Three-dimensional simulations of core-collapse supernovae: from shock revival to shock breakout

Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching, Germany
e-mail: annop@mpa-garching.mpg.de

Received: 18 September 2014
Accepted: 5 February 2015

Abstract

We present three-dimensional hydrodynamic simulations of the evolution of core-collapse supernovae (SN) from blast-wave initiation by the neutrino-driven mechanism to shock breakout from the stellar surface, using an axis-free Yin-Yang grid and considering two 15 M_⊙ red supergiants (RSG) and two blue supergiants (BSG) of 15 M_⊙ and 20 M_⊙. We demonstrate that the metal-rich ejecta in homologous expansion still carry fingerprints of asymmetries at the beginning of the explosion, but the final metal distribution is massively affected by the detailed progenitor structure. The most extended and fastest metal fingers and clumps are correlated with the biggest and fastest-rising plumes of neutrino-heated matter, because these plumes most effectively seed the growth of Rayleigh-Taylor (RT) instabilities at the C+O/He and He/H composition-shell interfaces after the passage of the SN shock. The extent of radial mixing, global asymmetry of the metal-rich ejecta, RT-induced fragmentation of initial plumes to smaller-scale fingers, and maximum Ni and minimum H velocities depend not only on the initial asphericity and explosion energy (which determine the shock and initial Ni velocities), but also on the density profiles and widths of C+O core and He shell and on the density gradient at the He/H transition, which leads to unsteady shock propagation and the formation of reverse shocks. Both RSG explosions retain a large global metal asymmetry with pronounced clumpiness and substructure, deep penetration of Ni fingers into the H-envelope (with maximum velocities of 4000–5000 km s^-1 for an explosion energy around 1.5 bethe) and efficient inward H-mixing. While the 15 M_⊙ BSG shares these properties (maximum Ni speeds up to ~3500 km s^-1), the 20 M_⊙ BSG develops a much more roundish geometry without pronounced metal fingers (maximum Ni velocities only ~2200 km s^-1) because of reverse-shock deceleration and insufficient time for strong RT growth and fragmentation at the He/H interface.