Connecting the lifecycles of galaxies and their central black holes

理解为什么星系--包括我们自己的星系，银河系--看起来是这样的，这是我们理解我们周围的宇宙使命的重要组成部分。在大多数(如果不是全部)星系(包括银河系)的中心，有一个超大质量黑洞，质量是太阳的数百万到数十亿倍。这些黑洞似乎是星系的关键组成部分，决定了它们的大部分结构和演化，尽管如何和为什么仍不清楚。在我的研究期间，我将确定这些黑洞是如何增长的，这种增长何时发生在星系的生命周期中，以及这些黑洞如何影响它们所在的星系。随着它们内部的气体形成恒星，它们进化得很慢，这些恒星的年龄超过数十亿年，星系的整体形状和结构逐渐改变。相比之下，黑洞中心的大质量黑洞似乎增长得相对较快，只有几百万年的短暂“增长爆发”。在这些生长爆发期间，物质落向黑洞，加热，并可以产生跨越整个电磁频谱的巨大辐射。拥有这样一个不断增长的黑洞的星系被描述为具有“活动星系核”或AGN。近年来，天文学家已经开始了解形成活动星系核的黑洞附近物质的结构，以及这些结构如何产生不同波长的辐射--包括X射线、光学和红外光以及射电发射。这些结构导致了在不同星系中观察到的各种现象，所有这些现象都与由不断增长的超大质量黑洞提供动力的活动星系核有关。然而，我们不知道对于单个活动星系核来说，这些结构在数百万年或更长时间内是如何变化的，在与星系演化相关的时间尺度上。在未来领导者联谊会的过程中，我将开发新的技术来连接星系及其中心黑洞的生命周期，探索数百万到数十亿年的时间尺度。我将确定物质是如何进入星系中心的，这种物质是如何形成活动星系核的，活动星系核在数百万年的过程中是如何变化和最终消失的，活动星系核在这段时间对银河系有什么影响，以及整个过程在星系的整个生命周期中重复的频率。研究如此长的时间尺度的过程是极其具有挑战性的。我们不能在这段时间内观测一个星系，因此，我将使用新的天文观测来提供数百万个星系及其活动星系核的“快照”，每个星系都处于不同的生命阶段。我将带领一个研究团队开发从这些静态快照中提取信息的新方法。在这些研究的基础上，我们将建立一个新的模型来解释单个AGN的生命周期，该模型可以解释我们各种快照中AGN种群的采样。我们还将研究有无活动星系核的星系的性质，从而确定某些类型的星系是否更有可能有活动星系核。在这样做的过程中，我们将确定星系内部负责将物质驱动到其中心区域并为活动星系核活动提供燃料的物理机制。我们的工作将结合来自一系列新的天文调查的数据。我们将使用主要的地面望远镜正在进行的新调查，测量带有生命周期重要信息的星系大样本的光谱图，结合eROSITA(今年发射的新空间望远镜)提供的天空X射线成像，红外数据和可用于跟踪这些星系内活动星系核结构变化的射电波长新调查。我们还将与处于数据密集型科学前沿的公司建立联系，为我们的工作提供信息，并确保我们开发的分析技术具有更广泛的影响。

Understanding why galaxies - including our own galaxy, the Milky Way - look the way they do is a vital part of our mission to understand the Universe around us. At the centre of most, if not all, galaxies (including the Milky Way) lies a supermassive black hole, with a mass that is millions to billions of times the mass of the Sun. These black holes appear to be crucial component of galaxies, determining much of their structure and evolution, although how and why is still unclear. During my fellowship, I will determine how these black holes grow, when this growth occurs within the lifecycle of a galaxy, and how these black holes affect the galaxies they lie in.Galaxies have long lives. They evolve slowly as the gas within them forms stars, these stars age over billions of years, and the overall shape and structure of a galaxy gradually changes. By comparison, the massive black holes at their centres appear to grow relatively rapidly, in short-lived "growth spurts" lasting at most a few million years. During these growth spurts, material falls towards the black hole, heats up and can produce huge amounts of radiation spanning the entire electromagnetic spectrum. A galaxy with such a growing black hole is described as having an "active galactic nucleus" or AGN. Over recent years, astronomers have started to understand the structure of the material close to a black hole that forms an AGN and how these structures produce radiation at different wavelengths - including X-rays, optical and infrared light and radio emission. These structures result in a wide range of observed phenomena in different galaxies, all of which can be associated with an AGN powered by a growing supermassive black hole. However, we do not know how these structures change over millions of years or longer for an individual AGN, over timescales relevant for galaxy evolution.Over the course of a Future Leaders Fellowship, I will develop new techniques to connect the lifecycles of galaxies and their central black holes, probing timescales of millions to billions of years. I will determine how material is brought into the centre of a galaxy, how this material forms an AGN, how the AGN changes and eventually fades over the course of many millions of years, what impact the AGN has on the galaxy during this time, and how often this whole process repeats throughout the lifetime of a galaxy.Studying processes on such long timescales is extremely challenging. We cannot watch a single galaxy over this time, so instead, I will use new astronomical surveys of the sky that provide "snapshots" of many millions of galaxies and their AGN, each at a different life stage. I will lead a team of researchers to develop new methods to extract information from these static snapshots. Based on these studies, we will build a new model to explain the lifecycles of individual AGN that can explain the sampling of the AGN population in our various snapshots. We will also study the properties of galaxies both with and without AGN, allowing us to determine whether certain types of galaxies are more likely to have an AGN. In doing so, we will determine the physical mechanisms within galaxies that are responsible for driving material into their central regions and fuelling the periods of AGN activity.Our work will combine data from an array of new astronomical surveys. We will use new surveys that are underway with the premier ground-based telescopes, measuring the spectrum of light from large samples of galaxies that is imprinted with vital information on their lifecycles, combined with X-ray imaging of the sky provided by eROSITA (a new space telescope launching this year), infrared data and new surveys at radio wavelengths that can be used to track the variation in AGN structure within these galaxies. We will also build links with companies at the forefront of data-intensive science to inform our work and ensure the analysis techniques we develop have a broader impact.