Applied Physics/Physics Colloquium: Imaging the dark matter with millions of stars

Imaging the dark matter with millions of stars
Tuesday, May 4, 2021 - 4:30pm
David Hogg (NYU)
Abstract / Description: 

The ESA Gaia mission has delivered amazingly accurate spatial and kinematic measurements for millions of stars, and rapidly improving information on a billion more. Ground-based spectroscopic surveys deliver additional important information about the birth conditions of these stars. Orbital times in the Galaxy are measured in tens of millions of years, so how do we use this snapshot of kinematic and birth information to learn the gravitational force law in the Milky Way, and, in turn, the distribution of dark matter? There are classical stellar-dynamics approaches that (more-or-less) find consistency relationships among second moments (velocity dispersions). But new approaches have appeared in the last few years that deliver images of stellar orbits. I discuss these new orbit-imaging methods and their promise and limitations. They might end up being the most precise tools we will ever have for constraining the dark matter and its dynamics.