Finding LoTSS of hosts for GRBs: a search for galaxy - gamma-ray burst coincidences at low frequencies with LOFAR

TL;DR

This study uses LOFAR data to identify and analyze potential host galaxies of gamma-ray bursts, revealing high star formation rates and ULIRG characteristics in these candidates, thus advancing low-frequency radio galaxy studies.

Contribution

The paper presents the first systematic search for GRB host galaxies using LOFAR low-frequency radio data, identifying promising candidates and characterizing their properties.

Findings

18 sources meet chance alignment criteria for GRB hosts

Hosts show high star formation rates ($10^1$-$10^3$ M$_\

Most candidates are consistent with ULIRG classifications

Abstract

The LOFAR Two-Metre Sky Survey (LoTSS) is an invaluable new tool for investigating the properties of sources at low frequencies and has helped to open up the study of galaxy populations in this regime. In this work, we perform a search for host galaxies of gamma-ray bursts (GRBs). We use the relative density of sources in Data Release 2 of LoTSS to define the probability of a chance alignment, $P_{\rm chance}$, and find 18 sources corresponding to 17 GRBs which meet a $P_{\rm chance}$<1% criterion. We examine the nature and properties of these radio sources using both LOFAR data and broadband information, including their radio spectral index, star formation rate estimates and any contributions from active galactic nucleus emission. Assuming the radio emission is dominated by star formation, we find that our sources show high star formation rates ($10^1$-$10^3$ $M_{\odot}$ yr$^{-1}$) compared with both a field galaxy sample and a sample of core-collapse supernova hosts, and the majority of putative hosts are consistent with ultraluminous infrared galaxy (ULIRG) classifications. As a result of our analyses, we define a final sample of eight likely GRB host candidates in the LoTSS DR2 survey.