Three-dimensional Magnetohydrodynamic Shocks and Associated Plasma Heating in the Solar Atmosphere

Abstract

We investigate the three-dimensional (3D) formation and evolution of magnetohydrodynamic (MHD) shock waves and their role in plasma heating within a solar bipolar active region. Using 3D compressible, resistive MHD simulations, we model the emergence of magnetic flux from the convection zone into a magnetized corona. Our results reveal that initial plasmoid ejections launch hot plasma jets preceded by slow-mode shocks. Unlike established 2D models, these ejections originate from multiple sites along the emerging field's periphery, resulting in shocks with a complex, inverted-U 3D morphology. Beneath these fronts, the heated plasma forms flattened, sheet-like columns. Furthermore, we find that sustained gas pressure gradients, driven by dense plasma accumulation from plasmoids, power a cool, dense upflow adjacent to the main reconnection jet. During the main reconnection phase, the collision of ejected plasmoids with the ambient field triggers the formation of fast-mode termination shocks. By mapping viscous heating directly onto these irregular 3D shock surfaces, we demonstrate that energy dissipation is highly localized. This finding provides a physical link between shock-induced viscous heating and the observed temperature enhancements at the apex of post-flare loops.