Orientation bias of optically selected galaxy clusters and its impact on stacked weak-lensing analyses
| Autor: | Eli S. Rykoff, Matthew R. Becker, E. Rozo, M. T. Busha, Christopher P. Davis, Marcio A. G. Maia, A. Kathy Romer, L. Baruah, Christopher J. Miller, Yuanyuan Zhang, Timothy A. McKay, J. P. Dietrich, Risa H. Wechsler, Jiangang Hao, J. Song, Ricardo L. C. Ogando, Luiz N. da Costa, Christophe Benoist |
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| Rok vydání: | 2014 |
| Předmět: |
Physics
Cosmology and Nongalactic Astrophysics (astro-ph.CO) Line-of-sight FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Galaxy Galaxy groups and clusters QB0980 Space and Planetary Science Cluster (physics) Dark energy Circular symmetry Weak gravitational lensing Galaxy cluster Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 443:1713-1722 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/stu1282 |
| Popis: | Weak-lensing measurements of the averaged shear profiles of galaxy clusters binned by some proxy for cluster mass are commonly converted to cluster mass estimates under the assumption that these cluster stacks have spherical symmetry. In this paper we test whether this assumption holds for optically selected clusters binned by estimated optical richness. Using mock catalogues created from N-body simulations populated realistically with galaxies, we ran a suite of optical cluster finders and estimated their optical richness. We binned galaxy clusters by true cluster mass and estimated optical richness and measure the ellipticity of these stacks. We find that the processes of optical cluster selection and richness estimation are biased, leading to stacked structures that are elongated along the line-of-sight. We show that weak-lensing alone cannot measure the size of this orientation bias. Weak lensing masses of stacked optically selected clusters are overestimated by up to 3-6 per cent when clusters can be uniquely associated with haloes. This effect is large enough to lead to significant biases in the cosmological parameters derived from large surveys like the Dark Energy Survey, if not calibrated via simulations or fitted simultaneously. This bias probably also contributes to the observed discrepancy between the observed and predicted Sunyaev-Zel'dovich signal of optically-selected clusters. Comment: Accepted for publication in MNRAS, minor changes to figures following referee comments |
| Databáze: | OpenAIRE |
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