The nature of dark matter (DM) remains one of the leading unsolved problems in cosmology today, and absent any direct detection of the particles themselves, the structure of nearby dwarf galaxies remains one of the most promising avenues for learning about the temperature and self-interaction properties of DM because any deviations from the standard cold dark matter model should happen at low masses.
Modern ideas regarding how galaxies form in the Universe involve some form of "hierarchical" process by which small systems progressively merged into ever larger systems like our Milky Way Galaxy. A key element of this paradigm regards how mergers proceed, which, in turn, relies on understanding the nature of the DM needed to drive the formation of galaxies within the observed lifetime of the Universe. Dwarf galaxies are the smallest, simplest entities with DM that also contain visible baryonic material in the form of stars and/or gas. As such, they---and particularly their dark halos---represent our best local analogs of the building blocks that initiated the hierarchical process. The broad goal of this project is to use empirical techniques---primarily kinematic observations of stars in nearby dwarf galaxies---to determine key properties of DM halos in these systems in a largely model-independent way.
The specific aims of this project include (1) learning how DM is distributed within individual galaxies by measuring the central mass densities and core properties of DM halos, (2) exploring how the evolution of the baryonic matter may have altered the DM components in galaxies, (3) determining if DM halos are truly scale free, (4) mapping the extents of DM halos in dwarfs and understanding how their dark and visible components have merged into the greater halo of our Galaxy, and (5) laying the groundwork to reconstruct the properties of the primordial population of dwarfs that contributed to the assembly of our Galaxy. This project builds on decades of NSF-sponsored instrument building and research grants to aid our understanding of the nature of DM.
The investigators will engage in educational activities with several K-12 teachers, give public talks, and participate in events such as "Ask an Astronomer." The project will also support graduate student training throughout the grant period.
