Cosmic expansion parametrization: Implication for curvature and $\text{H}_{0}$ tension

TL;DR

This paper introduces a flexible parametrization of cosmic expansion that includes curvature and high-redshift effects, enabling analysis of late-time modifications to address the Hubble tension with various cosmological data sets.

Contribution

It presents a new analytical parametrization of the comoving distance and Hubble parameter that accounts for curvature and high-redshift behaviors, and studies its implications for the Hubble tension.

Findings

Late time modifications can resolve Hubble tension between CMB & SHOES

Late time modifications cannot resolve tension with combined CMB+BAO+SN data

Strong constraints from combined data prevent shifting H0 towards local measurements

Abstract

We propose an analytical parametrization of the comoving distance and Hubble parameter to study the cosmic expansion history beyond the vanilla $\Lambda$CDM model. The parametrization is generalized enough to include the contribution of spatial curvature and to capture the higher redshift behaviors. With this parameterization, we study the late time cosmic behavior and put constraints on the cosmological parameters like present values of Hubble parameter ($H_{0}$), matter energy density parameter ($\Omega_{m0}$), spatial curvature energy density parameter ($\Omega_{k0}$) and baryonic matter energy density parameter ($\Omega_{b0}$) using different combinations data like CMB (Cosmic microwave background), BAO (baryon acoustic oscillation), and SN (Pantheon sample for type Ia supernovae). We also rigorously study the Hubble tension in the framework of late time modification from the standard $\Lambda$CDM model. We find that the late time modification of the cosmic expansion can solve the Hubble tension between CMB $\&$ SHOES (local distance ladder observation for $H_{0}$), between CMB+BAO $\&$ SHOES and between CMB+SN $\&$ SHOES, but the late time modification can not solve the Hubble tension between CMB+BAO+SN and SHOES. That means CMB, BAO, and SN data combined put strong enough constraints on $H_{0}$ (even with varying $\Omega_{k0}$) and on other background cosmological parameters so that the addition of $H_{0}$ prior from SHOES (or from similar other local distance observations) can not significantly pull the $H_{0}$ value towards the corresponding SHOES value.