Fast neutrino flavor conversions near the supernova core with realistic flavor-dependent angular distributions

TL;DR

This paper investigates rapid neutrino flavor conversions near supernova cores using realistic angular distributions, revealing they can occur within meters and nanoseconds, potentially impacting supernova dynamics and element formation.

Contribution

It provides a detailed analysis of fast neutrino flavor conversions near supernova cores with realistic flux and angular distributions, highlighting their rapid onset and broader conditions for occurrence.

Findings

Fast conversions occur within tens of nanoseconds and meters from the core.

Neutrino angular asymmetries facilitate flavor instabilities.

Implications for supernova explosion mechanisms and nucleosynthesis.

Abstract

It has been recently pointed out that neutrino fluxes from a supernova can show substantial flavor conversions almost immediately above the core. Using linear stability analyses and numerical solutions of the fully nonlinear equations of motion, we perform a detailed study of these fast conversions, focussing on the region just above the supernova core. We carefully specify the instabilities for evolution in space or time, andfind that neutrinos travelling towards the core make fast conversions more generic, i.e., possible for a wider range of flux ratios and angular asymmetries that produce a crossing between the zenith-angle spectra of $\nu_e$ and ${\bar\nu_e}$. Using fluxes and angular distributions predicted by supernova simulations, we find that fast conversions can occur within tens of nanoseconds, only a few meters away from the putative neutrinospheres. If these fast flavor conversions indeed take place, they would have important implications for the supernova explosion mechanism and nucleosynthesis.