The Role of Magnetic Topology in the Heating of Active Region Coronal Loops

TL;DR

This study explores how magnetic field topology influences coronal loop heating, revealing that transient brightenings are linked to separator regions with high free energy, while steady loops are located elsewhere, suggesting different heating mechanisms.

Contribution

It introduces new modeling techniques to connect magnetic topology with coronal heating patterns, highlighting the role of separators and free energy in transient versus steady emissions.

Findings

Loops with transient brightenings are in separator-rich, high free energy regions.

Steady emission loops are outside separator domains, indicating different heating processes.

Separator regions with high free energy correlate with impulsive heating events.

Abstract

We investigate the evolution of coronal loop emission in the context of the coronal magnetic field topology. New modeling techniques allow us to investigate the magnetic field structure and energy release in active regions. Using these models and high resolution multi-wavelength coronal observations from the Transition Region and Coronal Explorer (TRACE) and the X-ray Telescope (XRT) on Hinode, we are able to establish a relationship between the light curves of coronal loops and their associated magnetic topologies for NOAA Active Region 10963. We examine loops that show both transient and steady emission, and we find that loops that show many transient brightenings are located in domains associated with a high number of separators. This topology provides an environment for continual impulsive heating events through magnetic reconnection at the separators. A loop with relatively constant X-ray and EUV emission, on the other hand, is located in domains that are not associated with separators. This result implies that larger-scale magnetic field reconnections are not involved in heating plasma in these regions, and the heating in these loops must come from another mechanism, such as small-scale reconnections (i.e., nanoflares) or wave heating. Additionally, we find that loops that undergo repeated transient brightenings are associated with separators that have enhanced free energy. In contrast, we find one case of an isolated transient brightening that seems to be associated with separators with a smaller free energy.