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.
