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LoCuSS : testing hydrostatic equilibrium in galaxy clusters.

Smith, G. P. and Mazzotta, P. and Okabe, N. and Ziparo, F. and Mulroy, S. L. and Babul, A. and Finoguenov, A. and McCarthy, I. G. and Lieu, M. and Bahé, Y. M. and Bourdin, H. and Evrard, A. E. and Futamase, T. and Haines, C. P. and Jauzac, M. and Marrone, D. P. and Martino, R. and May, P. E. and Taylor, J. E. and Umetsu, K. (2016) 'LoCuSS : testing hydrostatic equilibrium in galaxy clusters.', Monthly notices of the Royal Astronomical Society : letters., 456 (1). L74-L78.


We test the assumption of hydrostatic equilibrium in an X-ray luminosity selected sample of 50 galaxy clusters at 0.15 < z < 0.3 from the Local Cluster Substructure Survey (LoCuSS). Our weak-lensing measurements of M500 control systematic biases to sub-4 per cent, and our hydrostatic measurements of the same achieve excellent agreement between XMM–Newton and Chandra. The mean ratio of X-ray to lensing mass for these 50 clusters is βX=0.95±0.05βX=0.95±0.05, and for the 44 clusters also detected by Planck, the mean ratio of Planck mass estimate to LoCuSS lensing mass is βP=0.95±0.04βP=0.95±0.04. Based on a careful like-for-like analysis, we find that LoCuSS, the Canadian Cluster Comparison Project, and Weighing the Giants agree on βP≃0.9−0.95βP≃0.9−0.95 at 0.15 < z < 0.3. This small level of hydrostatic bias disagrees at ∼5σ with the level required to reconcile Planck cosmology results from the cosmic microwave background and galaxy cluster counts.

Item Type:Article
Keywords:Gravitational lensing: weak, Galaxies: clusters: general, Cosmology: observations.
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2016 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:04 November 2015
Date deposited:11 February 2016
Date of first online publication:02 December 2015
Date first made open access:No date available

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