Low-frequency Probes of the Persistent Radio Sources associated with Repeating FRBs

TL;DR

This study uses low-frequency radio observations to detect and analyze persistent radio sources associated with three repeating FRBs, providing new insights into their environments and supporting the magnetoionic medium origin hypothesis.

Contribution

It presents the first low-frequency detection of a PRS associated with FRB 20240114A and offers detailed analysis of its properties, expanding the understanding of FRB environments.

Findings

Detected a PRS at 650 MHz for FRB 20240114A

Confirmed the PRS is likely associated with the FRB host galaxy

Provided upper limits on PRS for FRB 20240619D

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 (uGMRT) at low radio frequencies. Towards FRB~20240114A, we report the detection of compact source at 650\,MHz with a flux density of 65.6$\pm$8.1\,$\mu$Jy/beam. 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 persistent radio source (PRS) associated with the FRB 20240114A. 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.