Identifying Alfvén wave modes in the solar corona

Abstract

Context. Oscillations are observed to be pervasive throughout the solar corona, however, positively identifying different wave modes remains challenging. Improving this identification would provide a powerful tool for investigating coronal wave heating and improving seismological inversions. Aims. To establish whether theoretical methods used to identify MHD wave modes in numerical simulations can be employed on observational datasets. Methods. We apply wave identifiers based on fundamental wave characteristics such as compressibility and direction of propagation to a fully 3D numerical simulation of a transversly oscillating coronal loop. The same wave identifiers are applied to the line-of-sight integrated synthetic emission derived from the numerical simulation data to investigate whether this method could feasibly be useful for observational studies. Results. We established that, for particular line(s)-of-sight and assumptions about the magnetic field, we can correctly identify properties of the Alfvén mode in synthetic observations of a transversely oscillating loop. Under suitable conditions, we find strong agreement between the simulation and synthetic emission results. Conclusions. For the first time, we have provided a proof-of-concept that this theoretically-derived classification of MHD wave modes, can be applied to observational data.