Intracluster light in clusters of galaxies at redshifts 0.4 < z < 0.8^⋆

¹ LAM, OAMP, Pôle de l’Étoile Site de Château-Gombert, 38 rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13 France
e-mail: loic.guennou@oamp.fr
² Núcleo de Astrofísica Teórica, Universidade Cruzeiro do Sul, R. Galvão Bueno 868, 01506–000 São Paulo, SP, Brazil
³ UPMC Université Paris 06, UMR 7095, Institut d’Astrophysique de Paris, 75014 Paris, France
⁴ CNRS, UMR 7095, Institut d’Astrophysique de Paris, 75014 Paris, France
⁵ Department Physics & Astronomy, Northwestern University, Evanston, IL 60208-2900, USA
⁶ Fermi National Accelerator Laboratory, PO Box 500, Batavia, IL 60510, USA
⁷ OCA, Cassiopée, Boulevard de l’Observatoire, BP 4229, 06304 Nice Cedex 4, France
⁸ INAF/Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34143 Trieste, Italy
⁹ Department of Physics and Astronomy, Ohio University, 251B Clippinger Lab, Athens, OH 45701, USA
¹⁰ Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
¹¹ Steward Observatory, University of Arizona, 933 N. Cherry Ave. Tucson, AZ 85721, USA
¹² Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60615, USA
¹³ Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
¹⁴ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
¹⁵ Observatorio do Valongo, UFRJ, Ladeira do Pedro Antonio 43, Saude, Rio de Janeiro 20080-090, Rio de Janeiro, Brazil
¹⁶ Dept. of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
¹⁷ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 382 via Pueblo Mall, Stanford, CA 94305-4060, USA

Received: 15 June 2011
Accepted: 18 September 2011

Abstract

Context. The study of intracluster light (ICL) can help us to understand the mechanisms taking place in galaxy clusters, and to place constraints on the cluster formation history and physical properties. However, owing to the intrinsic faintness of ICL emission, most searches and detailed studies of ICL have been limited to redshifts z < 0.4.

Aims. To help us extend our knowledge of ICL properties to higher redshifts and study the evolution of ICL with redshift, we search for ICL in a subsample of ten clusters detected by the ESO Distant Cluster Survey (EDisCS), at redshifts 0.4 < z < 0.8, that are also part of our DAFT/FADA Survey.

Methods. We analyze the ICL by applying the OV WAV package, a wavelet-based technique, to deep HST ACS images in the F814W filter and to V-band VLT/FORS2 images of three clusters. Detection levels are assessed as a function of the diffuse light source surface brightness using simulations.

Results. In the F814W filter images, we detect diffuse light sources in all the clusters, with typical sizes of a few tens of kpc (assuming that they are at the cluster redshifts). The ICL detected by stacking the ten F814W images shows an 8σ detection in the source center extending over a ~50 × 50 kpc² area, with a total absolute magnitude of −21.6 in the F814W filter, equivalent to about two L^∗ galaxies per cluster. We find a weak correlation between the total F814W absolute magnitude of the ICL and the cluster velocity dispersion and mass. There is no apparent correlation between the cluster mass-to-light ratio (M/L) and the amount of ICL, and no evidence of any preferential orientation in the ICL source distribution. We find no strong variation in the amount of ICL between z = 0 and z = 0.8. In addition, we find wavelet-detected compact objects (WDCOs) in the three clusters for which data in two bands are available; these objects are probably very faint compact galaxies that in some cases are members of the respective clusters and comparable to the faint dwarf galaxies of the Local Group.

Conclusions. We show that the ICL is prevalent in clusters at least up to redshift z = 0.8. In the future, we propose to detect the ICL at even higher redshifts, to determine wether there is a particular stage of cluster evolution where it was stripped from galaxies and spread into the intracluster medium.