2021ApJ...921..113S

We present three-dimensional simulations of core-collapse supernovae using the FLASH code that follow the progression of the explosion to the stellar surface, starting from neutrino radiation hydrodynamic simulations of the neutrino-driven phase performed with the CHIMERA code. We consider a 9.6 M_☉ zero-metallicity progenitor starting from both 2D and 3D CHIMERA models and a 10 M_☉ solar-metallicity progenitor starting from a 2D CHIMERA model, all simulated until shock breakout in 3D while tracking 160 nuclear species. The relative velocity difference between the supernova shock and the metal-rich Rayleigh-Taylor (R-T) "bullets" determines how the metal-rich ejecta evolves as it propagates through the density profile of the progenitor and dictates the final morphology of the explosion. We find maximum ⁵⁶Ni velocities of ∼1950 and ∼1750 km s^–1 at shock breakout from 2D and 3D 9.6 M_☉ CHIMERA models, respectively, due to the bullets' ability to penetrate the He/H shell. When mapping from 2D, we find that the development of higher-velocity structures is suppressed when the 2D CHIMERA model and 3D FLASH model meshes are aligned. The development of faster-growing spherical-bubble structures, as opposed to the slower-growing toroidal structure imposed by axisymmetry, allows for interaction of the bullets with the shock and seeds further R-T instabilities at the He/H interface. We see similar effects in the 10 M_☉ model, which achieves maximum ⁵⁶Ni velocities of ∼2500 km s^–1 at shock breakout.