Testing the radio halo-cluster merger scenario

The case of RXC J2003.5–2323

¹ Harvard-Smithsonian Centre for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
² INAF - Istituto di Radioastronomia, via Gobetti 101, 40129, Bologna, Italy e-mail: tventuri@ira.inaf.it
³ Dipartimento di Fisica, Università di Roma Tor Vergata, via della Ricerca Scientifica 1, 00133, Roma, Italy
⁴ Dipartimento di Astronomia, Universitá di Bologna, via Ranzani 1, 40127, Bologna, Italy
⁵ INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127, Bologna, Italy

Received: 8 April 2009
Accepted: 15 May 2009

Abstract

Aims. We present a combined radio, X-ray, and optical study of the galaxy cluster RXC J2003.5–2323. The cluster hosts one of the largest, most powerful, and distant giant radio halos known to date, suggesting that it may be undergoing a strong merger. The aim of our multiwavelength study is to investigate the radio-halo cluster merger scenario.

Methods. We studied the radio properties of the giant radio halo in RXC J2003.5–2323 by means of new radio data obtained at 1.4 GHz with the Very Large Array, and at 240 MHz with the Giant Metrewave Radio Telescope, in combination with previously published GMRT data at 610 MHz. The dynamical state of the cluster was investigated by means of X-ray Chandra observations and optical ESO-NTT observations.

Results. Our study confirms that RXC J2003.5–2323 is an unrelaxed cluster. The unusual filamentary and clumpy morphology of the radio halo could be due to a combination of the filamentary structure of the magnetic field and turbulence in the inital stage of a cluster merger.