On the characteristics of fast neutrino flavor instabilities in three-dimensional core-collapse supernova models

Sajad Abbar,H.-Thomas Janka,Robert Glas,Francesco Capozzi,Irene Tamborra

doi:10.1103/physrevd.103.063033

Abstract

We assess the occurrence of fast neutrino flavor instabilities in two three-dimensional state-of-the-art core-collapse supernova simulations performed using a two-moment three-species neutrino transport scheme: one with an exploding 9$\mathrm{M_{\odot}}$ and one with a non-exploding 20$\mathrm{M_{\odot}}$ model. Apart from confirming the presence of fast instabilities occurring within the neutrino decoupling and the supernova pre-shock regions, we detect flavor instabilities in the post-shock region for the exploding model. These instabilities are likely to be scattering-induced. In addition, the failure in achieving a successful explosion in the heavier supernova model seems to seriously hinder the occurrence of fast instabilities in the post-shock region. This is a consequence of the large matter densities behind the stalled or retreating shock, which implies high neutrino scattering rates and thus more isotropic distributions of neutrinos and antineutrinos. Our findings suggest that the supernova model properties and the fate of the explosion can remarkably affect the occurrence of fast instabilities. Hence, a larger set of realistic hydrodynamical simulations of the stellar collapse is needed in order to make reliable predictions on the flavor conversion physics.

Highlights

Massive stars can end their lives in the form of corecollapse supernova (CCSN) explosions, where a huge amount of energy (∼3 × 1053 ergs) is released of which almost 99% is in the form of neutrinos of all flavors [1,2,3]
In what follows we focus on the electron lepton number (ELN) crossings in the region outside the proto-neutron star (PNS) to avoid any repetition of the results already discussed in Ref. [48]
We bring up the possibility of having backward ELN crossings in the SN post-shock region

Summary

INTRODUCTION

Massive stars can end their lives in the form of corecollapse supernova (CCSN) explosions, where a huge amount of energy (∼3 × 1053 ergs) is released of which almost 99% is in the form of neutrinos of all flavors [1,2,3]. The associated asymmetric lepton number emission implies that the distribution of α is not uniform above the PNS and there can exist zones for which α is relatively close to one This increases the chance for the occurrence of ELN crossings in such SN zones. Most of the previous studies of the occurrence of fast instabilities have been based on either 1D/2D SN models or post-processing calculations in which the full neutrino Boltzmann equation is solved for static SN density profiles derived from less fashionable CCSN simulations. We demonstrate that there can be an important connection between the fate of the explosion and the chance for the occurrence of fast instabilities in CCSNe, i.e., the occurrence of ELN crossings can be seriously hindered in nonexploding SN models with high mass accretion rates

SUPERNOVA MODELS

SEARCHING FOR FAST INSTABILITIES

LINEAR STABILITY ANALYSIS

Findings

DISCUSSION AND CONCLUSIONS