A Comprehensive Analysis of Repeating Fast Radio Bursts

Nearly 700 fast radio burst (FRB) sources have been detected so far, of which 29 are found to burst out repeatedly. Although a firm connection between at least some FRBs and magnetars has been established, the trigger mechanism and radiation process in these enigmatic phenomena are still highly controversial. In this study, we build a sample of 16 repeating FRBs from which at least five bursts have been detected, including the most active four repeaters of FRBs 20121102A, 20180916B, 20190520B, and 20201124A. Various key parameters of their bursts are collected from the literature, which include the arrival time, pulse width, dispersion measure (DM), Faraday rotation measure (RM), bandwidth, waiting time, peak flux, and fluence. The distribution and time evolution of these parameters are investigated. Potential correlations between various parameter pairs are also extensively explored. The behaviors of different repeaters are then compared. It is found that the DM of FRB 20121102A seems to increase continuously on a long timescale. While the DM of most repeaters varies in a narrow range of +/- 3 cm-3 pc, FRB 20190520B is found to have a large variation range of +/- 12 cm-3 pc. The RM evolves with time in a much more chaotic behavior in different repeaters. A linear correlation is found between the absolute mean RM and DMHost, which may provide a method to estimate the redshift of FRBs. Generally, the waiting time shows a similar bimodal distribution for the active repeating sources. The implications of these features to the underlying physics are discussed.