Competition between shock and turbulent heating in coronal loop system

TL;DR

This study uses high-resolution 2.5D MHD simulations to investigate the dominant heating mechanisms in coronal loops, revealing a shift from shock to turbulence heating above the magnetic canopy, with implications for solar chromosphere models.

Contribution

It demonstrates the spatial resolution dependence of coronal heating mechanisms and highlights the transition from shock to turbulence heating across the magnetic canopy.

Findings

Shock heating dominates below the magnetic canopy.

MHD turbulence provides significant heating above the canopy.

Temperature at loop top increases with spatial resolution.

Abstract

2.5-dimensional magnetohydrodynamic (MHD) simulations are performed with high spatial resolution in order to distinguish between competing models of the coronal heating problem. A single coronal loop powered by Alfv\'{e}n waves excited in the photosphere is the target of the present study. The coronal structure is reproduced in our simulations as a natural consequence of the transportation and dissipation of Alfv\'{e}n waves. Further, the coronal structure is maintained as the spatial resolution is changed from 25 to 3 km, although the temperature at the loop top increases with the spatial resolution. The heating mechanisms change gradually across the magnetic canopy at a height of 4 Mm. Below the magnetic canopy, both the shock and the MHD turbulence are dominant heating processes. Above the magnetic canopy, the shock heating rate reduces to less than 10 % of the total heating rate while the MHD turbulence provides significant energy to balance the radiative cooling and thermal conduction loss or gain. The importance of compressibility shown in the present study would significantly impact on the prospects of successful MHD turbulence theory in the solar chromosphere.