Evolution of density perturbations in decaying vacuum cosmology: The case of non-zero perturbations in the cosmological term

TL;DR

This paper investigates the evolution of density perturbations in a cosmological model with a decaying vacuum energy, revealing that such models are less favored than the standard cosmological model when perturbations are considered.

Contribution

It extends previous work by including non-zero perturbations in the cosmological term, providing a more complete analysis of decaying vacuum cosmology.

Findings

Decaying vacuum models are disfavored compared to the standard model.

Including perturbations alters the compatibility with observational data.

The model with a decaying cosmological term does not fit observations as well as the standard model.

Abstract

We extend the results of a previous paper where a model of interacting dark energy, with a cosmological term decaying linearly with the Hubble parameter, is tested against the observed mass power spectrum. In spite of the agreement with observations of type Ia supernovas, baryonic acoustic oscillations and the cosmic microwave background, we had shown previously that no good concordance is achieved if we include the mass power spectrum. However, our analysis was based on the ad hoc assumption that the interacting cosmological term is strictly homogeneous. Now we perform a more complete analysis, by perturbing such a term. Although our conclusions are still based on a particular, scale invariant choice of the primordial spectrum of dark energy perturbations, we show that a cosmological term decaying linearly with the Hubble parameter is indeed disfavored as compared to the standard model.