What are Switchbacks?

TL;DR

This paper introduces a model of Alfvén waves that explains the switchbacks observed by the Parker Solar Probe as resulting from traversals through curved magnetic field lines, revealing their 3D twisting and localized reversals.

Contribution

It presents a novel 3D Alfvén wave model with rotational discontinuities that reproduces observed switchback features in the solar wind.

Findings

Model reproduces large-amplitude field reversals

Switchbacks arise from curved magnetic field segments

Localized reversals match spacecraft observations

Abstract

We present a solitary Alfv\'en wave model that exhibits nontrivial three-dimensional twisting of open magnetic field lines while preserving constant $|B|$. Embedded rotational discontinuities sharply deflect the otherwise uniform field lines, producing localized, large-amplitude field reversals in one-dimensional profiles that closely resemble the ``switchbacks'' observed by the Parker Solar Probe in the inner heliosphere. This indicates that switchbacks, as seen in one-dimensional spacecraft time series, arise from traversals through strongly curved segments of open magnetic field lines.