Kinetic Simulation of Slow Magnetosonic Waves and Quasi-periodic Upflows in the Solar Corona

TL;DR

This paper presents a kinetic simulation model combining slow magnetosonic waves and beam flows to explain observed quasi-periodic disturbances in the solar corona, highlighting the role of Landau resonance and damping mechanisms.

Contribution

The study introduces a novel 'wave + flow' kinetic model that explains coronal disturbances through Landau resonance and wave damping, differing from previous purely MHD interpretations.

Findings

Weak periodic beam flows are generated via Landau resonance.

Slow waves damp to 1/e after two periods due to Landau damping and Coulomb collisions.

The phase difference between strongest blue asymmetry and blueshift is about 1/4 period.

Abstract

Quasi-periodic disturbances of emission-line parameters are frequently observed in the corona. These disturbances propagate upward along the magnetic field with speeds $\sim100~\rm{km~s}^{-1}$. This phenomenon has been interpreted as evidence of the propagation of slow magnetosonic waves or argued to be signature of the intermittent outflows superposed on the background plasmas. Here we aim to present a new "wave + flow" model to interpret these observations. In our scenario, the oscillatory motion is a slow mode wave, and the flow is associated with a beam created by the wave-particle interaction owing to Landau resonance. With the help of a Vlasov model, we simulate the propagation of the slow mode wave and the generation of the beam flow. We find that weak periodic beam flows can be generated owing to Landau resonance in the solar corona, and the phase with strongest blueward asymmetry is ahead of that with strongest blueshift by about 1/4 period. We also find that the slow wave damps to the level of 1/e after the transit time of two wave periods, owing to Landau damping and Coulomb collisions in our simulation. This damping time scale is similar to that resulting from thermal-conduction in the magnetohydrodynamics regime. The beam flow is weakened/attenuated with increasing wave period and decreasing wave amplitude since Coulomb collision becomes more and more dominant over the wave action. We suggest that this "wave + flow" kinetic model provides an alternative explanation for the observed quasi-periodic propagating perturbations in various parameters in the solar corona.