Diffuse light and building history of the galaxy cluster Abell 2667

¹ INAF - Osservatorio Astronomico di Capodimonte, Naples, Italy
² Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, 13012 Marseille, France e-mail: giovanni.covone@oamp.fr
³ Institut d'Astrophysique de Paris, CNRS, Université Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France
⁴ Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France
⁵ Instituto de Astronomia, Geofísica e C. Atmosf./USP, R. do Matão 1226, 05508-090 São Paulo/SP, Brazil
⁶ Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France

Received: 3 August 2005
Accepted: 8 May 2006

Abstract

Aims.We searched for diffuse intracluster light in the galaxy cluster Abell 2667 () from HST images in three broad band-filters.

Methods.We applied an iterative multi-scale wavelet analysis and reconstruction technique to these images, which allows to subtract stars and galaxies from the original images.

Results.We detect a zone of diffuse emission southwest of the cluster center (DS1) and a second faint object (ComDif) within DS1. Another diffuse source (DS2) may be detected at lower confidence level northeast of the center. These sources of diffuse light contribute to 10-15% of the total visible light in the cluster. Whether they are independent entities or part of the very elliptical external envelope of the central galaxy remains unclear. Deep VLT VIMOS integral field spectroscopy reveals a faint continuum at the positions of DS1 and ComDif but do not allow a redshift to be computed, so we conclude if these sources are part of the central galaxy or not. A hierarchical substructure detection method reveals the presence of several galaxy pairs and groups defining a similar direction to the one drawn by the DS1 – central galaxy – DS2 axis. The analysis of archive XMM-Newton and Chandra observations shows X-ray emission elongated in the same direction. The X-ray temperature map shows the presence of a cool core, a broad cool zone stretching from north to south, and hotter regions towards the northeast, southwest, and northwest. This might suggest shock fronts along these directions produced by infalling material, even if uncertainties remain quite large on the temperature determination far from the center.

Conclusions.These various data are consistent with a picture in which diffuse sources are concentrations of tidal debris and harassed matter expelled from infalling galaxies by tidal stripping and undergoing an accretion process onto the central cluster galaxy; as such, they are expected to be found along the main infall directions. Note, however, that the limited signal to noise of the various data and the apparent lack of large numbers of well-defined independent tidal tails, besides the one named ComDif, preclude definitive conclusions on this scenario.