Neutrino Dark Matter

Abstract

There is a puzzling contradiction: direct observations favor a low-mass density universe, but the only model which fits universe structure over more than three orders of magnitude in distance scale has a mix of hot (neutrino) and cold dark matter consistuting a critical density universe. If all present indications for neutrino mass are valid, that hot dark matter is shared by two neutrino species (nu_mu and nu_tau). These results also require at least one light sterile neutrino to exist to explain the solar nu_e deficit (nu_e -> nu_s), so that nu_mu -> nu_tau accounts for the atmospheric neutrino anomaly, with anti-nu_mu -> anti-nu_e being observed in the LSND experiment. This experiment, when analyzed appropriately, does not conflict with any others and is compatible with the mass difference needed for dark matter. Support for this mass pattern is provided by the need for a sterile neutrino to make possible heavy-element nucleosynthesis in supernovae.