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

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-Lévy , G. M. Bernstein , E. Bertin (1) , 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 , P. Fosalba , J. Frieman , C. Gangkofner , E. Gaztanaga , D. Gerdes , D. Gruen , R. A. Gruendl , N. Gupta , C. Hennig , W. L. Holzapfel , K. Honscheid , B. Jain , D. James , K. Kuehn , N. Kuropatkin , O. Lahav , T. S. Li , H. Lin , M. A. G. Maia , M. March , J. L. Marshall , Paul Martini , M. Mcdonald , C. J. Miller , R. Miquel , B. Nord , R. Ogando , A. A. Plazas , C. L. Reichardt , A. K. Romer , A. Roodman , M. Sako , E. Sanchez , M. Schubnell , I. Sevilla , R. C. Smith , B. Stalder , A. A. Stark , V. Strazzullo , E. Suchyta , M. E. C. Swanson , G. Tarle , J. Thaler , D. Thomas , D. Tucker , V. Vikram , A. von Der Linden , A. R. Walker , R. H. Wechsler , W. Wester , A. Zenteno , K. E. Ziegler

1 IAP - Institut d'Astrophysique de Paris

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 500> ∝ B_λln M₅₀₀ + C_λln 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].

Keywords: catalogues; methods: data analysis; galaxies: abundances; galaxies: clusters: general; galaxies: haloes; galaxies: statistics; cosmology: miscellaneous; large-scale structure of Universe; Astrophysics - Cosmology and Nongalactic Astrophysics

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

A. Saro, S. Bocquet, E. Rozo, B. A. Benson, J. Mohr, et al.. Constraints on the richness-mass relation and the optical-SZE positional offset distribution for SZE-selected clusters. Monthly Notices of the Royal Astronomical Society, 2015, 454, pp.2305-2319. ⟨10.1093/mnras/stv2141⟩. ⟨insu-03644672⟩