Halo densities and pericenter distances of the bright Milky Way satellites as a test of dark matter physics

Abstract

We provide new constraints on the dark matter halo density profile of Milky Way (MW) dwarf spheroidal galaxies (dSphs) using the phase-space distribution function (DF) method. After assessing the systematics of the approach against mock data from the Gaia Challenge project, we apply the DF analysis to the entire kinematic sample of well-measured MW dwarf satellites for the first time. Contrary to previous findings for some of these objects, we find that the DF analysis yields results consistent with the standard Jeans analysis. In particular, in this study we rediscover (i) a large diversity in the inner halo densities of dSphs (bracketed by Draco and Fornax), and (ii) an anticorrelation between inner halo density and pericenter distance of the bright MW satellites. Regardless of the strength of the anticorrelation, we find that the distribution of these satellites in density versus pericenter space is inconsistent with the results of the high-resolution N-body simulations that include a disc potential. Our analysis motivates further studies on the role of internal feedback and dark matter microphysics in these dSphs.