Evidence for line-of-sight structure in a comparison of X-ray and optical observations of the high-redshift cluster RCS043938-2904.7

Abstract

We present new Chandra observations of a high redshift (z~1) galaxy cluster discovered in the Red-Sequence Cluster Survey (RCS): RCS043938-2904.7. X-ray luminosity measurements and mass estimates are consistent with L_X-T_X and M_delta-T_X relationships obtained from low-redshift data. Assuming a single cluster, X-ray mass estimates are a factor of ~10-100 below the red-sequence optical richness mass estimate. Optical spectroscopy reveals that this cluster comprises two components which are close enough to perhaps be physically associated. We present simple modeling of this two-component system which then yields an X-ray mass and optical richness consistent with expectations from statistical samples of lower redshift clusters. An unexpectedly high gas mass fraction is measured assuming a single cluster, which independently supports this interpretation. Additional observations will be necessary to confirm the excess gas mass fraction and to constrain the mass distribution.

23 pages, 6 Figures, ApJ Accepted; v2:revised for content and typos v3:notification of acceptance

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• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Discovery of a Ringlike Dark Matter Structure in the Core of the Galaxy Cluster Cl 0024+17
• Cosmological Constraints from the Red-Sequence Cluster Survey
• Red Sequence Cluster Finding in the Millennium Simulation
• X-ray Galaxy Clusters in NoSOCS: Substructure and the Correlation of Optical and X-ray Properties
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Cited by in corpus (1)

• Chandra X-ray Observations of the 0.6 < z < 1.1 Red-Sequence Cluster Survey Sample