Ghost Condensates and Pure Kinetic k-Essence Condensates in the Presence of Field–Fluid Non-Minimal Coupling in the Dark Sector

Abstract

In this article, we try to determine the conditions when a ghost field, in conjunction with a barotropic fluid, produces a stable accelerating expansion phase of the universe. It is seen that, in many cases, the ghost field produces a condensate and drives the fluid energy density to zero in the final accelerating phase, but there can be other possibilities. We have shown that a pure kinetic k-essence field (which is not a ghost field) interacting with a fluid can also form an interaction-induced condensate and produce a stable accelerating phase of the universe. In the latter case, the fluid energy density does not vanish in the stable phase.

Dynamical analysis of coupled curvature-matter scenario in viable f(R) dark energy models at de Sitter phase

“…Dynamical systems techniques are powerful for studying cosmic evolution in both generic cosmological models and specific solutions. Recent applications include assessing the stability of scalar field dark energy models [37][38][39][40][41] and exploring f (R) gravity [42][43][44][45]. Comprehensive investigations into dynamical systems within f (R) gravity theories are documented in various research endeavors, such as [45][46][47][48][49].…”