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Paper: Nanoflares and Coronal X-Ray Variability
Volume: 325, The Solar-B Mission and the Forefront of Solar Physics
Page: 271
Authors: Jain, R.; Katsukawa, Y.; Tsuneta, S.; Vekstein, G.
Abstract: A possibility of probing nanoflares with variability in the coronal X-ray emission is discussed. We present results of numerical simulation of X-ray coronal loops by using a Monte Carlo code, which mimics a sporadic nature of the nanoflare heating. The aim is to investigate how the imposed power-law energy spectrum of heating events (nanoflares) translates into fluctuations in the intensity of the X-ray emission, which can be detected observationally as X-ray and EUV brightenings. It was found that probability distribution of these fluctuations is very sensitive to the power-law index α of the energy spectrum of nanoflares. If α > 3, intensity fluctuations have a noise-like nature with a Gaussian distribution originating from interference of many small nanoflares. For spectral indices 2 < α ≤ 3, histograms of the intensity deviation from the mean value show positive skewness indicating significant role of bigger events. Comparison of these results with the analysis of small fluctuations of coronal X-ray intensity observed with Yohkoh SXT telescope yields an estimate of 1023 erg for the energy of nanoflares in the active region.
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