A simple relationship for the spectro-temporal structure of bursts from FRB 121102

Understand

We consider a simple dynamical and relativistic model to explain the spectro-temporal structure often displayed by repeating fast radio bursts (FRBs).

• We show how this model can account for the downward frequency drift in a sequence of sub-bursts of increasing arrival time (the "sad trombone" effect) and their tendency for exhibiting a reduced pulse width with increasing frequency of observation.
• Most importantly, this model also predicts a systematic inverse relationship between the (steeper) slope of the frequency drift observed within a single sub-burst and its temporal duration.
• Using already published data for FRB 121102 we find and verify the relationship predicted by this model.