Self-sustained asymmetry of lepton-number emission: a new phenomenon during the supernova shock-accretion phase in three dimensions
- Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805 München (Germany)
- Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)
- Rechenzentrum der Max-Planck-Gesellschaft, Boltzmannstr. 2, D-85741 Garching (Germany)
During the stalled-shock phase of our three-dimensional, hydrodynamical core-collapse simulations with energy-dependent, three-flavor neutrino transport, the lepton-number flux (ν {sub e} minus ν-bar {sub e}) emerges predominantly in one hemisphere. This novel, spherical-symmetry breaking neutrino-hydrodynamical instability is termed LESA for 'Lepton-number Emission Self-sustained Asymmetry'. While the individual ν {sub e} and ν-bar {sub e} fluxes show a pronounced dipole pattern, the heavy-flavor neutrino fluxes and the overall luminosity are almost spherically symmetric. Initially, LESA seems to develop stochastically from convective fluctuations. It exists for hundreds of milliseconds or more and persists during violent shock sloshing associated with the standing accretion shock instability. The ν {sub e} minus ν-bar {sub e} flux asymmetry originates predominantly below the neutrinosphere in a region of pronounced proto-neutron star (PNS) convection, which is stronger in the hemisphere of enhanced lepton-number flux. On this side of the PNS, the mass accretion rate of lepton-rich matter is larger, amplifying the lepton-emission asymmetry, because the spherical stellar infall deflects on a dipolar deformation of the stalled shock. The increased shock radius in the hemisphere of less mass accretion and minimal lepton-number flux ( ν-bar {sub e} flux maximum) is sustained by stronger convection on this side, which is boosted by stronger neutrino heating due to 〈ϵ{sub ν-bar{sub e}}〉>〈ϵ{sub ν{sub e}}〉. Asymmetric heating thus supports the global deformation despite extremely nonstationary convective overturn behind the shock. While these different elements of the LESA phenomenon form a consistent picture, a full understanding remains elusive at present. There may be important implications for neutrino-flavor oscillations, the neutron-to-proton ratio in the neutrino-heated supernova ejecta, and neutron-star kicks, which remain to be explored.
- OSTI ID:
- 22365141
- Journal Information:
- Astrophysical Journal, Vol. 792, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ASYMMETRY
DEFORMATION
DIPOLES
EMISSION
ENERGY DEPENDENCE
FLAVOR MODEL
HYDRODYNAMICS
INSTABILITY
LEPTON NUMBER
LUMINOSITY
NEUTRINOS
NEUTRON STARS
OSCILLATIONS
SIMULATION
SPHERICAL CONFIGURATION
STOCHASTIC PROCESSES
SUPERNOVAE
SYMMETRY BREAKING
THREE-DIMENSIONAL CALCULATIONS