Saturation of the Tayler instability in a rotating, stratified plasma

As stars evolve beyond their core-hydrogen-burning phase, angular momentum conservation forces their contracting cores to spin up and their expanding envelopes to spin down. However, observations show a much smaller core-envelope rotation difference than expected, indicating anomalous transport of angular momentum between the core and envelope. One proposed source of this transport is MHD turbulence driven by the Tayler-Spruit dynamo, which might provide significant transport despite the rotating and strongly stratified nature of these plasmas. However, conflicting reduced models have been put forth to predict the efficiency of this transport and how it varies with properties of the star. These conflicting predictions stem from different assumptions regarding the saturation mechanism of the Tayler instability, a key element of the Tayler-Spruit dynamo.

Here, we present a suite of 3D MHD simulations of the Tayler instability in a rotating, stratified cylinder to model the local dynamics near the rotation axis of a star. To test the assumptions of different reduced models, we investigate how this instability saturates, and how the saturated state varies across different parameter regimes relevant to stellar interiors.