There is No Missing Satellites Problem
  A critical challenge to the cold dark matter (CDM) paradigm is that there are
fewer satellites observed around the Milky Way than found in simulations of
dark matter substructure. We show that there is a match between the observed
satellite counts corrected by the detection efficiency of the Sloan Digital Sky
Survey (for luminosities $L \gtrsim$ 340 L$_\odot$) and the number of luminous
satellites predicted by CDM, assuming an empirical relation between stellar
mass and halo mass. The "missing satellites problem", cast in terms of number
counts, is thus solved. We also show that warm dark matter models with a
thermal relic mass smaller than 4 keV are in tension with satellite counts,
putting pressure on the sterile neutrino interpretation of recent X-ray
observations. Importantly, the total number of Milky Way satellites depends
sensitively on the spatial distribution of satellites, possibly leading to a
"too many satellites" problem. Measurements of completely dark halos below
$10^8$ M$_\odot$, achievable with substructure lensing and stellar stream
perturbations, are the next frontier for tests of CDM.
