Can cosmic rotation resolve the Hubble tension? Constraints from CMB and large-scale structure

TL;DR

This study explores whether cosmic rotation can resolve the Hubble tension by analyzing CMB and large-scale structure data, finding current constraints favor negligible rotation but some late-time data suggest higher rotation levels.

Contribution

The paper introduces a relativistic cosmological model with background rotation and adapts the CLASS code for MCMC analysis against observational data.

Findings

CMB data constrain present-day rotation to be negligible.

Late-time probes allow higher rotation and increase the Hubble constant.

Higher rotation correlates with higher σ8, conflicting with DES-Y3 measurements.

Abstract

We investigate a relativistic cosmological model with background rotation, sourced by a non-perfect fluid with anisotropic stress. A modified version of the CLASS Boltzmann code is employed to perform Monte Carlo Markov Chain analyses against Cosmic Microwave Background (CMB) and late-time datasets. The results show that current CMB data constrain the present-day rotation parameter to be negligible. As a consequence, the derived cosmological parameters remain consistent with the standard $\Lambda$CDM values. In contrast, late-time probes such as Type Ia supernovae (SNe) and Baryonic Acoustic Oscillations (BAO) allow for a higher level of rotation and yield an increased Hubble constant. However, this comes at the cost of a higher $\sigma_8$, which remains in tension with DES-Y3 measurement. Combining CMB, SNe and BAO data confirms the preference for non-rotation.