Information Horizon of Stellar Flares

Abstract:

Because the dynamics of stellar flares are modulated by magnetic activity cycles, they provide a window to the underlying dynamics. Using mutual information, we compare the process that creates stellar flares with a nonstationary Poisson process, which is the expected result of a system having SOC (self-organized criticality) behavior with time variable driving. From the stellar intensity data collected by the Kepler satellite, we designate flare events based on a sudden elevation in the intensity of the light curve above a threshold condition. The waiting times are calculated as the time difference between flare events, and surrogate datasets are constructed using the flare rate as a function of time, where the flare rate represents the probability of a flare event at that time. When the mutual information of the time-lagged waiting time distributions is plotted for both the original and surrogate data, an increase in the mutual information is present for the original data as compared to the surrogates, indicating that there is short term memory stored within the stellar flare-producing process. We seek to extend this analysis to other stars observed in the Kepler missions to examine the role of rotation velocity on the short-term memory. These results are compared with the solar waiting time distribution. We also use these results to explore the choice of intensity threshold for identification of flares, such that the mutual information is preserved.