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

Micol Benetti, David A. Cook, Saulo Carneiro

TL;DR

The paper tests whether a relativistic rotating cosmology with a Gödel-type background can resolve the Hubble tension by embedding rotation through anisotropic stress and modifying the background evolution in CLASS. Using Planck 2018 CMB and Pantheon+BAO data, they constrain the present-day rotation parameter $l_0$ to be effectively zero, leaving ΛCDM parameters unchanged. While late-time probes alone allow larger rotation and higher $H_0$, this comes with an excessive $\sigma_8$ and does not improve the joint fit; overall, the data show no robust evidence that cosmic rotation can reconcile early- and late-time $H_0$ estimates. The work highlights the robustness of ΛCDM against background rotation and indicates that perturbative rotational effects and pre-inflationary scenarios warrant future exploration.

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 $Λ$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 $σ_8$, which remains in tension with DES-Y3 measurement. Combining CMB, SNe and BAO data confirms the preference for non-rotation.

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

TL;DR

The paper tests whether a relativistic rotating cosmology with a Gödel-type background can resolve the Hubble tension by embedding rotation through anisotropic stress and modifying the background evolution in CLASS. Using Planck 2018 CMB and Pantheon+BAO data, they constrain the present-day rotation parameter to be effectively zero, leaving ΛCDM parameters unchanged. While late-time probes alone allow larger rotation and higher , this comes with an excessive and does not improve the joint fit; overall, the data show no robust evidence that cosmic rotation can reconcile early- and late-time estimates. The work highlights the robustness of ΛCDM against background rotation and indicates that perturbative rotational effects and pre-inflationary scenarios warrant future exploration.

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 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 , which remains in tension with DES-Y3 measurement. Combining CMB, SNe and BAO data confirms the preference for non-rotation.

Paper Structure

This paper contains 8 sections, 40 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Rotating spacetime
  3. Radiation era
  4. Matter era
  5. The energy content
  6. Cosmological parameters
  7. Results
  8. Conclusion

Figures (2)

  • Figure 1: CMB $TT$-spectra for $l_0 = 2 \times 10^{-5}$ (yellow) and $l_0 = 2 \times 10^{-4}$ (blue). All the other parameters were fixed in the standard model fiducial values.
  • Figure 2: Confidence regions for the rotating model using CMB Planck 2018 $TTTEEE$+$lowE$+lensing data Planck:2019nip, Pantheon SNe Scolnic:2017caz combined with BAO data Beutler:2011hxRoss:2014qpaAlam:2016hwk, and a full analysis combining early- and -late time data. A SH0ES prior on $H_0$Riess:2020fzl has been imposed for the SNe+BAO analysis, but not for the full (CMB+SNe+BAO) analysis A prior on the baryon density parameter was used in all the analysis Cooke:2017cwo.