MW-6D Survey: HST Treasury Program

Together with PI Nitya Kallivayalil, I am co-leading the MW-6D Survey, Hubble Space Telescope (HST) Treasury Program of 164 orbits for Milky Way Cosmology: Laying the Foundation for Full 6-D Dynamical Mapping of the Nearby UniverseThis HST survey is providing the initial baselines for measuring proper-motion (across the sky) velocities, stellar populations, and star-formation histories for all of the known satellite dwarf galaxies around the Milky Way. We will 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 measurements. Our key science goals are:

  • dynamically measure the mass distribution of the Milky Way’s dark-matter halo
  • understand the role of the Milky Way’s environment on the evolution of dwarf galaxies
  • use the stellar populations in dwarf galaxies as relic probes of the epoch of reionization
  • test physical associations of dwarf galaxies, including groups and planes of satellites
  • measure internal stellar kinematics of dwarf galaxies, to constrain their inner density profiles and test the nature of cold dark matter

Nitya Kallivayalil and I are joined by amazing 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.

My group at UC Davis is leading the dynamical modeling component of this program, using our Latte suite of FIRE-2 simulations of Milky Way-like galaxies to build cosmologically informed models for the full orbital histories across cosmic time for each of the satellite galaxies around the Milky Way.