The XXL Survey

XXV. Cosmological analysis of the C1 cluster number counts^★

¹ Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
e-mail: fpacaud@astro.uni-bonn.de
² AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
³ Aix Marseille Univ., CNRS, CNES, LAM, Marseille, France
⁴ Department of Physics and Michigan Center for Theoretical Physics, University of Michigan, Ann Arbor, MI 48109, USA
⁵ Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA
⁶ Institut d’Astrophysique de Paris (UMR7095: CNRS & UPMC-Sorbonne Universities), 75014, Paris, France
⁷ INAF–IASF Milano, Via Bassini 15, 20133 Milano, Italy
⁸ HH Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, UK
⁹ INAF-OAS Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129, Bologna, Italy
¹⁰ Dipartimento di Fisica e Astronomia, Alma Mater Studiorum Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
¹¹ Department of Astronomy and Space Sciences, Faculty of Science, 41 Istanbul University, 34119 Istanbul, Turkey
¹² European Space Astronomy Centre (ESA/ESAC), Operations Department, Villanueva de la Canãda, Madrid, Spain
¹³ Department of Space, Earth and Environment, Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden
¹⁴ INAF–Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Via E. Bianchi 46, 20121 Merate, Italy
¹⁵ CEA Saclay, DRF/Irfu/DEDIP/LILAS, 91191 Gif-sur-Yvette Cedex, France
¹⁶ Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia
¹⁷ Laboratoire Lagrange, UMR 7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06304 Nice, France
¹⁸ INFN–Sezione di Bologna, viale Berti Pichat 6/2, 40127, Bologna, Italy
¹⁹ INAF–Osservatorio astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy
²⁰ European Southern Observatory, Alonso de Cordova 3107, Vitacura, 19001 Casilla, Santiago 19, Chile
²¹ Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 1A1, Canada
²² National Observatory of Athens, Lofos Nymfon, 11810 Athens, Greece
²³ Physics Department of Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece

Received: 4 August 2018
Accepted: 11 September 2018

Abstract

Context. We present an estimation of cosmological parameters with clusters of galaxies.

Aims. We constrain the Ω_m, σ₈, and w parameters from a stand-alone sample of X-ray clusters detected in the 50 deg² XMM-XXL survey with a well-defined selection function.

Methods. We analyse the redshift distribution of a sample comprising 178 high signal-to-noise ratio clusters out to a redshift of unity. The cluster sample scaling relations are determined in a self-consistent manner.

Results. In a lambda cold dark matter (ΛCDM) model, the cosmology favoured by the XXL clusters compares well with results derived from the Planck Sunyaev-Zel’dovich clusters for a totally different sample (mass/redshift range, selection biases, and scaling relations). However, with this preliminary sample and current mass calibration uncertainty, we find no inconsistency with the Planck CMB cosmology. If we relax the w parameter, the Planck CMB uncertainties increase by a factor of ~10 and become comparable with those from XXL clusters. Combining the two probes allows us to put constraints on Ω_m = 0.316 ± 0.060, σ₈ = 0.814 ± 0.054, and w = −1.02 ± 0.20.

Conclusions. This first self-consistent cosmological analysis of a sample of serendipitous XMM clusters already provides interesting insights into the constraining power of the XXL survey. Subsequent analysis will use a larger sample extending to lower confidence detections and include additional observable information, potentially improving posterior uncertainties by roughly a factor of 3.