Simulating coronal loop implosion and compressible wave modes in a flare hit active region

TL;DR

This study models the implosion of magnetic loops in solar active regions using 3D ideal magnetohydrodynamics, demonstrating how transmitted disturbances and plasma beta influence loop dynamics and generate observable wave modes.

Contribution

It introduces a simplified 3D MHD simulation approach that isolates the transmitted disturbance to study loop implosion and wave mode generation, aligning well with observational data.

Findings

Simulated loop implosions closely match observed phenomena.

Transmitted disturbances primarily drive the implosion dynamics.

Compressible wave modes like kink and sausage are generated during the process.

Abstract

There is considerable observational evidence of implosion of magnetic loop systems inside solar coronal active regions following high energy events like solar flares. In this work, we propose that such collapse can be modeled in three dimensions quite accurately within the framework of ideal magnetohydrodynamics. We furthermore argue that the dynamics of loop implosion is only sensitive to the transmitted disturbance of one or more of the system variables, e.g. velocity generated at the event site. This indicates that to understand loop implosion, it is sensible to leave the event site out of the simulated active region. Towards our goal, a velocity pulse is introduced to model the transmitted disturbance generated at the event site. Magnetic field lines inside our simulated active region are traced in real time, and it is demonstrated that the subsequent dynamics of the simulated loops closely resemble observed imploding loops. Our work highlights the role of plasma $\beta$ in regards to the rigidity of the loop systems and how that might affect the imploding loops' dynamics. Compressible magnetohydrodynamic modes such as kink and sausage are also shown to be generated during such processes, in accordance with observations.