Stable phantom-divide crossing in two scalar models with matter

TL;DR

This paper develops two scalar field cosmological models that achieve stable crossing of the phantom divide, overcoming instabilities present in single scalar models, and includes matter effects in the reconstruction process.

Contribution

It introduces a general reconstruction framework for two scalar models with matter, enabling stable phantom crossing unlike single scalar models.

Findings

Models demonstrate stable phantom crossing.

Reconstruction method includes matter effects.

Comparison with observational data supports viability.

Abstract

We construct cosmological models with two scalar fields, which has the structure as in the ghost condensation model or k-essence model. The models can describe the stable phantom crossing, which should be contrasted with one scalar tensor models, where the infinite instability occurs at the crossing the phantom divide. We give a general formulation of the reconstruction in terms of the e-foldings N by including the matter although in the previous two scalar models, which are extensions of the scalar tensor model, it was difficult to give a formulation of the reconstruction when we include matters. In the formulation of the reconstruction, we start with a model with some arbitrary functions, and find the functions which generates the history in the expansion of the universe. We also give general arguments for the stabilities of the models and the reconstructed solution. The viability of a model is also investigated by comparing the observational data.