The magnetorotational instability as a jet launching mechanism

TL;DR

This paper demonstrates that large-scale magnetorotational instability modes in strongly magnetized discs can naturally generate magnetically driven outflows, linking turbulence and jet launching mechanisms in astrophysical accretion discs.

Contribution

It reveals a direct connection between MRI turbulence and jet launching, showing that MRI modes can produce outflows similar to disc winds, a novel insight into disc-jet physics.

Findings

MRI modes produce outflows in strongly magnetized discs

Outflows share characteristics with known disc wind solutions

Outflows are dynamically unstable in 3D simulations

Abstract

Magnetorotational turbulence and magnetically driven disc winds are often considered as separate processes. However, realistic astrophysical discs are expected to be subject to both effects, although possibly at different times and locations. We investigate here the potential link between these two phenomena using a mixed numerical and analytical approach. We show in particular that large-scale MRI modes which dominate strongly magnetised discs (plasma beta~10) naturally produce magnetically driven outflows in the nonlinear regime. We show that these outflows share many similarities with local and global disc wind solutions found in the literature. We also investigate the 3D stability of these outflows and show that they are unstable on dynamical timescales. The implications of these results for the transition between a jet-emitting disc and a standard "viscous" disc are discussed.