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. M. Bahé, 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

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


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 betweenXMM-Newton and Chandra. The mean ratio of X-ray to lensing mass for these 50 clusters is βX = 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 ± 0.04. Based on a careful like-for-like analysis, we find that LoCuSS, the Canadian Cluster Comparison Project, and Weighing the Giants agree on βP = 0.9-0.95 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 (US)
Pages (from-to)L74-L78
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Feb 11 2016


  • Cosmology: observations
  • Galaxies: clusters: general
  • Gravitational lensing: weak

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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