0 Assigned ID: 939 ----- Attempting Submission 1 (Fri Apr 11 22:15:16 GMT 2014) ----- HST Phase I Proposal 939 (APT_Proposal.apt) successfully submitted. ----- Attempting Submission 2 (Fri Apr 11 23:58:46 GMT 2014) ----- Grasping the way gas gets in and out of galaxies is fundamental to our understanding of galaxy formation and evolution, and COS observations are slowly providing a better picture of these gas flows. Recent COS observations of the circumgalactic medium (CGM) have revealed two puzzles: the bimodal metallicity distribution of Lyman Limit Systems (LLSs) proximate to galaxies (Lehner et al. 2013) and the low volume density for cold absorbers in the CGM (Werk et al. 2014). We propose to address both of these issues through the execution and analysis of grid-based cosmological hydrodynamics simulations of unprecedented resolution. By modeling galaxies at very high resolution using a physically-motivated, momentum-based feedback method, we will perform the first grid-based studies of the CGM at this scale, allowing us to identify analogs to the observed cold absorber population responsible for these puzzles. We will trace the simulated cold absorbers through time to understand their origins, producing a full picture of how they acquire and expel their gas. QUASAR ABSORPTION LINES AND IGM Default Medium false true false false true SUPPORTED