Solar flare catalog from 3 years of Chandrayaan-2 XSM observations

Abstract

We present a catalog of 6266 solar flares detected by the X-Ray Solar Monitor onboard the Chandrayaan-2 lunar orbiter between 1.55 and 12.4 keV (1 and 8 Å) from 2019 September 12 to 2022 November 4, including 1469 type A flares. The catalog represents the first large sample, including both type A, hot thermal flares, and type B, impulsive flares, with a sub-A class sensitive instrument. We also detect 213 sub-A and 1330 A class flares. Individual flares are fit with an exponentially-modified Gaussian function and multi-flare groups are decomposed into individual flares. We validate our findings with flare catalogs made using visual inspection as well as automatic pipelines on Geostationary Operational Environmental Satellite and Solar Dynamics Observatory data. We find a clear bimodality in the ratio of the width to decay time between type A and B flares. We infer a power-law index of ${\alpha }_F=1.92\pm 0.09$ for the background-subtracted peak flux distribution of XSM flares, which is consistent with the value $\sim 2$ reported in the literature. We also infer ${\alpha }_F=1.90\pm 0.09$ for type B, and ${\alpha }_F=1.94\pm 0.08$ for type A flares, which has previously not been reported in the literature. These comparable values hint at a similarity in their generative processes.

29 pages, 15 figures, 5 tables

References in corpus (10)

• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• RHESSI Microflare Statistics II. X-ray Imaging, Spectroscopy & Energy Distributions
• Automated Solar Flare Statistics in Soft X-rays over 37 Years of GOES Observations - The Invariance of Self-Organized Criticality during Three Solar Cycles
• Solar Energetic Particles (Second Edition)
• Risks for life on habitable planets from superflares of their host stars
• The Thermal Properties of Solar Flares Over Three Solar Cycles Using GOES X-ray Observations
• The development of lower-atmosphere turbulence early in a solar flare
• A new catalogue of solar flare events from soft x-ray GOES signal in the period 1986-2020
• Coronal Elemental Abundances during A-class Solar Flares Observed by Chandrayaan-2 XSM
• The morphology of average solar flare time profiles from observations of the Sun's lower atmosphere