Dwarf Galaxies in 2010: Revealing Galaxy Formation's Threshold and
  Testing the Nature of Dark Matter
  Over the past five years, searches in Sloan Digital Sky Survey data have more
than doubled the number of known dwarf satellite galaxies of the Milky Way, and
have revealed a population of ultra-faint galaxies with luminosities smaller
than typical globular clusters, L ~ 1000 Lsun. These systems are the faintest,
most dark matter dominated, and most metal poor galaxies in the universe.
Completeness corrections suggest that we are poised on the edge of a vast
discovery space in galaxy phenomenology, with hundreds more of these extreme
galaxies to be discovered as future instruments hunt for the low-luminosity
threshold of galaxy formation. Dark matter dominated dwarfs of this kind probe
the small-scale power-spectrum, provide the most stringent limits on the
phase-space packing of dark matter, and offer a particularly useful target for
dark matter indirect detection experiments. Full use of dwarfs as dark matter
laboratories will require synergy between deep, large-area photometric
searches; spectroscopic and astrometric follow-up with next-generation optical
telescopes; and subsequent observations with gamma-ray telescopes for dark
matter indirect detection.
