Unifying dark components and crossing the phantom divide with a classical Dirac field

TL;DR

This paper presents a cosmological model combining a classical Dirac field with a cosmological constant, capable of unifying dark matter and dark energy, and explaining the crossing of the phantom divide.

Contribution

It introduces a modified $\\Lambda$CDM model with a classical Dirac field that reproduces dark matter and dark energy behaviors, including the phantom divide crossing.

Findings

Identifies the scale factor where dark energy crosses the phantom divide.

Proposes a parameter set constrained by current astrophysical observations.

Demonstrates the model's ability to unify dark components in a single framework.

Abstract

In this paper we consider a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model whit cosmological constant, containing a stiff fluid and a classical Dirac field. The proposed cosmological scenario describes the evolution of effective dark matter and dark energy components reproducing, with the help of that effective multifluid configuration, the quintessential behavior. We find the value of the scale factor where the effective dark energy component crosses the phantom divide. The model we introduce, which can be considered as a modified $\La$CDM one, is characterized by a set of parameters which may be constrained by the astrophysical observations available up to date.