The Unpredictability of the Most Energetic Solar Events

TL;DR

This paper demonstrates that the occurrence of the most energetic solar events is highly irregular and unpredictable, not following solar activity indices, due to non-Poisson processes and complex internal solar dynamics.

Contribution

It reveals the non-Poisson nature of major solar events and links their irregular occurrence to complex internal solar magnetic processes.

Findings

Major solar events do not follow sunspot numbers.

Irregularity linked to non-Poisson process.

Occurrence patterns are unpredictable beyond weeks.

Abstract

Observations over the past two solar cycles show a highly irregular pattern of occurrence for major solar flares, gamma-ray events, and solar energetic particle (SEP) fluences. Such phenomena do not appear to follow the direct indices of solar magnetic activity, such as the sunspot number. I show that this results from the non-Poisson occurrence for the most energetic events. This Letter also points out a particularly striking example of this irregularity in a comparison between the declining phases of the recent two solar cycles (1993-1995 and 2004-2006, respectively) and traces it through the radiated energies of the flares, the associated SEP fluences, and the sunspot areas. These factors suggest that processes in the solar interior involved with the supply of magnetic flux up to the surface of the Sun have strong correlations in space and time, leading to a complex occurrence pattern that is presently unpredictable on timescales longer than active region lifetimes (weeks) and not correlated well with the solar cycle itself.