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

Abstract

Temporal and spectral characteristics of X-ray emission from 60 flares of intensity ≥C class observed by Solar X-ray Spectrometer (SOXS) during 2003-2011 are presented.We analyse the X-ray emission observed in four and three energy bands by the Si and 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 to energy band, which is indicative of its energyindependent nature. Moreover, magnetic field complexity of the flaring region is found to be 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 the 25-30 keV decreases with increasing energy suggesting conduction cooling to be dominant in the lower energies. Analysis of 340 spectra from 14 flares reveals that the peak of Differential Emission Measure (DEM) evolution delays 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 energy dependent as well as magnetic field configuration of the active region.

Call and Response: A Time-resolved Study of Chromospheric Evaporation in a Large Solar Flare

“…Spectra were fit using a methodology similar to that adopted by Milligan et al (2014). The thermal portion of the RHESSI spectrum was best fit by a multithermal model, similar to studies by Aschwanden (2007), Battaglia et al (2015), and Choithani et al (2018). The multithermal model selected was characterized by a power-law differential emission measure (DEM) between a fixed minimum plasma temperature (0.5 keV) and a variable maximum plasma temperature.…”