Will there be again a transition from acceleration to deceleration in course of the dark energy evolution of the universe?

TL;DR

The paper investigates whether the universe can re-enter a decelerating phase during its dark-energy–dominated evolution by modeling two interacting dark components (warm dark matter and dark energy) in a FRW universe. It derives a general framework with an autonomous two-fluid system and a deceleration parameter q, analyzes fixed points of holographic dark energy with two coupling forms (degenerate, non-hyperbolic), and examines three models—modified Chaplygin gas, holographic DE, and a phenomenological DE-like fluid—to assess the possibility of multiple transitions. Most models predict a single deceleration-to-acceleration transition, while the phenomenological model can yield a second, future transition under specific parameter constraints. The findings are consistent with current observations of sustained acceleration and underscore the meaningful role of DM–DE interactions in shaping future cosmic dynamics, with concrete predictions testable by time-distance, CMB, and BAO data.

Abstract

In this work we consider the evolution of the interactive dark fluids in the background of homogeneous and isotropic FRW model of the universe. The dark fluids consist of a warm dark matter and a dark energy and both are described as perfect fluid with barotropic equation of state. The dark species interact non-gravitationally through an additional term in the energy conservation equations. An autonomous system is formed in the energy density spaces and fixed points are analyzed. A general expression for the deceleration parameter has been obtained and it is possible to have more than one zero of the deceleration parameter. Finally, vanishing of the deceleration parameter has been examined with some examples.