Hydrodynamic instabilities in long-term three-dimensional simulations of neutrino-driven supernovae of 13 red supergiant progenitors

Abstract

We present long-term three-dimensional (3D) simulations of Type-IIP supernovae (SNe) for 13 non-rotating, single-star, red-supergiant (RSG) progenitors with zero-age-main-sequence masses between 12.5 M${}_{\odot }$ and 27.3 M${}_{\odot }$. The explosions were modelled with a parametric treatment of neutrino heating to obtain defined energies, ${}^{56}$Ni yields, and neutron-star properties in agreement with previous results. Our 3D SN models were evolved from core bounce until 10 days to study how the large-scale mixing of chemical elements depends on the progenitor structure. Rayleigh-Taylor instabilities (RTIs), which grow at the (C+O)/He and He/H interfaces and interact with the reverse shock forming after the SN shock has passed the He/H interface, play a crucial role in the outward mixing of ${}^{56}$Ni into the hydrogen envelope. We find most extreme ${}^{56}$Ni mixing and the highest maximum ${}^{56}$Ni velocities in lower-mass (LM) explosions despite lower explosion energies, and the weakest ${}^{56}$Ni mixing in the 3D explosions of the most massive RSGs. The efficiency of radial ${}^{56}$Ni mixing anti-correlates linearly with the helium-core mass and correlates positively with the magnitude of a local maximum of $\ddot{I}r^3$ in the helium shell. This maximum causes shock deceleration and therefore facilitates high growth factors of RTI at the (C+O)/He interface in the LM explosions. Therefore fast-moving ${}^{56}$Ni created by the asymmetric neutrino-heating mechanism is carried into the ubiquitous RT-unstable region near the He/H interface and ultimately far into the envelopes of the exploding RSGs. Our correlations may aid improving mixing prescriptions in 1D SN models and deducing progenitor structures from observed SN properties.

29 pages, 20 figures, 5 tables. Submitted to MNRAS