Cosmology from a running vacuum model driven by a scalar field

TL;DR

This paper explores a model where the vacuum energy density varies over time, driven by a scalar field, and derives analytical solutions consistent with recent observational data, offering new insights into cosmological evolution.

Contribution

It introduces a novel approach linking a decaying vacuum energy to a scalar field and derives analytical solutions using first-order formalism.

Findings

Analytical solutions match Planck data.

Decaying vacuum energy can be modeled with a scalar field.

Physical implications of variable vacuum energy are discussed.

Abstract

The possibility that the vacuum energy density $\rho_\Lambda$ is, indeed, varying in time, has been investigated lately from the running vacuum models perspective. Motivated by such models, in the present work, we relate the decaying vacuum energy $\rho_\Lambda(t)$ with a scalar field $\phi$. We derive the equations of motion from such a premise and implement the first-order formalism in order to obtain analytical solutions to the cosmological parameters. We show that those are in agreement with recent Planck observational data. We discuss the physical consequences of having $\rho_\Lambda(t)$ related to $\phi$.