Irregularity in Active Fast Radio Burst Repeaters and Magnetar Periodic Radio Pulses: Time, Energy, and Frequency Analyses

TL;DR

This study analyzes time, energy, and frequency data from repeating FRBs and a magnetar to identify patterns and similarities, suggesting a possible shared origin or mechanism behind these astrophysical phenomena.

Contribution

It introduces a comprehensive analysis of time-series data from multiple repeating FRBs and a magnetar, revealing commonalities in their randomness and chaos characteristics.

Findings

Waiting times show high randomness and low chaos, similar to magnetar pulses.

Energy fluctuations occupy similar phase space regions but with greater scatter.

Potential beaming effects or emission variability may explain energy behavior differences.

Abstract

Fast Radio Bursts (FRBs) are millisecond-duration radio pulses with largely unknown origins, with a subset exhibiting repeating behavior. Magnetars highly magnetized neutron stars and a leading progenitor candidate for FRBs also produce similar but much fainter millisecond radio pulses, suggesting a possible connection between the two phenomena. The irregularity of the time series of repeating FRBs and magnetar pulses may provide insight into the underlying progenitor activity. In this study, we analyze time-series data from three repeating FRB sources (four datasets) and the Galactic magnetar SGR J1935+2154 to investigate potential patterns in burst arrival times, energy fluctuations, and peak-frequency shifts. We quantify the degree of randomness (Pincus Index; PI) and chaos (Largest Lyapunov Exponent; LLE) for these three parameters. We find that waiting times across all repeating FRBs exhibit high PI (high randomness) and low LLE (low chaos), consistent with the behavior of magnetar radio pulses. This similarity suggests that both may share a common triggering mechanism. In contrast, the energy fluctuations of both repeating FRBs and magnetar pulses occupy the same region in PI-LLE phase space but display much larger scatter than the other two domains. We discuss the possibility that beaming effects or strong variability in radio-emission efficiency may explain their distinct behavior in the energy domain.