Hawking - How supermassive black holes shape our Universe: at the interface of galaxy formation, cosmology and multi-messenger astronomy

我们的家乡银河系在其中心有一个超大质量黑洞(SMBH)，被称为人马座A*，质量是太阳的400多万倍。SMBH位于大多数(如果不是全部)星系的中心，从低质量的矮小星系到巨大星系团中的巨型椭圆形星系。尽管与承载它们的星系相比，它们的体积很小，但SMBH和星系的性质通过共同进化紧密联系在一起。SMBH代表了宇宙中一些最极端的物体，起到了令人难以置信的高效引擎的作用，可以将物质的很大一部分剩余质量能量(还记得爱因斯坦著名的公式E=MC^2)转化为能量，即以辐射、风和喷流的形式存在的反馈。这些过程赋予了SMBH话语权，使其能够在从黑洞视界到远远超出宿主星系的广泛范围内进行通信。在接下来的十年和以后，许多任务(如SKA、雅典娜、欧几里得、JWST和LISA)不仅将提供对宇宙的光观测，而且还将与LISA一起在引力波中提供宇宙观测，从而彻底改变SMBH的多信使天文学。从SMBH双星到单个星系，再到代表宇宙中最大质量物体并包含数千个星系的巨大星系团，人们将在局部宇宙中观察到这些系统，直到它的年龄不到当前年龄的四分之一。我们将收到比以往任何时候都多的数据，以深入了解SMBH及其星系在宇宙时间内的共同演化。为了帮助解释过多的新观测数据，拥有可靠和现实的理论模型进行比较至关重要。塑造SMBH的性质及其宇宙环境的大量复杂物理过程以及涉及的巨大规模构成了一个巨大的挑战。使用强大的超级计算机，我将执行最先进的模拟，将新的新模型和技术结合在一起，提供一种独特的方法来捕获多个尺度和不同环境中的各种物理过程。这包括对双星中的SMBH对及其周围的气体盘进行小规模模拟，对单个星系、星系群和星系团进行高分辨率模拟，以及捕捉到宇宙中具有代表性的体积的大型宇宙盒。这些模拟将结合起来为一系列与SMBH相关的问题提供答案，例如：-SMBH释放的能量如何塑造星系、群和星系团的性质？-星系团的状态，如它的湍流程度或其磁场的性质，如何影响来自SMBH的反馈？-我们如何使用星系团来探索宇宙的基本属性(宇宙学)？-SMBH的反馈在什么尺度上可以产生重大影响？-SMBH如何聚集和合并？-SMBH合并的多信使特征是什么？这些模拟及其成果将为解释未来20年发射的许多观测任务提供重要资源，正是通过协同工作，理论和观测的结合将增强我们对天体物理学和宇宙学的理解。

Our home galaxy, the Milky Way, plays host to a super-massive black hole (SMBH) at its centre, dubbed Sagittarius A*, with a mass more than 4 million times that of the sun. SMBHs reside in the centres of most (if not all) galaxies, from low-mass dwarf galaxies to giant ellipticals in vast galaxy clusters. Despite their small sizes compared to the galaxies that host them, SMBH and galaxy properties are intimately linked through co-evolution. SMBHs represent some of the most extreme objects in the Universe and act as incredibly efficient engines that can convert a large fraction of the rest mass energy (remember Einstein's famous equation E=mc^2) of material that falls under their gravitational spell into energy, known as feedback, in the form of radiation, winds and jets. These processes give the SMBH its voice, allowing it to communicate across a vast range of scales, from the black hole event horizon to far beyond the host galaxy. Over the coming decade and beyond, many missions (e.g. SKA, Athena, Euclid, JWST and LISA) will provide observations of the Universe not only in light but with LISA also in gravitational waves, and hence revolutionise multi-messenger astronomy of SMBHs. Systems ranging from SMBH binaries to individual galaxies, up to vast clusters that represent the most massive objects in the Universe and contain thousands of galaxies, will be observed in the local Universe and out to when it was less than a quarter of its current age. We will receive more data than ever before providing insights into the co-evolution of SMBHs and their galaxies over cosmic time. To help to interpret the plethora of new observational data, it is vital to have robust and realistic theoretical models to compare to. The vast array of complex physical processes that shape the properties of SMBHs and their cosmic environment and the huge range of scales involved presents a formidable challenge. Using powerful supercomputers, I will perform state-of-the-art simulations that combine novel new models and techniques to provide a unique method for capturing a wide range of physical processes on multiple scales and in different environments. This includes small-scale simulations of pairs of SMBHs in binaries and the gas discs that surround them, high-resolution simulations of individual galaxies, groups and clusters, and large cosmological boxes that capture a representative volume of the Universe. These simulations will combine to provide answers to a range of questions related to SMBHs, such as:- How does energy released by SMBHs shape galaxy, group and cluster properties?- How does the state of a cluster, such as how turbulent it is or the properties of its magnetic fields, impact feedback from the SMBHs?- How can we use galaxy clusters to probe the underlying properties of the Universe (Cosmology)? - On what scales can feedback from SMBHs have a significant influence?- How do SMBHs come together and merge?- What are the multi-messenger signatures of SMBH mergers?Overall, the simulations and their outputs will provide a vital resource for interpreting the many observational missions launching over the next two decades, and it is by working in tandem that the combination of theory and observation will enhance our understanding of both astrophysics and cosmology.