Magnetoacoustic cutoff effect in numerical simulations of the partially ionized solar atmosphere

Abstract

The cutoff effect is a significant determinant of solar magnetohydrodynamic wave propagation and hence pivotal in energy transfer studies, such as solar plasma heating and seismological diagnostics. Despite continuous efforts, no good agreement between observed waveperiods and theory or numerical simulations was found. Our objective is to investigate the magnetoacoustic cutoff effect in the partially ionized solar atmosphere, factoring in the two-fluid effects. We developed a two-fluid MHD numerical model and used it to simulate a quiet region of the Sun from the top of the convective zone to the low corona. Our findings show that the ongoing granulation excites a wide range of waves propagating into the upper atmospheric layers. The cutoff waveperiods strongly depend on the height. Two-fluid waveperiods obtained with numerical simulations reproduce the recent observations at a very good level of compliance. Furthermore, direct comparison with strongly coupled cases that imitate the single-fluid approximation have shown that the waveperiod propagation pattern is only present in fully two-fluid simulations. We conclude that the presence of neutrals and therefore collisional terms change the dynamics of the magnetized plasma, in comparison with the single-fluid approximation. This effect is more prominently seen in the upper photosphere and chromosphere. This article is part of the theme issue ‘Partially ionized plasma of the solar atmosphere: recent advances and future pathways’.