The XXL Survey
1 Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
2 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85748 Garching bei München, Germany
3 H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
4 Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille), UMR 7326, 13388 Marseille, France
5 Service d’Astrophysique AIM, CEA/DSM/IRFU/SAp, CEA Saclay, 91191 Gif-sur-Yvette, France
6 School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
7 Service d’Électronique des Détecteurs et d’Informatique, CEA/DSM/IRFU/SEDI, CEA Saclay, 91191 Gif-sur-Yvette, France
8 Department of Astronomy and Space Sciences, Faculty of Science, Istanbul University, 34119 Istanbul, Turkey
9 Laboratoire Lagrange, UMR 7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06304 Nice, France
10 European Space Astronomy Centre, ESA, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
11 Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
12 INAF, IASF Milano, via Bassini 15, 20133 Milano, Italy
13 Department of Astronomy, University of Geneva, ch. d’Écogia 16, 1290 Versoix, Switzerland
14 Departments of Physics and Astronomy, and Michigan Center for Theoretical Physics, University of Michigan, Ann Arbor, MI 48109, USA
15 Astrophysics and Cosmology Research Unit, University of KwaZulu-Natal, 4041 Durban, South Africa
16 Australian Astronomical Observatory, PO BOX 915, 1670 North Ryde, Australia
17 Department of Earth and Space Sciences, Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden
18 INAF–Osservatorio Astronomico di Brera, via Brera 28, 20122 Milano, Italy
19 Institute for Astronomy & Astrophysics, Space Applications & Remote Sensing, National Observatory of Athens, 15236 Palaia Penteli, Athens, Greece
20 National Center for Supercomputing Applications and Department of Astronomy University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
21 Department of Physics and Astronomy, Macquarie University, Sydney NSW 2109, Australia
22 INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio, 5, 35122 Padova, Italy
23 European Southern Observatory,Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago de Chile, Chile
24 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
25 Faculty of Physics, Ludwig-Maximilians University, Scheinerstrasse 1, 81679 Munich, Germany
26 Institut de Physique Théorique, CEA/DSM/IPhT and CNRS/URA 2306, 91191 Gif-sur-Yvette Cedex, France
27 Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC, Canada
28 Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
29 ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
30 Astrophysics Department, Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
Received: 3 July 2015
Accepted: 25 November 2015
Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. The survey will ultimately uncover several hundreds of galaxy clusters out to a redshift of ~2 at a sensitivity of ~10-14 erg s-1 cm-2 in the [0.5–2] keV band.
Aims. This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 × 10-14 erg s-1 cm-2 on the source flux within a 1′ aperture.
Methods. The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample.
Results. The bright cluster sample consists of systems with masses between M500 = 7 × 1013 and 3 × 1014 M⊙, mostly located between z = 0.1 and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the prediction from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of σ8 and/or ΩM appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to z ~ 1. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters.
Key words: surveys / X-rays: galaxies: clusters / galaxies: clusters: intracluster medium / large-scale structure of Universe / cosmological parameters
Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. Based on observations made with ESO Telescopes at the La Silla and Paranal Observatories under programme ID 089.A-0666 and LP191.A-0268.
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© ESO, 2016