LoCuSS: comparison of observed X-ray and lensing galaxy cluster scaling relations with simulations

Abstract

The Local Cluster Substructure Survey (LoCuSS, Smith et al.) is a systematic multi-wavelength survey of more than 100 X-ray luminous galaxy clusters in the redshift range 0.14-0.3 selected from the ROSAT All Sky Survey. We used data on 37 LoCuSS clusters from the XMM-Newton archive to investigate the global scaling relations of galaxy clusters. The scaling relations based solely on the X-ray data (S-T, S-Yx, P-Y x , M-T, M-Y x , M-Mg as , M gas -T, L-T, L-Y x , and L-M) obey empirical self-similarity and reveal no additional evolution beyond the large-scale structure growth. They also reveal up to 17 per cent segregation between all 37 clusters and non-cool core clusters. Weak lensing mass measurements are also available in the literature for 19 of the clusters with XMM-Newton data. The average of the weak lensing mass to X-ray based mass ratio is 1.09 ± 0.08, setting the limit of the non-thermal pressure support to 9 ± 8 per cent. The mean of the weak lensing mass to X-ray based mass ratio of these clusters is ∼1, indicating good agreement between X-ray and weak lensing masses for most clusters, although with 31-51 per cent scatter. The scatter in the mass-observable relations (M-Y x , M-Mg as , and M-T) is smaller using X-ray based masses than using weak lensing masses by a factor of 2. With the scaled radius defined by the Y x profile - r YX,X 500 , rY X,W1 500 , and r YX,Si 500 , we obtain lower scatter in the weak lensing mass based mass-observable relations, which means the origin of the scatter is M W1 and M X instead of Y x . The normalization of the M-Yx relation using X-ray mass estimates is lower than the one from simulations by up to 18-24 per cent at 3cr significance. This agrees with the M-Y x relation based on weak lensing masses, the normalization of the latter being ∼20 per cent lower than the one from simulations at ∼2σ significance. This difference between observations and simulations is also indicated in the M-M gas and M-T relations. Despite the large scatter in the comparison of X-ray to lensing, the agreement between these two completely independent observational methods is an important step towards controlling astrophysical and measurement systematics in cosmological scaling relations.