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Cambridge, MA, United States

Jones C.,SAO CfA 60 Garden Street | Forman W.,SAO CfA 60 Garden Street | Fogarty K.,SAO CfA 60 Garden Street | Fogarty K.,Johns Hopkins University | And 3 more authors.
Astronomische Nachrichten | Year: 2013

Clusters of galaxies were first recognized through overdensities of galaxies. With the advent of X-ray telescopes, large numbers of clusters were by found by the spatially extended nature of their X-ray emission. Today with the availability of millimeter wave telescopes capable of finding clusters through the Sunyaev-Zeldovich effect, it is possible to compare the overall characteristics of clusters detected by different methods and the specific properties of individual clusters measured in different ways. Here we compare the X-ray properties of relatively low redshift clusters measured with the Chandra Observatory with their SZ signal measured in the Planck mission. Based on a sample of 114 Planck detected clusters of galaxies, we show the SZ signal strengths are strongly correlated with X-ray measured mass proxies, in particular those measured through the cluster X-ray luminosities, so long as the cluster core is excluded, and those measured from YX, the product of the gas temperature and gas mass, which is an X-ray analog of the SZ signal YSZ. A comparison of the hundred brightest X-ray clusters and the hundred Planck clusters with the highest SZ signals shows that the Planck ESZ cluster sample is more X-ray luminous and more massive than X-ray cluster sample, due in part to the larger volume that Planck clusters are detected over, due to the nearly redshift independence of the SZ strength. As previously found, on average the SZ cluster samples show a larger fraction of clusters undergoing mergers than do X-ray selected samples. For the Planck ESZ cluster PLCKESZ G189.84-37.24, we report the detection of extended X-ray emission associated with an overdensity of distant galaxies located 6′.5 from the Planck ESZ position. Future X-ray observations of the Planck low redshift (z < 0.35) cluster sample will better define the low redshift cluster mass function for comparison to high redshift SZ selected cluster samples to better constrain cosmological parameters, particularly the equation of state for dark energy. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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