Cold + Hot Dark Matter Cosmology with $m(ν_μ) \approx m(ν_τ) \approx 2.4$ ev

Abstract

Cold + Hot Dark Matter (CHDM) $Ω=1$ cosmological models require a total neutrino mass $\sim 5$ eV. Because recent data support the $ν_μ\to ν_τ$ oscillation explanation of the cosmic ray $ν_μ$ deficit, which requires that $m(ν_μ) \approx m(ν_τ)$, this suggests that $m(ν_μ) \approx m(ν_τ) \approx 2.4$ eV. The linear calculations and N-body simulation reported here indicate that an $Ω=1$ CHDM model with two 2.4 eV neutrinos (designated C$ν^2$DM) agrees remarkably well with all available observations, but only if the Hubble parameter $h \approx 0.5$. We also show that even one 2.4 eV neutrino raises serious difficulties for low-$Ω$ flat CDM models.