Kink instabilities in jets from rotating magnetic fields

TL;DR

This study uses advanced simulations to analyze how magnetic field-driven jets from rotating sources develop kink instabilities, revealing the influence of rotation profiles and jet expansion on instability growth.

Contribution

It provides new insights into the development of kink instabilities in astrophysical jets driven by large-scale magnetic fields, highlighting the effects of rotation profiles and jet expansion.

Findings

Kink instabilities depend on the base velocity profile.

Rigid rotation induces shearless magnetic fields, amplifying instabilities.

Jet expansion limits the growth of Alfven mode instabilities.

Abstract

We have performed 2.5D and 3D simulations of conical jets driven by the rotation of an ordered, large-scale magnetic field in a stratified atmosphere. The simulations cover about three orders of magnitude in distance to capture the centrifugal acceleration as well as the evolution past the Alfven surface. We find that the jets develop kink instabilities, the characteristics of which depend on the velocity profile imposed at the base of the flow. The instabilities are especially pronounced with a rigid rotation profile, which induces a shearless magnetic field. The jet's expansion appears to be limiting the growth of Alfven mode instabilities.