Eight New Milky Way Companions Discovered in First-Year Dark Energy
  Survey Data
  We report the discovery of eight new Milky Way companions in ~1,800 deg^2 of
optical imaging data collected during the first year of the Dark Energy Survey
(DES). Each system is identified as a statistically significant over-density of
individual stars consistent with the expected isochrone and luminosity function
of an old and metal-poor stellar population. The objects span a wide range of
absolute magnitudes (M_V from -2.2 mag to -7.4 mag), physical sizes (10 pc to
170 pc), and heliocentric distances (30 kpc to 330 kpc). Based on the low
surface brightnesses, large physical sizes, and/or large Galactocentric
distances of these objects, several are likely to be new ultra-faint satellite
galaxies of the Milky Way and/or Magellanic Clouds. We introduce a
likelihood-based algorithm to search for and characterize stellar
over-densities, as well as identify stars with high satellite membership
probabilities. We also present completeness estimates for detecting ultra-faint
galaxies of varying luminosities, sizes, and heliocentric distances in the
first-year DES data.
