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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)


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Lagana, Tatiana F. [1, 2] ; Zhang, Yu-Ying [1, 3] ; Reiprich, Thomas H. [1] ; Schneider, Peter [1]
Total Authors: 4
[1] Univ Bonn, Argelander Inst Astron, D-53121 Bonn - Germany
[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfericas, Dept Astron, BR-05508090 Sao Paulo - Brazil
[3] Chinese Acad Sci, Natl Astron Observ, Beijing 100012 - Peoples R China
Total Affiliations: 3
Document type: Journal article
Source: ASTROPHYSICAL JOURNAL; v. 743, n. 1 DEC 10 2011.
Web of Science Citations: 30

It is believed that the global baryon content of clusters of galaxies is representative of the matter distribution of the universe, and can, therefore, be used to reliably determine the matter-density parameter Omega(m). This assumption is challenged by the growing evidence from optical and X-ray observations that the total baryon mass fraction increases toward rich clusters. In this context, we investigate the dependence of stellar and total baryon mass fractions as a function of mass. To do so, we used a subsample of 19 clusters extracted from the X-ray flux-limited sample HIFLUGCS that have available Sloan Digital Sky Survey Data Release 7 data. From the optical analysis we derived the stellar masses. Using XMM-Newton we derived the gas masses. Then, adopting a scaling relation we estimate the total masses. Adding the gas and the stellar mass fractions we obtain the total baryonic content that we find to increasewith clustermass, reaching seven-yearWilkinsonMicrowave Anisotropy Probe (WMAP7) prediction for clusters with M-500 = 1.6 x 10(15) M-circle dot. We observe a decrease of the stellar mass fraction (from 4.5% to similar to 1.0%) with increasing total mass where our findings for the stellar mass fraction agree with previous studies. This result suggests a difference in the number of stars formed per unit of halo mass, though with a large scatter for low-mass systems. That is, the efficiency of star formation varies on a cluster scale that lower mass systems are likely to have higher star formation efficiencies. It follows immediately that the dependence of the stellar mass fraction on total mass results in an increase of the mass-to-light ratio from lower to higher mass systems. We also discuss the consequences of these results in the context of determining the cosmic matter-density parameter Omega(m). (AU)

FAPESP's process: 08/04318-7 - Intracluster gas enrichment and star formation efficiency in clusters of galaxies
Grantee:Tatiana Ferraz Laganá
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 06/56213-9 - New physics from space: formation and evolution of structures in the universe
Grantee:Claudia Lucia Mendes de Oliveira
Support type: Research Projects - Thematic Grants