Crossing the phantom divide in an interacting generalized Chaplygin gas

TL;DR

This paper explores an interacting generalized Chaplygin gas model where dark energy's equation of state crosses the phantom divide, avoiding a Big Rip and addressing the coincidence problem through a specific density relation.

Contribution

It introduces a particular relation between dark densities allowing for a time-varying dark energy equation of state crossing the phantom divide, with densities decaying over time.

Findings

Dark energy crosses the phantom divide at recent epochs.

Densities decay during the universe's evolution, preventing a Big Rip.

A scaling solution emerges, addressing the coincidence problem.

Abstract

Unified generalized Chaplygin gas models assuming an interaction between dark energy and dark matter fluids have been previously proposed. Following these ideas, we consider a particular relation between dark densities, which allows the possibility of a time varying equation of state for dark energy that crosses the phantom divide at a recent epoch. Moreover, these densities decay during all the evolution of the Universe, avoiding a Big Rip. We find also a scaling solution, i.e. these densities are asymptotically proportional in the future, which contributes to the solution of the coincidence problem.