Astron. Nachr. / AN 334, No. 4/5, 462 – 465 (2013) / DOI 10.1002/asna.201211881 The XMM Cluster Survey: Present status and latest results P.T.P. Viana 1,2,⋆ , N. Mehrtens 3,4 , C.D. Harrison 5 , A.K. Romer 3,6 , C.A. Collins 7 , M. Hilton 8,9 , B. Hoyle 10 , S.T. Kay 11 , A.R. Liddle 3 , J.A. Mayers 3 , C.J. Miller 5 , P.J. Rooney 3 , M. Sahl´ en 12 , and J.P. Stott 13 1 Centro de Astrof´ ısica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal 2 Departamento de F´ ısica e Astronomia, Faculdade de Ciˆ encias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal 3 Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH, UK 4 Department of Physics and Astronomy, Texas A&M University, College Station, TX 77845-4242, USA 5 Astronomy Department, University of Michigan, Ann Arbor, MI 48109, USA 6 SEPnet, South East Physics Network (www.sepnet.ac.uk), UK 7 Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK 8 Centre for Astronomy & Particle Theory, School of Physics & Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK 9 Astrophysics & Cosmology Research Unit, School of Mathematics, Statistics & Computer Science, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa 10 Institut de Ci´ encies del Cosmos (ICCUB-IEEC), Departmento de F´ ısica, Mart´ ı i Franqu´ es 1, 08034 Barcelona, Spain 11 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK 12 The Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, SE-106 91 Stock- holm, Sweden 13 Extragalactic and Cosmology Group, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK Received 2012 Aug 24, accepted 2012 Sep 20 Published online 2013 May 2 Key words galaxies: clusters: general – X-rays: galaxies: clusters – surveys The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters using all publicly available data in the XMM-Newton Science Archive. Our recent first data release (XCS-DR1) contains 503 optically confirmed groups and clusters, among which 256 new to the literature and 357 whose X-ray emission was detected for the first time. We discuss their properties and provide an update on the work being done. As examples of the applications of XCS-DR1, we mention the 17 fossil groups/clusters identified with the help of the Sloan Digital Sky Survey. Their brightest galaxies have stellar populations and star-formation histories which are similar to normal brightest cluster galaxies, but their stellar masses are significantly larger and correspond to a much bigger fraction of the total group/cluster optical luminosity. We also highlight the 15 clusters expected to be also detected by the Planck satellite, and characterize the expected overlap between the final XCS and Planck cluster catalogues. c  2013 WILEY-VCH Verlag GmbH& Co. KGaA, Weinheim 1 Introduction Clusters of galaxies are the largest gravitationally collapsed structures in the Universe. While detailed studies of in- dividual galaxy clusters are essential for obtaining an in- sight into the small-scale processes that influence the evo- lution of their baryonic components, their use as cosmolog- ical probes, and as a window to the physical processes in- volved in the formation and evolution of large-scale struc- ture, requires the study of the cluster population as a whole. With this objective in mind, the XMM Cluster Survey (XCS) collaboration is carrying out a systematic search for serendipitous detections of galaxy clusters in the outskirts ⋆ Corresponding author: viana@astro.up.pt of publicly-available data in the XMM archive, using the X-ray extended emission typical of galaxy clusters (Romer et al. 2001). The main scientific goals of the XCS are to (i) constrain cosmological parameters, in particular through the evolution of the cluster mass function with redshift, (ii) determine how the properties of the cluster intergalac- tic medium change with time, namely through the evolution of the cluster X-ray luminosity-temperature scaling relation, (iii) study galaxy evolution in clusters to high redshift. Some of the XCS highlights are the detection, and sub- sequent multi-wavelength follow-up, of a z =1.46 cluster (XMMXCS J2215.9–1738; Stanford et al. 2006; Hilton et al. 2007, 2009, 2010), analyses of galaxy evolution in high- redshift clusters (Collins et al. 2009; Stott et al. 2010), the study of the interplay between the brightest cluster galaxy c  2013 WILEY-VCH Verlag GmbH& Co. KGaA, Weinheim