Quasi-Periodic Fast-Mode Wave Trains Associated with the 2015-Jun-22 M6.5 Flare in AR~12371: Observations and 3D MHD Modeling

TL;DR

This study combines multi-wavelength solar observations with 3D MHD simulations to understand the excitation and propagation of quasi-periodic fast-mode wave trains associated with a solar flare, revealing their connection to magnetic reconnection and coronal structures.

Contribution

It provides the first detailed modeling of QFP wave trains incorporating realistic coronal magnetic structures and demonstrates the influence of density structuring on wave visibility and behavior.

Findings

QFP wave trains propagate at 1140-1760 km/s following lower-speed EUV waves.

Wave periodicities of 2-4 minutes are linked to flare pulsations and magnetic reconnection.

Coronal density structuring significantly affects wave amplitude and propagation patterns.

Abstract

Quasi-periodic fast-propagating (QFP) wave trains are a distinctive form of magnetohydrodynamic disturbance frequently observed in the solar corona. Yet their excitation mechanism and propagation characteristics are not well understood. In this study, we investigate a well-observed QFP wave event associated with an M6.5-class flare and coronal mass ejection that occurred in active region (AR) 12371 on 2015 June 22 by combining multi-wavelength observations from SDO/AIA and HMI with data-inspired 3D MHD simulations. The QFP wave trains propagating at high speeds of 1140$-$1760 km~s$^{-1}$ are detected in the AIA 171 \AA\ channel, following global EUV wave fronts visible at 171 and 193~\AA\ traveling at considerably lower speeds of 300$-$510 km~s$^{-1}$. Wavelet analysis reveals consistent 2--4 minutes periodicities in both the QFPs and flare quasi-periodic pulsations (QPPs) observed in UV/EUV and hard X-ray emissions, suggesting a common origin likely linked to intermittent magnetic reconnection. Guided by these observations, we construct realistic 3D MHD models incorporating dense fan-loop structures and periodic drivers applied at different locations. The simulations reproduce the key characteristics of the observed wave trains. Comparison between cases with and without a coronal background (non-loop plasma emission) indicates that coronal density structuring significantly modifies the detected wave amplitudes and propagation patterns. Our results highlight the importance of realistic coronal magnetic configurations in modeling QFP dynamics and suggest that their observed association with fan loops in AIA 171 \AA\ may represent a temperature-dependent visibility effect rather than a genuine confinement of the waves.