Statistical Signatures of Nanoflare Activity. I. Monte Carlo Simulations and Parameter-space Exploration

Abstract

Small-scale magnetic reconnection processes in the form of nanoflares have become increasingly hypothesized as important mechanisms for the heating of the solar atmosphere, driving propagating disturbances along magnetic field lines in the Sun’s corona, and instigating rapid jetlike bursts in the chromosphere. Unfortunately, the relatively weak signatures associated with nanoflares place them below the sensitivities of current observational instrumentation. Here we employ Monte Carlo techniques to synthesize realistic nanoflare intensity time series from a dense grid of power-law indices and decay timescales. Employing statistical techniques, which examine the modeled intensity fluctuations with more than 107 discrete measurements, we show how it is possible to extract and quantify nanoflare characteristics throughout the solar atmosphere, even in the presence of significant photon noise. A comparison between the statistical parameters (derived through examination of the associated intensity fluctuation histograms) extracted from the Monte Carlo simulations and Solar Dynamics Observatory (SDO)/ Atmospheric Imaging Assembly (AIA) 171 and 94 Å observations of active region NOAA11366 reveals evidence for a flaring power-law index within the range of 1.82 α 1.90, combined with e-folding timescales of 385±26and 262±17s for the SDO/AIA 171 and 94Å channels, respectively. These results suggest that nanoflare activity is not the dominant heating source for the active region under investigation. This opens the door for future dedicated observational campaigns to not only unequivocally search for the presence of small-scale reconnection in solar and stellar environments but also quantify key characteristics related to such nanoflare activity.