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

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Author: Saro, A.
• Language: unknown
• Published: 2022
• Subjects: 79 ASTRONOMY AND ASTROPHYSICS; South Pole; South pole
• Online Access: http://www.osti.gov/servlets/purl/1246801; https://www.osti.gov/biblio/1246801; https://doi.org/10.1093/mnras/stv2141

In this study, we cross-match galaxy cluster candidates selected via their Sunyaev–Zel'dovich effect (SZE) signatures in 129.1 deg 2 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|M 500 > ∝ B λ lnM 500 + C λ lnE(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 lnM|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 ϵ [4, 4.5].