Studying 3D reconnection heating in the solar corona via gyrokinetic simulation

Coronal heating has been known to exist since the start of the 20th century, however, its exact mechanism has not been fully understood. One promising candidate is reconnection turbulence, driven by tearing modes arising from current sheets. In order to capture the kinetic properties of reconnection turbulence, previous work used the gyrokinetic framework to model 2D reconnection in the corona. Here, we construct a 3D loop geometry and simulate with hydrogen mass ratio and realistic coronal β to verify earlier 2D extrapolations with both linear and nonlinear simulations.

Linear studies show a difference of reconnection rates between 3D loop geometry, 3D slab geometry, and 2D slab geometry. The reconnection rates in these geometries are found to have γ_3D,loop<γ_2D<γ_3D,slab. While curvature stabilizes reconnection, parallel streaming can enhance it. Heating rates obtained from 3D nonlinear simulations with realistic field-line twist q=4 and q=3 are found to be consistent with the observed as well as 2D-extrapolated heating rates. In 3D, the parallel electric field is mostly electrostatic, unlike in the 2D case. Flux-rope merging events are also observed in the 3D nonlinear simulation; analysis of mergers are shown and compared with their counterpart in the 2D simulations.