Cosmological constraints from the Xray gas mass fraction in relaxed lensing clusters observed with Chandra
Abstract
We present precise measurements of the Xray gas mass fraction for a sample of luminous, relatively relaxed clusters of galaxies observed with the Chandra observatory, for which independent confirmation of the mass results is available from gravitational lensing studies. Parametrizing the total (luminous plus dark matter) mass profiles using the model of Navarro, Frenk & White, we show that the Xray gas mass fractions in the clusters asymptote towards an approximately constant value at a radius r_{2500}, where the mean interior density is 2500 times the critical density of the Universe at the redshifts of the clusters. Combining the Chandra results on the Xray gas mass fraction and its apparent redshift dependence with recent measurements of the mean baryonic matter density in the Universe and the Hubble constant determined from the Hubble Key Project, we obtain a tight constraint on the mean total matter density of the Universe, \Omega _{m}=0.30^{+0.04}_{0.03}, and measure a positive cosmological constant, \Omega _{\Lambda}=0.95^{+0.48}_{0.72}. Our results are in good agreement with recent, independent findings based on analyses of anisotropies in the cosmic microwave background radiation, the properties of distant supernovae, and the largescale distribution of galaxies.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 August 2002
 DOI:
 10.1046/j.13658711.2002.05601.x
 arXiv:
 arXiv:astroph/0205007
 Bibcode:
 2002MNRAS.334L..11A
 Keywords:

 gravitational lensing;
 galaxies: clusters: general;
 cosmological parameters;
 Xrays: galaxies: clusters;
 Astrophysics
 EPrint:
 Accepted for publication in MNRAS Letters (6 pages, 3 figures)