Dark matter halo properties of the Galactic dwarf satellites: implication for chemo-dynamical evolution of the satellites and a challenge to ΛCDM

Elucidating dark matter density profiles in the Galactic dwarf satellites is essential to understanding not only the quintessence of dark matter, but also the evolution of the satellites themselves. In this work, we present the current constraints on dark matter densities in the Galactic ultra-faint dwarf (UFD) and diffuse galaxies. Applying our constructed non-spherical mass models to the currently available kinematic data of the 25 UFDs and 2 diffuse satellites, we find that whereas most of the galaxies have huge uncertainties on the inferred dark matter density profiles, Eridanus~II, Segue~I, and Willman~1 favor cuspy central profiles even considering effects of a prior bias. We compare our results with the simulated subhalos on the plane between the dark matter density at 150~pc and the pericenter distance. We find that the most observed satellites and the simulated subhalos are similarly distributed on this plane, except for Antlia~2, Crater~2, and Tucana~3, which are less than one tenth of the density. Despite considerable tidal effects, the subhalos detected by commonly-used subhalo finders have difficulty in explaining such a huge deviation. We also estimate the dynamical mass-to-light ratios of the satellites and confirm the ratio is linked to stellar mass and metallicity. Tucana~3 deviates largely from these relations, while it follows the mass-metallicity relation. This indicates that Tucana~3 has a cored dark matter halo, despite a significant uncertainty in its ratios.