Coronal magnetic topology and the production of solar impulsive energetic electrons

TL;DR

This study links coronal magnetic field structures to the production and detection of solar impulsive energetic electrons, highlighting the role of open magnetic field lines and radio bursts in electron escape.

Contribution

It provides new insights into how coronal magnetic topology influences the release and detection of energetic electrons during solar events.

Findings

Open magnetic field lines facilitate electron escape to Earth.

Type III radio bursts are associated with electron injections.

Magnetic connectivity determines detectability of electrons at Earth.

Abstract

We investigate two candidate solar sources or active regions (ARs) in association with a solar impulsive energetic electron (SIEE) event on 2002 October 20. The solar particle release (SPR) times of SIEEs are derived by using their velocity dispersion with consideration of the instrumental effect. It is found that there are double electron injections at the Sun. The low-energy (<13 keV) electron injection coincides with a C6.6 flare in AR10154 and is accompanied with prominent type III radio bursts rather than a stronger M1.8 flare in AR10160. The M1.8 flare produces, however, faint type III radio bursts. Whereas electrons of 25 to 300 keV are released 9 min later when a jet-like CME travels to 2.6 solar radii. We further examine the coronal magnetic configurations above the two ARs based on the potential field source surface (PFSS) model. It is found that open field lines, rooted in AR10154 and well connected to the Earth, provide escaping channels for energetic electrons. Only a small portion of magnetic fields are opened above AR10160, being responsible for the faint type III radio bursts. These lines are, however, not well connected, making it impossible for SIEEs detection by near-Earth spacecraft. The results appear to establish a physical link between coronal magnetic topology, formation of type III radio bursts, and production of SIEEs.