Cold + Hot Dark Matter Cosmology with $m({\nu }_{\mu })\approx m({\nu }_{\tau })\approx 2.4$ ev

Abstract

Cold + Hot Dark Matter (CHDM) $\Omega =1$ cosmological models require a total neutrino mass $\sim 5$ eV. Because recent data support the ${\nu }_{\mu }\to {\nu }_{\tau }$ oscillation explanation of the cosmic ray ${\nu }_{\mu }$ deficit, which requires that $m({\nu }_{\mu })\approx m({\nu }_{\tau })$, this suggests that $m({\nu }_{\mu })\approx m({\nu }_{\tau })\approx 2.4$ eV. The linear calculations and N-body simulation reported here indicate that an $\Omega =1$ CHDM model with two 2.4 eV neutrinos (designated C${\nu }^2$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-$\Omega$ flat CDM models.