Motion magnification in coronal seismology

TL;DR

This paper presents a novel wavelet-based method for magnifying low-amplitude transverse oscillations in solar plasma features, improving detection and analysis of coronal loop oscillations in imaging data.

Contribution

The introduced dual tree complex wavelet transform method enables effective magnification of transverse motions in solar plasma features, enhancing oscillation detection capabilities.

Findings

Effective magnification of small-amplitude oscillations demonstrated on artificial data.

Method's robustness and independence from oscillation period confirmed.

Application to real solar data improved detection of decay-less oscillations.

Abstract

We introduce a new method for the investigation of low-amplitude transverse oscillations of solar plasma non-uniformities, such as coronal loops, individual strands in coronal arcades, jets, prominence fibrils, polar plumes, and other contrast features, observed with imaging instruments. The method is based on the two-dimensional dual tree complex wavelet transform (DT$\mathbb{C}$WT). It allows us to magnify transverse, in the plane-of-the-sky, quasi-periodic motions of contrast features in image sequences. The tests performed on the artificial data cubes imitating exponentially decaying, multi-periodic and frequency-modulated kink oscillations of coronal loops showed the effectiveness, reliability and robustness of this technique. The algorithm was found to give linear scaling of the magnified amplitudes with the original amplitudes provided they are sufficiently small. Also, the magnification is independent of the oscillation period in a broad range of the periods. The application of this technique to SDO/AIA EUV data cubes of a non-flaring active region allowed for the improved detection of low-amplitude decay-less oscillations in the majority of loops.