Physical model of intermediate-duration gamma-ray bursts

Determine the physical model underlying the intermediate-duration gamma-ray burst group, including its possible connection to X-ray flash events.

Background

Gamma-ray bursts are commonly classified into short and long events, but an intermediate-duration group with durations of a few seconds and spectral properties distinct from those of the two principal classes has also been identified. The paper states that the physical model for this intermediate group has not been fully established and notes a possible connection with X-ray flash events.