Journal Article

A parametric physical model for the intracluster medium and its use in joint SZ/X-ray analyses of galaxy clusters

James R. Allison, Angela C. Taylor, Michael E. Jones, Steve Rawlings and Scott T. Kay

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 1, pages 341-358
Published in print January 2011 | ISSN: 0035-8711
Published online December 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17447.x
A parametric physical model for the intracluster medium and its use in joint SZ/X-ray analyses of galaxy clusters

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We present a parametrized model of the intracluster medium that is suitable for jointly analysing pointed observations of the Sunyaev–Zel'dovich (SZ) effect and X-ray emission in galaxy clusters. The model is based on assumptions of hydrostatic equilibrium, the Navarro, Frenk and White model for the dark matter and a softened power-law profile for the gas entropy. We test this entropy-based model against high and low signal-to-noise ratio ratio mock observations of a relaxed and recently merged cluster from N-body/hydrodynamic simulations, using Bayesian hyperparameters to optimize the relative statistical weighting of the mock SZ and X-ray data. We find that it accurately reproduces both the global values of the cluster temperature, total mass and gas mass fraction (fgas), and the radial dependencies of these quantities outside the core (r > 100 kpc). For reference, we also provide a comparison with results from the single isothermal β model. We confirm previous results that the single isothermal β model can result in significant biases in derived cluster properties.

Keywords: methods: data analysis; galaxies: clusters: intracluster medium

Journal Article.  9273 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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