Astrophys. J. 688, 277–289 (2008)

Rest assured, astronomers: the missing satellite galaxies of the Milky Way are there — they just haven't been discovered yet, according to calculations by Erik Tollerud of the University of California, Irvine, and his colleagues.

Models that aim to capture how the clumpiness of dark matter has changed since the Big Bang suggest that the Milky Way should have hundreds, if not thousands, of neighbouring nuggets of dark matter thick enough for faint dwarf galaxies to form in them. But only 20 or so of these galaxies have been spotted.

By assessing the limits of the Sloan Digital Sky Survey, Tollerud and his co-workers have found that the number of known dwarf galaxies is consistent with the number of nearby dark-matter clumps predicted by models.