On the current solar magnetic activity in the light of its behaviour during the Holocene

TL;DR

This study investigates the Sun's magnetic activity over the Holocene using cosmogenic nuclide data, revealing patterns of grand minima and maxima that suggest a non-linear, oscillatory dynamo behavior influenced by the Lorentz force.

Contribution

It provides a novel analysis of Holocene solar magnetic activity patterns and links them to non-linear dynamo models with memory effects, based on cosmogenic radionuclide data.

Findings

71% of grand maxima were followed by grand minima

Patterns suggest the Sun acts as a relaxation oscillator

Magnetic activity exhibits non-uniform temporal distribution

Abstract

Solar modulation potential (SMP) reconstructions based on cosmogenic nuclide records reflect changes in the open solar magnetic field and can therefore help us obtain information on the behaviour of the open solar magnetic field over the Holocene period. We aim at comparing the Sun's large-scale magnetic field behaviour over the last three solar cycles with variations in the SMP reconstruction through the Holocene epoch. To achieve these objectives, we use the IntCal13 $^{14}$C data to investigate distinct patterns in the occurrences of grand minima and maxima during the Holocene period. We then check whether these patterns might mimic the recent solar magnetic activity by investigating the evolution of the energy in the Sun's large-scale dipolar magnetic field using the Wilcox Solar Observatory data. The cosmogenic radionuclide data analysis shows that $\sim$71\% of grand maxima during the period from 6600 BC to 1650 AD were followed by a grand minimum. The occurrence characteristics of grand maxima and minima are consistent with the scenario in which the dynamical non-linearity induced by the Lorentz force leads the Sun to act as a relaxation oscillator. This finding implies that the probability for these events to occur is non-uniformly distributed in time, as there is a memory in their driving mechanism, which can be identified via the back reaction of the Lorentz force.