Can the cosmological dark sector be modeled by a single scalar field?

TL;DR

This paper demonstrates that a single scalar field can effectively model the entire dark sector, including dark energy and dark matter, by showing its equivalence to a generalized Chaplygin gas within the cosmological framework.

Contribution

It extends previous work by showing that a mbda CDM dark sector can be represented by a single scalar field, unifying dark energy and dark matter models.

Findings

Scalar field models can replicate mbda CDM dark sector.

The solutions correspond to a non-adiabatic generalized Chaplygin gas.

The system admits a uniparametric family of solutions.

Abstract

In a previous paper it was shown that a minimally coupled scalar field of mass $M \sim H_0$ can describe both components of the dark sector in a unified way. In the solution found, the dark energy component decays linearly with the Hubble parameter, with a homogeneous creation of dark matter. In the present note we show that a $\Lambda$CDM dark sector can also be modeled by such a single field. More generally, we show that the system of Klein-Gordon and Einstein equations admits a uniparametric family of solutions that is equivalent to a non-adiabatic (with zero sound speed) generalised Chaplygin gas.