On the tension between growth rate and CMB data

Abstract

We analyze the claimed tension between redshift space distorsions measurements of $f(z){\sigma }_8(z)$ and the predictions of standard $\Lambda$CDM (Planck 2015 and 2018) cosmology. We consider a dataset consisting of 17 data points extending up to redshift $z=1.52$ and corrected for the Alcock-Paczynski effect. Thus, calculating the evolution of the growth factor in a $w$CDM cosmology, we find that the tension for the best fit parameters $w$, ${\Omega }_m$ and ${\sigma }_8$ with respect to the Planck 2018 $\Lambda$CDM parameters is below $2\sigma$ in all the marginalized confidence regions.

6 pages, 4 figures. Final version to appear in Eur. Phys. J. C