0 Assigned ID: 1222 ----- Attempting Submission 1 (Sat Apr 08 02:27:21 GMT 2017) ----- Ultra faint dwarf (UFD) galaxies (Mv > -7; Mstar < 10^5 Msun) are the least massive satellites of the Milky Way (MW) and M31. They are believed to be the relics of the first galaxies, making them ideal targets to hunt for chemical signatures of the first generation of stars. Star formation histories (SFHs) derived from deep HST/ACS imaging of several MW UFDs illustrate quenching of the era of reionization. However, new HST studies of the faintest dwarfs about M31 recently revealed more diverse SFHs, indicating that a wide range of evolutionary paths are possible for UFDs. Interpretation of these data is not possible without hydrodynamic cosmological simulations that account for not only the impact of reionization and stellar feedback, but also the host environment. Such simulations do not currently exist. We propose to create a large suite of cosmological, hydrodynamic simulations of UFD analogs that reside ~ 100 kpc from a MW type host at z = 0. These novel simulations will allow us to quantify the role of host's tidal field on the SFHs and gaseous evolution of UFDs for the first time. Furthermore, our recent work indicates that UFDs can retain substantial gas reservoirs prior to accretion by a massive host. We will create mock absorption line observations of our simulated UFDs at intermediate redshifts to establish or refute the connection between local UFDs as descendants of metal-poor damped Lyman alpha systems. The proposed simulation suite will thus be of critical importance to a wide range of ongoing HST programs designed to understand the gaseous, chemical, and dynamical evolution of the dwarf galaxies across cosmic time. Stellar Populations Galaxies and the IGM 0 Regular false false true SUPPORTED