Journal Article

Optimizing weak lensing mass estimates for cluster profile uncertainty

D. Gruen, G. M. Bernstein, T. Y. Lam and S. Seitz

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 416, issue 2, pages 1392-1400
Published in print September 2011 | ISSN: 0035-8711
Published online September 2011 | e-ISSN: 1365-2966 | DOI:
Optimizing weak lensing mass estimates for cluster profile uncertainty

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Weak lensing measurements of cluster masses are necessary for calibrating mass-observable relations (MORs) to investigate the growth of structure and the properties of dark energy. However, the measured cluster shear signal varies at fixed mass M200m due to inherent ellipticity of background galaxies, intervening structures along the line of sight and variations in the cluster structure due to scatter in concentrations, asphericity and substructure. We use N-body simulated haloes to derive and evaluate a weak lensing circular aperture mass measurement Map that minimizes the mass estimate variance 〈(MapM200m)2〉 in the presence of all these forms of variability. Depending on halo mass and observational conditions, the resulting mass estimator improves on Map filters optimized for circular NFW-profile clusters in the presence of uncorrelated large-scale structure (LSS) about as much as the latter improve on an estimator that only minimizes the influence of shape noise. Optimizing for uncorrelated LSS while ignoring the variation of internal cluster structure puts too much weight on the profile near the cores of haloes, and under some circumstances can even be worse than not accounting for LSS at all. We briefly discuss the impact of variability in cluster structure and correlated structures on the design and performance of weak lensing surveys intended to calibrate cluster MORs.

Keywords: gravitational lensing: weak; galaxies: clusters: general; cosmology: observations; dark matter

Journal Article.  7147 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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