A statistical study of magnetic flux emergence in solar active regions prior to strongest flares

TL;DR

This study analyzes magnetic flux emergence in solar active regions prior to strong flares, revealing that flux emergence is neither necessary nor sufficient for such flares, but flare-productive regions tend to have faster flux emergence.

Contribution

It provides a detailed statistical analysis of magnetic flux emergence patterns in active regions before major solar flares, highlighting differences between flare-productive and flare-quiet regions.

Findings

29 ARs showed monotonous flux emergence amidst quiet Sun

Flux emergence rate is higher in flare-productive ARs

Flux emergence is not a necessary or sufficient condition for strong flares

Abstract

Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24, we explored 100 active regions (ARs) that produced M5.0 or stronger flares. We focus on the presence/absence of the emergence of magnetic flux in these ARs 2-3 days before the strong flare onset. We found that 29 ARs in the sample emerged monotonously amidst quiet-Sun. A major emergence of a new magnetic flux within pre-existing AR yielding the formation of a complex flare-productive configuration was observed in another 24 cases. For 30 ARs, an insignificant (in terms of the total magnetic flux of pre-existing AR) emergence of a new magnetic flux within the pre-existing magnetic configuration was observed; for some of them the emergence resulted in a formation of a configuration with a small $\delta$-sunspot. 11 out of 100 ARs exhibited no signatures of magnetic flux emergence during the entire interval of observation. In 6 cases the emergence was in progress when the AR appeared on the Eastern limb, so that the classification and timing of emergence were not possible. We conclude that the recent flux emergence is not a necessary and/or sufficient condition for strong flaring of an AR. The flux emergence rate of analyzed here flare-productive ARs was compared with that of flare-quiet ARs analyzed in our previous studies. We revealed that the flare-productive ARs tend to display faster emergence than the flare-quiet ones do.