Mind the Gap: New Precise 14C Data Indicate the Nature of Extreme Solar Particle Events

Abstract

Extreme solar particle events of 775 CE, 994 CE, and 660 BCE are nearly two orders of magnitude stronger than those observed instrumentally. Because of the large observational gap between directly measured and historical events, it was unclear whether they can be produced by the Sun “normally” or from an unknown phenomenon. Recent works by Miyake et al. (2021, doi: https://doi.org/10.1029/2021GL093419) and Brehm et al. (2021, https://doi.org/10.1038/s41561-020-00674-0) start filling the gap with weaker yet extreme events approaching the detectability threshold. More such events are expected to be found in the future but the present result, if confirmed, would imply that the extreme solar events likely represent the high-energy/low-probability tail of the continuous distribution of solar eruptive events rather than a new unknown type of events. However, more statistic is needed for a solid conclusion. This would lead to better understanding of the processes producing such events that is important for their risk assessments for the modern technology.