Simulations of longitudinal oscillations in flaring coronal loops observed with SDO/AIA

Abstract:

Longitudinal intensity oscillations generated in flare-heated coronal loops were recently observed with SDO/AIA in 94 Å and 131 Å channels. These oscillations have been interpreted as standing or reflected propagating slow magnetoacoustic waves. They are mostly triggered by a circular-ribbon flare located at one footpoint of the loop, which may be associated with a fan-spine magnetic topology. The propagation, damping, and excitation mechanisms of such slow-mode waves in flaring loops are still poorly understood. Recent studies based on linear theory and 1D MHD simulations have demonstrated the determination of effective transport coefficients from observed oscillations by coronal seismology techniques (Wang et al 2015, 2018, 2019). Evidence for thermal conduction suppression and compressive viscosity enhancement has been found with this technique. The presence of anomalous transport processes in hot flaring plasma may help shed light on the wave excitation mechanism and long-standing puzzles such as long-duration EUV/X-ray flares. In this presentation, we report on the analyzed results for seven new oscillation events observed with SDO/AIA. By simulating the propagation of slow waves in a 2D and 3D MHD model of hot AR loop constrained by observations, we explore the effect of modified transport coefficients on the wave excitation and damping. We also study the effect of modified transport coefficients on the thermal evolution of a heated loop using a field-aligned HD model.