Low-frequency Probes of the Persistent Radio Sources Associated with Repeating Fast Radio Bursts

Abstract The discovery of persistent radio sources (PRSs) associated with three repeating fast radio bursts (FRBs) has provided insight into the local environments of these FRBs. Here, we present deep radio observations of the fields surrounding three highly active repeating FRBs, namely, FRB 20220912A, FRB 20240114A, and FRB 20240619D, using the upgraded Giant Metrewave Radio Telescope at low radio frequencies. Toward FRB 20240114A, we report the detection of compact source at 650 MHz with a flux density of 65.6 ± 8.1 μ Jy beam −1 . Our measurements of the spectral index, star formation rate of the host galaxy, and recently reported constraints on the physical size strongly argue for our detected source to be a PRS associated with the FRB 20240114A. We investigate possible origins of the PRS associated with FRB 20240114A. Based on its brightness and age, we rule out central engines formed via accretion-induced collapse of a white dwarf, while superluminous supernovae, long gamma-ray bursts, and neutron star merger channels remain viable. An off-axis GRB afterglow could also explain the observed emission. For FRB 20220912A, we detect radio emission that is most likely due to star formation in the host galaxy. For FRB 20240619D, we provide upper limits on the radio emission from an associated PRS or the host galaxy. The detection of the PRS associated with FRB 20240114A is a useful addition to the PRSs known to be associated with only three other FRBs so far, and further supports the origin of the PRS in the form of magnetoionic medium surrounding the FRB sources.