Excitation and evolution of coronal oscillations in self-consistent 3D radiative MHD simulations of the solar atmosphere

TL;DR

This study uses advanced 3D radiation-MHD simulations to analyze the excitation and evolution of various coronal oscillations, revealing the presence of different oscillation regimes and challenging static loop models.

Contribution

It provides the first self-consistent 3D simulation analysis of coronal oscillations considering realistic magnetic topology and evolution.

Findings

Detection of standing transverse and longitudinal oscillations.

Identification of two regimes of transverse oscillations: rapidly decaying and sustained.

Absence of harmonic drivers at loop footpoints.

Abstract

Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Excitation and evolution of oscillations in coronal loops is typically studied using highly idealised models of magnetic flux-tubes. In order to improve our understanding of coronal oscillations, it is necessary to consider the effect of realistic magnetic field topology and evolution. We study excitation and evolution of coronal oscillations in three-dimensional self-consistent simulations of solar atmosphere spanning from convection zone to solar corona using radiation-MHD code Bifrost. We use forward-modelled EUV emission and three-dimensional tracing of magnetic field to analyse oscillatory behaviour of individual magnetic loops. We further analyse the evolution of individual plasma velocity components along the loops using wavelet power spectra to capture changes in the oscillation periods. Various types of oscillations commonly observed in the corona are present in the simulation. We detect standing oscillations in both transverse and longitudinal velocity components, including higher order oscillation harmonics. We also show that self-consistent simulations reproduce existence of two distinct regimes of transverse coronal oscillations: rapidly decaying oscillations triggered by impulsive events and sustained small-scale oscillations showing no observable damping. No harmonic drivers are detected at the footpoints of oscillating loops. We show that coronal loop oscillations are abundant in self-consistent 3D MHD simulations of the solar atmosphere. The dynamic evolution and variability of individual magnetic loops suggest we need to reevaluate our models of monolithic and static coronal loops with constant lengths in favour of more realistic models.