A Near Universal Predictor for Dark Matter Content at the Center of Galaxies

We use a suite of 12 simulations of MW-mass galaxies run with the FIRE feedback implementation to explore the relationship between the properties of a galaxy’s stellar population and that of its dark matter (DM) component at small galactocentric radii. We show that the mass in stars within 1 kiloparsec (kpc) is a good predictor for both DM mass and density within the same region as well as the slope of the radial DM density profile from 1-5 kpc. This relationship holds for galaxies with central stellar masses (r < 1 kpc) between 10⁷–10^10.5 solar masses. We predict a similar relationship between the central stellar mass component and the shape of the dissipationless mass (stars + DM) profile. Finally, we use dynamical properties of the simulated galaxies’ stellar components in conjunction with those predicted for the Milky Way (MW) using observational data to predict what the MW’s central DM content should look like.