The XXL survey: XLII. Detection and characterization of the galaxy population of distant galaxy clusters in the XXL-N/VIDEO field: A tale of variety

TL;DR

This study identifies and characterizes 35 distant galaxy clusters at redshifts 0.8 to 1.93 using X-ray, optical, and NIR data, revealing diverse galaxy populations and early signs of galaxy quenching in dense environments.

Contribution

First comprehensive multi-wavelength analysis of distant galaxy clusters combining X-ray, optical, and NIR data to uncover their galaxy populations and evolutionary states.

Findings

35 candidate clusters identified, including 15 new discoveries.

Galaxy populations show a wide range of quenching levels.

Brightest cluster galaxies exhibit a bimodal color distribution.

Abstract

Context. Distant galaxy clusters provide an effective laboratory in which to study galaxy evolution in dense environments and at early cosmic times. Aims. We aim to identify distant galaxy clusters as extended X-ray sources coincident with overdensities of characteristically bright galaxies. Methods. We use optical and near-infrared (NIR) data from the Hyper Suprime-Cam (HSC) and VISTA Deep Extragalactic Observations (VIDEO) surveys to identify distant galaxy clusters as overdensities of bright, $z_{phot}\geq 0.8$ galaxies associated with extended X-ray sources detected in the ultimate XMM extragalactic survey (XXL). Results. We identify a sample of 35 candidate clusters at $0.80\leq z\leq 1.93$ from an approximately 4.5 deg$^2$ sky area. This sample includes 15 newly discovered candidate clusters, ten previously detected but unconfirmed clusters, and ten spectroscopically confirmed clusters. Although these clusters host galaxy populations that display a wide variety of quenching levels, they exhibit well-defined relations between quenching, cluster-centric distance, and galaxy luminosity. The brightest cluster galaxies (BCGs) within our sample display colours consistent with a bimodal population composed of an old and red subsample together with a bluer, more diverse subsample. Conclusions. The relation between galaxy masses and quenching seem to be already in place at $z\sim 1$, although there is no significant variation of the quenching fraction with the cluster-centric radius. The BCG bimodality might be explained by the presence of a younger stellar component in some BCGs but additional data are needed to confirm this scenario.