Chasing ICM cooling and AGN feedback from the macro to the meso scales in the galaxy cluster ZwCl 235

¹ Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
e-mail: francesco.ubertosi2@unibo.it
² Istituto Nazionale di Astrofisica (INAF) – Osservatorio di Astrofisica e Scienza dello Spazio (OAS), Via Gobetti 101, 40129 Bologna, Italy
³ Istituto Nazionale di Astrofisica (INAF) – Istituto di Radioastronomia (IRA), Via Gobetti 101, 40129 Bologna, Italy
⁴ University of California Observatories/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA

Received: 14 May 2022
Accepted: 14 November 2022

Abstract

Aims. We aim to investigate the interplay between the intracluster medium (ICM) and the active galactic nucleus (AGN) in ZwCl 235, a galaxy cluster with high X-ray flux, an extended central radio galaxy, and evidence of multiphase gas at its center.

Methods. Using archival data from the Chandra telescope, the Very Large Array Sky Survey (VLASS), the LOFAR Two-metre Sky Survey (LOTSS), and the VLBA telescope, we performed a complete study of ZwCl 235, dissecting the dynamics of the ICM, the thermodynamic state of the central gas, and the properties of the brightest cluster galaxy (BCG). By means of radial profiles and 2D spectral maps, we measured the temperature, entropy, and cooling time of the ICM, and we compared the morphology of the central radio galaxy with the surrounding medium.

Results. We find evidence that ZwCl 235 is a sloshing cool core cluster in which the activity of the central galaxy has excavated a pair of cavities and possibly uplifted enriched gas to an altitude of ∼30 kpc. In the cluster core, the lowest entropy ICM is preferentially found in a 20 kpc-long filament tangential to the southern radio lobe of the AGN. We argue that the observed cool (∼1.3 keV) filament is likely produced by a combination of sloshing and stimulated ICM cooling, which may be fueling the central supermassive black hole. Additionally, we determined that the X-ray emission of the BCG originates from a ∼1.4 keV plasma kernel, which extends for 5 kpc in radius and has a short cooling time (∼240 Myr), and it could represent the thermal corona of the BCG.

Conclusions. Overall, we propose that several sources (the large-scale ICM, the low entropy filament, and the ∼1.4 keV kernel) of cold material are currently feeding the central AGN, and that the ICM cooling cycle expectations are met from the macro scales (between 5−100 kpc) to the meso scales (≤5 kpc) of AGN feedback.