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

Romer, A K and The DES Collaboration, et al (2015) Constraints on the richness-mass relation and the optical-SZE positional offset distribution for SZE-selected clusters. Monthly Notices Of The Royal Astronomical Society, 454. pp. 2305-2319. ISSN 0035-8711

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Abstract

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 lambda-mass relation with the following function <ln lambda|M500> ∝ Blambdaln M500 + Clambdaln E(z) and use SPT-SZ cluster masses and RM richnesses lambda to constrain the parameters. We find B_lambda = 1.14^{+0.21}_{-0.18} and C_lambda =0.73^{+0.77}_{-0.75}. The associated scatter in mass at fixed richness is sigma _{ln M|lambda } = 0.18^{+0.08}_{-0.05} at a characteristic richness lambda = 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 xi = 4.5, using the RM catalogue to provide optical confirmation and redshifts for 15 additional clusters with xi ∈ [4, 4.5].

Item Type: Article
Keywords: Catalogues, Methods: data analysis, Galaxies: abundances, Galaxies: clusters: general, Galaxies: haloes, Galaxies: statistics, Cosmology: miscellaneous, Large-scale structure of Universe
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Richard Chambers
Date Deposited: 27 Jun 2016 11:36
Last Modified: 08 Mar 2017 18:48
URI: http://sro.sussex.ac.uk/id/eprint/61734

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Project NameSussex Project NumberFunderFunder Ref
Astrophysics and Cosmology - Sussex Consolidated GrantG1291STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/L000652/1