Three-dimensional simulations of SASI- and convection-dominated core-collapse supernovae

We investigate the effect of dimensionality on the transition to explosion in neutrino-driven core-collapse supernovae. Using parametrized hydrodynamic simulations of the stalled supernova shock in one, two (2D), and three spatial dimensions (3D), we systematically probe the extent to which hydrodynamic instabilities alone can tip the balance in favour of explosion. In particular, we focus on systems that are well into the regimes where the standing accretion shock instability (SASI) or neutrino-driven convection dominates the dynamics. We find that SASI-dominated models can explode with up to ∼20 per cent lower neutrino luminosity in 3D than in 2D, with the magnitude of this difference decreasing with increasing resolution. This improvement in explosion conditions is related to the ability of spiral modes to generate more non-radial kinetic energy than a single sloshing mode, increasing the size of the average shock radius, and hence generating better conditions for the formation of large-scale, high-entropy bubbles. In contrast, convection-dominated explosions show a smaller difference in their critical heating rate between 2D and 3D (<8 per cent), in agreement with previous studies. The ability of our numerical implementation to maintain arbitrary symmetries is quantified with a set of SASI-based tests. We discuss implications for the diversity of explosion paths in a realistic supernova environment.