Galaxy clusters for cosmology

Abstract

Using the gas mass fraction fgas measurements obtained on the basis of X-ray data for two samples of hot and dynamically relaxed galaxy clusters: 42 clusters with redshifts in the range of 0:05 < z < 1:1 collected and analysed by Allen et al. (2008) and 35 clusters at redshifts 0:15 < z < 0:30 selected and analysed by Landry et al. (2013), we obtained constraints on main cosmological parameters in two popular cases: wCDM model in which dark energy equation of state is constant in time and the model in which dark energy equation of state evolves with redshift according to the Chevalier–Polarski–Linder (CPL) parametrization. [...] This shows that galaxy clusters can be used as a good tool in cosmology. Moreover, we investigate the recent (i.e. at low redshift) expansion history of the Universe finding no evidence that the cosmic acceleration is now slowing down.