Formation of dwarf galaxies and small-scale problems of CDM

Abstract

The concordance cosmological model based on cold dark matter makes definitive predictions for the growth of galaxies in the Universe, which are being actively studied using numerical simulations. These predictions appear to contradict the observations of dwarf galaxies. Dwarf dark matter halos are more numerous and have steeper central density profiles than the observed galaxies. The first of these small-scale problems, the "missing satellites problem", can be resolved by accounting for the low efficiency of gas cooling and star formation in dwarf halos. A newly-discovered class of HyperVelocity Stars will soon allow us to test another generic prediction of CDM models, the triaxial shapes of dark matter halos. Measuring the proper motions of HVS will probe the gravitational potential out to 100 kpc and will constrain the axis ratios and the orientation of the Galactic halo.

invited talk at IAU Symposium 235, Prague, August 2006

References in corpus (5)

• Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: III. Constraints on the Flattening of the Galactic Halo
• HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star
• Probing the Shape of the Galactic Halo with Hyper-Velocity Stars
• Fossils of Reionization in the Local Group