# UCL Discovery

## Optical-SZE Scaling Relations for DES Optically Selected Clusters within the SPT-SZ Survey

Saro, A; Bocquet, S; Mohr, J; Rozo, E; Benson, BA; Dodelson, S; Rykoff, ES; ... Zenteno, A; + view all (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. 10.1093/mnras/stx594.

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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 deg$^2$ of the Dark Energy Survey (DES) science verification data, detecting a stacked SZE signal down to richness $\lambda\sim20$. The SZE signature is measured using matched-filtered maps of the 2500 deg$^2$ 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. (2010, A10) X-ray analysis. We measure the SPT signal to noise $\zeta$-$\lambda$, relation and two integrated Compton-$y$ $Y_\textrm{500}$-$\lambda$ relations for the DES-selected clusters and compare these to model expectations accounting for the SZE-optical center offset distribution. For clusters with $\lambda > 80$, 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 $0.61 \pm 0.12$ compared to the prediction. For clusters at $20 < \lambda < 80$, the measured SZE signal is smaller by a factor of $\sim$0.20-0.80 (between 2.3 and 10~$\sigma$ significance) compared to the prediction, with the SPT calibrated scaling relations and larger $\lambda$ 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 contamination of the observables and biases in the estimated masses. We discuss possible physical effects, as contamination from line-of-sight projections or from point sources, larger offsets in the SZE-optical centering or larger scatter in the $\lambda$-mass relation at lower richnesses.

Type: Article Optical-SZE Scaling Relations for DES Optically Selected Clusters within the SPT-SZ Survey An open access version is available from UCL Discovery 10.1093/mnras/stx594 http://dx.doi.org/10.1093/mnras/stx594 English © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. Methods: observational; methods: statistical; galaxies: abundances; galaxies: clusters: general; large-scale structure of Universe UCL > Provost and Vice Provost OfficesUCL > Provost and Vice Provost Offices > UCL BEAMSUCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical SciencesUCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy http://discovery.ucl.ac.uk/id/eprint/1540495