Physical origin of nonsimultaneous afterglow X-ray flares

Determine the physical origin of afterglow X-ray flares that are not observed simultaneously with prompt gamma-ray pulses, including whether they arise from central-engine activity, accretion-disk fragmentation, magnetar-engine processes, jet bow shocks, or other mechanisms.

Background

The study finds evidence for a common physical origin between prompt gamma-ray pulses and X-ray flares only when the two components are observed simultaneously in the same GRB. The authors explicitly distinguish these events from X-ray flares without simultaneous gamma-ray pulses, whose physical origin is not resolved.

Several competing explanations are cited for the nonsimultaneous flares, including fragmentation in the accretion disk, a delayed magnetar propeller regime, and emission from a jet bow shock or the relativistic jet. Establishing which mechanism operates requires observations and modeling beyond the simultaneous pulse--flare sample analyzed here.

References

However, the physical origin of those X-ray flares that are not observed simultaneously with gamma-ray pulses remains under debate.

— Evidence for a Similar Physical Origin Between Prompt Emission and X-Ray Flares of Gamma-Ray Bursts  (2610.09538 - Yu et al., 7 Oct 2026) in Section 5, Conclusions and Discussion

On the other hand, the origin of the X-ray flare, observed during the quiescent intervals of prompt emission, also remains uncertain. There are two possible ways to interpret such behavior.

— Evidence for a Similar Physical Origin Between Prompt Emission and X-Ray Flares of Gamma-Ray Bursts  (2610.09538 - Yu et al., 7 Oct 2026) in Section 5, Conclusions and Discussion