THE STRUCTURE OF DARK-MATTER HALOS IN DWARF GALAXIES

Recent observations indicate that dark matter halos have flat central density profiles. Cosmological simulations with nonbaryonic dark matte r, however, predict self-similar halos with central density cusps. Thi s contradiction has lead to the conclusion that dark matter must be ba ryonic. Here it is shown that the dark matter halos of dwarf spiral ga laxies represent a one-parameter family with self-similar density prof iles. The observed global halo parameters are coupled with each other through simple scaling relations which can be explained by the standar d cold dark matter model if one assumes that all the halos formed from density fluctuations with the same primordial amplitude. We find that the finite central halo densities correlate with the other global par ameters. This result rules out scenarios where the flat halo cores for med subsequently through violent dynamical processes in the baryonic c omponent. These cores instead provide important information on the ori gin and nature of dark matter in dwarf galaxies.