Excitation of vertical kink waves in a solar coronal arcade loop by a periodic driver

Abstract

Aims. We study an oscillatory driver as a possible excitation mechanism of vertical kink loop oscillations in the ideal MHD regime.Methods. We consider a solar coronal magnetic arcade with a dense photospheric layer. The two-dimensional numerical model that we implement includes the effects of nonlinearity and line curvature on the excitation and attenuation of fast magnetosonic kink waves. We investigate the effects of a driven sinusoidal pressure pulse and compare it with the impulsive excitation by a pressure pulse that impacts the overlying loop.Results. Our numerical simulations reveal wave signatures that are reminiscent of vertical loop oscillations seen in TRACE observational data.Conclusions. We conclude that attenuation of vertical kink oscillations can be reduced to the value observed by adopting an oscillatory instead of an impulsive excitation. An oscillatory driver also naturally explains why only a small subset of all loops is excited to oscillate transversally in an active region.