My research focuses on the intersection between galaxy formation and cosmology, with emphasis on near-field cosmology and galactic archaeology, through the use of next-generation cosmological simulations.

FIRE project and Latte simulations

I am co-developing the Feedback in Realistic Environments (FIRE) numerical model, a new ‘bottom-up’ approach of implementing stellar evolution models directly into ultra-high resolution cosmological simulations. The FIRE simulations are fully cosmological and model galaxies’ entire formation histories. They include not just the physics of dark matter and gravity but also the fluid dynamics, star formation, stellar radiation, and supernovae that drive the formation of galaxies and shape the distribution of dark matter in them.

As part of the FIRE project, I am leading the Latte Simulation Suite of cosmological zoom-in baryonic simulations of Milky Way-like galaxies. With these simulations, I am pursuing a multi-faceted program to elucidate the physics that governs the evolution the Milky Way and its satellite dwarf galaxies, to address fundamental questions regarding (1) the relative roles of gas accretion, stellar feedback, cosmic environment, and the epoch of reionization in driving galaxy formation, (2) the use of galactic archaeology to probe the formation histories of the Milky Way and galaxies in the local Universe, and (3) the nature of dark matter on the smallest scales.

MW-6D: HST Treasury Program

I am co-leading, with Nitya Kallivayalil (and 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 UniverseOur HST observations are providing 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)