LoCuSS: The Sunyaev-Zel'dovich Effect and Weak-lensing Mass Scaling Relation
Smith, Graham P.; Gralla, Megan; Mroczkowski, Tony; Marrone, Daniel P.; Okabe, Nobuhiro; Mazzotta, Pasquale; Takada, Masahiro; Hawkins, David; Lamb, James W.; Bonamente, Massimiliano; Joy, Marshall; Leitch, Erik M.; Sanderson, Alastair J. R.; Carlstrom, John E.; Greer, Christopher H.; Muchovej, Stephen; Martino, Rossella; Woody, David; Culverhouse, Thomas L.; Hasler, Nicole; Hennessy, Ryan; Miller, Amber; Plagge, Thomas; Pryke, Clem; Zhang, Yuying
United States, United Kingdom, Japan, Taiwan, Italy, Germany
Abstract
We present the first weak-lensing-based scaling relation between galaxy cluster mass, M WL, and integrated Compton parameter Y sph. Observations of 18 galaxy clusters at z ~= 0.2 were obtained with the Subaru 8.2 m telescope and the Sunyaev-Zel'dovich Array. The M WL-Y sph scaling relations, measured at Δ = 500, 1000, and 2500 ρ c , are consistent in slope and normalization with previous results derived under the assumption of hydrostatic equilibrium (HSE). We find an intrinsic scatter in M WL at fixed Y sph of 20%, larger than both previous measurements of M HSE-Y sph scatter as well as the scatter in true mass at fixed Y sph found in simulations. Moreover, the scatter in our lensing-based scaling relations is morphology dependent, with 30%-40% larger M WL for undisturbed compared to disturbed clusters at the same Y sph at r 500. Further examination suggests that the segregation may be explained by the inability of our spherical lens models to faithfully describe the three-dimensional structure of the clusters, in particular, the structure along the line of sight. We find that the ellipticity of the brightest cluster galaxy, a proxy for halo orientation, correlates well with the offset in mass from the mean scaling relation, which supports this picture. This provides empirical evidence that line-of-sight projection effects are an important systematic uncertainty in lensing-based scaling relations.