Ghost condensates and pure kinetic $k$-essence condensates in presence of field-fluid non-minimal coupling in the dark sector

TL;DR

This paper investigates conditions under which ghost fields and pure kinetic $k$-essence fields, interacting with a fluid, can produce stable accelerating expansion in the universe, highlighting different condensate formation scenarios.

Contribution

It demonstrates that both ghost fields and pure kinetic $k$-essence fields can form condensates through interactions, leading to stable cosmic acceleration, expanding understanding of dark sector dynamics.

Findings

Ghost fields can produce condensates and drive fluid energy to zero during acceleration.

Pure kinetic $k$-essence fields can form condensates without vanishing fluid energy density.

Interaction-induced condensates can sustain stable acceleration in the universe.

Abstract

In this article we try to find out 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.