期刊
ASTROPHYSICAL JOURNAL
卷 881, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/ab275c
关键词
convection; hydrodynamics; instabilities; methods: numerical; neutrinos; supernovae: general
资金
- European Research Council through grant ERC-AdG [341157-COCO2CASA]
- Deutsche Forschungsgemeinschaft [Sonderforschungbereich SFB 1258]
- Excellence Cluster Universe [EXC 153]
- Special Postdoctoral Researchers (SPDR) program
- iTHEMS cluster at RIKEN
- Leibniz Supercomputing Centre (LRZ) [pr62za]
A set of eight self-consistent, time-dependent supernova (SN) simulations in three spatial dimensions (3D) for 9 and 20 M-circle dot progenitors is evaluated for the presence of dipolar asymmetries of the electron lepton-number emission as discovered by Tamborra et al. and termed lepton-number emission self-sustained asymmetry (LESA). The simulations were performed with the AENUS-ALCAR neutrino/ hydrodynamics code, which treats the energy-and velocity-dependent transport of neutrinos of all flavors by a two-moment scheme with algebraic M1 closure. For each of the progenitors, results with fully multidimensional (FMD) neutrino transport and with ray-by-ray-plus (RbR+) approximation are considered for two different grid resolutions. While the 9 M-circle dot models develop explosions, the 20 M-circle dot progenitor does not explode with the employed version of simplified neutrino opacities. In all 3D models we observe the growth of substantial dipole amplitudes of the lepton-number (electron neutrino minus antineutrino) flux with stable or slowly time-evolving direction and overall properties fully consistent with the LESA phenomenon. Models with RbR+ transport develop LESA dipoles somewhat faster and with temporarily higher amplitudes, but the FMD calculations exhibit cleaner hemispheric asymmetries with a far more dominant dipole. In contrast, the RbR+ results display much wider multipole spectra of the neutrino emission anisotropies with significant power also in the quadrupole and higher-order modes. Our results disprove speculations that LESA is a numerical artifact of RbR+ transport. We also discuss LESA as a consequence of a dipolar convection flow inside of the nascent neutron star and establish, tentatively, a connection to Chandrasekhar's linear theory of thermal instability in spherical shells.
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