报告题目：Supermassive black hole mass measurements using molecular gas dynamics from the local universe to unprecedented redshifts

报告人：张恒悦 博士生（牛津大学）

报告摘要：Recent JWST observations implied that high-redshift supermassive black holes (SMBHs) are overmassive relative to the local SMBH mass-stellar mass relation, reshaping our understanding of the co-evolution of black holes and their host galaxies across cosmic time. However, these SMBH mass estimates are highly uncertain and rely on indirect methods calibrated using dynamical SMBH mass measurements in the local universe. Verifying the overmassive nature of high-z SMBHs and testing models of SMBH-galaxy co-evolution thus requires (1) improving the precision and accuracy of local SMBH mass measurements and (2) obtaining the first direct dynamical SMBH mass measurements at high redshifts. Here, I present works to achieve both goals. First, I present accurate SMBH mass measurements of two local early-type galaxies, NGC 383 and NGC 1574, using ALMA observations of CO gas kinematics that highly spatially resolve the SMBH's sphere of influence (SoI). The observations of NGC 383 have a higher resolution (in units of the Schwarzschild radius or the SoI radius) than all other SMBH mass measurements using molecular gas to date, which enables a 5%-precision SMBH mass constraint. Our work suggests that molecular-gas-dynamical SMBH mass measurements using observations that only marginally resolve the SoI tend to overestimate the SMBH mass. Additionally, I present ongoing efforts to dynamically measure the masses of SMBHs at z>2 for the first time, presenting initial results in the lensed submillimeter galaxy ID141, using a novel dynamical modelling package that forward models the gas kinematics and the lens configuration simultaneously in an automatically differentiable framework.

报告时间：2025年10月10日（周五） 10:30-11:30

报告地点：仙林园区3号楼402室

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