Unified dark energy from Chiral-Quintom model with a mixed potential in Friedmann–Lemaître–Robertson–Walker cosmology
Andronikos Paliathanasis
Abstract
Abstract For a spatially Friedmann–Lemaître–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 $$V\left( \phi ,\psi \right) =V_{0}e^{\lambda \phi }+U_{0}e^{\kappa \phi }\psi ^{\frac{1}{\sigma } }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>V</mml:mi> <mml:mfenced> <mml:mi>ϕ</mml:mi> <mml:mo>,</mml:mo> <mml:mi>ψ</mml:mi> </mml:mfenced> <mml:mo>=</mml:mo> <mml:msub> <mml:mi>V</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:msup> <mml:mi>e</mml:mi> <mml:mrow> <mml:mi>λ</mml:mi> <mml:mi>ϕ</mml:mi> </mml:mrow> </mml:msup> <mml:mo>+</mml:mo> <mml:msub> <mml:mi>U</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:msup> <mml:mi>e</mml:mi> <mml:mrow> <mml:mi>κ</mml:mi> <mml:mi>ϕ</mml:mi> </mml:mrow> </mml:msup> <mml:msup> <mml:mi>ψ</mml:mi> <mml:mfrac> <mml:mn>1</mml:mn> <mml:mi>σ</mml:mi> </mml:mfrac> </mml:msup> </mml:mrow> </mml:math> and we investigate the asymptotic limits of the cosmological parameters. This model for $$U_{0}=0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>U</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> , provides a generalization of the hyperbolic inflation where the equation of the state parameter can cross the phantom divide line. When $$U_{0}\ne 0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>U</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>≠</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> 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.