Diagnosing electron-neutrino lepton number crossings in core-collapse supernovae: A comparison of methods

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Main Authors: Cornelius, Marie, Tamborra, Irene, Heinlein, Malte, Janka, Hans-Thomas
Format: Preprint
Published: 2025
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author Cornelius, Marie
Tamborra, Irene
Heinlein, Malte
Janka, Hans-Thomas
author_facet Cornelius, Marie
Tamborra, Irene
Heinlein, Malte
Janka, Hans-Thomas
contents Fast neutrino flavor conversion may impact the explosion mechanism and nucleosynthesis in core-collapse supernovae. A necessary condition for fast flavor conversion is the presence of crossings in the angular distribution of the electron-neutrino lepton number (ELN) crossing. Because of the computational costs, flavor-dependent angular distributions are not computed by the vast majority of state-of-the-art hydrodynamical simulations; instead, angular distributions are reconstructed employing approximate methods in post-processing. In this work, we evaluate the performance of four methods adopted to diagnose the existence of ELN crossings. For selected post-bounce times, we extract the fluid and thermodynamic properties from spherically symmetric supernova simulations for an $18.6 M_\odot$ progenitor, testing cases with and without muons as well as with and without mixing-length treatment of proto-neutron star convection. We compare the occurrence of crossings in the angular distributions obtained by solving the Boltzmann equations with those in distributions reconstructed from angular moments of our Boltzmann solutions by using the maximum entropy and Minerbo schemes, and also with crossings identified via a polynomial weighting function applied to the angular moments. Our results show that the polynomial method and the Minerbo closure scheme have severe limitations. The maximum entropy approach captures most of the forward crossings, although it fails to reproduce or misidentifies crossings in a subset of our models. These findings highlight the need for robust modeling of the neutrino angular properties in order to assess the impact of flavor conversion on the supernova mechanism.
format Preprint
id arxiv_https___arxiv_org_abs_2506_20723
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Diagnosing electron-neutrino lepton number crossings in core-collapse supernovae: A comparison of methods
Cornelius, Marie
Tamborra, Irene
Heinlein, Malte
Janka, Hans-Thomas
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
Fast neutrino flavor conversion may impact the explosion mechanism and nucleosynthesis in core-collapse supernovae. A necessary condition for fast flavor conversion is the presence of crossings in the angular distribution of the electron-neutrino lepton number (ELN) crossing. Because of the computational costs, flavor-dependent angular distributions are not computed by the vast majority of state-of-the-art hydrodynamical simulations; instead, angular distributions are reconstructed employing approximate methods in post-processing. In this work, we evaluate the performance of four methods adopted to diagnose the existence of ELN crossings. For selected post-bounce times, we extract the fluid and thermodynamic properties from spherically symmetric supernova simulations for an $18.6 M_\odot$ progenitor, testing cases with and without muons as well as with and without mixing-length treatment of proto-neutron star convection. We compare the occurrence of crossings in the angular distributions obtained by solving the Boltzmann equations with those in distributions reconstructed from angular moments of our Boltzmann solutions by using the maximum entropy and Minerbo schemes, and also with crossings identified via a polynomial weighting function applied to the angular moments. Our results show that the polynomial method and the Minerbo closure scheme have severe limitations. The maximum entropy approach captures most of the forward crossings, although it fails to reproduce or misidentifies crossings in a subset of our models. These findings highlight the need for robust modeling of the neutrino angular properties in order to assess the impact of flavor conversion on the supernova mechanism.
title Diagnosing electron-neutrino lepton number crossings in core-collapse supernovae: A comparison of methods
topic High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2506.20723