A Statistical Investigation of the Neupert Effect in Solar Flares Observed with ASO-S/HXI

The Neupert effect refers to the strong correlation between the soft X-ray (SXR) light curve and the time-integrated hard X-ray (HXR) or microwave flux, which is frequently observed in solar flares. In this article, we therefore utilized the newly launched Hard X-ray Imager (HXI) on board the Advanced Space-based Solar Observatory to investigate the Neupert effect during solar flares. By checking the HXR light curves at 20 – 50 keV, a sample of 149 events that cover the flare impulsive phase were selected. Then, we performed a crosscorrelation analysis between the HXR fluence (i.e., the time integral of the HXR flux) and the SXR 1 – 8 Å flux measured by the Geostationary Operational Environmental Satellite. All the selected flares show high correlation coefficients (>0.90), which seem to be independent of the flare location and class. The HXR fluences tend to increase linearly with the SXR peak fluxes. Our observations indicate that all the selected flares obey the Neupert effect.