Constraining viscous dark energy models with the latest cosmological data

TL;DR

This paper introduces three new viscous dark energy models constrained by recent cosmological data, showing they slightly differ from standard models and can help resolve the H0 tension, while supporting a flat universe and excluding scale invariance.

Contribution

The paper proposes three novel viscous dark energy models and constrains them with latest data, highlighting their slight deviation from standard cosmology and their implications for cosmic curvature and primordial spectra.

Findings

Models slightly deviate from standard cosmology.

They alleviate the H0 tension.

A flat universe is supported by data.

Abstract

Based on the assumption that the dark energy possessing bulk viscosity is homogenously and isotropically permeated in the universe, we propose three new viscous dark energy (VDE) models to characterize the accelerating universe. By constraining these three models with the latest cosmological observations, we find that they just deviate very slightly from the standard cosmological model and can alleviate effectively the current $H_0$ tension between the local observation by the Hubble Space Telescope and the global measurement by the Planck Satellite. Interestingly, we conclude that a spatially flat universe in our VDE model with cosmic curvature is still supported by current data, and the scale invariant primordial power spectrum is strongly excluded at least at the $5.5\sigma$ confidence level in three VDE models as the Planck result. We also give the $95\%$ upper limits of the typical bulk viscosity parameter $\eta$ in three VDE scenarios.