Solar Flare 1/f Fluctuations from Amplitude Modulated Five Minute Oscillation

TL;DR

This study analyzes solar flare time sequences revealing 1/f fluctuations linked to low-energy phenomena, and proposes a model involving amplitude modulation by solar oscillations and magnetic reconnection, with implications for other astrophysical and geophysical phenomena.

Contribution

It introduces a novel explanation for solar flare 1/f fluctuations based on amplitude modulation by solar oscillations and magnetic reconnection, supported by spectral analysis.

Findings

Low-energy flares exhibit 1/f fluctuations in power spectrum.

Flare timing sequences show clearer 1/f fluctuations.

The proposed model links 1/f fluctuations to solar oscillations and magnetic reconnection.

Abstract

We first study the solar flare time sequence based on the GOES16 data. We find that the power spectrum density of the low-energy (E\leq E_{mean}) flare shows 1/f fluctuations, but the high-energy (E>E_{mean}) flare shows a flat spectrum. Further, we found that the flare timing time-sequence shows 1/f fluctuations clearer. These facts indicate that the solar flare 1/f fluctuations are associated with low-energy phenomena. We investigate the origin of this 1/f fluctuations based on our recent proposal: 1/f fluctuations arise from amplitude modulation and demodulation. We speculate that this amplitude modulation is encoded by the resonance with the Solar Five-minute Oscillation (SFO) and demodulated by magnetic reconnection. We partially demonstrate this scenario by analyzing the SFO eigenmodes resolving the frequency degeneracy in the azimuthal order number m by solar rotation and resonance. Since 1/f fluctuation is robust, we speculate that the solar flare 1/f fluctuations may be inherited by the various phenomena around the Sun, such as the sunspot numbers and the cosmic rays. Finally, we compare the solar flares and the earthquakes, both showing 1/f fluctuations. Interestingly, the same analysis for solar flares is possible for earthquakes if we read SFO as Earth's Free Oscillation, and magnetic reconnection as fault rupture. Furthermore, we point out the possibility that the same analysis also applies to the activity of the black hole/disk system if we read SFO as the Quasi-Periodic Oscillation of a black hole.