Revealing the drivers of galaxy formation in the densest cosmic environments

我们的宇宙中最令人困惑的一个方面是各种各样的星系形状和颜色，从蓝色（形成恒星的）螺旋盘到红色（不再形成恒星的）椭圆形。这些差异被认为是由于气体流入和流出的变化（“重子循环”），当星系落向诸如星系团等密集居住的宇宙环境时，这一过程可以被特别清晰地研究。但是我们并不清楚这些变化是如何以及为什么发生的，特别是在早期的宇宙和低质量的“矮”星系中，以及哪些其他过程可能是重要的，特别是恒星被潮汐剥离成漫射的“星团内光”。我将通过创建最先进的星系团定义计算机模拟来解决这个问题，以解释地面和太空望远镜的主要新观测结果，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WEAVE光谱仪。利用我和其他人的大量开发工作，这些模拟将首次真实地模拟星团星系中形成恒星的气体。从小的“群体”到最大的观测到的星系团，它们也将包括在当地宇宙中被充分研究过的四个星系团的相似物。从这些模拟中，我将创建合成观测，模拟它们在从x射线到光学到无线电的不同波长下的样子。将这些与实际观测结果进行比较，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。与此同时，我将详细分析模拟输出，通过时间跟踪单个星系，以确定哪些物理过程是从基础物理的强制定律中产生的。结合起来，这两种方法将解决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星系形成过程中气体进出的作用。

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.