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arXiv · 1006.4861

The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles. I. Observations

Markus J. Aschwanden
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Abstract

We analyze the occurrence frequency distributions of peak fluxes $P$, total fluxes $E$, and durations $T$ of solar flares over the last three solar cycles (during 1980--2010) from hard X-ray data of HXRBS/SMM, BATSE/CGRO, and RHESSI. From the synthesized data we find powerlaw slopes with mean values of $α_P=1.72\pm0.08$ for the peak flux, $α_E=1.60\pm0.14$ for the total flux, and $α_T=1.98\pm0.35$ for flare durations. We find a systematic anti-correlation of the powerlaw slope of peak fluxes as a function of the solar cycle, varying with an approximate sinusoidal variation $α_P(t)=α_0+Δα\cos{[2π(t-t_0)/T_{cycle}]}$, with a mean of $α_0=1.73$, a variation of $Δα=0.14$, a solar cycle period $T_{cycle}=12.6$ yrs, and a cycle minimum time $t_0=1984.1$. The powerlaw slope is flattest during the maximum of a solar cycle, which indicates a higher magnetic complexity of the solar corona that leads to an overproportional rate of powerful flares.

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Markus J. Aschwanden. 2010-10-06. The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles. I. Observations. https://doi.org/10.1007/s11207-011-9755-0

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