Exploring the Excitation Sources of Quasi-Periodic Fast-Mode Wave Trains Observed in Solar Eruptive Events

Quasi-periodic, fast-mode propagating (QFP) wave trains are a new phenomenon first discovered by SDO/AIA. The QFP wave trains are closely associated with solar flares and mostly occur during the impulsive phase. Based on observational and theoretical studies two major scenarios have been proposed to interpret the origin of QFPs: periodic driving related to magnetic reconnection and dispersion evolution of broadband perturbation. However, some key questions are still unclear, such as can we distinguish two kinds of excitation mechanisms based on theoretically predicted observables, can we determine in what condition certain mechanism plays a dominant role or both mechanisms may work together, and how we estimate the total energy carried by observed QFP waves. The quantitative answers to these questions are crucial for our developing reliable coronal seismological tools. In this study, we choose to analyze several QFP events that occurred in active regions near the solar disk center so that we can explore their excitation mechanisms based on 3D MHD modeling in a realistic magnetic configuration (e.g., PFSS model calculated from SDO/HMI observations). We set up the AR model including temperature and density structure (e.g., fanlike loops) based on DEM analysis of SDO/AIA images, initially in polytropic equilibrium. We determine the excitation source of observed QFPs by testing various perturbation drivers with different modes (kink or sausage) and different waveforms (periodic or broadband) using resistive 3D MHD code NLRAT by best matching the observed features (periodicities, propagation direction, wave amplitudes, damping, etc.) using forward modeling. Analysis of magnetic topology with SDO/HMI and flare QPPs with RHESSI and Fermi/GBM can provide additional constraints on the location and periodicities of perturbation driver. We also use the AWSoM global MHD model to study the generation and propagation of QFPs by launching a CME that can self-consistently produce an impulsive flare, from which we may determine the dominant source for QFPs origin.