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Cluster richness-mass calibration with cosmic microwave background lensing

Research output: Research - peer-reviewArticle

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Original languageEnglish
Pages (from-to)795-799
JournalNature Astronomy
Journal publication date31 Jan 2018
Volume1
Early online date9 Oct 2017
DOIs
StatePublished - 31 Jan 2018

Abstract

Identifying galaxy clusters through overdensities of galaxies in photometric surveys is the oldest and arguably the most economic and mass-sensitive detection method, compared to X-ray and Sunyaev-Zel'dovich Effect surveys that detect the hot intracluster medium. However, a perennial problem has been the mapping of optical 'richness' measurements on to total cluster mass. Emitted at a conformal distance of 14 Gpc, the cosmic microwave background acts as a backlight to all intervening mass in the Universe, and therefore has been gravitationally lensed. Here we present a calibration of cluster optical richness at the 10 per cent level by measuring the average cosmic microwave background lensing convergence measured by Planck towards the positions of large numbers of optically-selected clusters, detecting the deflection of photons by haloes of total mass of the order 10**14 solar masses. Although mainly aimed at the study of larger-scale structures, the Planck lensing reconstruction can yield nearly unbiased results for stacked clusters on arcminute scales. The lensing convergence only depends on the redshift integral of the fractional overdensity of matter, so this approach offers a clean measure of cluster mass over most of cosmic history, largely independent of baryon physics.

Notes

This document is the Accepted Manuscript of the following article: James E. Geach, and John A. Peacock, ‘Cluster richness–mass calibration with cosmic microwave background lensing’, Nature Astronomy, Vol. 1: 795-799, 2017. Under embargo until 9 April 2018. This manuscript version is made available under Springer Nature terms for reuse, see http://www.nature.com/authors/policies/license.html#terms The final, definitive version of this paper has been published in Nature Astronomy, at doi: https://doi.org/10.1038/s41550-017-0259-1.

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