Cosmology With Low-Redshift Observations: No Signal For New Physics

TL;DR

This study analyzes multiple low-redshift cosmological observations and finds that the standard $\\Lambda$CDM model remains the best fit, showing no evidence for new physics beyond it.

Contribution

The paper provides a comprehensive Bayesian analysis of low-redshift data, reaffirming the adequacy of the $\\Lambda$CDM model and constraining key cosmological parameters.

Findings

$\\Lambda$CDM fits data best with $H_0=70.3$ km/s/Mpc

Derived $S_8$ is consistent with large-scale structure surveys

No evidence found for physics beyond $\\Lambda$CDM

Abstract

We analyse various low-redshift cosmological data from Type-Ia Supernova, Baryon Acoustic Oscillations, Time-Delay measurements using Strong-Lensing, $H(z)$ measurements using Cosmic Chronometers and growth measurements from large scale structure observations for $\Lambda$CDM and some different dark energy models. By calculating the Bayesian Evidence for different dark energy models, we find out that the $\Lambda$CDM still gives the best fit to the data with $H_{0}=70.3^{+1.36}_{-1.35}$ Km/s/Mpc (at $1\sigma$). This value is in $2\sigma$ or less tension with various low and high redshift measurements for $H_{0}$ including SH0ES, Planck-2018 and the recent results from H0LiCOW-XIII. The derived constraint on $S_{8}=\sigma_{8}\sqrt{{\Omega_{m0}}/{0.3}}$ from our analysis is $S_{8} = 0.76^{+0.03}_{-0.03}$, fully consistent with direct measurement of $S_{8}$ by KiDS+VIKING-450+DES1 survey. We hence conclude that the $\Lambda$CDM model with parameter constraints obtained in this work is consistent with different early and late Universe observations within $2\sigma$. We therefore, do not find any compelling reason to go beyond concordance $\Lambda$CDM model.