Tailed radio galaxies as tracers of galaxy clusters. Serendipitous discoveries with the GMRT

¹ INAF - Istituto di Radioastronomia, via Gobetti 101, 40129, Bologna, Italy e-mail: tventuri@ira.inaf.it
² Harvard-Smithsonian Centre for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA

Received: 1 June 2009
Accepted: 14 July 2009

Abstract

Aims. We report on the discovery of four new radio galaxies with tailed morphology. Tailed radio galaxies are generally found in rich environments, therefore their presence can be used as tracer of a cluster.

Methods. The radio galaxies were found in the fields of Giant Metrewave Radio Telescope (GMRT) observations carried out at 610 MHz and 327 MHz devoted to other studies. We inspected the literature and archives in the optical and X-ray bands to search for galaxy clusters or groups hosting them.

Results. All the tailed radio galaxies serendipitously found in the GMRT fields are located in rich environments. Two of them belong to the candidate cluster NCS J090232+204358, located at = 0.0746; one belongs to the cluster MaxBCGJ 223.97317+22.15620 at = 0.2619; finally we suggest that the fourth one is probing a galaxy cluster at , located behind A 262, and so far undetected in any band. Our results strengthen the relevance of high sensitivity and high resolution radio data in the detection of galaxy clusters at intermediate redshift.