Probing two approaches to Unified Dark Dynamics

TL;DR

This paper reviews two models aiming to unify dark matter, dark energy, and inflation into single frameworks, testing their consistency with cosmological observations and highlighting their potential to simplify the standard cosmological model.

Contribution

It updates and compares two unification models—dark fluid and scalar field—that encompass multiple dark components within a single theoretical framework.

Findings

Dark fluid model emulates standard cosmology with dark degeneracy.

Scalar field model achieves triple unification from inflation to present.

Models are tested against known cosmological probes.

Abstract

Dark matter and dark energy are essential in the description of the late Universe, since at least the epoch of equality. On the other hand, the inflation is also necessary and demands a "dark" component, usually associated to a scalar field that dominated the dynamics and kinematics in the very early Universe. Yet, these three dark components of standard model of cosmology are independent from each other, although there are alternative models that pursue to achieve a triple unification, or at least a double. In the present work we present an update of two models that we have considered in recent years. The first is the "dark fluid" model in which dark matter and dark energy are the same thing, achieving a double unification with specific properties that exactly emulate the standard model of cosmology, given the dark degeneracy that exists in the LCDM model. The second model is given by a single F(X) scalar field Lagrangian, with which one is able to model the whole cosmological dynamics, from inflation to today, representing a triple unification model. We highlight the main properties of these models, as well as we test them against known cosmological probes.