Co-occurrence of SGRE and SEP events

Coronal mass ejections (CMEs) have been suggested to be the source of high-energy protons producing sustained gamma-ray emission (SGRE) events at the Sun, where the >100 MeV gamma-ray emission observed by Fermi Large Area Telescope (LAT) lasts beyond the end of the associated X-ray flare. Large SEP events observed at 1 au are produced by shocks driven by fast and wide (FW) CMEs. However, there are more large SEP events than SGRE events and more FW CMEs than the large SEP events. Magnetic connectivity of the observer to the shock nose affects the detectability of SEP events at 1 au. [Makela et∼al., 2023] found that the SGRE-producing halo CMEs associated with type II radio bursts and/or a large SEP events have higher space speeds and initial accelerations than those without an SGRE event. In this paper, we consider characteristics of CME eruptions associated with co-occurring SEP and SGRE events.