Long-time 3D supernova simulations of non-rotating progenitors with magnetic fields

TL;DR

This study conducts 3D MHD simulations of non-rotating supernova progenitors, finding magnetic fields influence explosion energies and neutron star properties, but do not dominate the explosion mechanism or cause spin-kick alignment.

Contribution

First 3D MHD simulations of non-rotating supernova progenitors across a range of masses, analyzing magnetic effects on explosion dynamics and neutron star characteristics.

Findings

Four out of five models produce explosions.

Magnetic fields reach only about 1% of kinetic energy in the gain region.

Extrapolated neutron star spins are consistent with observations.

Abstract

We perform five 3D magnetohydrodynamic (MHD) core-collapse supernova simulations for non-rotating progenitors between 9.5 $M_\odot$ and 24 $M_\odot$. Four of the five models produce explosions while one fails. The exploding models are extended to between 0.9 s and 1.6 s post-bounce to study a possible impact of magnetic fields on explosion and remnant properties. Diagnostic explosion energies grow at a similar pace as in previous non-magnetic models. They reach between 0.11 foe and 0.61 foe, but are still growing by the end of the simulations. Neutron star kicks reach no more than 300 km s$^{-1}$, and although these are also still growing, they are unlikely to be in conflict with observed pulsar velocities. Extrapolated neutron star spin periods are between 45 ms and 1.8 s, consistent with observed birth spin rates. Magnetic torques only contribute about 10% to the spin-up of the neutron star. The inclusion of magnetic fields does not provide a mechanism for spin-kick alignment in our simulations. Surface dipole fields are in the range of $10^{12}-10^{13}$ G, much smaller than the root-mean-square field strength. Different from previous simulations, magnetic fields in the gain region only reach at most O(1%) of kinetic equipartition, likely because relatively early shock revival cuts off accretion as a power source for field amplification, which appears to be driven primarily by shear flows at the bottom of the gain region.