Speaker
Description
We use surface brightness and velocity dispersion data to constrain the properties of 10 Milky Way dwarf spheroidal galaxies (dSphs), which span over an order of magnitude in effective radius, over 4 orders of magnitude in stellar mass, and show no signs of tidal disruption. To alleviate the degeneracy between galaxy mass and velocity anisotropy (beta), the “M-beta degeneracy”, we consider boundary conditions of the spherical Jeans equation as r --> 0. These boundary conditions constrain the coefficients of a general beta parametrization at the centers of each dSph dark matter (DM) halo, which we model separately with either a cored (Burkert) or cuspy (NFW) DM density profile. The resulting best-fit NFW models tend to fit the data more poorly than do the best-fit Burkert models. The best-fit NFW models also require more (radial, tangential) velocity anisotropies at (small, large) dSph radii than do the best-fit Burkert models. For both the best-fit Burkert and NFW models, we find strong correlations between the scale radius, R_*, and effective radius, R_{eff}, of the dSph luminous matter distributions and all best-fit, DM halo parameters.
