# MHD simulations of coronal supra-arcade downflows including anisotropic thermal conduction

## TL;DR

This study uses MHD simulations including anisotropic thermal conduction to investigate the evolution and lifetime of coronal supra-arcade downflows, revealing conditions under which they can persist longer in turbulent, magnetized plasma.

## Contribution

It systematically incorporates anisotropic thermal conduction into MHD simulations of SADs, exploring how turbulence and magnetic field configurations affect their longevity.

## Key findings

- Thermal conduction can prevent SADs from vanishing if magnetic fields enclose cavities.
- Turbulence parameters influence whether SADs are thermally isolated or dissipate.
- Kelvin-Helmholtz instabilities and magnetic islands extend SADs' lifetime.

## Abstract

Coronal supra-arcade downflows (SADs) are observed as dark trails descending towards hot turbulent fan shaped regions. Due to the large temperature values, and gradients in these fan regions the thermal conduction should be very efficient. While several models have been proposed to explain the triggering and the evolution of SADs, none of these scenarios address a systematic consideration of thermal conduction. Thus, we accomplish this task numerically simulating the evolution of SADs within this framework. That is, SADs are conceived as voided (subdense) cavities formed by non-linear waves triggered by downflowing bursty localized reconnection events in a perturbed hot fan. We generate a properly turbulent fan, obtained by a stirring force that permits control of the energy and vorticity input in the medium where SADs develop. We include anisotropic thermal conduction and consider plasma properties consistent with observations. Our aim is to study if it is possible to prevent SADs to vanish by thermal diffusion. We find that this will be the case, depending on the turbulence parameters. In particular, if the magnetic field lines are able to envelope the voided cavities, thermally isolating them from the hot environment. Velocity shear perturbations that are able to generate instabilities of the Kelvin-Helmholtz type help to produce magnetic islands, extending the life-time of SADs.