Constraining disformal couplings with Redshift Space Distortion

TL;DR

This paper investigates a disformally coupled quintessence model affecting large-scale structure growth, using Redshift Space Distortion data to constrain parameters and address the sigma-8 tension in cosmology.

Contribution

It introduces a disformal coupling in a quintessence model and constrains its parameters using observational data, exploring its impact on structure growth.

Findings

Disformal effects influence the growth rate of large-scale structures.

Total matter perturbation evolution is largely unaffected by the disformal parameter.

Redshift Space Distortion data constrains the model parameters, potentially alleviating the sigma-8 tension.

Abstract

We study a quintessence model for which the scalar field is disformally coupled to dark matter. The background mimics the LCDM cosmological evolution and the quintessence potential is not specified. A disformal effect due to the quintessential mass is seen in the growth rate of the cosmological structure on large scales. The disformal parameter renders no appreciable effect on the evolution of the total matter perturbation. An analysis of the conformal parameter and quintessential mass is investigated using the Redshift Space Distortion data to find the best-fit values that might explain the well-known sigma-8 tension.