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The Second Most Distant Cluster of Galaxies in the Extended Medium Sensitivity SurveyWe report on our ASCA, Keck, and ROSAT observations of MS 1137.5+6625, the second most distant cluster of galaxies in the Einstein Extended Medium Sensitivity Survey (EMSS), at redshift 0.78. We now have a full set of X-ray temperatures, optical velocity dispersions, and X-ray images for a complete, high-redshift sample of clusters of galaxies drawn from the EMSS. Our ASCA observations of MS 1137.5 +6625 yield a temperature of 5.7 (+2.1)(-1.1) keV and a metallicity of 0.43 (+40)(-3.7) solar, with 90% confidence limits. Keck II spectroscopy of 22 cluster members reveals a velocity dispersion of 884 (+185)(-124) km 24/s. This cluster is the most distant in the sample with a detected iron line. We also derive a mean abundance at z = 0.8 by simultaneously fitting X-ray data for the two z = 0.8 clusters, and obtain an abundance of Z(sub Fe) = 0.33 (+.26)(-.23). Our ROSAT observations show that MS 1137.5+6625 is regular and highly centrally concentrated. Fitting of a Beta model to the X-ray surface brightness yields a core radius of only 71/h kpc (q(sub o) = 0.1) with Beta = 0.70(+.45)(-.15) The gas mass interior to 0.5/h Mpc is thus 1.2 (+0.2)(-0.3) X 10(exp 13) h(exp - 5/2) Solar Mass (q(sub o) = 0.1). If the cluster's gas is nearly isothermal and in hydrostatic equilibrium with the cluster potential, the total mass of the cluster within this same region is 2.1(+1.5)(-0.8) X 10exp 14)/h Solar Mass, giving a gas fraction of 0.06 +/-0.04 h (exp -3/2). This cluster is the highest redshift EMSS cluster showing evidence for a possible cooling flow (about 20-400 Solar Mass/yr). The velocity dispersion, temperature, gas fraction, and iron abundance of MS 1137.5+6625 are all statistically the same as those properties in lower red- shift clusters of similar luminosity. With this cluster's temperature now in hand, we derive a high-redshift temperature function for EMSS clusters at 0.5 < z < 0.9 and compare it with temperature functions at lower redshifts, showing that the evolution of the temperature function is relatively modest. Supplementing our high-redshift sample with other data from the literature, we demonstrate that neither the cluster luminosity-temperature relation, nor cluster metallicities, nor the cluster gas evolved with redshift. The very modest degree of evolution in the luminosity-temperature relation inferred from these data is inconsistent with the absence of evolution in the X-ray luminosity functions derived from ROSAT cluster surveys if a critical density structure formation model is assumed.
Document ID
20000025435
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Donahue, Megan
(Space Telescope Science Inst. Baltimore, MD United States)
Voit, G. Mark
(Space Telescope Science Inst. Baltimore, MD United States)
Scharf, Caleb A.
(Space Telescope Science Inst. Baltimore, MD United States)
Gioia, Isabella M.
(Hawaii Univ. Honolulu, HI United States)
Mullis, Christopher R.
(Hawaii Univ. Honolulu, HI United States)
Hughes, John P.
(Rutgers Univ. Piscataway, NJ United States)
Stocke, John T.
(Colorado Univ. Boulder, CO United States)
Date Acquired
August 19, 2013
Publication Date
December 20, 1999
Publication Information
Publication: The Astrophysical Journal
Publisher: American Astronomical Society
Volume: 527
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: NAG5-3257
CONTRACT_GRANT: NAG5-3432
CONTRACT_GRANT: GO-05987.02-94A
CONTRACT_GRANT: NAG5-3208
CONTRACT_GRANT: NAG5-6236
CONTRACT_GRANT: NSF AST-95-00515
Distribution Limits
Public
Copyright
Other

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