Running cosmological constant with observational tests

TL;DR

This paper explores a dynamic cosmological constant model where dark energy varies with the Hubble parameter, deriving perturbation equations, and constraining the model using observational data to test its viability against the standard cosmological model.

Contribution

It introduces a linear running cosmological constant model, derives its perturbation equations, and constrains its parameters with current observational data.

Findings

Constraints on the running parameter: σH₀/Λ₀ ≲ 2.63×10⁻² for matter coupling.

Constraints on the running parameter: σH₀/Λ₀ ≲ 6.74×10⁻² for radiation-matter coupling.

Power spectra of CMB and matter distribution derived for the model.

Abstract

We investigate the running cosmological constant model with dark energy linearly proportional to the Hubble parameter, $\Lambda = \sigma H + \Lambda_0$, in which the $\Lambda$CDM limit is recovered by taking $\sigma=0$. We derive the linear perturbation equations of gravity under the Friedmann-Lema\"itre-Robertson-Walker cosmology, and show the power spectra of the CMB temperature and matter density distribution. By using the Markov chain Monte Carlo method, we fit the model to the current observational data and find that $\sigma H_0/ \Lambda_0 \lesssim 2.63 \times 10^{-2}$ and $6.74 \times 10^{-2}$ for $\Lambda(t)$ coupled to matter and radiation-matter, respectively, along with constraints on other cosmological parameters.