Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An X-ray Selected Galaxy Cluster at z=1.11 in the Rosat Deep Cluster
  Survey   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 PSPC 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 ~ 1.0. Spectroscopic observations at the
Keck II telescope secured 9 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 arcsec 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 a
bolometric luminosity L_x = 2.48^{+0.33}_{-0.26} x 10^44 ergs/s, a temperature
of kT = 7.2^{+2.2}_{-1.4} keV, and a mass within r = 1 Mpc of 7.0 x 10^14 M_sun
(H_0=65 km/s/Mpc, Omega_m = 0.3, and Lambda = 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 ICM and an old galaxy population already in place at z >
1.

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The categories of this paper are: q-alg
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an