Cosmological Constraints from Galaxy Clusters and Groups in the eROSITA Final Equatorial Depth Survey

Understand

We present the first cosmological study of a sample of $eROSITA$ clusters, which were identified in the $eROSITA$ Final Equatorial Depth Survey (eFEDS).

• In a joint selection on X-ray and optical observables, the sample contains $455$ clusters within a redshift range of $0.1<z<1.2$, of which $177$ systems are covered by the public data from the Hyper Suprime-Cam (HSC) survey that enables uniform weak-lensing cluster mass constraints.
• With minimal assumptions, at each cluster redshift $z$ we empirically model (1) the scaling relations between the cluster halo mass and the observables, which include the X-ray count rate, the optical richness, and the weak-lensing mass, and (2) the X-ray selection in terms of the completeness function $\mathtt{C}$.
• Using the richness distribution of the clusters, we directly measure the X-ray completeness and adopt those measurements as informative priors for the parameters of $\mathtt{C}$.