Effect of magnetically dependent heating on the behaviour of magnetoacoustic waves in coronal plasma with thermal misbalance

Abstract

ABSTRACT The magnetic nature of coronal heating has been actively investigated within the framework of theoretical models and statistical analysis of observational data for decades. At present, a rather wide range of possible mechanisms has been proposed in the literature that requires additional verification. In this paper, we investigate the possibility of analysing the magnetic nature of coronal heating by means of magnetoacoustic (MA) waves propagating in coronal structures. To address this issue, we perform the analysis of fast and slow waves using a magnetic slab geometry. Applying the assumption of strong magnetic structuring, we derive the dispersion relation, which allows us to study the properties of MA waves. To analyse the dependence of phase velocity and wave decrement/increment on wavenumber, we numerically solved the obtained equations using the parameters corresponding to ‘warm’ coronal loop. It is shown that oscillations on the fundamental harmonic in a plasma with a weak magnetic field, where the effect of phase velocity dispersion is most pronounced, are best suited for diagnostics of magnetic heating using slow MA waves. In turn, the geometry remains the primary source for fast MA wave dispersion. Magnetic heating can either suppress or increase the damping of fast and slow MA waves. Moreover, the amplification of fast MA waves accompanied by damping of slow MA waves can be achieved. This issue is of interest in the context of the excitation of the decayless kink oscillations in the solar coronal loops.