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Date and Time of the Query: 2019-04-24 T05:18:43 PDT
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For refcode 2009ApJS..182...12C:
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2009ApJS..182...12C Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy Clusters Cavagnolo, Kenneth W.; Donahue, Megan; Voit, G. Mark; Sun, Ming Abstract. We present radial entropy profiles of the intracluster medium (ICM) for a collection of 239 clusters taken from the Chandra X-ray Observatory's Data Archive. Entropy is of great interest because it controls ICM global properties and records the thermal history of a cluster. Entropy is therefore a useful quantity for studying the effects of feedback on the cluster environment and investigating any breakdown of cluster self-similarity. We find that most ICM entropy profiles are well fitted by a model which is a power law at large radii and approaches a constant value at small radii: K(r) = K_0_ + K_100_(r/100 kpc)^{alpha}^, where K_0_ quantifies the typical excess of core entropy above the best-fitting power law found at larger radii. We also show that the K_0_ distributions of both the full archival sample and the primary Highest X-Ray Flux Galaxy Cluster Sample of Reiprich (2001) are bimodal with a distinct gap between K_0_ ~ 30-50 keV cm^2^ and population peaks at K_0_ ~ 15 keV cm^2^ and K_0_ ~ 150 keV cm^2^. The effects of point-spread function smearing and angular resolution on best-fit K_0_ values are investigated using mock Chandra observations and degraded entropy profiles, respectively. We find that neither of these effects is sufficient to explain the entropy-profile flattening we measure at small radii. The influence of profile curvature and number of radial bins on best-fit K_0_ is also considered, and we find no indication that K_0_ is significantly impacted by either. For completeness, we include previously unpublished optical spectroscopy of H{alpha} and [N II] emission lines discussed in Cavagnolo et al. (2008a). All data and results associated with this work are publicly available via the project Web site. Key words: astronomical data bases: miscellaneous, cooling flows, X-rays: galaxies: clusters, X-rays: general
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