Cosmic expansion and structure formation in running vacuum cosmologies

TL;DR

This paper explores models where vacuum energy varies with redshift, focusing on quantum field vacuum effects that produce a mild dynamical dark energy component, closely resembling but distinct from the standard Lambda-CDM model, and examines their impact on structure formation.

Contribution

It introduces a quantum field vacuum model with variable vacuum energy affecting cosmological evolution and structure formation, extending previous models with new dynamical dark energy insights.

Findings

Vacuum energy exhibits mild dynamical evolution observable today.

Model closely resembles Lambda-CDM but with distinguishable features.

Generalizes structure formation properties under quantum vacuum effects.

Abstract

We investigate the dynamics of the FLRW flat cosmological models in which the vacuum energy varies with redshift. A particularly well motivated model of this type is the so-called quantum field vacuum, in which both kind of terms $H^{2}$ and constant appear in the effective dark energy density affecting the evolution of the main cosmological functions at the background and perturbation levels. Specifically, it turns out that the functional form of the quantum vacuum endows the vacuum energy of a mild dynamical evolution which could be observed nowadays and appears as dynamical dark energy. Interestingly, the low-energy behaviour is very close to the usual $\Lambda$CDM model, but it is by no means identical. Finally, within the framework of the quantum field vacuum we generalize the large scale structure properties, namely growth of matter perturbations, cluster number counts and spherical collapse model.