Low-frequency-selected Fast Radio Burst Host Galaxy Candidates

TL;DR

This study demonstrates that low-frequency radio observations can effectively identify host galaxies of fast radio bursts, including dust-obscured and optically faint galaxies, complementing traditional optical methods.

Contribution

It introduces a radio-based method for FRB host galaxy identification, expanding the search to dust-obscured and optically faint galaxies, and demonstrates its feasibility with pilot data.

Findings

Identified 3 potential host galaxies with active star formation.

Radio-based selection can find hosts missed by optical surveys.

Dust attenuation affects star formation rate estimates from Hα data.

Abstract

We present a pilot study on the host galaxy environments of CHIME/FRBs by cross-matching baseband-localised events with the LOFAR Two-metre Sky Survey Data Release 2 (LoTSS DR2) at 144 MHz. Unlike traditional methods reliant on optical imaging, our radio-based selection allows for the identification of dust-obscured or optically faint star-forming galaxies. Of the 140 CHIME FRBs considered, 33 lie within the LoTSS DR2 footprint, and 16 show potential radio counterparts. Through multi-wavelength analysis, spectral energy distribution (SED) fitting, and redshift constraints from the Macquart relation, we identify two secure and one tentative host candidates, all consistent with active star formation. However, their H$\alpha$-derived star formation rates appear underestimated, likely due to significant dust attenuation, as suggested by infrared colours and compact optical morphologies. Our results highlight the value of low-frequency radio data in complementing optical host searches and demonstrate the feasibility of host identification even in the absence of optical confirmation. With forthcoming data from LoTSS DR3 and the full CHIME/FRB baseband release, this method offers a promising path toward statistically robust studies of FRB host galaxies and their environments.