Validating the Sub-Burst Slope Law: A Comprehensive Multi-Source Spectro-Temporal Analysis of Repeating Fast Radio Bursts

TL;DR

This study provides a comprehensive analysis of repeating FRBs, confirming key theoretical predictions about their spectro-temporal properties and revealing new relationships between burst characteristics across multiple sources.

Contribution

It validates the sub-burst slope law and the TRDM model across a large, diverse sample of FRBs, establishing new empirical relationships and uncovering consistent drift rate behaviors.

Findings

Confirmed the quadratic relationship between sub-burst slope and frequency

Validated the linear dependence of bandwidth on frequency

Discovered that multi-component burst drift rates follow the same law as sub-burst slopes

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 multi-component bursts from 11 data sets, with centre frequencies ranging from 149--7144 MHz and durations spanning from 73 $\mu$s--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 multi-component 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.