Towards a Predictive Theory of Galaxy Formation: Cosmological Gas Accretion and Galactic Outflows

星系形成的宇宙学模拟为理解宇宙结构的演化提供了最完整的方法。这种模拟的最终目标是从基本原理追溯星系的形成；但巨大的动态范围，以及星系中涉及重子物质的许多鲜为人知的物理效应，使这成为一个极其困难的计算挑战。在这个项目中，将使用最先进的宇宙学模拟来构建一个可见宇宙的模型。模拟将包括暗物质和重子，并将采用在新代码AREPO中实现的新颖移动网格技术。使用收敛测试，将有可能确定哪些结果对恒星形成、黑洞生长和反馈的处理变化是可靠的，这些将以比早期研究更具有物理动机的方式处理。科学工作将集中在理解：1)在宇宙学背景下星系盘的形成以及反馈对星系形态和运动学的影响；2)星系晕内气体流入的性质和圆盘对气体的吸积；3)吸积气体与星系流出的化学富集物质之间的相互作用及其对环星系介质的影响；4)星系及其中心超大质量黑洞的共同演化。模拟结果，包括完整模拟的快照、星系目录、图像和视频，将通过一个基于网络的界面提供给研究界。该项目将支持一名博士后和一名研究生的工作；此外，还将为马萨诸塞州剑桥市的高中生开设一系列讲座，内容涉及宇宙及其组成部分的演化。

Cosmological simulations of galaxy formation provide the most complete approach for understanding the evolution of structure in the universe. The ultimate goal of such simulations is to trace the formation of galaxies from first principles; but the enormous dynamic range, and the many poorly understood physical effects involving baryonic matter in galaxies, make this an extremely difficult computational challenge. In this project, a model for the visible universe will be constructed using state-of-the-art cosmological simulations. The simulations will include both dark matter and baryons, and will employ a novel moving mesh technique implemented in the new code AREPO. Using convergence tests, it will be possible to determine which results are robust to variations in the treatment of star formation, black hole growth, and feedback, which will be handled in ways that are more physically motivated than in earlier studies. The scientific effort will focus on understanding: 1) the formation of galactic disks in a cosmological context and the impact of feedback on galaxy morphology and kinematics; 2) the nature of gas inflows into galaxy halos and the accretion of gas by disks; 3) the interaction between accreted gas and galactic outflows of chemically enriched material and consequences for the circumgalactic medium; and 4) the co-evolution of galaxies and their central supermassive black holes. The simulation results, including snapshots of the full simulations, galaxy catalogs, images, and videos, will be made available to the research community through a web-based interface. The project will support the work of a postdoctoral scholar and a graduate student; in addition, a series of lectures will be developed to be given to high school students in Cambridge, MA on topics covering the evolution of the Universe and its constituents.