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The Sunyaev-Zel'dovich Effect of Nearby Clusters in the 3-Year WMAP Data

Published online by Cambridge University Press:  01 August 2006

Jian Hu
Affiliation:
Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084, China. email: [email protected]
Jianyin Nie
Affiliation:
Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084, China. email: [email protected] Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918-3, Beijing 100039, China
Shuangnan Zhang
Affiliation:
Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084, China. email: [email protected] Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918-3, Beijing 100039, China Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899, USA
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Abstract

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We explore the thermal Sunyaev-Zel'dovich (SZ) effect of a sample of 31 clusters in the three-year data of the Wilkinson Microwave Anisotropy Probe (WMAP), and detect strong SZ signal at the ~10 σ level. By comparing the co-added SZ profile of the sample clusters with the prediction based on the X-ray observations of ROSAT and XMM-Newton, we find the SZ profiles are consistent with the isothermal β-model of intracluster medium (ICM), but the central region (<0°.2) may be contaminated by the central radio sources in the clusters. We derive a mean outer radius of the ICM distribution at ~1.2 ± 0.4rvir (68% CL). The existence of the ICM outer edge could be the first evidence of ICM accretion shock, which is important for understanding the formation and evolution of clusters. We also estimate the mean gas mass fraction of the ICM from the overall amplitude of the SZ signals as fgas = 0.10 ± 0.05, which is consistent with the X-ray observation and lower than the cosmic average baryon fraction.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2007

References

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