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_WDM>6.5 keV (free-streaming length, λ_fs≲10 h^-1 kpc ), (ii) the velocity-independent DM-proton scattering cross section, σ₀<8.8 ×10^-29 cm² for a 100 MeV DM particle mass [DM-proton coupling, c_p≲(0.3 GeV )-²], and (iii) the mass of fuzzy DM, m_ϕ>2.9 ×10^-21 eV (de Broglie wavelength, λ_dB≲0.5 kpc ). These constraints are complementary to other observational and laboratory constraints on DM properties.