Projects per year
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 -Y-X, P-Y-X, M-T, M-Y-X,M-M-gas, 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-thermalpressure support to 9 +/- 8 per cent. The mean of the weak lensing mass to X-ray based mass ratio of these clusters is similar to 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-M-gas, 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(500)(YX, X) , r(500)(YX, wl) and r(500)(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-wl and M-X instead of Y-X. The normalization of the M-Y-X relation using X-ray mass estimates is lower than the one from simulations by up to 18 - 24 per cent at 3 sigma significance. This agrees with the M-Y-X relation based on weak lensing masses, the normalization of the latter being similar to 20 per cent lower than the one from simulations at similar to 2 sigma 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.
- cosmology : observations
- X-rays : galaxies : clusters cosmology : dark matter
- gravitational lensing
- galaxies : clusters : general