Quantifying the $S_8$ tension and evidence for interacting dark energy from redshift-space distortion measurements

Understand

In recent years, Cosmic Microwave Background (CMB) observations, Weak Lensing surveys, and $f\sigma_8(z)$ measurements from Redshift-Space Distortions (RSD) have revealed a significant ($\sim$3$-$5$\sigma$) discrepancy in the inferred value of the matter clustering parameter $S_8$.

• In this work, we investigate the implications of RSD for a cosmological framework postulating an interaction between Dark Energy (DE) and Dark Matter (DM).
• We explore scenarios where DM can transfer energy-momentum to DE or vice versa.
• The energy-momentum flow is characterized by the strength and the sign of the coupling parameter $\xi$.