Localisation and host galaxy identification of new Fast Radio Bursts with MeerKAT

TL;DR

This work advances fast radio burst science by sub-arcsecond localising 15 MeerKAT-detected FRBs, enabling robust host galaxy identifications for most events. The authors combine TB-based imaging, SeeKAT, optical follow-up, and Bayesian host association (PATH) with SED modeling (CIGALE) to derive host properties and spectroscopic redshifts for several hosts, including several at z > 0.3. A key contribution is the demonstration that foreground structures, such as galaxy clusters, can dominate the observed dispersion measures for some FRBs, emphasizing the need to account for line-of-sight DM before cosmological interpretation. The resulting high-redshift FRB sample, with eight arcsecond-localised hosts and six spectroscopic redshifts, provides a valuable resource for probing FRB progenitors, galaxy evolution, and the baryon content of the IGM via the Macquart relation, with significant implications for cosmological applications.

Abstract

Accurately localising fast radio bursts (FRBs) is essential for understanding their birth environments and for their use as cosmological probes. Recent advances in radio interferometry, particularly with MeerKAT, have enabled the localisation of individual bursts with arcsecond precision. In this work, we present the localisation of 15 apparently non-repeating FRBs detected with MeerKAT. Two of the FRBs, discovered in 2022, were localised in 8 second images from the projects which MeerTRAP was commensal to, while eight were localised using the transient buffer (TB) pipeline, and another one through SeeKAT, all with arcsecond precision. Four additional FRBs lacked TB triggers and sufficient signal, limiting their localisation only to arcminute precision. For eight of the FRBs in our sample, we identify host galaxies with greater than 90% confidence, and one with 80% confidence, while two FRBs have ambiguous associations. We measured spectroscopic redshifts for six host galaxies, ranging from 0.33 to 0.85, demonstrating MeerKAT's sensitivity to high redshift FRBs. We modelled the spectral energy distributions of host galaxies with sufficient photometric coverage to derive their stellar population and star formation properties. This work represents one of the largest uniform samples of well-localised distant FRBs to date, laying the groundwork for using MeerKAT FRBs as cosmological probes and understand how FRB hosts evolve at high redshift.

Figures (22)

• Figure 1: Localisation images of the FRBs presented in this work. In each row, the left panel shows an image before the arrival time of the burst (off), and the right panel the image during the burst (on). The images are centred at the FRB location, and have a FoV of 6$\times$6. The beam size of each observation is shown on the bottom left corner of each panel as a white ellipse.
• Figure 2: Localisation of FRB 20220222C. The error region is shown as a white ellipse, and the background image shows a composite image with the $r$, $z$, and $J$ band observations. The candidate hosts are indicated by coloured circles of half-light radii labelled G1-3.
• Figure 3: Localisation of FRB 20220224C. The error region is shown by a white ellipse, and the background is a composite image from the $r$ and $i$ observations and the $g$ image from DESI-DR10. The candidate host galaxy is indicated by a coloured circle labelled G1.
• Figure 4: Localisation of FRB 20230125D. The error region is shown by a white ellipse, and the background image is a Gemini-S observation. The candidate host galaxy is indicated by a coloured circle labelled G1.
• Figure 5: Localisation of FRB 20230503E. The error region is shown by a white ellipse, and the background image is from DESI-DR10. The candidate host galaxies are indicated by coloured circles labelled G1-2. The source inside the FRB error region is a star.