Exploring the origin of quasi-periodic pulsations during a white-light flare

We explored the origin of quasi-periodic pulsations (QPPs) in multiple wavelengths of a white-light flare, which occurred at the edge of a sunspot group. A short period at about 3 minutes is simultaneously observed in wavebands of HXR, microwave, and Lyα during the flare impulsive phase. The onset of flare QPPs is almost simultaneous with the start of magnetic cancellation between positive and negative fields, indicating that it is most likely triggered by accelerated electrons that are associated with periodic magnetic reconnections. A long period at about 8 minutes is only detected in the white-light emission, suggesting the presence of cutoff frequency. The similar periods of 3 and 8 minutes are measured at the umbra and penumbra in the adjacent sunspot. Moreover, the NLFFF extrapolation results suggest that the flare area and sunspots are connected by the magnetic field lines. Our observations support the scenario that the short-period QPP is modulated by the slow magnetoacoustic wave originating from the sunspot umbra, while the long-period QPP is probably modulated by the slow-mode magnetoacoustic gravity wave leaking from the sunspot penumbra.