Major electron events and coronal magnetic configurations of the related solar active regions

TL;DR

This study analyzes 26 major electron events from 2002 to 2006, linking their timing, spectra, and magnetic configurations of solar active regions to understand particle escape mechanisms.

Contribution

It provides a statistical correlation between coronal magnetic topologies and the timing and spectral properties of major electron events.

Findings

Open field-line events are mostly prompt with harder spectra.

Closed field-line events tend to be delayed with softer spectra.

Magnetic topology influences particle escape and spectral characteristics.

Abstract

A statistical survey of 26 major electron events during the period 2002 February through the end of solar cycle 23 is presented. We have obtained electron solar onset times and the peak flux spectra for each event by fitting to a powerlaw spectrum truncated by an exponential high-energy tail. We also derived the coronal magnetic configurations of the related solar active regions (ARs) from the potential-field source-surface model. It is found that (1) 10 of the 11 well-connected open field-line events are prompt events whose solar onset times coincide with the maxima of flare emission and 13 of the 14 closed field-line events are delayed events. (2) A not-wellconnected open field-line event and one of the closed field-line events are prompt events, they are both associated with large-scale coronal disturbances or dimming. (3)An averaged harder spectrum is found in open field-line events compared with the closed ones. Specifically, the averaged spectral index is of 1.6 +/- 0.3 in open field-line events and of 2.0 +/- 0.4 in closed ones. The spectra of three closed field-line events show infinite rollover energies E0. These correlations clearly establish a significant link between the coronal magnetic field-line topology and the escape of charged particles from the flaring ARs into interplanetary space during the major solar energetic particle events.