An S-shaped arc in the galaxy cluster RX J0054.0-2823^*

¹ Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstr. 12-14, 69120 Heidelberg, Germany
² Department of Astronomy and Astrophysics, P. Universidad Catolica de Chile, Casilla 306, Santiago, Chile
³ Laboratoire Physique Théorique et Astroparticules, UMR5207 In2p3/Montpellier University, 34095 Montpellier, France e-mail: edmond.giraud@lpta.in2p3.fr
⁴ European Southern Observatory, Alonso de Córdova 3107, Santiago, Chile

Received: 19 February 2006
Accepted: 29 September 2006

Abstract

Context.The center of the galaxy cluster RX J0054.0-2823 at is a dynamically active region that includes an interacting system of three galaxies surrounded by a large halo of intra-cluster light.

Aims.We report here the discovery of an S-shaped feature of total length 11´´  in the central region of this cluster and discuss its physical nature.

Methods.We test the gravitational lensing assumption by doing a mass modeling of the central part of the galaxy cluster.

Results. We very naturally reproduce position and form of this S-shaped feature as a gravitationally lensed background object at redshift between 0.5 and 1.0.

Conclusions.We conclude that the lensing nature is the very probable explanation for this S-shaped arc; the ultimate proof will be the spectroscopic confirmation by measuring the high redshift of this elongated feature with surface brightness  mag arcsec^-2.