0 Assigned ID: 3620 ----- Attempting Submission 1 (Fri Mar 25 22:03:37 GMT 2022) ----- Binary star systems are a natural by-product of star formation and evolution. While binaries are likely common throughout the universe, statistically quantifying the fraction of stars residing in binary systems has proven to be difficult. Recent work has shown that the rate of binaries appears to be anti-correlated with the metallicity of the stars, at least in the solar neighborhood. However, extrapolating this relationship in order to model binary fractions in the early universe is less than ideal. For that, using relics of that time period would provide valuable context. Fortunately, the Milky Way (MW) is surrounded by a number of such relics in the dwarf spheroidal (dSph) and ultra-faint dwarf (UFD) galaxy population. However, the heterogeneity in the MW satellite sample, with a variety of different methodologies including spectroscopic and photometric used to measure the binary fraction, dramatically complicates drawing broader conclusions about the formation and subsequent impact of binaries. As such, we propose to systematically measure the binary fractions across all classical dSphs and UFD galaxies for which deep archival HST observations exist. This dataset will offer an unprecedented opportunity to examine the relationship across a wide range of galaxy properties (e.g., metallicty, host mass, star formation history) and the binary fraction of those systems, informing our models of star formation and galaxy evolution back to the early universe. Dr. Louis Strigari is an expert in cosmology, using cosmological simulations to interpret the properties of MW ultra-faint dwarf (UFD) galaxies. Yuewen Qi is a graduate student working with Dr. Strigari on identifying extended stellar features around the classical MW satellites. Addy Evans is a graduate student working with Dr. Strigari on the dynamics of globular clusters to search for signals of dark matter. Moonzarin Reza is a graduate student working with Dr. Strigari on analyzing data from the Dark Energy Survey to measure new morphological and structural properties of UFD galaxies. Prof. Jennifer Marshall is an expert in spectroscopy and instrumentation, in particular studying metal-poor stars in the halo of the MW to constrain its formation mechanisms. Dr. Paul Zivick is a postdoctoral researcher with expertise in the kinematics and population dynamics of dwarf galaxies. Dr. Nitya Kallivayalil is an expert in near-field cosmology, using HST imaging and Gaia to study the dynamical properties of MW satellites. Hannah Richstein is a graduate student working with Dr. Kallivayalil and has extensive experience in UFD photometry having worked on measuring star formation histories of UFDs in the HST Treasury program of Milky Way satellites. Jack Warfield is a graduate student working with Dr. Kallivayalil on combining multiple epochs of HST imaging and the Gaia Early Data Release 3 catalog to provide an alternative way to measure proper motions of MW satellite galaxies. Dr. Alex Drlica-Wagner is an expert in using large cosmic surveys like DES to understand the fundamental nature of dark matter and dark energy. Will Cerny is a student working with Dr. Drlica-Wagner in identifying new substructure and potential dwarf galaxies in DES data using the UGaLi toolkit. Dr. Andrew Pace is an expert in combining spectroscopic and proper motion studies of dwarf galaxies to understand the internal structure and evolution of the galaxies. Dr. Tobias Fritz is an expert in rigorous statistical modeling of the systemic kinematics of dwarf galaxies and the resulting orbital parameters. Galaxies 0 Regular false false false false false false SUPPORTED