{
  "id": "astro-ph/9703176",
  "version": "v2",
  "published": "1997-03-27T00:59:01.000Z",
  "updated": "1997-03-27T01:11:33.000Z",
  "title": "Constraints on Ω_0 and Cluster Evolution Using the ROSAT LogN-LogS",
  "authors": [
    "B. Mathiesen",
    "A. E. Evrard"
  ],
  "comment": "MNRAS LaTeX style format, submitted to MNRAS 3/26/97. Thirteen pages, eleven postscript figures. Uses epsf macros to include figures",
  "doi": "10.1046/j.1365-8711.1998.01217.x",
  "categories": [
    "astro-ph"
  ],
  "abstract": "We examine the likelihoods of different cosmological models and cluster evolutionary histories by comparing semi-analytical predictions of X-ray cluster number counts to observational data from the ROSAT satellite. We model cluster abundance as a function of mass and redshift using a Press-Schechter distribution, and assume the temperature T(M,z) and bolometric luminosity L_X(M,z) scale as power laws in mass and epoch, in order to construct expected counts as a function of X-ray flux. The L_X-M scaling is fixed using the local luminosity function while the degree of evolution in the X-ray luminosity with redshift L_X \\propto (1+z)^s is left open, with s an interesting free parameter which we investigate. We examine open and flat cosmologies with initial, scale-free fluctuation spectra having indices n = 0, -1 and -2. An independent constraint arising from the slope of the luminosity-temperature relation strongly favors the n = -2 spectrum. The expected counts demonstrate a strong dependence on \\Omega_0 and s, with lesser dependence on \\lambda_0 and n. Comparison with the observed counts reveals a \"ridge\" of acceptable models in the \\Omega_0 - s plane, roughly following the relation s = 6 \\Omega_0 and spanning low-density models with a small degree of evolution to \\Omega = 1 models with strong evolution. Models with moderate evolution are revealed to have a strong lower limit of \\Omega_0 \\gtrsim 0.3, and low-evolution models imply that \\Omega_0 < 1 at a very high confidence level. We suggest observational tests for breaking the degeneracy along this ridge, and discuss implications for evolutionary histories of the intracluster medium.",
  "revisions": [
    {
      "version": "v2",
      "updated": "1997-03-27T01:11:33.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "rosat logn-logs",
      "constraint",
      "x-ray cluster number counts",
      "expected counts",
      "local luminosity function"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "LaTeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 461036
    }
  }
}