Neutrino flavor instabilities in a time-dependent supernova model

TL;DR

This paper investigates how collective neutrino flavor oscillations behave in a time-dependent supernova environment, revealing that they start at similar radii as in stationary models but can vary rapidly over time.

Contribution

It extends previous stationary models by analyzing neutrino flavor instabilities in a dynamic, time-dependent supernova setting, highlighting the potential for rapid temporal variations.

Findings

Oscillations start at similar radii in both models

Rapid local physical changes can influence oscillation onset

Neutrino oscillations can vary quickly over time in supernovae

Abstract

A dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial) spherical symmetry about the center of the supernova and the (directional) axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this paper we analyze the neutrino flavor instabilities in a time-dependent supernova model. Our results show that collective neutrino oscillations start at approximately the same radius in both the stationary and time-dependent supernova models unless there exist very rapid variations in local physical conditions on timescales of a few microseconds or shorter. Our results also suggest that collective neutrino oscillations can vary rapidly with time in the regimes where they do occur which need to be studied in time-dependent supernova models.