CAREER: The Dynamics of the Milky Way's Local Group Substructure as the Key to Understanding Dark Matter and Galaxy Formation

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

There is overwhelming astrophysical evidence that less than 5 percent of the universe is made from ordinary - or baryonic - matter. The rest of the cosmos appears to be constituted from "dark matter," which has the gravitational properties of matter but which hardly interacts with light (25 percent), together with "dark energy," which acts to repel the force of gravity. Astrophysicists have further developed this model into one in which dark matter takes the form of slow-moving particles, and dark energy is associated with a "cosmological constant" first introduced by Einstein. The model has had remarkable successes in explaining many of the observed characteristics of the universe. Nonetheless, there remain mismatches between the model and the observed properties of our own Milky Way galaxy and its neighbors. The work supported by this CAREER award will use the Gemini Observatory, of which the NSF is a founding partner, to tackle these fundamental problems and provide new constraints on the nature of dark matter. The PI, Dr. Nitya Kallivayalil, will also launch and lead a major collaboration with Spelman College, America's oldest historically Black college for women to create a pipeline for training future STEM leaders from under-represented groups. The specific goals of the PI's program are to use the world-leading adaptive optics technologies employed by the Gemini Observatory, together with its innovative large and long observing programs, to measure the 6-dimensional phase space of tracers of the Milky Way's gravitational potential. This requires accurate proper motions, in addition to radial velocities for field stars and satellites widely distributed throughout the halo. The PI will definitively constrain the dark-halo shape, orientation, radial profile and total mass of the Milky Way; determine the infall times of its satellite galaxies; and constrain the central density distributions of dwarf galaxies to assess whether they have cusp- or core-like profiles. Furthermore, the PI's partnership with Spelman College will involve a Research Experiences for Undergraduates REU program for Spelman students, as well as curriculum development at the college.