Speaker
Description
We present a cosmological analysis based on the properties of X-ray selected clusters of galaxies from the CODEX survey, which have been spectroscopically validated as part of the SPIDERS programme within SDSS DR16. The sample contains a total of 2740 clusters over an area of 5,300deg$^{2}$, making it the largest spectroscopic cluster catalogue ever constructed. Optical richness is used as a proxy for the cluster mass, and the combination of X-ray, optical and spectroscopic information ensures that only confirmed virialised systems are considered. Clusters are binned in redshift, $z \in \left[0.1, 0.6\right)$ and optical richness, $\lambda \in \left[20, 244\right)$ and the counts in each bin are modelled as a function of cosmological and scaling relation parameters. A high-purity sub-sample of 1017 clusters is used in the fiducial analysis and best fit cosmological parameters are found to be $\Omega_0=0.31^{+0.04}_{-0.03}$ and $\sigma_8=0.72^{+0.03}_{-0.03}$. These results are consistent with previous measurements in the literature and the precision is comparable to other state-of-the-art cluster cosmology experiments.
