Polarization of decayless kink oscillations in a 3D MHD coronal loop model

TL;DR

This study demonstrates the self-consistent emergence of decayless kink oscillations in a 3D MHD coronal loop model, revealing their linear polarization and spontaneous nature, which aids understanding of their driving mechanisms and potential role in coronal heating.

Contribution

First demonstration of decayless kink waves emerging self-consistently in a 3D MHD coronal loop simulation, showing their polarization and spontaneous excitation.

Findings

Oscillations match observed properties.

Oscillations arise spontaneously without external driver.

Exhibit linear polarization with non-aligned oscillation planes.

Abstract

Decayless kink oscillations are frequently observed in solar coronal loops and are considered potential contributors to coronal heating. Despite the ubiquity of this wave phenomenon, its driving mechanism remains unclear. Studies to derive the polarization state of these oscillations, which would be a key to identifying the drivers, have been limited due to observational constraints. We analyze a 3D MHD simulation of coronal loops using the MURaM code. Synthetic extreme ultraviolet (EUV) emission maps, combined with velocity diagnostics, are used to identify and characterize transverse wave motions in the simulated loop structures. This is the first demonstration of decayless kink waves emerging self-consistently in a 3D MHD loop-in-a-box model. The simulation produces persistent, low-amplitude, decayless kink oscillations that closely match observed properties. These oscillations arise spontaneously, without any imposed periodic driver, and exhibit clear linear polarization with oscillation planes not aligned to the principal axes. The observed coherency of linear polarization with oscillation cycles favors a self-sustained or quasi-steady type wave driver over a stochastic or broadband source.