Measuring $\Omega_m$ with the ROSAT Deep Cluster Survey
Abstract
We analyze the ROSAT Deep Cluster Survey (RDCS) to derive cosmological constraints from the evolution of the cluster X-ray luminosity distribution. The sample contains 103 galaxy clusters out to z=0.85 and flux-limit Flim=3 10^{-14} cgs (RDCS-3) in the [0.5-2.0] keV energy band, with a high-z extension containing four clusters at 0.90<z<1.26 and F>1 10^{-14} cgs (RDCS-1). Model predictions for the cluster mass function are converted into the X-ray luminosity function in two steps. First we convert mass into intra-cluster gas temperature by assuming hydrostatic equilibrium. Then temperature is converted into X-ray luminosity by using the most recent data on the Lx-T relation for nearby and distant clusters. These include the Chandra data for seven distant clusters at 0.57<z<1.27. From RDCS-3 we find \Omega_m=0.35+/-0.12 and \sigma_8=0.66+/-0.06 for a spatially flat Universe with cosmological constant, with no significant constraint on \Gamma . Even accounting for theoretical and observational uncertainties in the mass/X-ray luminosity conversion, an Einstein-de-Sitter model is always excluded at far more than the 3sigma level.
Cite
@article{arxiv.astro-ph/0106428,
title = {Measuring $\Omega_m$ with the ROSAT Deep Cluster Survey},
author = {S. Borgani and P. Rosati and P. Tozzi and S. A. Stanford and P. E. Eisenhardt and C. Lidman and B. Holden and R. Della Ceca and C. Norman and G. Squires},
journal= {arXiv preprint arXiv:astro-ph/0106428},
year = {2009}
}
Comments
10 pages, 4 figures, to appear in Astrophysical Journal