Neutrino Luminosity and Matter-Induced Modification of Collective Neutrino Flavor Oscillations in Supernovae

TL;DR

This paper investigates how a density bump in supernovae affects low-energy electron neutrino flavor evolution, revealing nonadiabatic effects and their impact on the neutrino signal spectrum.

Contribution

It demonstrates the influence of a density bump on neutrino flavor evolution and spectral features in supernovae, highlighting the interplay of matter effects and neutrino interactions.

Findings

Density bump causes nonadiabatic flavor evolution of low-energy nu_e.

Neutronization burst luminosity shifts bump-affected neutrino energies.

Bump-affected neutrinos influence spectral swap formation at higher energies.

Abstract

We show that the bump in the electron number density profile at the base of the hydrogen envelope in O-Ne-Mg core-collapse supernovae causes an interesting interplay between neutrino-electron and neutrino-neutrino forward scattering effects in the flavor evolution of low-energy nu_e in the neutronization burst. The bump allows a significant fraction of the low-energy nu_e to survive by rendering their flavor evolution nonadiabatic. Increasing the luminosity of the neutronization burst shifts the bump-affected nu_e to lower energy with reduced survival probability. Similarly, lowering the luminosity shifts the bump-affected neutrinos to higher energies. While these low energy neutrinos lie near the edge of detectability, the population of bump-affected neutrinos has direct influence on the spectral swap formation in the neutrino signal at higher energies.