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The Growth of Cool Cores and Evolution of Cooling Properties in a Sample of 83 Galaxy Clusters at 0.3 < z < 1.2 Selected from the SPT-SZ Survey

McDonald, M. and Lueker, M. and Padin, S. and Shirokoff, E. and Vieira, J. D. (2013) The Growth of Cool Cores and Evolution of Cooling Properties in a Sample of 83 Galaxy Clusters at 0.3 < z < 1.2 Selected from the SPT-SZ Survey. Astrophysical Journal, 774 (1). Art. No. 23. ISSN 0004-637X.

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We present first results on the cooling properties derived from Chandra X-ray observations of 83 high-redshift (0.3 < z < 1.2) massive galaxy clusters selected by their Sunyaev-Zel'dovich signature in the South Pole Telescope data. We measure each cluster's central cooling time, central entropy, and mass deposition rate, and compare these properties to those for local cluster samples. We find no significant evolution from z ~ 0 to z ~ 1 in the distribution of these properties, suggesting that cooling in cluster cores is stable over long periods of time. We also find that the average cool core entropy profile in the inner ~100 kpc has not changed dramatically since z ~ 1, implying that feedback must be providing nearly constant energy injection to maintain the observed "entropy floor" at ~10 keV cm^2. While the cooling properties appear roughly constant over long periods of time, we observe strong evolution in the gas density profile, with the normalized central density (ρ_g,0/ρ_(crit)) increasing by an order of magnitude from z ~ 1 to z ~ 0. When using metrics defined by the inner surface brightness profile of clusters, we find an apparent lack of classical, cuspy, cool-core clusters at z > 0.75, consistent with earlier reports for clusters at z > 0.5 using similar definitions. Our measurements indicate that cool cores have been steadily growing over the 8 Gyr spanned by our sample, consistent with a constant, ~150 M_☉ yr^(–1) cooling flow that is unable to cool below entropies of 10 keV cm^2 and, instead, accumulates in the cluster center. We estimate that cool cores began to assemble in these massive systems at z_(cool)=1.0^(+1.0)_(-0.2), which represents the first constraints on the onset of cooling in galaxy cluster cores. At high redshift (z ≳0.75), galaxy clusters may be classified as "cooling flows" (low central entropy, cooling time) but not "cool cores" (cuspy surface brightness profile), meaning that care must be taken when classifying these high-z systems. We investigate several potential biases that could conspire to mimic this cool core evolution and are unable to find a bias that has a similar redshift dependence and a substantial amplitude.

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McDonald, M.0000-0001-5226-8349
Additional Information:© 2013 American Astronomical Society. Received 2013 May 13; accepted 2013 June 27; published 2013 August 12. M.M. acknowledges support by NASA through a Hubble Fellowship grant HST-HF51308.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The South Pole Telescope program is supported by the National Science Foundation through grant ANT-0638937. Partial support is also provided by the NSF Physics Frontier Center grant PHY-0114422 to the Kavli Institute of Cosmological Physics at the University of Chicago, the Kavli Foundation, and the Gordon and Betty Moore Foundation. Support for X-ray analysis was provided by NASA through Chandra Award Nos. 12800071, 12800088, and 13800883 issued by the Chandra X-Ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA. Galaxy cluster research at Harvard is supported by NSF grant AST-1009012 and at SAO in part by NSF grants AST-1009649 and MRI-0723073. Argonne National Laboratory’s work was supported under U.S. Department of Energy contract DE-AC02-06CH11357.
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF51308.01-A
NASANAS 5-26555
Kavli FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Department of Energy (DOE)DE-AC02-06CH11357
Subject Keywords: early universe; galaxies: clusters: general; galaxies: clusters: intracluster medium; X-rays: galaxies: clusters
Issue or Number:1
Record Number:CaltechAUTHORS:20130924-112553621
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Official Citation:The Growth of Cool Cores and Evolution of Cooling Properties in a Sample of 83 Galaxy Clusters at 0.3 < z < 1.2 Selected from the SPT-SZ Survey M. McDonald et al. 2013 ApJ 774 23
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41503
Deposited By: Ruth Sustaita
Deposited On:24 Sep 2013 19:58
Last Modified:09 Mar 2020 13:19

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