The uncommon intracluster medium features of the first massive clusters selected independently of their baryon content

Abstract

Our current knowledge of the thermodynamic properties of galaxy clusters comes primarily from detailed studies of clusters selected by their minority components: hot baryons. Most of these studies select the clusters using the component that is being investigated, the intracluster medium (ICM), making the sample choice prone to selection effects. Weak-gravitational lensing allows us to select clusters by the total mass component and, being independent of the type of matter, makes the sample choice unbiased with respect to the baryon content. In this paper, we study four galaxy clusters at intermediate redshift ($0.25 2σ$) features, while we observed on average two rare features in each one of the seven explored properties: richness, core-excised luminosity, Compton parameter, pressure and electron pressure profiles, and central values of them. The abundance of rare and unique features in such a small sample indicates a fundamental bias in our knowledge of the thermodynamic properties of clusters when derived from ICM-selected samples.