Cosmology Intertwined III: $f \sigma_8$ and $S_8$

TL;DR

This paper discusses tensions in cosmological data related to matter density and structure growth, exploring potential new physics and emphasizing comprehensive data fitting over single-parameter analysis.

Contribution

It highlights the importance of analyzing multiple cosmological parameters simultaneously to address tensions and anomalies in current data.

Findings

Identification of tensions between Planck data and weak lensing measurements.

Discussion of models that could resolve these tensions.

Emphasis on fitting multiple data sets with a single model.

Abstract

The standard $\Lambda$ Cold Dark Matter cosmological model provides a wonderful fit to current cosmological data, but a few tensions and anomalies became statistically significant with the latest data analyses. While these anomalies could be due to the presence of systematic errors in the experiments, they could also indicate the need for new physics beyond the standard model. In this Letter of Interest we focus on the tension of the Planck data with weak lensing measurements and redshift surveys, about the value of the matter energy density $\Omega_m$, and the amplitude or rate of the growth of structure ($\sigma_8,f\sigma_8$). We list a few interesting models for solving this tension, and we discuss the importance of trying to fit with a single model a full array of data and not just one parameter at a time.