1205.3103 (F. W. High et al.)

Weak-Lensing Mass Measurements of Five Galaxy Clusters in the South Pole Telescope Survey Using Magellan/Megacam    [PDF]

F. W. High, H. Hoekstra, N. Leethochawalit, T. de Haan, L. Abramson, K. A. Aird, R. Armstrong, M. L. N. Ashby, M. Bautz, M. Bayliss, G. Bazin, B. A. Benson, L. E. Bleem, M. Brodwin, J. E. Carlstrom, C. L. Chang, H. M. Cho, A. Clocchiatti, M. Conroy, T. M. Crawford, A. T. Crites, S. Desai, M. A. Dobbs, J. P. Dudley, R. J. Foley, W. R. Forman, E. M. George, M. D. Gladders, A. H. Gonzalez, N. W. Halverson, N. L. Harrington, G. P. Holder, W. L. Holzapfel, S. Hoover, J. D. Hrubes, C. Jones, M. Joy, R. Keisler, L. Knox, A. T. Lee, E. M. Leitch, J. Liu, M. Lueker, D. Luong-Van, A. Mantz, D. P. Marrone, M. McDonald, J. J. McMahon, J. Mehl, S. S. Meyer, L. Mocanu, J. J. Mohr, T. E. Montroy, S. S. Murray, T. Natoli, D. Nurgaliev, S. Padin, T. Plagge, C. Pryke, C. L. Reichardt, A. Rest, J. Ruel, J. E. Ruhl, B. R. Saliwanchik, A. Saro, J. T. Sayre, K. K. Schaffer, L. Shaw, T. Schrabback, E. Shirokoff, J. Song, H. G. Spieler, B. Stalder, Z. Staniszewski, A. A. Stark, K. Story, C. W. Stubbs, R. Suhada, S. Tokarz, A. van Engelen, K. Vanderlinde, J. D. Vieira, A. Vikhlinin, R. Williamson, O. Zahn, A. Zenteno

We use weak gravitational lensing to measure the masses of five galaxy clusters selected from the South Pole Telescope (SPT) survey, with the primary goal of comparing these with the SPT Sunyaev-Zel'dovich (SZ) and X-ray based mass estimates. The clusters span redshifts 0.28 < z < 0.43 and have masses M_500 > 2x10^14 h^-1 M_sun, and three of the five clusters were discovered by the SPT survey. We observed the clusters in the gri passbands with the Megacam imager on the Magellan Clay 6.5m telescope. We measure a mean ratio of weak lensing aperture masses to inferred aperture masses from the SZ data, both within an aperture of R_500,SZ derived from the SZ mass, of 1.12 +/- 0.15. We measure a mean ratio of spherical weak lensing masses evaluated at R_500,SZ to spherical SZ masses of 1.06 +/- 0.18, and a mean ratio of spherical weak lensing masses evaluated at R_500,WL to spherical SZ masses of 1.09 +/- 0.23. We verify in mock catalogs based on N-body simulations that all three mass ratio tests are unbiased to the 2% level under simple assumptions. We explore potential sources of systematic error in the mass comparisons and conclude that all are subdominant to the statistical uncertainty. Expanding the sample of SPT clusters with weak lensing observations has the potential to significantly improve the SPT cluster mass calibration and the resulting cosmological constraints from the SPT cluster survey. These are the first weak-lensing detections using Megacam on the Magellan Clay telescope.

View original: http://arxiv.org/abs/1205.3103