Mass profile and dynamical status of the z ~ 0.8 galaxy cluster LCDCS 0504^⋆

¹ Astrophysics and Cosmology Research Unit, University of KwaZulu-Natal, Durban 4041, South Africa
e-mail: guennou@ukzn.ac.za
² Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
³ INAF/Osservatorio Astronomico di Trieste, via Tiepolo 11, 34143 Trieste, Italy
⁴ Institut d’Astrophysique de Paris (UMR 7095: CNRS & UPMC), 98bis Bd Arago, 75014 Paris, France
⁵ Departamento de Astronomia, Instituto de Astronomia Geofìsica e Ciências Atmosfèricas, Universidade de São Paulo, Rua do Matão 1226, 05508-900 São Paulo, Brazil
⁶ Department Physics & Astronomy & Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University, Evanston, IL 60208-2900, USA
⁷ Department of Physics and Astronomy, Ohio University, 251B Clippinger Lab, Athens, OH 45701, USA
⁸ Fermi National Accelerator Laboratory, PO Box 500, Batavia, IL 60510, USA
⁹ CSC/STSCi, 3700 San Martin Dr., Baltimore, MD 21218, USA
¹⁰ OCA, Cassiopée, Boulevard de l’Observatoire, BP 4229, 06304 Nice Cedex 4, France
¹¹ INAF/Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
¹² 23 rue d’Yerres, 91230 Montgeron, France
¹³ Steward Observatory, University of Arizona, 933 N. Cherry Ave. Tucson, AZ 85721, USA
¹⁴ Department of Astronomy & Astrophysics, University of Toronto, 50 St George Street Toronto, Ontario M5S 3H4, Canada
¹⁵ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
¹⁶ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 2575 Sand Hill Rd., Menlo Park, CA 94025, USA
¹⁷ Laboratório de Astrofísica Teórica e Observacional, Universidade Estadual de Santa Cruz, Ilhéus, Brazil
¹⁸ Gemini Observatory, Casilla 603 La Serena, Chile
¹⁹ Argelander-Institut für Astronomie, Universitët Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
²⁰ Physics Department, University of California, Santa Barbara, CA 93601, USA
²¹ University of Vienna, Department of Astrophysics, Türkenschanzstr. 17, 1180 Wien, Austria

Received: 5 August 2013
Accepted: 16 March 2014

Abstract

Context. Constraints on the mass distribution in high-redshift clusters of galaxies are currently not very strong.

Aims. We aim to constrain the mass profile, M(r), and dynamical status of the z ~ 0.8 LCDCS 0504 cluster of galaxies that is characterized by prominent giant gravitational arcs near its center.

Methods. Our analysis is based on deep X-ray, optical, and infrared imaging as well as optical spectroscopy, collected with various instruments, which we complemented with archival data. We modeled the mass distribution of the cluster with three different mass density profiles, whose parameters were constrained by the strong lensing features of the inner cluster region, by the X-ray emission from the intracluster medium, and by the kinematics of 71 cluster members.

Results. We obtain consistent M(r) determinations from three methods based on kinematics (dispersion-kurtosis, caustics, and MAMPOSSt), out to the cluster virial radius, ≃1.3 Mpc and beyond. The mass profile inferred by the strong lensing analysis in the central cluster region is slightly higher than, but still consistent with, the kinematics estimate. On the other hand, the X-ray based M(r) is significantly lower than the kinematics and strong lensing estimates. Theoretical predictions from ΛCDM cosmology for the concentration–mass relation agree with our observational results, when taking into account the uncertainties in the observational and theoretical estimates. There appears to be a central deficit in the intracluster gas mass fraction compared with nearby clusters.

Conclusions. Despite the relaxed appearance of this cluster, the determinations of its mass profile by different probes show substantial discrepancies, the origin of which remains to be determined. The extension of a dynamical analysis similar to that of other clusters of the DAFT/FADA survey with multiwavelength data of sufficient quality will allow shedding light on the possible systematics that affect the determination of mass profiles of high-z clusters, which is possibly related to our incomplete understanding of intracluster baryon physics.