Journal article
The Fraction of Cool-core Clusters in X-Ray versus SZ Samples Using Chandra Observations
The Astrophysical Journal, Vol.843(1), 76
07/01/2017
DOI: 10.3847/1538-4357/aa7461
Abstract
We derive and compare the fractions of cool-core clusters in the Planck Early Sunyaev–Zel'dovich sample of 164 clusters with $z\leqslant 0.35$ and in a flux-limited X-ray sample of 100 clusters with $z\leqslant 0.30$, 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 r500 to that within r500; (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 r500; and (4) the central gas density, measured at 0.01 r500. 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 r500 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.
Details
- Title: Subtitle
- The Fraction of Cool-core Clusters in X-Ray versus SZ Samples Using Chandra Observations
- Creators
- Felipe Anade-SantosChristine Jones - Western UniversityWilliam R Forman - Center for Astrophysics Harvard & SmithsonianLorenzo Lovisari - Center for Astrophysics Harvard & SmithsonianAlexey Vikhlinin - Center for Astrophysics Harvard & SmithsonianReinout J van WeerenStephen S MurrayMonique Arnaud - Délégation Paris 7Gabriel W Pratt - CEA SaclayJessica DémoclèsRalph Kraft - Center for Astrophysics Harvard & SmithsonianPasquale Mazzotta - University of Rome Tor VergataHans BöhringerGayoung Chon - Max Planck Institute for Extraterrestrial PhysicsSimona Giacintucci - United States Naval Research LaboratoryTracy E Clarke - United States Naval Research LaboratoryStefano Borgani - University of TriesteLarry David - Center for Astrophysics Harvard & SmithsonianMarian Douspis - Institut d'Astrophysique SpatialeHåkon Dahle - University of OsloEtienne Pointecouteau - RocheShea Brown - University of Iowa, Physics and AstronomyNabila Aghanim - Institut d'Astrophysique SpatialeElena Rasia - Trieste Astronomical Observatory
- Resource Type
- Journal article
- Publication Details
- The Astrophysical Journal, Vol.843(1), 76
- DOI
- 10.3847/1538-4357/aa7461
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Language
- English
- Date published
- 07/01/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428768102771
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