Probing Galaxy Formation and Cosmology with Dwarf Galaxies in Voids

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This program will combine observations of neutral hydrogen with existing Sloan Digital Sky Survey imaging and spectroscopy, plus satellite imaging, to study certain types of galaxies in regions largely devoid of galaxies. The main purpose is to address critical questions about galaxy formation and cosmology. Broader impacts of the work include training of undergraduate and graduate students. An astronomy outreach program for elementary school students will be run by Dr. Vogeley and his group at a school in a minority, economically-challenged neighborhood, with talks, interactive activities, and visits to the Joseph Lynch Observatory at Drexel. The current best cosmological model (lambda cold dark matter) severely over-predicts the abundance of void dwarfs unless star formation is strongly suppressed in low-mass dark matter halos, or the spectrum of halo masses is modified. The void environment, in which gas-stripping galaxy interactions are extremely rare, is therefore a crucial test of our understanding of the processes affecting galaxy formation. The exact degree of mismatch between predicted halos and observed galaxies will be quantified, the detailed star formation and gas properties of void dwarfs will be measured, and comparison will be made to high-resolution cosmological simulations.