Dark Matter and Dark Energy from a single scalar field

TL;DR

This paper proposes a unified scalar field model that explains both dark matter and dark energy, fitting observational data well and favoring higher Hubble parameter values without additional tuning.

Contribution

It introduces a modified Peccei-Quinn approach where a single scalar field accounts for both dark matter and dark energy, matching observational data.

Findings

Model fits WMAP data using MCMC techniques.

Performs as well as LCDM and dynamical dark energy models.

Favors higher values of the Hubble parameter.

Abstract

The strong CP problem was solved by Peccei & Quinn by introducing axions, which are a viable candidate for DM. Here the PQ approach is modified so to yield also Dark Energy (DE), which arises in fair proportions, without tuning any extra parameter. DM and DE arise from a single scalar field and, in the present ecpoch, are weakly coupled. Fluctuations have a fair evolution. The model is also fitted to WMAP release, using a MCMC technique, and performs as well as LCDM, coupled or uncoupled Dynamical DE. Best-fit cosmological parameters for different models are mostly within 2-$\sigma$ level. The main peculiarity of the model is to favor high values of the Hubble parameter.