LoCuSS: Testing hydrostatic equilibrium in galaxy clusters
Finoguenov, A.; Smith, G. P.; Okabe, N.; Ziparo, F.; Bourdin, H.; Mazzotta, P.; Babul, A.; Evrard, A. E.; Umetsu, K.; Marrone, D. P.; McCarthy, I. G.; Haines, C. P.; Futamase, T.; Jauzac, M.; Lieu, M.; Taylor, J. E.; Bahé, Y. M.; Martino, R.; Mulroy, S. L.; May, P. E.
United Kingdom, Italy, Japan, Canada, Finland, Germany, United States, Chile, South Africa, Taiwan
Abstract
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.