Unified dark energy from Chiral-Quintom model with a mixed potential in Friedmann--Lemaître--Robertson--Walker cosmology

Abstract: For a spatially Friedmann-Lema^{\i}tre-Robertson-Walker cosmology, we propose a multi-scalar field gravitational model. Specifically, we consider a two-scalar field cosmological model in which the kinetic components of the scalar fields establish a two-dimensional sphere of Lorentzian signature. For our Chiral-Quintom model we choose a mixed potential term $V( \phi ,\psi) =V_{0}e^{\lambda\phi}+U_{0}e^{\kappa\phi}\psi^{\frac{1}{\sigma}}$ and we investigate the asymptotic limits of the cosmological parameters. This model for $U_{0}=0$, provides a generalization of the hyperbolic inflation where the equation of the state parameter can cross the phantom divide line. When $U_{0}\neq0$ we observe that this cosmological model exhibits asymptotic solutions that encompass accelerated universes, big rip singularities, and dust-like solutions. Hence, this multi-scalar field model it can be regarded as as a dark energy unify model which describes a variety of asymptotic cosmological scenarios.