Abstract:
The paper seeks to explore the initiation of an X1.8 class solar flare (SOL2024-10-09T0125) and the related quasi-periodic pulsations (QPPs), which are situated within NOAA active region 13848. To achieve this, we perform a multi-wavelength analysis of the event utilizing data from the Solar Dynamic Observatory (SDO) and Aditya-L1. Importantly, the observations indicate the emergence of a sigmoidal brightening at the onset of the flare, alongside the evolution of a complex morphology of flare brightenings and ribbons around the peak time of the flare. Furthermore, QPPs are detected during the impulsive phase of the flare, exhibiting a dominant period of approximately 4 minutes in the hard X-ray light curve. In order to comprehend the initiation of the flare, we construct the coronal magnetic field at a pre-flare stage by employing the non-force-free-field (NFFF) extrapolation model. The extrapolated magnetic field illustrates the existence of various significant magnetic features, including a magnetic flux rope, a three-dimensional (3D) null, sheared arcade, and quasiseparatrix layers (QSLs) within the flaring region. The recurrent reconnection occurring at these features is proposed to play a role in the initiation of the flare as well as the associated QPPs.
