Excitation of Multi-periodic Kink Motions in Solar Flare Loops: Possible Application to Quasi-periodic Pulsations

TL;DR

This study uses 3D MHD simulations and microwave modeling to explore how kink-like motions in solar flare loops can produce observable quasi-periodic pulsations, highlighting the role of leaky kink modes in short-period QPPs.

Contribution

It introduces the first detailed simulation linking kink-like MHD waves to observable microwave QPPs, emphasizing the significance of leaky kink modes.

Findings

Two periodicities are generated: 57s and 5.8s.

Microwave oscillations are detectable in some viewing angles.

Leaky kink modes may explain short-period QPPs.

Abstract

Magnetohydrodynamic (MHD) waves are often invoked to interpret quasi-periodic pulsations (QPPs) in solar flares. We study the response of a straight flare loop to a kink-like velocity perturbation using three-dimensional MHD simulations and forward model the microwave emissions using the fast gyrosynchrotron code. Kink motions with two periodicities are simultaneously generated,with the long-period component P_L = 57s being attributed to the radial fundamental kink mode and the short-period component P_S=5.8s to the first leaky kink mode. Forward modeling results show that the two-periodic oscillations are detectable in the microwave intensities for some lines of sight. Increasing the beam size to (1")^2 does not wipe out the microwave oscillations. We propose that the first leaky kink mode is a promising candidate mechanism to account for short-period QPPs. Radio telescopes with high spatial resolutions can help distinguish between this new mechanism with such customary interpretations as sausage modes.