Speaker
Description
The size and density profiles of dark matter (DM) halos have been extensively studied in simulations and observations. In simulations, DM halo properties are `universal' and can be scaled appropriately. However, unlike simulations, determining the sizes from observations has been limited to larger mass halos. For example, the splashback radius is now measured in cluster-sized halos, and efforts are on to determine it for galaxy groups. For DM halos hosting galaxies, there are no such measurements, and one has to extrapolate model fits to outer radii to get a size (ex, the virial radii). Using data from the GAIA satellite, we present the first ever look at the halo boundary properties for a galaxy-sized DM halo - that of our own Milky Way. With a uniform sampling of the galaxy DM profile from inner-to-outer radii, this gives the tightest ever constraints on the density, mass, size, DM phase-space up to/beyond the virial radius, and possibly a first determination of the DM halo boundary at galaxy scales.
