Localization of quasi-periodic pulsations in hard X-ray, microwave and Lya emissions from an X6.4 flare

arXiv:2408.05463v1 Announcement Type: new Abstract: We report simultaneous observations of quasi-periodic pulsations (QPPs) in the hard X-ray (HXR), microwave, Ly{\alpha}, and ultraviolet (UV) emission wavelengths during the impulsive phase of an X6.4 flare on 2024 February 22 (SOL2024-02-22T22:08). The X6.4 flare shows three successive, repetitive pulsations in the HXR and microwave wavebands, and they have extremely large modulation depth. The onset of the flare QPPs is nearly simultaneous with the onset of magnetic cancellation between the positive and negative fields. Wavelet power spectra suggest the presence of double periods, centered at about 200 s and 95 s, respectively. Long-period QPPs can also be detected in the Ly$\alpha$ and UV wavebands in the flare area, and they could be observed in the adjacent sunspot. Our observations indicate that the flare QPPs are most likely triggered by accelerated electrons associated with periodic magnetic reconnections. The long period of about 200 s is probably modulated by the slow magnetoacoustic wave from the neighboring sunspot, while the short period of about 95 s could be considered as its second harmonic mode.