The Second Most Distant Cluster of Galaxies in the EMSS

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dc.creatorDonahue, Megan
dc.creatorVoit, G. Mark
dc.creatorScharf, Caleb A.
dc.creatorGioia, Isabella M.
dc.creatorMullis, Christopher R.
dc.creatorHughes, John P.
dc.creatorStocke, John T.
dc.date1999-06-17
dc.date1999-07-23
dc.date.accessioned2026-07-07T02:32:04Z
dc.date.available2026-07-07T02:32:04Z
dc.descriptionWe report on our ASCA, Keck, and ROSAT observations of MS1137.5+6625, the second most distant cluster of galaxies in the Einstein Extended Medium Sensitivity Survey (EMSS), at redshift 0.78. We now have X-ray temperatures, velocity dispersions, and X-ray images for a complete, high-redshift sample of EMSS clusters. ASCA observations of MS1137.5+6625 yield a temperature of 5.7 +2.1, -1.1 keV and a metallicity of 0.43 +0.40,-0.37 solar (90% confidence). Keck-II spectroscopy of 22 cluster members reveals a velocity dispersion of 884 +185, -124 km/s. ROSAT observations show that MS1137.5+6625 is regular and centrally concentrated. A beta-model fit yields a core radius of only 71 h^{-1} kpc (q_0=0.1) with beta=0.70 +0.45,-0.15. The gas fraction is 0.06 +/-0.04 h^{-3/2}. This is the highest redshift EMSS cluster with a possible cooling flow (~20-400 solar masses/yr). The velocity dispersion, temperature, gas fraction, and iron abundance of MS1137 are statistically the same as those properties in low-z clusters of similar luminosity. We derive a high-z temperature function for EMSS clusters with 0.5 < z < 0.9 and compare it with temperature functions at lower redshifts, showing that evolution of the temperature function is relatively modest. Supplementing our high-z sample with other data, we demonstrate that neither the cluster L-T relation, nor cluster metallicities, nor the cluster gas fraction has detectably evolved with redshift. The very modest degree of evolution in the L-T 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.
dc.description29 pages, 7 figures. Accepted by the ApJ. Minor changes to Table 4 and 5 regarding CL0016 (MS0015...) fluxes
dc.identifierhttps://arxiv.org/abs/astro-ph/9906295
dc.identifierhttp://arxiv.org/abs/astro-ph/9906295
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/14381
dc.subjectAstrophysics
dc.titleThe Second Most Distant Cluster of Galaxies in the EMSS
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