超大质量星系中的随机黑洞增长与恒星质量相关
Stochastic black hole growth tracks stellar mass in ultramassive galaxies
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中文总结 AI 辅助
本研究利用JWST观测八个超大质量星系，发现其黑洞质量与恒星质量紧密相关而非速度弥散，并存在随机性，表明极端动力学过程影响黑洞增长。
中文摘要 AI 辅助
在过去的三十年中，人们已经确定星系球状体包含超大质量黑洞（BHs），其质量与宿主星系的特性密切相关。这些相关性中最具预测性的是黑洞质量与恒星速度弥散之间的关系（$M_{\rm BH}-\sigma$关系），以及黑洞质量与核球光度或恒星质量之间的关系（$M_{\rm BH}-M_\star$关系）。星系演化的理论模型预测，对于最大质量的星系，其晚期增长主要通过贫气体的“干”并合进行，$M_\star$应成为比$\sigma$更好的黑洞质量预测因子。然而，由于这类星系极为罕见且中心表面亮度低，对$M_{\rm BH}-\sigma$关系的真正偏离一直难以观测。在此，我们报告了詹姆斯·韦布空间望远镜（JWST）对八个超大质量星系中心黑洞的测量结果。我们发现了有史以来报道的与$M_{\rm BH}-\sigma$关系的最大偏离，大多数黑洞质量超过$10^{10}$太阳质量。在这个极端质量区间，星系紧密遵循$M_{\rm BH}-M_\star$关系，散射极小，成功证实了理论预测。此外，我们观察到显著的随机性：对于一个超大质量星系，中心速度弥散下降而非达到峰值，没有显示出中心质量的证据；虽然我们形式上只能给出上限，但数据完全与没有黑洞的情况一致。至关重要的是，这种物理上的二分性在原始运动学图中直接可见，无需任何拟合，并且我们的动力学建模也稳健地确认了这一点。这种出乎意料的多样性表明，极端多体动力学过程，如引力反冲或三体抛射，显著扰乱了宇宙中最大质量星系的黑洞增长。
英文摘要
Over the past three decades, it has been established that galaxy spheroids contain supermassive black holes (BHs) whose masses correlate tightly with the properties of their host galaxies. The most predictive of these correlations is between BH mass and stellar velocity dispersion (the $M_{\rm BH}-σ$ relation), alongside a relation with bulge luminosity or stellar mass (the $M_{\rm BH}-M_\star$ relation). Theoretical models of galaxy evolution predict that for the most massive galaxies, whose late-time growth proceeds mainly via gas-poor `dry' mergers, $M_\star$ should become a better predictor of BH mass than $σ$. However, genuine deviations from the $M_{\rm BH}-σ$ relation have remained difficult to observe due to the extreme rarity and low central surface brightness of such galaxies. Here we report James Webb Space Telescope (JWST) measurements of central BHs in a sample of eight ultramassive galaxies. We find the largest deviations from the $M_{\rm BH}-σ$ relation ever reported, with most BH masses exceeding $10^{10}$ solar masses. In this extreme mass regime, the galaxies tightly follow the $M_{\rm BH}-M_\star$ relation with minimal scatter, successfully confirming theoretical predictions. Furthermore, we observe significant stochasticity: For one ultramassive galaxy, the central dispersion drops rather than peaks, revealing no evidence for a central mass; while we can formally only place an upper limit, the data are entirely consistent with no BH at all. Crucially, this physical dichotomy is already evident directly in the raw kinematic maps prior to any fitting, and is robustly confirmed by our dynamical modelling. This unexpected diversity suggests that extreme multi-body dynamical processes, such as gravitational recoil or three-body ejections, significantly disrupt BH growth in the Universe's most massive galaxies.
发表机构
- University of Oxford（牛津大学）
- University of Michigan（密歇根大学）
- Space Telescope Science Institute（太空望远镜科学研究所）
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