The concurrent growth of supermassive black holes (SMBHs) and their host galaxies remains to be fully explored, especially at high redshift. While often understood as a consequence of self-regulation via AGN feedback, it can also be explained by alternative SMBH accretion models. Here, we expand on previous work by studying the growth of SMBHs with the help of a large suite of cosmological zoom-in simulations (MassiveFIRE) that are part of the Feedback in Realistic Environments (FIRE) project. The growth of SMBHs is modelled in post-processing with different black hole accretion models, placements, and merger treatments, and validated by comparing to on-the-fly calculations. Scaling relations predicted by the gravitational torque driven accretion (GTDA) model agree with observations at low redshift without the need for AGN feedback, in contrast to models in which the accretion rate depends strongly on SMBH mass. At high redshift, we find deviations from the local scaling relations in line with previous theoretical results. In particular, SMBHs are under-massive, presumably due to stellar feedback, but start to grow efficiently once their host galaxies reach $M_* \sim 10^{10} M_{\odot}$. We analyse and explain these findings in the context of a simple analytic model. Finally, we show that the predicted scaling relations depend sensitively on the SMBH location and the efficiency of SMBH merging, particularly in low-mass systems. These findings highlight the relevance of understanding the evolution of SMBH-galaxy scaling relations to predict the rate of gravitational wave signals from SMBH mergers across cosmic history.
Portrait of a Galaxy on FIRE: Is the $α$-bimodality a natural consequence of inside-out disc growth in a hierarchical formation scenario?
Tartu Observatory, University of Tartu（塔尔图大学塔尔图天文台）；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉古纳大学）；Tallinn University of Technology（塔林理工大学）
Interacting galaxies on FIRE-2: The connection between enhanced star formation and interstellar gas content
我们提出了一套全面的高分辨率（秒差距尺度），理想化的（非宇宙学）星系合并模拟（24轮，恒星质量比~2.5：1），以研究相互作用引起的恒星形成和星际介质（ISM）在各种温度密度制度的演变之间的联系。我们使用GIZMO代码和第二版的“真实环境中的反馈”模型（FIRE-2），该模型捕获了ISM的多阶段结构。我们的模拟旨在代表本地宇宙中的星系合并。在这项工作中，我们专注于“星系对周期”之间的第一次和第二次近心轴通道。我们分裂的ISM分为四个制度：热，温暖，冷，冷密集，热，电离，原子和分子的气体在真实星系中观察到的阶段的动机。我们发现，平均而言，相互作用提高了这对恒星的形成率（约30%，合并套件样本平均值），并提高了它们的冷致密气体含量（约18%）。这伴随着热气体的减少（~11%），冷气体的变化可以忽略不计（~4%的增加），以及热气体的大幅增加（~400%）。密度超过1000 cm ^3的冷密气体（冷超密区）的数量显著增加（约240%），但仅占冷密气体预算的0.15%（平均）。
Enhanced Multiphase Circumgalactic Medium and Gas Cycling in Galaxy Mergers
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Center for Astronomy and Astrophysics and Department of Physics, Fudan University（复旦大学天文与天体物理中心及物理系）；Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University（复旦大学核物理与离子束应用教育部重点实验室）；Department of Astrophysics, University of Zurich（苏黎世大学天体物理系）；Department of Physics and Astronomy, Pomona College（波莫纳学院物理与天文学系）；Department of Astronomy, Xiamen University（厦门大学天文学系）；Department of Physics and Astronomy, California State Polytechnic University, Pomona（加州州立理工大学波莫纳分校物理与天文学系）
