Constraints on the richness-mass relation and the optical-SZE positional offset distribution for SZE-selected clusters

• Main Authors: A. Saro, S. Bocquet, E. Rozo, B. A. Benson, J. Mohr, E. S. Rykoff, M. Soares-Santos, L. Bleem, S. Dodelson, P. Melchior, F. Sobreira, V. Upadhyay, J. Weller, T. Abbott, F. B. Abdalla, S. Allam, R. Armstrong, M. Banerji, A. H. Bauer, M. Bayliss, A. Benoit-Levy, G. M. Bernstein, E. Bertin, M. Brodwin, D. Brooks, E. Buckley-Geer, D. L. Burke, J. E. Carlstrom, R. Capasso, D. Capozzi, A. Carnero Rosell, M. Carrasco Kind, I. Chiu, R. Covarrubias, T. M. Crawford, M. Crocce, C. B. D'Andrea, L. N. da Costa, D. L. DePoy, S. Desai, T. de Haan, H. T. Diehl, J. P. Dietrich, P. Doel, C. E Cunha, T. F. Eifler, A. E. Evrard, A. Fausti Neto, E. Fernandez, B. Flaugher
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: South Pole; South pole
• Online Access: https://hdl.handle.net/20.500.12386/27415; https://doi.org/10.1093/mnras/stv2141; http://arxiv.org/abs/1506.07814v1; https://academic.oup.com/mnras/article/454/3/2305/1201112

We cross-match galaxy cluster candidates selected via their Sunyaev-Zel'dovich effect (SZE) signatures in 129.1 deg2 of the South Pole Telescope 2500d SPT-SZ survey with optically identified clusters selected from the Dark Energy Survey science verification data. We identify 25 clusters between 0.1 ≲ z ≲ 0.8 in the union of the SPT-SZ and redMaPPer (RM) samples. RM is an optical cluster finding algorithm that also returns a richness estimate for each cluster. We model the richness λ-mass relation with the following function <ln λ|M500> ∝ Bλln M500 + Cλln E(z) and use SPT-SZ cluster masses and RM richnesses λ to constrain the parameters. We find B_λ = 1.14^{+0.21}_{-0.18} and C_λ =0.73^{+0.77}_{-0.75}. The associated scatter in mass at fixed richness is σ _{ln M|λ } = 0.18^{+0.08}_{-0.05} at a characteristic richness λ = 70. We demonstrate that our model provides an adequate description of the matched sample, showing that the fraction of SPT-SZ-selected clusters with RM counterparts is consistent with expectations and that the fraction of RM-selected clusters with SPT-SZ counterparts is in mild tension with expectation. We model the optical-SZE cluster positional offset distribution with the sum of two Gaussians, showing that it is consistent with a dominant, centrally peaked population and a subdominant population characterized by larger offsets. We also cross-match the RM catalogue with SPT-SZ candidates below the official catalogue threshold significance ξ = 4.5, using the RM catalogue to provide optical confirmation and redshifts for 15 additional clusters with ξ ∈ [4, 4.5].