Dynamics of the Bianchi~V cosmological model inspired by quintessential $\alpha$-attractors

TL;DR

This paper analyzes scalar-field Bianchi V cosmologies using dynamical systems, revealing how inflationary attractors and curvature solutions behave in anisotropic models inspired by $eta$-attractors.

Contribution

It extends $eta$-attractor inflation models to anisotropic Bianchi V spacetimes, identifying equilibrium points and their stability properties.

Findings

Inflationary attractors are robust in anisotropic settings.

The Milne-type curvature solution can dominate at late times.

Various equilibrium points exhibit different stability depending on parameters.

Abstract

We investigate scalar-field cosmologies in the Bianchi V spacetime using a dynamical-systems framework. Motivated by representative $\alpha$-attractor potentials - the E-model and T-model - we apply averaging theorems and amplitude--phase reductions to monomial potentials $\sim \phi^{2n}$ of the scalar field, which approximate the attractor models near their minima, in the presence of matter with barotropic index $\gamma$. The reduced averaged system admits five generic isolated equilibria: Kasner vacua $\mathcal{K}_0^\pm$, the matter FLRW point $\mathcal{F}$, the scalar FLRW point $\mathcal{S}$, and the curvature Milne-type point $\mathcal{K}$, together with special families for tuned $(n,\gamma)$. We find that $\mathcal{K}_0^\pm$ are always sources, $\mathcal{F}$ is generically a saddle but can act as a sink for $\gamma<\min\{\tfrac{2n}{n+1},\tfrac{2}{3}\}$, $\mathcal{S}$ is a sink if $0<n<\tfrac{1}{2}$ and $\tfrac{2n}{n+1}<\gamma\leq 2$, while $\mathcal{K}$ becomes a sink whenever $\gamma>\tfrac{2}{3}$ and $n>\tfrac{1}{2}$. These results demonstrate that isotropic FLRW $\alpha$-attractor models extend naturally to anisotropic Bianchi~V cosmologies: inflationary attractors remain robust, while the Milne-type curvature solution emerges as the late-time state.