Neutrino quantum kinetics in a core-collapse supernova

Jun 13, 2024
25 pages
Published in:
  • JCAP 09 (2024) 021
  • Published: Sep 9, 2024
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Abstract: (IOP)
Our understanding of neutrino flavor conversion in the supernova core is stillpreliminary, despite its likely relevance to the neutrino-driven supernova mechanism. We presentmulti-angle and multi-energy numerical simulations of neutrino quantum kinetics within aspherically symmetric shell in the proximity of the region of neutrino decoupling. We rely oninputs from a one-dimensional core-collapse supernova model with a mass of 18.6 M_{⊙} andfind that, at early post-bounce times (tpb_{pb} ≲ 0.5 s), no crossing is present inthe angular distribution of the electron neutrino lepton number and flavor conversion is triggeredby slow collective instabilities. Angular crossings appear for tpb_{pb} ≳ 0.5 sand fast flavor conversion leads to flavor equipartition, with the spectral energy distribution of νe_{e} (ν̅e_{e}) and νx_{x} (ν̅x_{x}) becoming comparable. Notably, flavorequipartition is not a generic outcome of fast flavor conversion, rather it is a consequence ofthe relatively similar properties of neutrinos of different flavors characterizing the lateaccretion phase. Artificially tweaking the collision term to introduce an electron lepton numberangular crossing for tpb_{pb} ≲ 0.5 s, we observe that flavor equipartition isnot achieved. While our findings are restricted to a specific supernova model, and they only takeinto account the feedback of the neutrino background on the flavor conversion, they suggest a richphenomenology in the supernova core as a function of the post-bounce time which needs to befurther explored to assess its impact on the explosion mechanism.
Note:
  • 25 pages, 13 figures. Version accepted in JCAP
  • supernova neutrinos
  • neutrino properties
  • neutrino theory