Optical–SZE scaling relations for DES optically selected clusters within the SPT-SZ survey

Romer, K and The DES Collaboration, (2017) Optical–SZE scaling relations for DES optically selected clusters within the SPT-SZ survey. Monthly Notices of the Royal Astronomical Society, 468 (3). pp. 3347-3360. ISSN 0035-8711

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Abstract

We study the Sunyaev–Zel'dovich effect (SZE) signature in South Pole Telescope (SPT) data for an ensemble of 719 optically identified galaxy clusters selected from 124.6 deg² of the Dark Energy Survey (DES) science verification data, detecting a clear stacked SZE signal down to richness λ ∼ 20. The SZE signature is measured using matched-filtered maps of the 2500 deg2 SPT-SZ survey at the positions of the DES clusters, and the degeneracy between SZE observable and matched-filter size is broken by adopting as priors SZE and optical mass–observable relations that are either calibrated using SPT-selected clusters or through the Arnaud et al. (A10) X-ray analysis. We measure the SPT signal-to-noise ζ–λ relation and two integrated Compton-yY500–λ relations for the DES-selected clusters and compare these to model expectations that account for the SZE–optical centre offset distribution. For clusters with λ > 80, the two SPT-calibrated scaling relations are consistent with the measurements, while for the A10-calibrated relation the measured SZE signal is smaller by a factor of 0.61 ± 0.12 compared to the prediction. For clusters at 20 < λ < 80, the measured SZE signal is smaller by a factor of ∼0.20–0.80 (between 2.3σ and 10σ significance) compared to the prediction, with the SPT-calibrated scaling relations and larger λ clusters showing generally better agreement. We quantify the required corrections to achieve consistency, showing that there is a richness-dependent bias that can be explained by some combination of (1) contamination of the observables and (2) biases in the estimated halo masses. We also discuss particular physical effects associated with these biases, such as contamination of λ from line-of-sight projections or of the SZE observables from point sources, larger offsets in the SZE-optical centring or larger intrinsic scatter in the λ–mass relation at lower richnesses.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Billy Wichaidit
Date Deposited: 08 May 2017 15:16
Last Modified: 08 May 2017 15:22
URI: http://sro.sussex.ac.uk/id/eprint/67738

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Project NameSussex Project NumberFunderFunder Ref
Astronomy Centre Rolling GrantG0679STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/F002858/1