A non-linear solution to the $S_8$ tension?

Understand

Weak galaxy lensing surveys have consistently reported a lower amplitude for the matter fluctuation spectrum, as measured by the $S_8$ parameter, than expected in the $\Lambda{\rm CDM}$ cosmology favoured by $Planck$.

• However, the expansion history follows the predictions of the $Planck$ $\Lambda{\rm CDM}$ cosmology to high accuracy, as do measurements of lensing of the cosmic microwave background anisotropies.
• Redshift space distortion measurements also appear to be consistent with $Planck$ $\Lambda{\rm CDM}$.
• In this paper, we argue that these observations can be reconciled with the $Planck$ $\Lambda{\rm CDM}$ cosmology if the matter power spectrum is suppressed more strongly on non-linear scales than assumed in analyses of weak galaxy lensing.