LoCuSS: THE SUNYAEV–ZEL'DOVICH EFFECT AND WEAK-LENSING MASS SCALING RELATION

We present the first weak-lensing-based scaling relation between galaxy mass, M _WL, and integrated Compton parameter Y ₛph. Observations of 18 galaxy clusters at z \\~{}= 0.2 were with the Subaru 8.2 m telescope and the Sunyaev-Zel'dovich . The M WL-Y ₛph scaling relations, measured \Δ = 500, 1000, and 2500 \ρ_ c , are consistent in and normalization with previous results derived under the of hydrostatic equilibrium (HSE). We find an intrinsic in M_WL$ at fixed Y $_sphof 20%, larger than previous measurements of M_HSE$-Y $_sphscatter well as the scatter in true mass at fixed Y_sphfound in . Moreover, the scatter in our lensing-based scaling is morphology dependent, with 30%-40% larger M_WLundisturbed compared to disturbed clusters at the same Y_sph$ at r $_ 500$. Further examination suggests that segregation may be explained by the inability of our spherical lens to faithfully describe the three-dimensional structure of the , in particular, the structure along the line of sight. We find the ellipticity of the brightest cluster galaxy, a proxy for halo , correlates well with the offset in mass from the mean relation, which supports this picture. This provides empirical that line-of-sight projection effects are an important uncertainty in lensing-based scaling relations. }