Active-sterile Neutrino Oscillations in Neutrino-driven Winds: Implications for Nucleosynthesis.

A protoneutron star produced in a core-collapse supernova (CCSN) drives a wind by its intense neutrino emission. We implement active-sterile neutrino oscillations in a steady-state model of this neutrino-driven wind to study their effects on the dynamics and nucleosynthesis of the wind in a self-consistent manner. Using vacuum mixing parameters indicated by some experiments for a sterile $\nu_s$ of $\sim 1$~eV in mass, we observe interesting features of oscillations due to various feedback. For the higher $\nu_s$ mass values, we find that oscillations can reduce the mass loss rate and the wind velocity by a factor of $\sim 1.6$--2.7 and change the electron fraction critical to nucleosynthesis by a significant to large amount. In the most dramatic cases, oscillations shifts nucleosynthesis from dominant production of $^{45}$Sc to that of $^{86}$Kr and $^{90}$Zr during the early epochs of the CCSN evolution.