Chandra Observations of the Cl1604 Supercluster at z=0.9: Evidence for an Overdensity of Active Galactic Nuclei

Abstract

We present the results of Chandra observations of the Cl1604 supercluster at z~0.9. The system is the largest structure mapped at redshifts approaching unity, containing at least eight spectroscopically confirmed galaxy clusters and groups. Using two 50-ksec ACIS-I pointings we examine both the X-ray point source population and the diffuse emission from individual clusters in the system. We find a 2.5σexcess of point sources detected in the hard band (2-10 keV) relative to the number of sources found in blank fields observed by Chandra. No such excess is observed in the soft band (0.5-2 keV). The hard-band source density is 1.47 times greater than that of a blank field, in agreement with the previously reported correlation between overdensity amplitude and cluster redshift. Using a maximum likelihood technique we have matched 112 of the 161 detected X-ray point sources to optical counterparts and found 15 sources that are associated with the supercluster. All 15 sources have rest-frame luminosities consistent with emission from active galactic nuclei (AGN). We find that the supercluster AGN largely avoid the densest regions of the system and are instead distributed on the outskirts of massive clusters or within poorer clusters and groups. We have also detected diffuse emission from two of the eight clusters and groups in the system, clusters Cl1604+4304 and Cl1604+4314. The systems have bolometric luminosities of 1.43x10^44 and 8.20x10^43 h70^-2 erg s^-1 and gas temperatures of 3.50 (+1.82-1.08) and 1.64 (+0.65-0.45) keV, respectively. Using updated velocity dispersions, we compare the properties of these systems to the cluster scaling relations followed by other X-ray and optically selected galaxy clusters at high redshift.

24 pages, 14 figures, submitted to ApJ

References in corpus (17)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• A complete sample of twelve very X-ray luminous galaxy clusters at z>0.5
• The XMM-Newton wide-field survey in the COSMOS field II: X-ray data and the logN-logS
• Chandra Multiwavelength Project X-ray Point Source Catalog
• Spectroscopic Confirmation of a Large AGN Population in Clusters of Galaxies
• The Complex Structure of the Cl 1604 Supercluster at z~0.9
• Environmental dependence of AGN activity in the supercluster A901/2
• Chandra X-ray Observations of the 0.6 < z < 1.1 Red-Sequence Cluster Survey Sample
• Spatial Correlation Function of the Chandra Selected Active Galactic Nuclei
• The XMM-Newton wide-field survey in the COSMOS field: V. Angular Clustering of the X-ray Point Sources
• The XMM Cluster Survey: The Dynamical State of XMMXCS J2215.9-1738 at z=1.457
• The discovery of a massive supercluster at z=0.9 in the UKIDSS DXS
• A z=0.9 supercluster of X-ray luminous, optically-selected, massive galaxy clusters
• The X-ray properties of optically-selected z>0.6 clusters in the ESO Distant Cluster Survey
• Multiwavelength Mass Comparisons of the z~0.3 CNOC Cluster Sample
• Chandra point-source counts in distant galaxy clusters
• AEGIS: Chandra Observation of DEEP2 Galaxy Groups and Clusters

Cited by in corpus (14)

• Cosmic X-ray Surveys of Distant Active Galaxies: The Demographics, Physics, and Ecology of Growing Supermassive Black Holes
• The Evolution of Active Galactic Nuclei in Clusters of Galaxies to Redshift 1.3
• The Observations of Redshift Evolution in Large Scale Environments (ORELSE) Survey : I. The Survey Design and First Results on Cl 0023+0423 at z = 0.84 and RX J1821.6+6827 at z = 0.82
• Enhancement of AGN in a protocluster at z=1.6
• The 700 ks Chandra Spiderweb Field I: evidence for widespread nuclear activity in the Protocluster
• The Properties of Radio Galaxies and the Effect of Environment in Large Scale Structures at $z\sim 1$
• Properties of Galaxies Hosting X-ray Selected Active Galactic Nuclei in the Cl1604 Supercluster at z=0.9
• Tracing high redshift cosmic web with quasar systems
• The Clowes-Campusano Large Quasar Group Survey: I. GALEX selected sample of LBGs at z$\sim$1
• Spitzer's View of the Candidate Cluster and Protocluster Catalog (CCPC)
• XXL-HSC: Host properties of X-ray detected AGNs in XXL clusters
• Galaxy systems in the optical and infrared
• Environmental impact on star-forming galaxies in a $z\sim 0.9$ cluster during course of galaxy accretion
• Star formation quenching precedes morphological transformation in COSMOS-WEB's richest galaxy groups