Synthesising the repeating FRB population using frbpoppy

Abstract

The observed fast radio burst (FRB) population can be divided into one-off and repeating FRB sources. Either this division is a true dichotomy of the underlying sources, or selection effects and low activity prohibit us from observing repeat pulses from all constituents making up the FRB source population. We attempted to break this degeneracy through FRB population synthesis. With that aim in mind, we extended frbpoppy (which previously only handled one-off FRBs) to also simulate repeaters. We next modelled the Canadian Hydrogen Intensity Mapping Experiment FRB survey (CHIME/FRB). Using this implementation, we investigated the impact of luminosity functions on the observed dispersion measure (DM) and distance distributions of both repeating and one-off FRBs. We show that for a single, intrinsically repeating source population with a steep luminosity function, selection effects should shape the DM distributions of one-off and repeating FRB sources differently. This difference is not yet observed. We next show how the repeater fraction over time can help in determining the repetition rate of an intrinsic source population. We simulated this fraction for CHIME/FRB, and we show that a source population comprised solely of repeating FRBs can describe CHIME/FRB observations with the use of a flat luminosity function. From the outcome of these two methods, we thus conclude that all FRBs originate from a single and mostly uniform population of varying repeaters. Within this population, the luminosity function cannot be steep, and there must be minor differences in physical or behaviour parameters that correlate with the repetition rate.

Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope

“…However, at present only 20 repeating sources are published and the overall fraction of repeating sources in the FRB population is unknown. Whether all FRBs eventually repeat is an open question, one that is being tackled currently both with observational efforts (Fonseca et al 2020) and modelling (Gardenier et al 2019(Gardenier et al , 2021.…”

New insights into the criterion of fast radio burst in the light of FRB 20121102A

“…However, it is still under hot debate whether genuinely non-repeating FRBs exist (Caleb et al 2018(Caleb et al , 2019Palaniswamy et al 2018;Xiao et al 2021). A few works have discussed the possibility to judge this question using the number fraction of repeaters (Caleb et al 2019;Lu et al 2020;Ai et al 2021;Gardenier et al 2021). With the accumulation of observing time, this fraction will increase to 100% if all FRBs turn out to be repeating.…”

The physics of fast radio bursts

“…Still, it is fair to argue that all FRBs repeat on the supposition that their repeating modes are diverse. Several studies have tried to reproduce the observed statistical properties with different models of repeating [154,155]. For instance, the difference in pulse width distribution can be ascribed to FRB beaming [156].…”

“…Generally, with the accumulation of the observing time, the observed repeating fraction (defined as the number ratio of repeaters among all FRBs) is expected to increase to nearly 100% [124,151,157]. However, if there exist physically non-repeating FRBs, this fraction will peak at a certain observing time and the peak fraction is less than 100% [154,157]. The current total observing time of CHIME may be still insufficient to bring out the peak.…”

“…The current total observing time of CHIME may be still insufficient to bring out the peak. Also, the repeating fraction will decrease with the increasing redshift since the repetitions of FRBs with closer distances are easier to be detected [124,154]. This means that the DM distribution of repeaters should concentrate on a lower value than non-repeaters.…”