Indications for 3 Mpc-scale large-scale structure associated with an X-ray luminous cluster of galaxies at z=0.95

TL;DR

This paper reports the discovery and analysis of a high-redshift galaxy cluster at z=0.95, revealing its properties, galaxy population, and its association with a nearby system, contributing to understanding large-scale structure at cosmic noon.

Contribution

It presents the first detailed analysis of a 3 Mpc-scale large-scale structure associated with a z=0.95 galaxy cluster, combining X-ray, optical, and radio data.

Findings

Discovered a well-evolved galaxy cluster with specific X-ray luminosity.

Identified a second less-evolved cluster forming a bridge with the main cluster.

Observed a pronounced color transition in galaxy populations indicating age differences.

Abstract

X-ray luminous clusters of galaxies at z~1 are emerging as major cosmological probes and are fundamental tools to study the cosmic large-scale structure and environmental effects of galaxy evolution at large look-back times. We present details of the newly-discovered galaxy cluster XMMU J0104.4-0630 at z=0.947 and a probable associated system in the LSS environment. The clusters were found in a systematic study for high-redshift systems using deep archival XMM-Newton data for the serendipitous detection and the X-ray analysis, complemented by optical/NIR imaging observations and spectroscopy of the main cluster. We find a well-evolved, intermediate luminosity cluster with Lx=(6.4+-1.3)x10^43 erg/s (0.5-2.0 keV) and strong central 1.4 GHz radio emission. The cluster galaxy population exhibits a pronounced transition toward bluer colors at cluster-centric distances of 1-2 core radii, consistent with an age difference of 1-2 Gyr for a single burst solar metallicity model. The second, less evolved X-ray cluster at a projected distance of 6.4 arcmin (~3 Mpc) and a concordant red-sequence color likely forms a cluster-cluster bridge with the main target as part of its surrounding large-scale structure at z~0.95.