Core collapse with magnetic fields and rotation

TL;DR

This study uses axisymmetric simulations to explore how magnetic fields and rotation influence core collapse in massive stars, revealing conditions that can lead to explosions through magnetic and rotational effects.

Contribution

It demonstrates the role of magnetic fields and rotation in core-collapse supernovae, highlighting the importance of magneto-rotational instability in shock revival.

Findings

Stronger magnetic fields and faster rotation can trigger explosions.

Magnetic fields contribute significantly to shock revival and bipolar outflows.

Magneto-rotational instability amplifies magnetic fields in certain regions.

Abstract

We study the effects of magnetic fields and rotation on the core collapse of a star of an initial mass of M = 20 solar masses using axisymmetric simulations coupling special relativistic magnetohydrodynamics, an approximately relativistic gravitational potential, and spectral neutrino transport. We compare models of the same core with different, artificially added profiles of rotation and magnetic field. A model with weak field and slow rotation does not produce an explosion, while stronger fields and fast rotation open the possibility of explosions. Whereas the neutrino luminosities of the exploding models are the same as or even less than those of the non-exploding model, magnetic fields locally in equipartition with the gas pressure provide a strong contribution to the shock revival and the acceleration of bipolar outflows. Among the amplification processes generating such strong fields, we find the magneto-rotational instability. However, our limited grid resolution allows us to find it only in limited regions of the model with the strongest pre-collapse field ($10^{11}$ G) and fastest rotation.