• Open Access

Fast neutrino flavor instability in the neutron-star convection layer of three-dimensional supernova models

Robert Glas, H.-Thomas Janka, Francesco Capozzi, Manibrata Sen, Basudeb Dasgupta, Alessandro Mirizzi, and Günter Sigl
Phys. Rev. D 101, 063001 – Published 2 March 2020

Abstract

It has been speculated for a long time that neutrinos from a supernova (SN) may undergo fast flavor conversions near the collapsed stellar core. We perform a detailed study of this intriguing possibility, for the first time analyzing two time-dependent state-of-the-art three-dimensional (3D) SN models of 9M and 20M from recent papers of Glas et al. Both models were computed with multidimensional three-flavor neutrino transport based on a two-moment solver, and both exhibit the presence of the so-called lepton-number emission self-sustained asymmetry (LESA). The transport solution does not provide the angular distributions of the flavor-dependent neutrino fluxes, which are crucial to track the fast flavor instability. To overcome this limitation, we use a recently proposed approach based on the angular moments of the energy-integrated electron lepton-number distribution up to second order, i.e., angle-energy integrals of the difference between νe and ν¯e phase-space distributions multiplied by corresponding powers of the unit vector of the neutrino velocity. With this method we find the possibility of fast neutrino flavor instability at radii smaller than 20km, which is well interior to the neutrinosphere where neutrinos are still in the diffusive and near-equilibrium regime. Our results confirm recent observations in a two-dimensional (2D) (axisymmetric) SN model and in 2D and 3D models with a fixed matter background, which were computed with Boltzmann neutrino transport. However, the flavor unstable locations are not isolated points as discussed previously, but thin skins surrounding volumes where ν¯e are more abundant than νe. These volumes grow with time and appear first in the convective layer of the proto-neutron star (PNS), where a decreasing electron fraction and high temperatures favor the occurrence of regions with negative neutrino chemical potential. Since the electron fraction remains higher in the LESA dipole direction, where convective lepton-number transport out from the nonconvective PNS core slows down the deleptonization, flavor unstable conditions become more widespread in the opposite hemisphere. This interesting phenomenon deserves further investigation, since its impact on SN modeling and possible consequences for SN dynamics and neutrino observations are presently unclear.

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  • Received 3 December 2019
  • Accepted 14 January 2020

DOI:https://doi.org/10.1103/PhysRevD.101.063001

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by the Max Planck Society.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & AstrophysicsParticles & Fields

Authors & Affiliations

Robert Glas1,2,*, H.-Thomas Janka1,†, Francesco Capozzi3,‡, Manibrata Sen4,5,§, Basudeb Dasgupta6,∥, Alessandro Mirizzi7,8,¶, and Günter Sigl9,**

  • 1Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching, Germany
  • 2Physik Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
  • 3Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München, Germany
  • 4Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
  • 5Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
  • 6Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India
  • 7Dipartimento Interateneo di Fisica “Michelangelo Merlin,” Via Amendola 173, 70126 Bari, Italy
  • 8Istituto Nazionale di Fisica Nucleare - Sezione di Bari, Via Amendola 173, 70126 Bari, Italy
  • 9II. Institute for Theoretical Physics, Hamburg University, Luruper Chaussee 149, 22761 Hamburg, Germany

  • *rglas@mpa-garching.mpg.de
  • thj@mpa-garching.mpg.de
  • capozzi@mppmu.mpg.de
  • §manibrata@berkeley.edu
  • bdasgupta@theory.tifr.res.in
  • alessandro.mirizzi@ba.infn.it
  • **guenter.sigl@desy.de

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Vol. 101, Iss. 6 — 15 March 2020

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