Signatures of white dwarf galaxy halos

Population synthesis models are combined with constraints from deep galaxy surveys to show that only a small fraction (<~10%) of the dark mass in present-day galaxy halos could be in the form of white dwarf remnants of intermediate-mass stars. The bright early phases of halos containing such stars imply that they should be detectable in deep galaxy counts, especially in the near-infrared. Signatures of dark baryonic halos include luminous, low surface brightness galaxies and helium-enriched gas that has either collapsed into cold, dense clouds or else has been ejected into intergalactic space.