Year: 2026
Type: preprint
Abstract: Magnetic switchbacks are mostly Alfvénic local deflections, or even reversals, of the ambient magnetic field of the solar wind. Despite intense research their origin remains unclear and is highly debated. Here we describe a new simulation study demonstrating how torsional Alfvén waves can evolve into switchbacks. We use surface rotational motions to launch torsional Alfvén waves into the super-radially expanding magnetic field of a coronal hole. The simulations demonstrate that in such an expanding wind, the waves initially steepen as they propagate while also inducing a cylindrical parallel plasma jet. A combination of shear from the jet and wave evolution under the constraint of approximate spherical polarisation ($|\mathbf{B}|\approx const.$) then leads to the formation of switchbacks in a ring configuration. We explore the 3D nature of the switchbacks, how and where they from, and present scalings for their peak deflection and parallel and perpendicular length scales. We also derive an expression for switchback deflection in the linear regime which we contrast against our results. The results are discussed in relation to recent observations and previous switchback formation studies.
Source: arXiv (Cornell University)
Institutions: Durham University, Sorbonne Université, Instituto de Astrofísica de Canarias, Laboratoire de Physique des Plasmas, Imperial College London, Centre National de la Recherche Scientifique, École Polytechnique, Université Paris-Saclay, Observatoire de Paris, Institut Polytechnique de Paris, University of Otago
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223844544