Investigating the large-scale environment of wide-angle tailed radio galaxies in the local Universe

¹ Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
e-mail: vmissaglia@ia.forth.gr
² Institute of Astrophysics, Foundation for Research and Technology – Hellas, Voutes, 7110 Heraklion, Greece
³ INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
⁴ Istituto Nazionale di Fisica Nucleare, Sezione di Torino, 10125 Torino, Italy
⁵ Consorzio Interuniversitario per la Fisica Spaziale, Via Pietro Giuria 1, 10125 Torino, Italy
⁶ INAF – Istituto di Radioastronomia, Via Piero Gobetti 101, 40129 Bologna, Italy
⁷ Center for Astrophysics, Harvard & Smithsonian, 60 Garden Street, 02138 Cambridge, MA, USA
⁸ Dipartimento di Fisica “Ettore Pancini”, Università di Napoli Federico II, Via Cintia, 80126 Napoli, Italy
⁹ University of Geneva, Chemin d’Ecogia 16, Versoix, 1290 Switzerland
¹⁰ INAF/OAS, Via Piero Gobetti 101, 40129 Bologna, Italy
¹¹ INFN – Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
¹² INAF – Osservatorio Astronomico di Palermo “G. S. Vaiana”, Piazza del Parlamento 1, 90134 Palermo, Italy

Received: 10 October 2022
Accepted: 18 April 2023

Abstract

We present a statistical analysis of the large-scale (up to two Mpc) environment of a homogeneous and complete sample, both in radio and optical selection, of wide-angle tailed radio galaxies (WATs) in the local Universe (i.e., with redshifts z ≲ 0.15). The analysis is carried out using the parameters obtained from cosmological neighbors within two Mpc of the target source. Results regarding the large-scale environments of the WATs are then compared with those of Fanaroff–Riley type I (FR Is) and type II (FR IIs) radio galaxies listed in two other homogeneous and complete catalogs and selected with the same criterion adopted for the WATs catalog. We obtain indication that at low redshift, WATs inhabit environments with a larger number of galaxies than those of FR Is and FR IIs. In the explored redshift range, the physical size of the galaxy group or cluster in which the WATs reside appears to be almost constant with respect to FR Is and FR IIs, being around one Mpc. From the distribution of the concentration parameter, defined as the ratio between the number of cosmological neighbors lying within 500 kpc and within one Mpc, we conclude that WATs tend to inhabit the central region of the group or cluster in which they reside, in agreement with the general paradigm that WATs are the brightest cluster or group galaxy.