Phantom cosmology with arbitrary potential: New accelerating scaling attractors

TL;DR

This paper demonstrates that coupled phantom dark energy models with arbitrary potentials can produce accelerating scaling solutions, offering insights into cosmic acceleration and the coincidence problem.

Contribution

It introduces a general analysis of accelerating solutions in coupled phantom cosmology without specifying the potential, using dynamical systems methods.

Findings

Accelerating scaling solutions exist for arbitrary potentials.

Coupling between phantom energy and dark matter can address the coincidence problem.

Limitations include insufficient matter-dominated era before acceleration.

Abstract

In this article, we investigate the existence of accelerating scaling solutions in coupled phantom cosmology without assuming any specific potential for the phantom scalar field. The coupling between phantom dark energy and dark matter is motivated by the warm inflationary paradigm, with the dissipation coefficient assumed to be either constant or variable. The evolution equations are written in the form of autonomous systems, whose stability is studied using methods of qualitative analysis of dynamical systems. For this analysis, the only requirement imposed on the otherwise arbitrary phantom potential is that a particular dynamical variable, defined in terms of the potential and its derivative, must be invertible. For such a generic potential, we show that accelerated scaling solutions do exist, for both constant and variable dissipation coefficients. Although there is a limitation to these scaling solutions -- specifically, the current stage of accelerated expansion is not preceded by a long enough matter-dominated era -- our results show that the existence of a direct coupling between phantom dark energy and dark matter yields great potential for addressing the cosmic coincidence problem.