Turbulence fingerprint on collective oscillations of supernova neutrinos

Sajad Abbar

doi:10.1103/physrevd.103.045014

Abstract

We bring to light a novel mechanism through which turbulent matter density fluctuations can induce collective neutrino flavor conversions in core-collapse supernovae, i.e., the leakage of flavor instabilities between different Fourier modes. The leakage mechanism leaves its notable fingerprint on the flavor stability of a dense neutrino gas by coupling flavor conversion modes on different scales which in turn, makes the flavor instabilities almost ubiquitous in the Fourier space. The most remarkable consequence of this effect is in that it allows for the presence of significant flavor conversions in the deepest supernova regions even in the absence of the so-called fast modes. This is yet another crucial impact of turbulence on the physics of core-collapse supernovae which can profoundly change our understanding of neutrino flavor conversions in the supernova environment.

Highlights

Core-collapse supernova (CCSN) explosions are among the most energetic astrophysical phenomena in which neutrino emission is a major effect [1,2]
The turbulence-induced leakage of flavor instabilities implies that the notion of μ − k instability band developed in a homogenous neutrino gas is not very useful in a turbulent medium where what distinguishes different Fourier modes is only their initial amplitudes, jQkj
It dismisses the necessity of the occurrence of fast modes in order to observe significant flavor conversions near the PNS

Summary

INTRODUCTION

Core-collapse supernova (CCSN) explosions are among the most energetic astrophysical phenomena in which neutrino emission is a major effect [1,2]. This is because they occur on short enough scales in such a way that the unstable modes can experience significant flavor conversions before the physical conditions vary significantly In spite of their importance, fast modes do not seem to be a generic feature of CCSNe and even if they exist, they are thought to be present only in a finite region of the SN core [52,53,54,55,56,57]. We demonstrate that the presence of turbulence in CCSNe can induce collective neutrino flavor conversion modes via an entirely different mechanism, i.e., the leakage of flavor instabilities between different Fourier modes This novel effect can significantly influence neutrino flavor evolution in the SN environment and in particular, it can lead to the presence of traditional (slow) collective neutrino oscillations in the deepest SN regions even in the absence of fast modes. What makes this novel effect more promising is in that it survives even for tiny turbulence amplitudes

LINEAR STABILITY ANALYSIS

TURBULENT MATTER FLUCTUATIONS

TWO-BEAM MODEL

DISCUSSION AND CONCLUSIONS