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|Title:||The Fraction of Cool-core Clusters in X-Ray versus SZ Samples Using Chandra Observations||Authors:||Andrade-Santos, Felipe
Forman, William R.
van Weeren, Reinout J.
Murray, Stephen S.
Pratt, Gabriel W.
Clarke, Tracy E.
|Issue Date:||2017||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||843||Issue:||1||First Page:||76||Abstract:||We derive and compare the fractions of cool-core clusters in the Planck Early Sunyaev-Zel’dovich sample of 164 clusters with z≤slant 0.35 and in a flux-limited X-ray sample of 100 clusters with z≤slant 0.30, using Chandra observations. We use four metrics to identify cool-core clusters: (1) the concentration parameter, which is the ratio of the integrated emissivity profile within 0.15 r <SUB>500</SUB> to that within r <SUB>500</SUB>; (2) the ratio of the integrated emissivity profile within 40 kpc to that within 400 kpc; (3) the cuspiness of the gas density profile, which is the negative of the logarithmic derivative of the gas density with respect to the radius, measured at 0.04 r <SUB>500</SUB>; and (4) the central gas density, measured at 0.01 r <SUB>500</SUB>. We find that the sample of X-ray-selected clusters, as characterized by each of these metrics, contains a significantly larger fraction of cool-core clusters compared to the sample of SZ-selected clusters (44% ± 7% versus 28% ± 4% using the concentration parameter in the 0.15-1.0 r <SUB>500</SUB> range, 61% ± 8% versus 36% ± 5% using the concentration parameter in the 40-400 kpc range, 64% ± 8% versus 38% ± 5% using the cuspiness, and 53% ± 7% versus 39 ± 5% using the central gas density). Qualitatively, cool-core clusters are more X-ray luminous at fixed mass. Hence, our X-ray, flux-limited sample, compared to the approximately mass-limited SZ sample, is overrepresented with cool-core clusters. We describe a simple quantitative model that uses the excess luminosity of cool-core clusters compared to non-cool-core clusters at fixed mass to successfully predict the observed fraction of cool-core clusters in X-ray-selected samples.||URI:||http://hdl.handle.net/20.500.12386/26836||URL:||https://iopscience.iop.org/article/10.3847/1538-4357/aa7461||ISSN:||0004-637X||DOI:||10.3847/1538-4357/aa7461||Bibcode ADS:||2017ApJ...843...76A||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Sep 26, 2020
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