Spatial variation of periods of ion and neutral waves in a solar magnetic arcade

TL;DR

This study uses numerical simulations to analyze how ion and neutral waves propagate in a solar magnetic arcade, revealing how magnetic field configuration influences wave periods in the lower solar atmosphere.

Contribution

It provides new insights into the impact of magnetic field geometry on wave periods in a partially-ionized solar atmosphere using a two-fluid simulation approach.

Findings

Ion and neutral waves have periods of 250-350 s in the photosphere.

Wave periods depend on magnetic field configuration in the chromosphere.

Prominent wave periods are 180 s, 220 s, and 300 s in the arcade.

Abstract

We present a new insight into the propagation of ion magnetoacoustic and neutral acoustic waves in a magnetic arcade in the lower solar atmosphere. By means of numerical simulations, we aim to: (a) study two-fluid waves propagating in a magnetic arcade embedded in the partially-ionized, lower solar atmosphere; and (b) investigate the impact of the background magnetic field configuration on the observed wave-periods. We consider a 2D approximation of the gravitationally stratified and partially-ionized lower solar atmosphere consisting of ion+electron and neutral fluids that are coupled by ion-neutral collisions. In this model, the convection below the photosphere is responsible for the excitation of ion magnetoacoustic-gravity and neutral acoustic-gravity waves. We find that in the solar photosphere, where ions and neutrals are strongly coupled by collisions, ion magnetoacoustic-gravity and neutral acoustic-gravity waves have periods ranging from 250 s to 350 s. In the chromosphere, where the collisional coupling is weak, the wave characteristics strongly depend on the magnetic field configuration. Above the foot-points of the considered arcade, the plasma is dominated by a vertical magnetic field along which ion magnetoacoustic-gravity waves propagate. These waves exhibit a broad range of periods with the most prominent periods of 180 s, 220 s, and 300 s. Above the main loop of the solar arcade, where mostly horizontal magnetic field lines guide ion magnetoacoustic-gravity waves, the main spectral power reduces to the period of about 180 s and longer wave-periods do not exist. Our results are in agreement with the recent observational data reported by Wi\'sniewska et al. (2016) and Kayshap et al. (2018).