Weighing Supermassive Black Holes

了解星系的形成和演化是当代天体物理学的核心。黑洞质量和各种星系特性之间的关系意味着中心超大质量黑洞（SMBHs）的增长与星系的增长之间存在紧密联系，这些关系现在是大量观测和模拟的基础。然而，可靠的SMBH质量测量数量很少，独立测量方法的数量更少。布洛布教授领导的一个研究小组最近表明，星系的致密分子气体是它们的圆周速度的最佳示踪剂，因此也是它们质量的最佳示踪剂。最重要的是，在《自然》杂志上发表了首次SMBH质量测量结果之后，该团队现在已经证明，这些测量结果比其他方法更准确，也更容易进行。因此，是时候加大这些努力，更新我们对中小黑洞的认识。作为WISDOM团队（暗天体质量毫米波干涉测量）的一部分，该学生将使用当前的毫米/亚毫米望远镜，在跨越一系列形态类型、质量和核活动的本地星系的大样本中进行SMBH质量测量计划。这将主要使用ALMA，这是目前最大的地面望远镜项目，WISDOM已经在该项目上获得了大量的观测时间。目前已经掌握了大量的数据，未来还会有更多的数据，而且建立速度场模型和估计不确定性所需的工具也已经开发出来。因此，学生将利用一台运转良好的机器进行多次测量，从而探索SMBH质量和星系特性之间的关系，此外还将探测允许SMBH被注入的核尺度气体动力学。因此，该项目将显著增加可靠的SMBH质量的数量，并将彻底改变我们对SMBH和星系共同演化的理解。

Understanding the formation and evolution of galaxies is central to much of contemporary astrophysics. The relations between black hole mass and various galaxy properties imply a tight connection between the growth of central supermassive black holes (SMBHs) and that of galaxies, and these relations now underlie a staggering number of observations and simulations. However, the number of reliable SMBH mass measurements is small, and the number of independent measuring methods even smaller. A team led by Prof Bureau has recently shown that the dense molecular gas of galaxies is the best tracer of their circular velocities, and thus of their masses. Most importantly, following the first SMBH mass measurement published in Nature, the team has now shown that these measurements are both much more accurate and much easier to carry out than with other methods. It is thus time to scale up those efforts and renew our knowledge of SMBHs.As part of the WISDOM team (mm-Wave Interferometric Survey of Dark Object Masses), the student will use current mm/sub-mm telescopes to pursue a programme of SMBH mass measurements in a large sample of local galaxies spanning a range of morphological types, masses, and nuclear activities. This will primarily use ALMA, the largest ground-based telescope project in existence, on which WISDOM has received large allocations of observing time. There are thus much data in hand already, with more to come, and the tools necessary to model the velocity fields and estimate uncertainties have already been developed. The student will thus exploit a well-oiled machinery to make multiple measurements, and thus explore how SMBH masses and galaxy properties correlate, in addition to probing the nuclear-scale gas dynamics that allows SMBHs to be fed. The project will thus significantly increase the number of reliable SMBH masses available, and it will revolutionise our understanding of the co-evolution of SMBHs and galaxies.