Resolving shock heating, turbulence and baryon cycle in high redshift massive galaxies

在20世纪70年代和80年代发展起来的星系形成的标准图像中，在结构形成过程中，气体在巨大的暗物质晕中变得生机勃勃。在这里，它达到很高的温度，并有一个很长的冷却时间。这一理论受到了宇宙学星系形成模拟的质疑，该模拟发现，潜在的大量气体不会冲击热量并激活，而是将宇宙网中的冷气体直接输送到星系中。这极大地改变了星系的形成方式，导致更高的中心质量沉积速率，因此需要来自超新星和超大质量黑洞的强烈反馈，以防止过高的恒星形成速率。这些模拟通常缺乏所需的分辨率来可靠地解决结构吸积冲击，导致所谓的“冲击内冷却”。在我的博士学位期间，我的目标是在移动网格代码AREPO中开发新的计算方法，以前所未有的分辨率准确地实时解决吸积冲击。这将使我能够在没有“激波冷却”的情况下运行高红移大质量星系组合的完整宇宙学模拟，并可靠地确定气体从宇宙细丝流到位于这些细丝交叉处的星系时是如何冷却和加热的。此外，吸积激波的高分辨率将使我能够可靠地捕捉弯曲激波后涡度的产生，以估计湍流运动中储存了多少气体能量预算。这项工作的预测将直接关系到JWST和SKA未来的观测。我的方法可以进一步推广，以提高星系环星系介质内的空间分辨率，从而不仅可以准确地捕捉宇宙流入，也可以准确地捕捉星系流出的多相结构和团块。这可以与未来ALMA和MUSE的观测结果进行比较。

Within the standard picture of galaxy formation developed in the 1970s and 80s, during the structure formation process gas becomes virialised within massive dark matter haloes. Here it attains a high temperature and has a very long cooling time. This has since been questioned by cosmological galaxy formation simulations which find that potentially copious amounts of gas do not shock heat and virialise, but instead deliver cold gas from the cosmic web directly onto galaxies. This significantly changes the way galaxies are built up, leading to much higher central mass deposition rates and hence requiring strong feedback from supernovae and supermassive black holes to prevent excessive star formation rates. These simulations typically lack the required resolution to resolve structure accretion shocks reliably, leading to so-called `in-shock cooling'. During my PhD, I aim to develop novel computational methods within the moving mesh code AREPO to accurately resolve accretion shocks on-the-fly with unprecedented resolution. This will allow me to run full cosmological simulations of high redshift massive galaxy assembly free from 'in-shock cooling' and to reliably ascertain how gas is cooled and heated as it streams from cosmic filaments onto the galaxies located at the intersection of these filaments. Furthermore, very high resolution at accretion shocks will allow me to capture robustly the generation of vorticity in the wake of curved shocks to estimate how much of the gas energy budget is stored in turbulent motions. The predictions of this work will be directly relevant for future observations by JWST and SKA. My method can be further generalized to increase the spatial resolution within the circumgalactic medium of galaxies, hence allowing not only cosmic inflow but also galaxy outflow multi-phase structure and clumpiness to be captured accurately. This can then be compared against future ALMA and MUSE observations.