Mechanism of long-duration solar gamma-ray emission

Determine the physical mechanism(s) responsible for long-duration solar gamma-ray emission following flares, distinguishing among CME-driven shock acceleration, extended coronal acceleration, and trapping and leakage of ions in coronal loops.

Background

Gamma-ray emission observed well beyond the impulsive phase of solar flares challenges the standard reconnection-based acceleration picture and suggests alternative or additional mechanisms.

Identifying the dominant mechanism(s) is crucial for interpreting solar particle acceleration and for evaluating whether analogous processes operate in other stars.