PROFESSOR NEAL KATZ

QSO absorption line studies of the CGM using HST COS are the best direct way to study the accretion and galactic wind processes that are thought to dominate galaxy formation. Detailed numerical simulations are critical to interpret and understand these observations. Unfortunately, simulations are sensitive to wind implementations. Interactions at wind/halo gas interfaces in the CGM occur on scales that are much below the resolution of any current or near future galaxy formation simulation, making a "brute force" approach not viable. To mitigate this impasse, we propose to implement a new wind algorithm that explicitly models the "subgrid physics" in the wind-halo gas interaction analytically within a simulation, using the simulation to provide the physical characteristics that will inform the interaction. Unavoidably, this introduces a few free parameters but we can restrict them by matching observed galaxy. Previous simulations using a more standard wind model approaches reproduced many observed properties of galaxies and metal-line absorption, but our new wind implementation will allow us to tie empirical successes, and failures, more securely to the underlying wind physics, both the ejection (mass-loading factors and ejection speeds) and the interaction between the wind and gaseous halo, and allow us to identify absorption line features with specific physical processes.