HST Treasury Program: MW-6D

Space Telescope Science Institute has awarded Nitya Kallivayalil (as PI) and me (as co-PI), with co-investigators Jay Anderson, Gurtina Besla, Tom Brown, Alis Deason, Tobias Fritz, Marla Geha, Raja Guhathakurta, Evan Kirby, Steve Majewski, Josh Simon, Tony Sohn, Erik Tollerud, and Roeland van der Marel, a Hubble Space Telescope Treasury Program of 164 orbits for Milky Way Cosmology: Laying the Foundation for Full 6-D Dynamical Mapping of the Nearby Universe.

Our HST observations will provide the initial baselines for long-term proper-motion measurements for all of the known satellite dwarf galaxies around the Milky Way. Our goal is to measure the orbital motions of these satellites as they move across the sky over the next 3 – 10 years, to complete their full 6-dimensional orbital phase-space. Our key science goals are to:

(1) Dynamically measure the mass distribution of the Milky Way’s dark-matter halo
(2) Understand the role of the Milky Way’s environment on the evolution of dwarf galaxies
(3) Use dwarf galaxies as probes of the epoch of reionization
(4) Test physical associations of dwarf galaxies
(5) Eventually, measure internal stellar kinematics of dwarf galaxies, to test the nature of Cold Dark Matter (CDM)

As part of this Treasury Program, we also were awarded $726,000 in grant funding, to analyze these observations and develop our framework for dynamical modeling.