Measuring Hubble constant in an anisotropic extension of $\Lambda$CDM model

TL;DR

This study provides CMB-independent estimates of the Hubble constant within an anisotropic extension of the $$CDM model, showing that anisotropy can reduce the Hubble tension by about 2 sigma.

Contribution

It introduces an anisotropic $$CDM model and constrains $H_0$ using multiple independent data sets, demonstrating the impact of anisotropy on the Hubble tension.

Findings

Hubble constant estimated as 70.1+1.2-1.5 km/s/Mpc with BAO+BBN+CC+PP data.

Anisotropy of order 10^{-14} reduces the Hubble tension by approximately 2 sigma.

Anisotropy is positively correlated with $H_0$ in the model.

Abstract

Cosmic Microwave Background (CMB) independent approaches are frequently used in the literature to provide estimates of Hubble constant ($H_0$). In this work, we report CMB independent constraints on $H_0$ in an anisotropic extension of $\Lambda$CDM model using the Big Bang Nucleosynthesis (BBN), Baryonic Acoustic Oscillations (BAOs), Cosmic Chronometer (CC), and Pantheon+ (PP) compilation of Type Ia supernovae and SH0ES Cepheid host distance anchors data. In the anisotropic model, we find $H_{\rm 0}=70.1^{+1.2}_{-1.5}\; (72.67\pm 0.85)\;\rm km\, s^{-1}\, Mpc^{-1}$ both with 68\% CL from BAO+BBN+CC+PP (BAO+BBN+CC+PPSH0ES) data. The analyses of the anisotropic model with the two combinations of data sets reveal that anisotropy is positively correlated with $H_0$, and an anisotropy of the order $10^{-14}$ in the anisotropic model reduces the $H_0$ tension by $\sim 2\sigma$.