Gas mass fractions from XMM-Newton

The gas mass fraction from X-ray observations of clusters of galaxies provides an independent method to constrain cosmological parameters. This thesis presents a study, where the gas mass fraction of seven clusters of galaxies observed with XMM-Newton is measured. The selected clusters are hot, dynamically relaxed and span the redshift range z=0.14 to 0.89.

The cluster masses are derived under the assumptions of spherical symmetry and hydrostatic equilibrium, and the effects of parametrizations or assumptions on the distributions of the gas temperature, gas density and total gravitating mass are investigated. A model independent approach is adopted to compute the final mass results from spectral fitting only.

Due to the good angular resolution of Chandra and its well-constrained background, previous studies of the gas mass fraction are largely based on Chandra observations. This work presents a complementary and independent study of galaxy clusters, where the gas mass fractions is obtained by using XMM-Newton data only. Background and PSF effects were both carefully considered.

In order to check for consistency and biases, the results from this analysis are compared with previous X-rays studies from Chandra and XMM-Newton observations, and optical studies of strong gravitational lensing.