Einstein-Cartan cosmology and the S8 problem

TL;DR

This paper explores how Einstein-Cartan cosmology naturally predicts higher sigma_8 values at high redshifts, potentially resolving the discrepancies observed in low-redshift measurements compared to LCDM predictions.

Contribution

It demonstrates that Einstein-Cartan cosmology can account for the S_8 problem by predicting larger mass density and sigma_8(z) at high redshifts, unlike LCDM.

Findings

Einstein-Cartan cosmology predicts higher sigma_8 at high redshifts.

LCDM struggles to reconcile low and high redshift measurements.

The gauge invariant formalism clarifies sigma_8 evolution across redshifts.

Abstract

The measurements of cluster abundances, gravitational lensings, redshift space distortions and peculiar velocities at lower redshifts point out to much smaller sigma_8 than its value deduced from the measurements of the CMB fluctuations assuming the standard LCDM cosmology. High redshift measurements of ALMA and JWST imply even more striking problems for LCDM. We examine and compare the sigma_8 redshift dependence calculated within the gauge invariant formalism. Because the CMB fluctuations comprise a cosmological data from the recombination era to the present, the S_8 problem of the LCDM cosmology is not a surprise from the standpoint of the Einstein-Cartan cosmology because it predicts much larger mass density and sigma_8(z) than the LCDM model at high redshifts.