$\omega =-1$ crossing in quintessence models in Lyra's geometry

TL;DR

This paper explores quintessence cosmological models within Lyra's geometry, analyzing scalar field interactions and solutions, and finds stable scenarios with equation of state parameter between -1 and 1, despite crossing the cosmological constant boundary.

Contribution

It provides closed-form solutions for modified Friedmann equations in Lyra's geometry and examines conditions for stable quintessence models crossing the boundary.

Findings

Effective equation of state can cross -1 boundary.

Stable models require -1 ≤ ω ≤ 1.

Explicit solutions for four classes of models.

Abstract

We study the cosmology of quintessence models in an extended theory of gravity in Lyra's geometry. By analyzing the possible interactions between the quintessence scalar and the intrinsic displacement field in Lyra's geometry, we obtain the closed form solutions of the modified Friedmann equations for four classes of quintessence models. Though the presence of the geometrical displacement field promises the possibility for the effective equation of state $\omega$ of the quintessence-displacement mixture crossing the cosmological constant boundary, the reliable quintessence scenarios in Lyra's geometry with stable perturbation modes are still those in which $-1 \leq \omega \leq 1$.