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Complex dynamical regimes of the Tayler-Spruit dynamo

Paul Barrère1,2,*, Jérôme Guilet2,†, Basile Gallet3,‡, and Raphaël Raynaud4,§

  • *Contact author: paul.barrere@unige.ch
  • †Contact author: jerome.guilet@cea.fr
  • ‡Contact author: basile.gallet@cea.fr
  • §Contact author: raphael.raynaud@cea.fr
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Phys. Rev. Fluids 11, 103704 – Published 26 October, 2026

DOI: https://doi.org/10.1103/xp6d-7gl4

Abstract

Astrophysical dynamos feature various spatial structures and dynamical regimes, ranging from hemispherical magnetic fields to the random reversals of the geodynamo. The Tayler-Spruit dynamo, recently confirmed in direct numerical simulations, has been invoked to explain angular momentum transport in stellar radiative zones and magnetar formation in a proto-neutron star spun up by fallback accretion. Whether this dynamo mechanism can lead to different dynamical regimes remains an open question. Using three-dimensional direct numerical simulations, we model the dynamics of a stably stratified spherical Couette flow, with the outer sphere rotating faster than the inner one. While the generation of strong stationary and hemispherical dynamos has been observed in our previous studies, we report the existence of reversals and complex temporal dynamics. We observe that the dynamics is strongly correlated with the equatorial symmetry breaking of the flow. Focusing on a fiducial dynamo simulation, we propose an interpretation of its dynamics that consists of the coupling of two large-scale magnetic modes with opposite equatorial symmetries by the flow symmetry breaking. While this interpretation captures the simplest observed dynamics, the nonlinear interaction between a higher number of magnetic modes is certainly required to describe more complex regimes. The wide diversity of dynamical regimes generated by the Tayler-Spruit dynamo may have interesting implications for the geometry of the neutron star magnetic fields, and therefore neutron star emissions.

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Phys. Rev. Fluids 11, 103704– Published 26 October, 2026
  • Received 10 December 2025
  • Accepted 24 September 2026
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