Astrophys. J., 561, 13-21 (2001/November-1)
Measuring Ωm with the ROSAT deep cluster survey.
BORGANI S., ROSATI P., TOZZI P., STANFORD S.A., EISENHARDT P.R., LIDMAN C., HOLDEN B., DELLA CECA R., NORMAN C. and SQUIRES G.
Abstract (from CDS):
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=3x10–14 ergs.s–1.cm–2 (RDCS-3) in the [0.5-2.0] keV energy band, with a high-redshift extension containing four clusters at 0.90≤z≤1.26 and brighter than Flim=1x10–14 ergs.s–1.cm–2 (RDCS-1). We assume cosmological models to be specified by the matter density parameter Ωm, the rms fluctuation amplitude at the 8 h–1 Mpc scale σ8, and the shape parameter for the cold dark matter-like power spectrum Γ. Model predictions for the cluster mass function are converted into the X-ray luminosity function in two steps. First, we convert mass into intracluster gas temperature by assuming hydrostatic equilibrium. Then, temperature is converted into X-ray luminosity by using the most recent data on the LX-TX relation for nearby and distant clusters. These include the Chandra data for six distant clusters at 0.57≤z≤1.27. From RDCS-3 we find Ωm=0.35+0.13–0.10 and σ8=0.66+0.06–0.05 for a spatially flat universe with a cosmological constant, with no significant constraint on Γ (errors correspond to 1 σ confidence levels for three fitting parameters). Even accounting for both theoretical and observational uncertainties in the mass-X-ray luminosity conversion, an Einstein-de Sitter model is always excluded at far more than the 3 σ level. We also show that the number of X-ray-bright clusters in RDCS-1 at z>0.9 is expected from the evolution inferred at z<0.9 data.
Cosmology: Cosmological Parameters - Cosmology: Theory - Cosmology: Dark Matter - Galaxies: Clusters: General - X-Rays: Galaxies
Table 1: CDFS-CL1 = [GZW2002] XID 594.
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