Self-Organized Criticality in Stellar Flares

Abstract

Power law size distributions are the hallmarks of nonlinear energy dissipation processes governed by self-organized criticality. Here we analyze 75 data sets of stellar flare size distributions, mostly obtained from the {\sl Extreme Ultra-Violet Explorer (EUVE)} and the {\sl Kepler} mission. We aim to answer the following questions for size distributions of stellar flares: (i) What are the values and uncertainties of power law slopes? (ii) Do power law slopes vary with time ? (iii) Do power law slopes depend on the stellar spectral type? (iv) Are they compatible with solar flares? (v) Are they consistent with self-organized criticality (SOC) models? We find that the observed size distributions of stellar flare fluences (or energies) exhibit power law slopes of ${\alpha }_E=2.09\pm 0.24$ for optical data sets observed with Kepler. The observed power law slopes do not show much time variability and do not depend on the stellar spectral type (M, K, G, F, A, Giants). In solar flares we find that background subtraction lowers the uncorrected value of ${\alpha }_E=2.20\pm 0.22$ to ${\alpha }_E=1.57\pm 0.19$. Furthermore, most of the stellar flares are temporally not resolved in low-cadence (30 min) Kepler data, which causes an additional bias. Taking these two biases into account, the stellar flare data sets are consistent with the theoretical prediction $N(x)\propto x^{-{\alpha }_x}$ of self-organized criticality models, i.e., ${\alpha }_E=1.5$. Thus, accurate power law fits require automated detection of the inertial range and background subtraction, which can be modeled with the generalized Pareto distribution, finite-system size effects, and extreme event outliers.

16 pages, 7 Figures, 3 Tables

References in corpus (9)

• Power-law distributions in empirical data
• The Kepler Catalog of Stellar Flares
• Dragon-kings: mechanisms, statistical methods and empirical evidence
• Global Energetics of Solar Flares: V. Energy Closure in Flares and Coronal Mass Ejections
• Automated Solar Flare Statistics in Soft X-rays over 37 Years of GOES Observations - The Invariance of Self-Organized Criticality during Three Solar Cycles
• A statistical analysis of X-ray variability in pre-main sequence objects of the Taurus Molecular Cloud
• Stellar flares observed in long cadence data from the Kepler mission
• Coexistence of Self-Organized Criticality and Intermittent Turbulence in the Solar Corona
• Surveys of Clumps, Cores, and Condensations in Cygnus X: I. a New Catalog of ~0.1 pc Massive Dense Cores

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