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For refcode 1999MNRAS.305..834E:
Retrieve 36 NED objects in this reference.
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Copyright by Royal Astronomical Society. 1999MNRAS.305..834E ROSAT PSPC observations of 36 high-luminosity clusters of galaxies: constraints on the gas fraction S. Ettori and A. C. Fabian Accepted 1999 January 15. Received 1999 January 15: in original form 1998 May 28 ABSTRACT We present a detailed and homogeneous analysis of the ROSAT PSPC surface brightness profiles of 36 clusters of galaxies with high X-ray luminosity (L_X_ >~ 10^45^ erg s^-1^) and redshifts between 0.05 and 0.44. Using recent ASCA estimates of the temperature of the gas for most of the clusters in the sample, we apply both the deprojection technique and model fitting to the surface brightness profiles to constrain the gas and dark matter distributions under the assumption that the gas is both isothermal and hydrostatic. Applying robust estimators, we find that the gas fraction within r_500_ of the clusters in our sample has a distribution centred on f_gas_(r_500_) = O.168h_50_^_1.5^. The gas fraction ranges from 0.101 to 0.245 at the 95 per cent confidence level. The values of f_gas_ show highly significant variations between individual clusters, which may be explained if the dark matter has a significant baryonic component. Within a cluster, the average radial dependence of the gas mass fraction increases outward as r^S^, with s ~ 0.20. Combining these results with those of primordial nucleosynthesis calculations and the current estimate of H_0_, the above central location implies {OMEGA}_0,m_ <~ 0.56 at the 95 per cent confidence level. This upper limit decreases to 0.34 if we take the highest significant estimates for f_gas_. A significant decrease in cluster gas fraction with redshift from the local value, f_gas_,0, of 0.21, found assuming {OMEGA}_0,m_ = 1, is also reduced if {OMEGA}_0,m_ is low. Key words: galaxies: clusters: general - galaxies: fundamental parameters - intergalactic medium - cosmology: observations - dark matter - X-rays: galaxies.
Retrieve 36 NED objects in this reference.
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