BAQARO：在宇宙学背景下追踪随机黑洞增长历史与类星体光变曲线
BAQARO: Tracing Stochastic Black Hole Growth Histories and Quasar Lightcurves in a Cosmological Context
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中文总结 AI 辅助
BAQARO是一个半经验黑洞增长框架，利用FLAMINGO-10k模拟的亚晕合并树，通过六个参数再现观测约束，揭示黑洞通过随机超爱丁顿吸积快速增长，并合通道在低红移时变得重要。
中文摘要 AI 辅助
超大质量黑洞（BH）如何积累其质量，并驱动我们在宇宙时间中观测到的明亮类星体，仍然是星系演化中的核心开放问题。我们提出了BAQARO，一个半经验的黑洞增长框架。该模型基于从FLAMINGO-10k模拟中提取的亚晕合并树，通过同时捕捉平均趋势和随机变率的处方，将黑洞增长历史与其宿主亚晕的增长历史联系起来。BAQARO受到热光度类星体光度函数、紫外明亮类星体的成团性以及条件爱丁顿比率分布函数的约束。该模型具有六个自由参数，分别控制黑洞种子形成、气体吸积与晕增长之间的耦合，以及吸积的随机性和时间相干性，模型在$0 \lesssim z \lesssim 7$范围内再现了现有的观测约束。利用仿真器，我们进行了贝叶斯推断，并量化了每个观测量的约束能力。我们的主要发现是：（i）黑洞吸积很好地由晕中冷气体储库的聚集来描述，而不需要显式依赖于宇宙时间。（ii）黑洞在高红移时通过超爱丁顿吸积的随机爆发事件迅速积累其质量。（iii）这些爆发事件辐射效率低下，并持续约$\sim1\\,\mathrm{Myr}$的时间尺度，在类星体光变曲线、邻近区域和成团性测量中留下可观测的特征。（iv）并合增长通道始终是次要的，但在$z \lesssim 1$时变得越来越重要，特别是对于大质量黑洞。BAQARO的增长历史和类星体光变曲线为解释快速扩展的类星体观测图景提供了一个灵活的框架，从JWST探测到的高红移吸积到脉冲星计时阵列约束的低红移并合。
英文摘要
How supermassive black holes (BHs) assemble their mass and power the luminous quasars we observe across cosmic time remain central open questions in galaxy evolution. We present BAQARO, a semi-empirical framework for BH growth. Built on subhalo merger trees extracted from the FLAMINGO-10k simulation, the model links BH growth histories to those of their host subhalos through prescriptions that capture both average trends and stochastic variability. BAQARO is constrained by the bolometric quasar luminosity function, the clustering of UV-luminous quasars, and the conditional Eddington ratio distribution function. With six free parameters controlling BH seeding, the coupling between gas accretion and halo growth, and the stochasticity and temporal coherence of accretion, the model reproduces the available observational constraints over $0 \lesssim z \lesssim 7$. Using emulators, we perform Bayesian inference and quantify the constraining power of each observable. Our main findings are: (i) BH accretion is well described by the assembly of cold gas reservoirs in halos, without requiring an explicit dependence on cosmic time. (ii) BHs rapidly assemble their mass at high redshift through stochastic episodes of super-Eddington accretion. (iii) These episodes are radiatively inefficient and persist for timescales of $\sim1\,\mathrm{Myr}$, imprinting observable signatures on quasar lightcurves, proximity zones, and clustering measurements. (iv) The merger growth channel is always subdominant, but becomes increasingly important at $z \lesssim 1$, particularly for massive BHs. BAQARO growth histories and quasar lightcurves provide a flexible framework for interpreting the rapidly expanding landscape of quasar observations, from high-$z$ accretion probed by JWST to low-$z$ mergers constrained by pulsar timing arrays.
发表机构
- Center for Astrophysics | Harvard & Smithsonian（天体物理中心 | 哈佛与史密森尼学会）
- Leiden Observatory, Leiden University（莱顿天文台，莱顿大学）
- Department of Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）
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