LoCuSS: Subaru Weak Lensing Study of 30 Galaxy Clusters

We use high-quality Subaru/Suprime-Cam imaging data to conduct a detailed weak lensing study of the distribution of dark matter in a sample of 30 X-ray luminous galaxy clusters at 0.15 <= z <= 0.3. A weak lensing signal is detected at high statistical significance in each cluster, the total signal-to-noise ratio of the detections ranging from 5 to 13. Comparing spherical models to the tangential distortion profiles of the clusters individually, we are unable to discriminate statistically between a singular isothermal sphere (SIS) and Navarro. Frenk, and White (NFW) models. However, when the tangential distortion profiles are combined and then models are fitted to the stacked profile, the SIS model is rejected at 6 sigma and 11 sigma, respectively, for low (M-vir < 6 x 10(14) h(-1) M-circle dot) and high (M-vir > 6 x 10(14) h(-1) M-circle dot) mass bins. We also used individual cluster NFW model fits to investigate the relationship between the cluster mass and the concentration, finding that the concentration (c(vir)) decreases with increasing cluster mass The best-fit c(vir)-M-vir relation is: c(vir)(M-vir) = 8.75(-2.89)(+4.13) x (M-vir/10(14) h(-1) M-circle dot)(-alpha) with a alpha approximate to 0.40 +/- 0.19: i.e., a non-zero slope is detected at 2 sigma significance. This relation gives a concentration of c(vir) = 3.48(-1.15)(+1.65) for clusters with M-vir = 10(15) h(-1) M-circle dot, which is inconsistent at 4 sigma significance with the values of c(vir) similar to 10 reported for strong-lensing-selected clusters. We have found that the measurement error on the cluster mass is smaller at higher over-densities, Delta similar or equal to 500-2000, than at the virial over-density, Delta(vir) similar or equal to 110; typical fractional errors at Delta similar or equal to 500-2000 are improved to sigma(M-Delta)/M-Delta similar or equal to 0.1-0.2 compared with 0.2-0.3 at Delta(vir). Furthermore, comparing the 3D spherical mass with the 2D cylinder mass, obtained from the aperture mass method at a given aperture radius, theta(Delta), reveals M-2D(< theta(Delta))/M-3D(< r(Delta) = D-1 theta(Delta)) similar or equal to 1.46 and 1.32 for Delta = 500 and Delta(vir), respectively. The amplitude of this offset agrees well with that predicted by integrating an NFW model of cluster-scale halos along the line-of-sight.