Mass varying dark matter in effective GCG scenarios

TL;DR

This paper demonstrates that mass-varying dark matter coupled with dark energy can produce effective generalized Chaplygin gas scenarios, explaining cosmic acceleration and ensuring stability through a scalar field mechanism.

Contribution

It introduces a unified framework where mass-varying dark matter and dark energy coupling lead to effective GCG models with stable perturbations.

Findings

Reproduces conditions for current cosmic acceleration.

Maintains stability with positive squared speed of sound.

Aligns perturbation equations with background cosmology.

Abstract

A unified treatment of mass varying dark matter coupled to cosmon-{\em like} dark energy is shown to result in {\em effective} generalized Chaplygin gas (GCG) scenarios. The mass varying mechanism is treated as a cosmon field inherent effect. Coupling dark matter with dark energy allows for reproducing the conditions for the present cosmic acceleration and for recovering the stability resulted from a positive squared speed of sound $c_{s}^{\2}$, as in the GCG scenario. The scalar field mediates the nontrivial coupling between the dark matter sector and the sector responsible for the accelerated expansion of the universe. The equation of state of perturbations is the same as that of the background cosmology so that all the effective results from the GCG paradigm are maintained. Our results suggest the mass varying mechanism, when obtained from an exactly soluble field theory, as the right responsible for the stability issue and for the cosmic acceleration of the universe.