Revealing the drivers of galaxy formation in the densest cosmic environments

我们的宇宙最令人困惑的方面之一是星系形状和颜色的巨大变化，从蓝色(恒星形成的)螺旋盘到红色(不再是恒星形成的)椭圆形。这些差异被认为是由于气体进出的变化(重子循环)，当星系落入人口稠密的宇宙环境(如星系团)时，可以特别清楚地研究这一过程。但我们不清楚这些变化是如何发生的，为什么会发生，特别是在早期宇宙和低质量的“矮小”星系，还有哪些其他过程可能是重要的，特别是潮汐剥离恒星进入漫射的“星系团内光”。我将通过创建最先进的计算机模拟星系团来解释主要的新观测结果，包括最近发射的詹姆斯·韦伯太空望远镜和威廉·赫歇尔望远镜上的新编织光谱仪，来解释主要的新观测结果。利用我和其他人的广泛开发工作，这些模拟将首次真实地模拟星系团中恒星形成的气体。从小的“群”到最大的观测星系团，它们还将包括与本地宇宙中四个经过充分研究的星系团的相似之处。从这些模拟中，我将创建合成观测，模拟它们在不同波长下的样子，从X射线到光学再到射电。将这些与实际观测相比较，我将对模拟模型和我们对其中编码的星系形成的理解进行严格的测试。同时，我将详细分析模拟结果，追踪各个星系的时间，以确定哪些物理过程是从基本物理强加的定律中产生的。这两种方法结合在一起，将解开星系如何在最极端的宇宙环境中形成和演化的谜团，以及它们可以告诉我们关于气体在星系形成中的作用以及气体在星系形成中的流出所起的作用。

One of the most perplexing aspects of our Universe is the huge variety of galaxy shapes and colours, from blue (star-forming) spiral discs to red (no longer star-forming) ellipticals. These differences are thought to be due to changing in- and outflows of gas (the "baryon cycle"), a process that can be investigated particularly cleanly when galaxies fall towards densely inhabited cosmic environments such as galaxy clusters. But we do not understand well how and why these changes occur, especially in the early Universe and for low-mass "dwarf" galaxies, and which other processes might be important, especially tidal stripping of stars into the diffuse "intra-cluster light".I will solve this problem by creating state-of-the-art defining computer simulations of galaxy clusters to interpret major new observations with ground- and space-based telescopes, including by the recently launched James Webb Space Telescope and with the new WEAVE spectrograph on the William Herschel Telescope. Exploiting extensive development work by myself and others, these simulations will realistically model the star forming gas in cluster galaxies for the first time. Spanning the full range from small "groups" to the most massive observed clusters, they will also include close analogues of four well-studied clusters in the local Universe.From these simulations, I will create synthetic observations, mimicking what they would look like in different wavelengths from X-rays through optical to radio. Comparing these with real observations, I will perform stringent tests of the simulation model and our understanding of galaxy formation encoded within it. In parallel, I will analyse the simulation outputs in detail, tracking individual galaxies through time to identify which physical processes emerge from the imposed laws of fundamental physics. In combination, these two approaches will solve the mystery of how galaxies form and evolve in the most extreme cosmic environments, and what they can tell us about the role of gas in- and outflows for galaxy formation in general.