, we develop and apply a novel physically-motivated model for MBH gas accretion, taking into account the angular momentum of the gas in the radiatively efficient regime, to estimate the gas accretion rate from the sub-grid accretion disc. Results. Without any stellar feedback, an initial $10^4~\mathrm{M}_\odot$ MBH is able to steadily grow over time, roughly doubling its mass after 800 Myr. Surprisingly, the growth of the MBH is more than doubled when only ISR feedback is considered, compared to the no stellar feedback run. This is due to the star formation rate (SFR) being highly suppressed (to a similar level or slightly above that when SNII feedback is considered), enabling a higher cumulative net gas inflow onto the MBH from not only the cold neutral- and molecular medium phases, but also the unstable- and warm neutral medium phases. With SNII feedback included, the gas accretion onto the MBH is episodic over time, and is suppressed by more than an order of magnitude already during the first 150 Myr. When combining SNII with ISR feedback, the growth of the MBH remains suppressed due to SNII feedback, but to a lesser extent compared to the SNII-only feedback run, due to a slightly lower SFR, and hence a reduced number of SNII events.

研究动机与目标

• 评估星际反馈对MBH在低质量矮星系中的成长的单独与累积影响。
• 评估不同初始MBH质量在现实IS M物理条件下对气体吸积的影响。
• 测试在孤立环境中人为诱导的中心气体流入是否能提升MBH吸积。

提出的方法

• 使用ArepoNoctua框架进行高分辨率辐射流体动力学模拟，具有显式的非平衡化学反应。
• 用NL97时变非平衡网络对气体化学进行建模，以捕捉H2、CO及加热/冷却过程。
• 实现两条恒星反馈通道：单独追踪的SNII爆炸和OB星的在场辐射传输（离子化辐射）。
• 实现一种新颖的亚网格MBH气体吸积模型，考虑角动量效应，包括从r_acc到r_circ再到MBH的两阶段吸积流。
• 将气体动力学分辨到亚秒差距尺度，以通过质量通量法而不是Bondi-Hoyle-Lyttleton速率来建模MBH吸积。
• 研究一组具有不同初始MBH质量且带/不带星际反馈的模拟，以分离调控效应。

实验结果

研究问题

• RQ1 SNII与ISR反馈在低质量矮星系中分别及共同如何调控MBH的气体吸积？
• RQ2 初始MBH质量如何在星际反馈存在时影响黑洞吸积气体的能力？
• RQ3 在孤立的矮星系中，人工诱导的中心气体流入是否能够克服反馈抑制并促进MBH生长？

主要发现

• 星际反馈，尤其是SNII，强烈抑制MBH的气体吸积，使前150 Myr的持续增长变得困难。
• 在没有星际反馈的情况下，10^4 M_sun的MBH在800 Myr内大致增长两倍，但ISR反馈可使相对于无反馈的增长翻倍，因为星形成减少且净气体流入增加。
• ISR反馈单独作用对星形成的抑制小于SNII，从而使MBH在来自多种ISM阶段的气体累积流入增加。
• SNII反馈导致间歇性的气体吸积事件，并在早期阶段将MBH增长抑制超过一个数量级；SNII+ISR的组合比仅SNII更抑制吸积但仍有抑制作用。
• 只有初始MBH质量约为10^5 M_sun时，在SNII反馈存在的情况下才能稳定在辐射有效区间吸积气体；10^3 M_sun在800 Myr后几乎不吸积。
• 人工诱导的气体流入即使对高初始MBH质量也未能提升长期MBH吸积，提示在此孤立设置中，局部引力势能主导通过气体吸积的MBH生长。