Constraints on fast radio burst emission in the aftermath of gamma-ray bursts

Context. Fast radio bursts (FRBs) are highly energetic radio transients with a duration of some milliseconds. Their physical origin is still unknown. Many models consider magnetars as possible FRB sources, which is supported by the observational association of FRBs with the galactic magnetar SGR 1935+2154. Magnetars are also thought to be the source of the power of a fraction of gamma-ray bursts (GRBs), which means that the two extreme phenomena might have a common progenitor. Aims. We placed constrains on this hypothesis by searching for possible associations between GRBs and FRBs with currently available catalogues and by estimating whether an association can be ruled out based on the lack of a coincident detection. Methods. We cross-matched all the Neil Gehrels Swift Observatory (Swift) GRBs detected so far with all the well-localised FRBs reported in the FRBSTATS catalogue, and we looked for FRB-GRB associations considering both spatial and temporal constraints. We also simulated a synthetic population of FRBs associated with Swift GRBs to estimate how likely a joint detection with current and future radio facilities is. Results. We recovered two low-significance possible associations that were reported before from a match of the catalogues: GRB 110715A/FRB 20171209A and GRB 060502B/FRB 20190309A. However, our study shows that based on the absence of any unambiguous association so far between Swift GRBs and FRBs, we cannot exclude that the two populations are connected because of the characteristics of current GRB and FRB detectors. Conclusions. Currently available observational data are not sufficient to clearly exclude or confirm whether GRBs and FRBs are physically associated. In the next decade, the probability of detecting joint GRB-FRB events will be higher with new generations of GRB and FRB detectors, if any: future observations will therefore be key to placing more stringent constraints on the hypothesis that FRBs and GRBs have common progenitors.