2001/10/31 by S. A. Stanford, B. Holden, B. P. Holden +8 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Brightest cluster galaxy #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Intracluster medium #Luminosity #Physics #ROSAT #Redshift #Surface brightness #astro-ph
paper · pdf · doi:10.1086/338442
19 pages, 7 figures: Figures 1,4,6 included as separate jpg files. Accepted for publication in The Astronomical Journal
arxiv created 2001/10/31 · openalex publication_date 2002/02/01 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
We report the discovery of an X-ray–luminous galaxy cluster at z = 1.11. RDCS J0910+5422 was selected as an X-ray cluster candidate in the ROSAT Deep Cluster Survey on the basis of its spatial extent in a ROSAT Position Sensitive Proportional Counter image. Deep optical and near-IR imaging reveal a red galaxy overdensity around the peak of the X-ray emission, with a significant excess of objects with J - K and I - K colors typical of elliptical galaxies at z ∼ 1. Spectroscopic observations at the Keck II telescope secured nine galaxy redshifts in the range 1.095 < z < 1.120, yielding a mean cluster redshift of ⟨ z ⟩ = 1.106. Eight of these galaxies lie within a 30'' radius around the peak X-ray emission. A deep Chandra ACIS exposure on this field shows extended X-ray morphology and allows the X-ray spectrum of the intracluster medium to be measured. The cluster has bolometric luminosity L x = 2.48 × 10 44 ergs s -1 , temperature kT = 7.2 keV, and mass within r = 1 Mpc of 7.0 × 10 14 M ⊙ ( H 0 = 65 km s -1 Mpc -1 , Ω m = 0.3, and Ω Λ = 0.7). The spatial distribution of the cluster members is elongated, which is not due to an observational selection effect, and followed by the X-ray morphology. The X-ray surface brightness profile and the spectrophotometric properties of the cluster members suggest that this is an example of a massive cluster in an advanced stage of formation with a hot intracluster medium and an old galaxy population already in place at z > 1.