Letter to the Editor

Localizing short-period pulsations in hard X-rays and γ-rays during an X9.0 flare

Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China

^⋆ Corresponding author; lidong@pmo.ac.cn

Received: 26 December 2024
Accepted: 17 February 2025

Abstract

Context. The feature of quasi-periodic pulsations (QPPs) is frequently observed in the light curve of solar and stellar flares. However, the short-period QPP is rarely reported in the high energy range of hard X-rays (HXRs) and γ-rays.

Aims. We investigated the QPP at a shorter period of about 1 s in high-energy channels of HXRs and γ-ray continuum during an X9.0 flare on October 3, 2024 (SOL2024-10-03T12:08).

Methods. The X9.0 flare was simultaneously measured by the Hard X-ray Imager (HXI), the Konus-Wind (KW), and the Spectrometer/Telescope for Imaging X-rays (STIX). The shorter period was determined by the fast Fourier transform with a Bayesian-based Markov Chain Monte Carlo and the wavelet analysis method. The HXR images were restructured from HXI and STIX observations.

Results. The flare QPP at a shorter period of about 1 s was simultaneously observed in HXI 20–50 keV, 50–80 keV, and 80–300 keV, and KW 20–80 keV, 80–300 keV, and 300–1200 keV during the impulsive phase of the white-light flare. The restructured images show that the HXR sources are mainly separated into two fragments, regarding as double footpoints. Moreover, the footpoints move significantly during the flare QPP. Our results suggest that the intermittent and impulsive energy releases during the powerful flare are mainly caused by the interaction of hot plasma loops that are rooted in double footpoints.

Conclusion. We localized the flare QPP at a shorter period of about 1 s in HXR and γ-ray continuum emissions during a white-light flare, which is well explained by the interacting loop model.