Impulsive Solar Energetic Electron Events Observed by the Expanded Owens Valley Solar Array

Impulsive solar energetic electron (SEE) events, primarily characterized by an enhanced in situ energetic electron population with a relatively short and impulsive time profile, are often thought to originate from solar flares. Here we report three flare-associated in situ SEE events recorded by multiple spacecraft including Parker Solar Probe, Solar Orbiter, STEREO, and WIND from 2019 to 2021. All the in situ SEE events are accompanied by impulsive microwave bursts recorded by the Expanded Owens Valley Solar Array (EOVSA). These events are well magnetically connected to flare-producing active regions. They are also associated with interplanetary type III radio bursts that extend to the decameter–kilometer wavelength range (300 kHz–30 MHz). We performed joint timing and spectral analysis based on the radio bursts and the in situ SEE events. By utilizing microwave imaging spectroscopy and complementary EUV and X-ray data, we also identify the source regions of these SEE events near the solar surface. The close temporal and spatial relationship indicate that they are all accelerated in the core region of the associated flares in the low corona. We also discuss their transport from near the solar surface to interplanetary space.