Fast Neutrino Flavor Conversion in Core-Collapse Supernovae: A Parametric Study in 1D Models

TL;DR

This study investigates how fast neutrino flavor conversions affect core-collapse supernova dynamics and neutrino emissions using parametric 1D simulations, revealing impacts on shock expansion, energy transport, and proto-neutron star contraction.

Contribution

It introduces a parametric implementation of fast flavor conversions in 1D supernova models, providing new insights into their effects on neutrino spectra and supernova evolution.

Findings

FFC hardens electron neutrino spectra, aiding shock expansion

FFC increases heavy-lepton neutrino luminosities, affecting energy transport

FFC-induced cooling accelerates proto-neutron star contraction

Abstract

We explore the impact of small-scale flavor conversions of neutrinos, the so-called fast flavor conversions (FFCs), on the dynamical evolution and neutrino emission of core-collapse supernovae (CCSNe). In order to do that, we implement FFCs in the spherically symmetric (1D) CCSN simulations of a 20 solar-mass progenitor model parametrically, assuming that FFCs happen at densities lower than a systematically varied threshold value and lead to an immediate flavor equilibrium consistent with lepton number conservation. We find that besides hardening the electron neutrino and antineutrino spectra, which helps the expansion of the shock by enhanced postshock heating, FFCs can cause significant, nontrivial modifications of the energy transport in the SN environment via increasing the heavy-lepton neutrino luminosities. In our non-exploding models this results in extra cooling of the layers around the neutrinospheres, which triggers a faster contraction of the proto-neutron star and hence, in our 1D models, hampers the CCSN explosion. Although our study is limited by the 1D nature of our simulations, it provides valuable insights into how neutrino flavor conversions in the deepest CCSN regions can impact the neutrino release and the corresponding response of the stellar medium.