# LoCuSS: Testing hydrostatic equilibrium in galaxy clusters

Smith, GP and Mazzotta, P and Okabe, N and Ziparo, F and Mulroy, SL and Babul, A and Finoguenov, A and McCarthy, IG and Lieu, M and Bahe, Y and Bourdin, H and Evrard, AE and Futamase, T and Haines, CP and Jauzac, M and Marrone, DP and Martino, R and May, PE and Taylor, JE and Umetsu, K (2015) LoCuSS: Testing hydrostatic equilibrium in galaxy clusters. Monthly Notices of the Royal Astronomical Society, 456 (1). L74-L75. ISSN 0035-8711

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 $M_{500}$ 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 $\beta_{\rm X}=0.95\pm0.05$, and for the 44 clusters also detected by Planck, the mean ratio of Planck mass estimate to LoCuSS lensing mass is $\beta_{\rm P}=0.95\pm0.04$. Based on a careful like-for-like analysis, we find that LoCuSS, the Canadian Cluster Comparison Project (CCCP), and Weighing the Giants (WtG) agree on $\beta_{\rm P}\simeq0.9-0.95$ at $0.15<z<0.3$. This small level of hydrostatic bias disagrees at $\sim5\sigma$ with the level required to reconcile Planck cosmology results from the cosmic microwave background and galaxy cluster counts.