Probing the Association of Galaxy Clusters with Bent-Tailed Radio Sources Using the MeerKAT Galaxy Cluster Legacy Survey

Abstract

A bent-tailed radio galaxy (BT) is an active radio-loud galaxy in which its double jet presents a bend in the same direction, possibly as a result of interaction with the intracluster medium (ICM). Our dataset was extracted from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS). The MGCLS is a survey consisting of observations of 116 clusters at declinations ranging from -85° to ∼ 0°. Through visual inspection of the continuum images aided by an automated source finder, we have separated BT radio sources from other extended radio sources in the MGCLS images. As a result of the study, we present the largest catalogue of BTs to date using the MGCLS sample, from which we extracted 1292 BTs, of which 83% are wide-angle-tailed radio galaxies (WATs) and 17% are narrow-angle-tailed radio galaxies (NATs). As expected, most of the BT sources are estimated to fall below the traditional Fanaroff-Riley divide. We find that around 65% of BTs are associated with massive clusters (1014.5 to 1015 h−1 MJ) for a subsample of 37 galaxy clusters, within which we identified 401 BTs. Contrary to expectations, we do not observe a significant increase in the number of BTs in merging clusters; 45% of the clusters in MGCLS that we have confirmed as merging also contain 45% of the BTs. This may be due to MeerKAT presenting a more complete picture of the BT population. We observed a high number density of BTs in the cluster center region, with an exponential decrease as the distance from the cluster center increases. This pilot study provides the largest sample of BT sources and is well-suited for future studies, including machine-learning-based exploration, as well as highlighting the requirements of future studies using SKA precursors and pathfinders.