Daniel P. Marrone, Graham P. Smith, Nobuhiro Okabe, Massimiliano Bonamente, John E. Carlstrom, Thomas L. Culverhouse, Megan Gralla, Christopher H. Greer, Nicole Hasler, David Hawkins, Ryan Hennessy, Marshall Joy, James W. Lamb, Erik M. Leitch, Rossella Martino, Pasquale Mazzotta, Amber Miller, Tony Mroczkowski, Stephen Muchovej, Thomas Plagge, Clem Pryke, Alastair J. R. Sanderson, Masahiro Takada, David Woody, Yu-Ying Zhang
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 Delta=500, 1000, and 2500 rho_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.
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http://arxiv.org/abs/1107.5115
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