LoCuSS: Testing hydrostatic equilibrium in galaxy clusters

G. P. Smith, P. Mazzotta, N. Okabe, F. Ziparo, S. L. Mulroy, A. Babul, A. Finoguenov, I. G. McCarthy, M. Lieu, Y. Bahe, H. Bourdin, A. E. Evrard, T. Futamase, C. P. Haines, M. Jauzac, D. P. Marrone, R. Martino, P. E. May, J. E. Taylor, K. Umetsu

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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 β_X= 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 β_P= 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 β_P ≃ 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.
Original languageEnglish
Pages (from-to)L74-78
JournalRoyal Astronomical Society. Monthly Notices
Early online date2 Dec 2015
Publication statusPublished - 11 Feb 2016

Bibliographical note

5 pages, 1 figure, accepted by MNRAS


  • astro-ph.CO


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