Study of temporal and spectral characteristics of the X-ray emission from solar flares

Temporal and spectral characteristics of X-ray emission from 60 flares of intensity ≥C class observed by the Solar X-ray Spectrometer(SOXS) during 2003–2011 are presented. We analyze the X-ray emission observed in four and three energy bands by the Si and Cadmium-Zinc-Telluride(CZT)detectors, respectively. The number of peaks in the intensity profile of the flares varies between 1 and 3. We find moderate correlation(R ≈0.2) between the rise time and the peak flux of the first peak of the flare irrespective of energy band, which is indicative of its energy-independent nature. Moreover, the magnetic field complexity of the flaring region is found to be highly anti-correlated(R = 0.61) with the rise time of the flares while positively correlated(R = 0.28) with the peak flux of the flare. The time delay between the peak of the X-ray emission in a given energy band and that in 25–30 keV decreases with increasing energy, suggesting conduction cooling is dominant in the lower energies. Analysis of 340 spectra from 14 flares reveals that the peak of differential emission measure(DEM) evolution is delayed by 60–360 s relative to that of the temperature, and this time delay is inversely proportional to the peak flux of the flare. We conclude that temporal and intensity characteristics of flares are dependent on energy as well as the magnetic field configuration of the active region.