Collective flavor oscillations of supernova neutrinos and r-process nucleosynthesis

Abstract

Neutrino-neutrino interactions inside core-collapse supernovae may give riseto collective flavor oscillations resulting in swap between flavors. These oscillations depend on the initial energy spectra, and relative fluxes or relative luminosities of the neutrinos.It has been observed that departure from energy equipartition among different flavors can give rise to one or more sharp spectral swap over energy, termed as splits. We study the occurrence of splits in the neutrino and antineutrinospectra, varying the initial relative fluxes for different models of initial energy spectrum, in both normal and inverted hierarchy. These initialrelative flux variations give rise to several possible split patterns whereasvariation over different models of energy spectra give similar results. We explore the effect of these spectral splits on the electron fraction, Ye,that governs r-process nucleosynthesis inside supernovae. Since spectral splits modify the electron neutrino and antineutrino spectra in the region where r-process is postulated to happen, and since the pattern of spectral splits depends on the initial conditions of the spectra and the neutrino mass hierarchy, we show that the condition Ye < 0.5 required for successfulr-process nucleosynthesis will lead to constraints on the initial spectral conditions, for a given neutrino mass hierarchy.