Type III Radio Bursts from Solar Eruptions and their Connection to GLE and SGRE Events

TL;DR

This study compares properties of CMEs associated with GLE and SGRE events, finding they have higher speeds and longer-duration type III radio bursts than typical CMEs, supporting the idea of shock-driven particle acceleration.

Contribution

It provides new comparative analysis of CME characteristics in GLE and SGRE events, highlighting their higher speeds and longer radio burst durations relative to typical CMEs.

Findings

CME speeds are higher in GLE and SGRE events.

Type III burst durations are longer in GLE and SGRE events.

Results support shock-driven particle acceleration hypothesis.

Abstract

We report on the close similarity of coronal mass ejection (CME) properties in ground level enhancement (GLE) in solar energetic particle (SEP) events and sustained gamma ray emission (SGRE) from the Sun as indicated by low frequency type III radio bursts observed in the interplanetary medium. The complex type III bursts have an average 1 MHz duration of 36 and 34 min in the SGRE and GLE events, respectively. Similarly, the CMEs underlying SGRE and GLE have average space speeds of 1866 and 2084 km/s, respectively. These are larger than the corresponding values (32 min, 1407 km/s) for a control sample of type III bursts associated with frontside halo CMEs with sky plane speed exceeding 800 km/s. These results are consistent with the idea that energetic CME driven shocks accelerate particles to very high energies that are responsible for GLE and SGRE events.