An Improved Accounting: Searching for Faint Dwarf Galaxies Beyond the Local Group

Ohio State University, The, Columbus OH

Investigators

Abstract

Faint dwarf galaxies are the building blocks of large galaxies, and are hypothesized to be the most abundant galaxies in the Universe. Because of their low mass (thus, low gravitational binding energies), they are the most susceptible to any process that removes or prevents gas from condensing to form stars. However, because they are so dim, the only well-studied sample of faint dwarfs consists of those in the Local Group of Galaxies that includes our own Milky Way galaxy. This project expects to answer some of the open questions about faint dwarf galaxies using deep imaging data: How abundant are they in the local Universe? What is the relation between the mass of their stars and their halos of invisible "dark matter"? Which processes terminate star formation in faint dwarf galaxies? The researchers will also leverage dwarf galaxy searches as a way to increase student access to STEM careers. They will develop a dwarf-galaxy-hunting project for gifted high-school students attending the Ohio Supercomputer Center's annual two-week Summer Institute, and increase access to the program including through scholarships to be funded via this project. The team will produce a "This Is How We Science" video blog (vlog). This vlog will follow the researchers through the milestones and daily tasks associated with the project, and will also feature a how-to guide for young students interested in scientific careers. The project will take a census of faint dwarf galaxies in the nearby Universe using existing deep, multi-wavelength Large Binocular Telescope imaging data from a "failed supernova" survey led by the Co-PI. The 21 host galaxies span the range of galaxy types expected to host most of the faint dwarfs in the local Universe. Analytic, semi-analytic, and numerical tools will be used to infer the relationship between the stellar masses of the faint dwarfs and their dark-matter halos, and to infer the faint dwarf number density in the local Universe. These models will also be used to investigate the relative strength of environmental, internal, and global quenching of star formation, as a function of host type and faint dwarf stellar mass.