Building Up and Tearing Down Galaxies: the Impact of Infalling and Outflowing Gas on Galaxy Evolution

星系通过内部能量过程驱动的流出和星系间物质和从卫星系统剥离的气体的流入，与周围的星际环境交换质量。这种交换与时间的平衡被认为可以解释一些关键的星系属性。计划中的团队将通过结合空间和地面气相光谱、星系的地面光学成像和光谱以及宇宙学背景下的星系数值模拟来研究星系与其周围星系气体之间的关系，从而测试星系组装的现代模型。具体地说，他们将：(1)利用类星体吸收线的高分辨率光谱观测来测量环星系气体中的金属丰度分布；(2)确定冷气体的覆盖因子，作为与吸收星系的距离的函数；(3)将环星系气体的物理和统计特性与中心星系的物理和统计特性进行比较；以及(4)开发新的模拟和诊断方法，以比较模型预测和观测结果。研究生和本科生将参与该项目，部分观测工作将纳入本科课程。该团队将为一个天文馆展览的发展做出贡献，并将通过一个网站传播观测数据和模拟结果。

Galaxies exchange mass with the surrounding intergalactic environment through outflows driven by energetic processes inside them and infall of intergalactic matter and of gas stripped from satellite systems. The balance of this exchange with time is thought to explain a number of key galaxy properties. The proposing team will test modern models of galaxy assembly by studying the relationship between galaxies and their circumgalactic gas using a combination of space- and ground-based gas-phase spectroscopy, ground-based optical imaging and spectroscopy of galaxies, and numerical simulations of galaxies in a cosmological context. Specifically, they will: (1) measure the metallicity distribution in circumgalactic gas using high-resolution spectral observations of quasar absorption lines; (2) determine the covering factor of cold gas as a function of distance from the absorbing galaxies; (3) compare the physical and statistical properties of the circumgalactic gas with those of the central galaxies; and (4) develop new simulations and diagnostics to compare model predictions with observations. Graduate and undergraduate students will participate in the project, and parts of the observational work will be incorporated in an undergraduate course. The team will contribute to the development of a planetarium show, and will disseminate observational data and simulation results through a website.