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Updated: May 28, 2025

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
Galaxy clusters as probes of cosmic isotropy
1Leiden Observatory, Leiden University, PO Box 9513, Leiden 2300 RA, The Netherlands.
Abstract:
Scaling relations of galaxy clusters are a powerful probe of cosmic isotropy in the late Universe. Owing to their strong cosmological dependence, galaxy cluster scaling relations can obtain tight constraints on the spatial variation of cosmological parameters, such as the Hubble constant ([Formula: see text]), and detect large-scale bulk flow motions. Such tests are crucial to scrutinise the validity of [Formula: see text]CDM in the local Universe and determine at what cosmic scales (if any) extra-galactic objects converge to isotropy within the cosmic microwave background rest frame. This review describes the methodology for conducting cosmic isotropy tests with cluster scaling relations and examines possible systematic biases. We also discuss the results of past studies that reported statistically significant observed anisotropies in the local Universe. Finally, we explore the future potential of cluster scaling relations as a cosmic isotropy probe given the large amount of multi-wavelength cluster data expected in the near future.This article is part of the discussion meeting issue 'Challenging the standard cosmological model'.
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To choose a cluster sample, divide the population into clusters (groups) and then randomly select some of the clusters. All the members from these clusters are in the cluster sample. For example, if you randomly sample four departments from your...

