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Solar flares often display pulsating and oscillatory signatures in theemission, known as quasi-periodic pulsations (QPP). QPP are typicallyidentified during the impulsive phase of flares, yet in some cases, theirpresence is detected late into the decay phase. Here, we report extensive finestructure QPP that are detected throughout the large X8.2 flare from 2017September 10. Following the analysis of the thermal pulsations observed in theGOES/XRS and the 131 A channel of SDO/AIA, we find a pulsation period of ~65 sduring the impulsive phase followed by lower amplitude QPP with a period of~150 s in the decay phase, up to three hours after the peak of the flare. Wefind that during the time of the impulsive QPP, the soft X-ray source observedwith RHESSI rapidly rises at a velocity of approximately 17 km/s following theplasmoid/coronal mass ejection (CME) eruption. We interpret these QPP in termsof a manifestation of the reconnection dynamics in the eruptive event. Duringthe long-duration decay phase lasting several hours, extended downwardcontractions of collapsing loops/plasmoids that reach the top of the flarearcade are observed in EUV. We note that the existence of persistent QPP intothe decay phase of this flare are most likely related to these features. TheQPP during this phase are discussed in terms of MHD wave modes triggered in thepost-flaring loops.

Persistent Quasi-Periodic Pulsations During a Large X-Class Solar Flare