Proto-Neutron Star Convection and the Neutrino-Driven Wind: Implications for the $ν$p-Process

Abstract: Recent studies of the neutrino-driven wind from proto-neutron stars have indicated that the wind is likely proton-rich for much of its lifetime, and the high flux of neutrinos can induce $\nu$p-process nucleosynthesis allowing for the formation of heavy elements. It has also been shown that gravito-acoustic waves, generated by convection within the proto-neutron star, can significantly alter the dynamics and nucleosynthesis in the wind. Therefore, we present a study of the effects of convection-driven waves on the nucleosynthesis in proton-rich neutrino-driven winds, focusing on the $\nu$p-process. We find that wave effects can strongly impact $\nu$p-process nucleosynthesis even at wave luminosities a factor of $10^{-5}$ smaller than the total neutrino luminosity. The momentum flux of the waves accelerates the wind, reducing the net neutrino heating and the persistent neutron abundance created by p($\bar{\nu}e,e^+$), which impedes $\nu$p-process nucleosynthesis. However, this effect is generally counteracted by the effects of waves on seed nucleus formation, as the acceleration of the wind and the heating that occurs as these waves shock both favor a more $\alpha$-rich environment with very little heavy seed-nucleus formation. Overall, higher wave luminosities correlate (albeit non-monotonically) with heavier element $\nu$p-processing, up to $A\approx 200$ in some cases. At very high wave luminosities ($\gtrsim 10^{-3}L\nu$), early shock heating by the waves disrupts $\alpha$ recombination, and drives a suppressed, fast-outflow r-process proceeding up to $A\approx 200$. This occurs despite an assumed neutrino spectrum that predicts a proton-rich wind with equilibrium $Y_e=0.6$.