Unified model of baryonic matter and dark components

TL;DR

This paper proposes a unified cosmological model combining baryonic matter, dark matter, and dark energy through an interacting two-fluid system with an exponential scalar field potential, constrained by observational data.

Contribution

It introduces an exotic quintessence scalar field model that unifies baryonic, dark matter, and dark energy components, and analyzes its perturbation evolution.

Findings

Transition redshift z_{acc}=0.66 indicating onset of acceleration

Estimated universe age t_0=19.8 Gyr from model fit

Energy density perturbations decrease over time

Abstract

We investigate an interacting two-fluid cosmological model and introduce a scalar field representation by means of a linear combination of the individual energy densities. Applying the integrability condition to the scalar field equation we show that this "exotic quintessence" is driven by an exponential potential and the two-fluid mixture can be considered as a model of three components. These components are associated with baryonic matter, dark matter and dark energy respectively. We use the Simon, Verde & Jimenez (2005) determination of the redshift dependence of the Hubble parameter to constrain the current density parameters of this model. With the best fit density parameters we obtain the transition redshift between non accelerated and accelerated regimes z_{acc}=0.66 and the time elapsed since the initial singularity t_0= 19.8 Gyr. We study the perturbation evolution of this model and find that the energy density perturbation decreases with the cosmological time.