Search for persistent radio emission towards selected localised Fast Radio Burst positions using the MeerKAT Telescope

TL;DR

This study investigates whether FRB environments host persistent radio sources (PRS) by surveying well-localised FRB positions with MeerKAT in the L-band as part of a larger 25-position program. Using standard interferometric data reduction and multi-frequency synthesis across epochs, the authors search for steady radio emission at FRB locations and assess flux variability. They report two candidate PRSs associated with FRB20221106 and FRB20181112, and a non-detection for FRB20190102, with observed variability and extended morphologies that complicate the origin (PRS vs. host). The results constrain FRB environments and highlight the necessity of high-resolution follow-up with e-MERLIN to disentangle compact PRSs from host-galaxy emission, improving our understanding of FRB progenitors and surrounding media.

Abstract

Fast Radio Bursts (FRBs) are millisecond-duration radio pulses originating from cosmological distances, as indicated by their large dispersion measures. While numerous FRBs have now been localised to their host galaxies, a distinct class of compact electromagnetic counterpart, a Persistent Radio Source (PRS), has also been identified in some cases. Currently, only three, and possible a fourth repeating FRBs (FRB20121102A, FRB20190417A, FRB20190520B, and FRB20240114A) have confirmed associations with a PRS. Insight into progenitors, local environments, and the evolution of FRBs can be clarified by characterising these PRSs. In this work, we present 2 detected candidate PRSs using MeerKAT radio telescope data and one non-detection (as part of a larger study involving 25 FRB positions). Both FRB20221106 and FRB20181112 were found to have a host galaxy, and whether the detected radio continuum emission comes from the host galaxy or PRS is still an open question. High-resolution observations from a telescope such as e-MERLIN are required to resolve this question. If a compact PRS is detected, this telescope will provide the size, and investigate the flux variability and spectral shape of this compact PRS. Lastly, in the case of FRB220190102, which was observed over two epochs, no radio continuum was detected. However, a flux upper limit is provided for both epochs.

Figures (3)

• Figure 1: MeerKAT image of the FRB20221106 position with a $\sim$1$^{\prime\prime}$ localisation uncertainty Shannon2025 as indicated by the green circle, observed during three different epochs. The black eclipse in the bottom left corner represents the beam size of MeerKAT, and the positional uncertainty of the detected radio source is $\sim$0.3$^{\prime\prime}$, which is smaller than the beam size. The white contours indicate continuum radio emission that coincides with the FRB position, represented at 3, 9, and 12 times the image's RMS.
• Figure 2: Same as in Figure 1, but for FRB20181112, observed during two different epochs with $\sim$0.5$^{\prime\prime}$ uncertainty of the FRB position Prochaska. The positional uncertainty of the detected radio source is $\sim$0.5$^{\prime\prime}$, again smaller than the beam. Although the emission is faint and extended, the FRB position lies well within the detected source extent.
• Figure 3: Same as Figure 2, but for FRB20190102.