RXJ 1821.6+6827: a Cool Cluster at z=0.81 from the ROSAT NEP Survey

Abstract

We present an analysis of the properties of the cluster of galaxies RXJ 1821.6+6827, or NEP 5281, at a redshift z=0.816+/-0.001. RXJ 1821.6+6827 was discovered during the optical identification of the X-ray sources in the North Ecliptic Pole (NEP) region of the ROSAT All-Sky Survey and it is the highest redshift cluster of galaxies of the NEP survey. We have measured spectroscopic redshifts for twenty cluster galaxies using the Keck-I and the Canada-France-Hawai'i (CFH) telescopes. The value for the cluster velocity dispersion is sigma_V=775(+182,-113) km s-1. The cluster was also observed by XMM-Newton. Both the optical and X-ray data are presented in this paper. The cluster has an unabsorbed X-ray flux in the 2-10 keV energy band of F(2-10 keV)=1.24(+0.16,-0.23) x 10-13 erg cm2 s-1 and a K-corrected luminosity in the same band of L(2-10 keV)=6.32(+76,-0.73)x10^44 h_50^-2 erg s-1 (90% confidence level). The cluster X-ray bolometric luminosity is L(BOL,X)=1.35(+0.08,-0.21)x10^45 h_50^-2 erg s-1. The data do not allow fitting both metal abundance and temperature at the same time. The abundance is unconstrained and can vary in the range 0.28-1.42 Z_sun while the best fit X-ray temperature is T=4.7(+1.2,-0.7) keV. This emission weighted X-ray temperature is a little lower, barely within the uncertainties, than the predicted temperature, T=6.34(+0.13,-0.35) keV, from the L_X-T_X relation of local clusters published in the literature. The optically measured velocitydispersion is consistent with the velocity dispersion expected from the sigma_V-T_X relationship. We also examine the point X-ray source RXJ1821.9+6818, or NEP 5330, located to the south east of the cluster which was identified as a QSO at z=1.692+/-0.008 in the ROSAT NEP survey.

arXiv comment13 pages including 5 postscript figures and 3 tables. Accepted for publication in the A&A main Journal. A postscript version with Fig. 2 can be downloaded from http://www.ira.cnr.it/~gioia/PUB/publications.html

References in corpus (30)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• Mass Estimates of X-Ray Clusters
• The Lx-T Relation and Temperature Function for Nearby Clusters Revisited
• The Evolution of X-ray Clusters of Galaxies
• The Lx-T Relation and Intracluster Gas Fractions of X-ray Clusters
• Optical Mass Estimates of Galaxy Clusters
• Measuring ${\Omega }_m$ with the ROSAT Deep Cluster Survey
• HST Photometry and Keck Spectroscopy of the Rich Cluster MS1054-03: Morphologies, Butcher-Oemler Effect and the Color-Magnitude Relation at z=0.83
• Measuring Cosmological Parameters from the Evolution of Cluster X-ray Temperatures
• The Luminosity-Temperature Relation at z=0.4 for Clusters of galaxies
• Scaling laws in X-ray Galaxy Clusters at redshift between 0.4 and 1.3
• Observational Tests of the Mass-Temperature Relation for Galaxy Clusters
• Velocity Dispersions and X-Ray Temperatures of Galaxy Clusters
• A Very Hot, High Redshift Cluster of Galaxies: More Trouble for Omega_0 = 1
• Chandra and XMM-Newton Observations of RDCS1252.9-2927, A Massive Cluster at z=1.24
• Evolution of the cluster X-ray scaling relations since z>0.4
• Correlations of Richness and Global Properties in Galaxy Clusters
• THE CANADA-FRANCE REDSHIFT SURVEY II: Spectroscopic Program; Data for the 0000-00 and 1000+25 Fields
• Cosmological Constraints from the ROSAT Deep Cluster Survey
• The Velocity Dispersion of MS1054-03: A Massive Galaxy Cluster at High Redshift
• Cosmological constraints from evolution of cluster baryon mass function at z~0.5
• RXJ1716.6+6708: a young cluster at z=0.81
• The ROSAT North Ecliptic Pole Survey: The Optical Identifications
• The Evolution of the Galaxy Cluster Luminosity-Temperature Relation
• The First Detailed X-ray Observations of High-Redshift, Optically-Selected Clusters: XMM-Newton Results for Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90
• The WARPS survey - IV: The X-ray luminosity-temperature relation of high redshift galaxy clusters
• Cluster Evolution in the ROSAT North Ecliptic Pole Survey
• The North Ecliptic Pole Supercluster
• An X-ray review of MS1054-0321: hot or not?
• The Velocity Dispersion -- Temperature Correlation from a Limited Cluster Sample

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