Beyond MACS: Physical properties of extremely X-ray luminous clusters at $z > 0.5$

TL;DR

This paper presents a comprehensive study of over 100 extremely X-ray luminous galaxy clusters at redshifts 0.5-0.9, analyzing their properties, gravitational lensing capabilities, and galaxy evolution to understand massive cluster formation.

Contribution

It provides the first extensive dataset of high-redshift, massive galaxy clusters with multi-wavelength observations, revealing their physical properties and evolutionary states.

Findings

Clusters exhibit exceptional gravitational lensing power.

Identification of substructure and galaxy evolution in dense environments.

Data release enables further studies of massive cluster formation.

Abstract

We present a sample of over 100 highly X-ray luminous galaxy clusters at $z\sim$ 0.5-0.9, discovered by the extended Massive Cluster Survey (eMACS) in ROSAT All-Sky Survey (RASS) data. Follow-up observations of a subset at higher resolution and greater depth with the Chandra X-ray Observatory are used to map the gaseous intra-cluster medium, while strong-gravitational-lensing features identified in Hubble Space Telescope imaging allow us to constrain the total mass distribution. We present evidence of the exceptional gravitational-lensing power of these massive systems, search for substructure along the line of sight by mapping the radial velocities of cluster members obtained through extensive ground-based spectroscopy, and identify dramatic cases of galaxy evolution in high-density cluster environments. The available observations of the eMACS sample presented here provide a wealth of insights into the properties of very massive clusters ($\gtrsim 10^{15} M_\odot$) at $z > 0.5$, which act as powerful lenses to study galaxies in the very distant Universe. We also discuss the evolutionary state, galaxy population, and large-scale environment of eMACS clusters and release to the community all data and science products to further the understanding of the first generation of truly massive clusters to have formed in the Universe.