Canonical and phantom scalar fields as an interaction of two perfect fluids

TL;DR

This paper explores how canonical and phantom scalar fields in FRW cosmologies can be interpreted as two interacting perfect fluids, providing a framework for deriving exact and numerical solutions through specific interaction terms.

Contribution

It introduces an interpretation of scalar fields as interacting fluids with a chosen interaction term, enabling the construction of various FRW cosmological models.

Findings

Provides a method to obtain exact solutions for scalar field cosmologies.

Shows how interaction terms determine scalar field potentials.

Enables modeling of closed, open, and flat FRW universes.

Abstract

In this article we investigate and develop specific aspects of Friedmann-Robertson-Walker (FRW) scalar field cosmologies related to the interpretation that canonical and phantom scalar field sources may be interpreted as cosmological configurations with a mixture of two interacting barotropic perfect fluids: a matter component $\rho_1(t)$ with a stiff equation of state ($p_1=\rho_1$), and an "effective vacuum energy" $\rho_2(t)$ with a cosmological constant equation of state ($p_2=-\rho_2$). An important characteristic of this alternative equivalent formulation in the framework of interacting cosmologies is that it gives, by choosing a suitable form of the interacting term $Q$, an approach for obtaining exact and numerical solutions. The choice of $Q$ merely determines a specific scalar field with its potential, thus allowing to generate closed, open and flat FRW scalar field cosmologies.