2007/10/31 by Benjamin Cain, David G. Gilbank, David Gilbank +10 · 2 citations
Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/586694
published as ApJ 679: 293-300, 2008 May 20 · 23 pages, 6 Figures, ApJ Accepted; v2:revised for content and typos v3:notification of acceptance
arxiv created 2008/01/24 · openalex publication_date 2008/05/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present new Chandra observations of a high-redshift ( z ∼ 1) galaxy cluster discovered in the Red-Sequence Cluster Survey (RCS): RCS 043938-2904.7. X-ray luminosity measurements and mass estimates are consistent with L X - T X and M δ - 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.