The XMM Cluster Survey: forecasting cosmological and cluster scaling-relation parameter constraints |
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| Authors: | Martin Sahlén Pedro T P Viana rew R Liddle A Kathy Romer Michael Davidson Mark Hosmer Ed Lloyd-Davies Kivanc Sabirli Chris A Collins Peter E Freeman Matt Hilton Ben Hoyle Scott T Kay Robert G Mann Nicola Mehrtens Christopher J Miller Robert C Nichol S Adam Stanford Michael J West † |
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| Institution: | Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH;Departamento de Matemática Aplicada da Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal;Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal;SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 9HJ;Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA-15217, USA;Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD;Astrophysics &Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu–Natal, Private Bag X54001, Durban 4000, S. Africa;South African Astronomical Observatory, P.O. Box 9, Observatory, 7935, Cape Town, S. Africa;ICG, University of Portsmouth, Portsmouth PO1 2EG;Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL;Cerro-Tololo Inter-American Observatory, National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA;Department of Physics, University of California at Davis, 1 Shields Avenue, Davis, CA 95616-8677, USA;Institute of Geophysics &Planetary Physics, Lawrence Livermore National Laboratory, L-413, P.O. Box 808, 7000 E. Avenue, Livermore, CA 94551, USA;Gemini Observatory, Casilla 603, La Serena, Chile;European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19, Chile |
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| Abstract: | We forecast the constraints on the values of σ8, Ωm and cluster scaling-relation parameters which we expect to obtain from the XMM Cluster Survey (XCS). We assume a flat Λ cold dark matter Universe and perform a Monte Carlo Markov Chain analysis of the evolution of the number density of galaxy clusters that takes into account a detailed simulated selection function. Comparing our current observed number of clusters shows good agreement with predictions. We determine the expected degradation of the constraints as a result of self-calibrating the luminosity–temperature relation (with scatter), including temperature measurement errors, and relying on photometric methods for the estimation of galaxy cluster redshifts. We examine the effects of systematic errors in scaling relation and measurement error assumptions. Using only ( T , z ) self-calibration, we expect to measure Ωm to ±0.03 (and ΩΛ to the same accuracy assuming flatness), and σ8 to ±0.05, also constraining the normalization and slope of the luminosity–temperature relation to ±6 and ±13 per cent (at 1σ), respectively, in the process. Self-calibration fails to jointly constrain the scatter and redshift evolution of the luminosity–temperature relation significantly. Additional archival and/or follow-up data will improve on this. We do not expect measurement errors or imperfect knowledge of their distribution to degrade constraints significantly. Scaling-relation systematics can easily lead to cosmological constraints 2σ or more away from the fiducial model. Our treatment is the first exact treatment to this level of detail, and introduces a new 'smoothed ML' (Maximum Likelihood) estimate of expected constraints. |
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| Keywords: | methods: statistical galaxies: clusters: general cosmological parameters cosmology: observations cosmology: theory X-rays: galaxies: clusters |
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