Is Galactic Dark Matter White?

Abstract

We calculate the expected white dwarf luminosity functions and discovery functions in photometric passbands, assuming that these stellar remnants provide a substantial fraction of the sought Galactic dark matter, as suggested on various observational grounds. We demonstrate the extremely rapid variation of the photometric signature of halo white dwarfs with time and thus the powerful diagnostic of white dwarf colors to determine the age of the Galactic halo. We also consider the various indirect constraints implied by a white dwarf-dominated halo. These calculations will guide present and future observational projects at faint magnitudes. This will enable us to determine not only the nature of the Galactic dark matter but also the age and the initial conditions of Galaxy formation.