On the dynamics of unified k-essence cosmologies

TL;DR

This paper investigates the phase space dynamics of a unified dark matter, dark energy, and inflation model with a specific Lagrangian form, demonstrating its viability across various initial conditions and analyzing its constraints.

Contribution

It provides a detailed phase space analysis of a unified k-essence cosmology model, highlighting conditions for successful inflation, matter era, and dark energy domination.

Findings

Model admits a wide range of initial conditions for successful cosmology

Inflationary phase can be followed by matter and dark energy domination

Constraints on specific models are identified

Abstract

We analyze the phase space of a particular unified model of dark matter, dark energy, and inflation that we recently studied in [Phys. Rev. D 83, 063502 (2011)] whose Lagrangian is of the form L(X,phi) = F(X) - V(phi). We show that this model possesses a large set of initial conditions consistent with a successful cosmological model in which an inflationary phase is possible, followed by a matter era to end with dark energy domination. In order to understand the success of the model, we study the general features that unified dark matter (UDM) models should comply and then we analyze some particular models and find their constrictions.