GENERAL-RELATIVISTIC SIMULATIONS OF THREE-DIMENSIONAL CORE-COLLAPSE SUPERNOVAE

Abstract

We study the three-dimensional (3D) hydrodynamics of the post-core-bounce\nphase of the collapse of a 27-solar-mass star and pay special attention to the\ndevelopment of the standing accretion shock instability (SASI) and\nneutrino-driven convection. To this end, we perform 3D general-relativistic\nsimulations with a 3-species neutrino leakage scheme. The leakage scheme\ncaptures the essential aspects of neutrino cooling, heating, and lepton number\nexchange as predicted by radiation-hydrodynamics simulations. The 27-solar-mass\nprogenitor was studied in 2D by B. Mueller et al. (ApJ 761:72, 2012), who\nobserved strong growth of the SASI while neutrino-driven convection was\nsuppressed. In our 3D simulations, neutrino-driven convection grows from\nnumerical perturbations imposed by our Cartesian grid. It becomes the dominant\ninstability and leads to large-scale non-oscillatory deformations of the shock\nfront. These will result in strongly aspherical explosions without the need for\nlarge-scale SASI shock oscillations. Low-l-mode SASI oscillations are present\nin our models, but saturate at small amplitudes that decrease with increasing\nneutrino heating and vigor of convection. Our results, in agreement with\nsimpler 3D Newtonian simulations, suggest that once neutrino-driven convection\nis started, it is likely to become the dominant instability in 3D. Whether it\nis the primary instability after bounce will ultimately depend on the physical\nseed perturbations present in the cores of massive stars. The gravitational\nwave signal, which we extract and analyze for the first time from 3D\ngeneral-relativistic models, will serve as an observational probe of the\npostbounce dynamics and, in combination with neutrinos, may allow us to\ndetermine the primary hydrodynamic instability.\n