Enhanced muonization by active-sterile neutrino mixing in protoneutron stars

We study νμ-νs and ν¯μ-ν¯s mixing in the protoneutron star (PNS) created in a core-collapse supernova (CCSN). We point out the importance of the feedback on the general composition of the PNS in addition to the obvious feedback on the νμ lepton number. We show that for our adopted mixing parameters δm2∼102 keV2 and sin22θ consistent with the current constraints, sterile neutrino production is dominated by the Mikheyev-Smirnov-Wolfenstein conversion of ν¯μ into ν¯s and that the subsequent escape of ν¯s increases the νμ lepton number, which in turn enhances muonization of the PNS primarily through νμ+n→p+μ-. While these results are qualitatively robust, their quantitative effects on the dynamics and active neutrino emission of core-collapse supernovae should be evaluated by including νμ-νs and ν¯μ-ν¯s mixing in the simulations.