Establish the origin of shortest-timescale blazar variability

Establish the physical origin of the shortest-timescale, approximately hour-scale fluctuations in blazar emission.

Background

The paper distinguishes longer-timescale variability, which is commonly attributed to shock-driven particle energization, from sub-day variability, which may involve radiative cooling or other processes. It emphasizes that the physical origin of the shortest, approximately hour-scale fluctuations remains unresolved. The proposed multi-zone model attributes such variability to spatial magnetic-field fluctuations, but this is presented as a model explanation rather than a generally established mechanism.