Coupled phantom cosmological model motivated by the warm inflationary paradigm

TL;DR

This paper explores a coupled phantom dark-energy model inspired by warm inflation, revealing that coupling leads to accelerated scaling solutions but does not resolve the cosmological coincidence problem, and affects the universe's late-time behavior.

Contribution

It introduces a new coupled phantom dark-energy model motivated by warm inflation and analyzes its late-time dynamics using qualitative and numerical methods.

Findings

Coupled model admits accelerated scaling solutions.

These solutions are not final states, thus not solving the coincidence problem.

Coupling alters the asymptotic equation-of-state, making solutions less phantom.

Abstract

In this article, we investigate a coupled phantom dark-energy cosmological model in which the coupling term between a phantom scalar field with an exponential potential and a pressureless dark-matter fluid is motivated by the warm inflationary paradigm. Using methods of qualitative analysis of dynamical systems, complemented by numerical solutions of the evolution equations, we study the late-time behavior of our model. We show that contrary to the uncoupled scenario, the coupled phantom model admits accelerated scaling solutions. However, they do not correspond to a final state of the universe's evolution and, therefore, cannot be used to solve the cosmological coincidence problem. Furthermore, we show that, for certain coupling parameter values, the total equation-of-state parameter's asymptotic behavior is significantly changed when compared to the uncoupled scenario, allowing for solutions less phantom even for steeper potentials of the phantom scalar field.