Differences in Periodic Magnetic Helicity Injection Behavior between Flaring and Non-flaring Active Regions: Case Study

Abstract

The evolution of magnetic helicity has a close relationship with solar eruptions and is of interest as a predictive diagnostic. In this case study, we analyse the evolution of the normalised emergence, shearing and total magnetic helicity components in the case of three flaring and three non-flaring active regions (ARs) using SHARPs (Spaceweather Helioseismic Magnetic Imager Active Region Patches) vector magnetic field data. The evolution of the three magnetic helicity components is analysed with wavelet transforms, revealing significant common periodicities of the normalised emergence, shearing and total helicity fluxes before flares in the flaring ARs. The three non-flaring ARs do not show such common periodic behaviour. This case study suggests that the presence of significant periodicities in the power spectrum of magnetic helicity components could serve as a valuable precursor for flares.

On the differences in the periodic behaviour of magnetic helicity flux in flaring active regions with and without X-class events

“…In this study, similar to Korsós et al (2020), active regions that contain X-class flares will be called flaring ARs. While active regions that do not contain X-class flares are defined as non-flaring ARs.…”

“…While active regions that do not contain X-class flares are defined as non-flaring ARs. As in Korsós et al (2020), a random sample of 14 flaring and 14 non-flaring active regions are selected based on the following criteria:…”

“…The magnetic helicity carries information about the complexity of the magnetic field topology, and is therefore linked to the free magnetic energy of ARs, and the occurrence of flares. Thus diagnostics related to the magnetic helicity may be valuable for flare prediction (Pariat, E. et al 2017;Thalmann et al 2019;Korsós et al 2020).…”

“…Recently, Prior et al (2020) showed that the multiresolution wavelet decomposition is a useful tool to analyze the magnetic helicity. Based on their theoretical work, Korsós et al (2020) investigated the dynamic evolution of emergence (EM), shearing (SH), and total (T) magnetic helicity flux terms using a wavelet analysis in the case of three flaring and three non-flaring ARs. They found a relationship between the oscillatory behavior of the three magnetic helicity flux components and the associated flare activities.…”

“…To further test the conjecture of Korsós et al (2020), this work extends their approach by applying a more extensive set of diagnostics on a larger number of ARs. In this work, we investigate 14 flaring and 14 non-flaring ARs, and apply additional statistical tests, e.g.…”