A large scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae

TL;DR

This study uses global 3D GRMHD simulations to show that MRI-driven turbulence in rapidly rotating protoneutron stars can generate large-scale magnetic fields and bipolar outflows, supporting their role in supernovae and gamma-ray bursts.

Contribution

It provides the first global 3D GRMHD simulation evidence that MRI-driven turbulence creates large-scale magnetic fields and outflows in rapidly rotating core-collapse supernovae.

Findings

MRI-driven turbulence produces large-scale ordered magnetic fields.

Bipolar magnetorotational outflows are generated.

Results support progenitor models for supernovae and gamma-ray bursts.

Abstract

Magnetohydrodynamic (MHD) turbulence is of key importance in many high-energy astrophysical systems, where MHD instabilities can amplify local magnetic field over very short time scales. Specifically, the magnetorotational instability (MRI) and dynamo action have been suggested as a mechanism to grow magnetar-strength magnetic field ($\ge10^{15} G$) and magnetorotationally power the explosion of a rotating massive star. Such stars are progenitor candidates for type Ic-bl hypernova explosions and make up all supernovae connected to long gamma-ray bursts (GRBs). The MRI has been studied with local high-resolution shearing box simulations in 3D or with global 2D simulations, but it is an open question whether MRI-driven turbulence can result in the creation of a large-scale ordered and dynamically relevant field. Here we report results from global 3D general-relativistic magnetohydrodynamic (GRMHD) turbulence simulations and show that MRI-driven MHD turbulence in rapidly rotating protoneutron stars produces an inverse cascade of energy. We find a large-scale ordered toroidal field that is consistent with the formation of bipolar magnetorotationally driven outflows. Our results demonstrate that rapidly rotating massive stars are plausible progenitors for both type Ic-bl supernovae and long GRBs, present a viable formation scenario for magnetars, and may account for potentially magnetar-powered superluminous supernovae.