Krause, Elisabeth and Pierpaoli, Elena and Dolag, Klaus and Borgani, Stefano (2012) Merger-induced scatter and bias in the cluster mass–Sunyaev–Zel’dovich effect scaling relation. Monthly Notices of the Royal Astronomical Society, 419 (2). pp. 1766-1779. ISSN 0035-8711 http://resolver.caltech.edu/CaltechAUTHORS:20120224-115029323
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We examine sources of scatter in scaling relations between galaxy cluster mass and thermal Sunyaev–Zel’dovich (SZ) effect using cluster samples extracted from cosmological hydrodynamical simulations. Overall, the scatter of the mass–SZ scaling relation is well correlated with the scatter in the mass–halo concentration relation with more concentrated haloes having stronger integrated SZ signals at fixed mass. Additional sources of intrinsic scatter are projection effects from correlated structures, which cause the distribution of scatter to deviate from lognormality and skew it towards higher inferred masses, and the dynamical state of clusters. We study the evolution of merging clusters based on simulations of 39 clusters and their cosmological environment with high time resolution. This sample enables us to study for the first time the detailed evolution of merging clusters around the scaling relation for a cosmologically representative distribution of merger parameters. Major mergers cause an asymmetric scatter such that the inferred mass of merging systems is biased low. We find mergers to be the dominant source of bias towards low inferred masses: over 50 per cent of outliers on this side of the scaling relation underwent a major merger within the last Gyr. As the fraction of dynamically disturbed clusters increases with redshift, our analysis indicates that mergers cause a redshift-dependent bias in scaling relations. Furthermore, we find the SZ morphology of massive clusters to be well correlated with the clusters’ dynamical state, suggesting that morphology may be used to constrain merger fractions and identify merger-induced outliers of the scaling relation.
|Additional Information:||© 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS. Accepted 2011 September 16. Received 2011 September 15; in original form 2011 July 28. Article first published online: 18 Nov 2011. We thank SilviaAmeglio for providing SZ maps and halo concentration measurements for cluster sample B, and Nick Battaglia, Chris Hirata and James Taylor for useful discussions. The JOBRUNNER web application was constructed by Laurent Bourges and Gerard Lemson as part of the activities of the German Astrophysical Virtual Observatory. EK is supported by the US National Science Foundation (AST-0807337), the US Department of Energy (DE-FG03- 02-ER40701) and the David and Lucile Packard Foundation. EP acknowledges support from NASA grant NNX07AH59G and JPL Planck subcontract 1290790. EP and EK were supported by NSF grant AST-0649899 during the early stages of this work. KD acknowledges the support by the DFG Priority Programme 1177 and additional support by the DFG Cluster of Excellence ‘Origin and Structure of the Universe’. SB acknowledges partial support by the European Commissions FP7 Marie Curie Initial Training Network CosmoComp (PITN-GA-2009-238356), by the PRIN-INAF-2009 Grant ‘Towards an Italian Network for Computational Cosmology’ and by the PD51 INFN Grant.|
|Subject Keywords:||large-scale structure of Universe; galaxies: clusters: general|
|Official Citation:||Krause, E., Pierpaoli, E., Dolag, K. and Borgani, S. (2012), Merger-induced scatter and bias in the cluster mass–Sunyaev–Zel’dovich effect scaling relation. Monthly Notices of the Royal Astronomical Society, 419: 1766–1779. doi: 10.1111/j.1365-2966.2011.19844.x|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||24 Feb 2012 21:25|
|Last Modified:||15 Nov 2012 18:41|
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