Validating the sub-burst slope law: a comprehensive multisource spectro-temporal analysis of repeating fast radio bursts

Abstract

ABSTRACT We conduct a comprehensive spectro-temporal analysis of repeating fast radio bursts (FRBs) utilizing nine distinct sources, the largest sample to date. Our data set includes 175 sub-bursts and 31 multicomponent bursts from 11 data sets, with centre frequencies ranging from 149 to 7144  MHz and durations spanning from 73 µs to 13 ms. Our findings are consistent with the predictions of the triggered relativistic dynamical model (TRDM) of FRB emission. We affirm the predicted quadratic relationship between sub-burst slope and central frequency, as well as a linear dependence of the sub-burst bandwidth on central frequency that is consistent with mildly relativistic Doppler broadening of narrow-band emission. Most importantly, we confirm the sub-burst slope law, a predicted inverse relationship between sub-burst slope and duration, to hold consistently across different sources. Remarkably, we also discover that the drift rates of multicomponent bursts follow the same law as the sub-burst slopes, an unexplained result that warrants further investigation. These findings not only support the TRDM as a viable framework for explaining several aspects of FRB emission, but also provide new insights into the complex spectro-temporal properties of FRBs.