Milky Way Satellite Census. III. Constraints on Dark Matter Properties
  from Observations of Milky Way Satellite Galaxies
  We perform a comprehensive study of Milky Way (MW) satellite galaxies to
constrain the fundamental properties of dark matter (DM). This analysis fully
incorporates inhomogeneities in the spatial distribution and detectability of
MW satellites and marginalizes over uncertainties in the mapping between
galaxies and DM halos, the properties of the MW system, and the disruption of
subhalos by the MW disk. Our results are consistent with the cold,
collisionless DM paradigm and yield the strongest cosmological constraints to
date on particle models of warm, interacting, and fuzzy dark matter. At $95\%$
confidence, we report limits on (i) the mass of thermal relic warm DM, $m_{\rm
WDM} > 6.5\ \mathrm{keV}$ (free-streaming length, $\lambda_{\rm{fs}} \lesssim
10\,h^{-1}\ \mathrm{kpc}$), (ii) the velocity-independent DM-proton scattering
cross section, $\sigma_{0} < 8.8\times 10^{-29}\ \mathrm{cm}^{2}$ for a $100\
\mathrm{MeV}$ DM particle mass (DM-proton coupling, $c_p \lesssim (0.3\
\mathrm{GeV})^{-2}$), and (iii) the mass of fuzzy DM, $m_{\phi}> 2.9 \times
10^{-21}\ \mathrm{eV}$ (de Broglie wavelength, $\lambda_{\rm{dB}} \lesssim 0.5\
\mathrm{kpc}$). These constraints are complementary to other observational and
laboratory constraints on DM properties.
