Accelerated expansion through interaction

TL;DR

This paper proposes a model where the universe's transition to accelerated expansion is driven purely by dark matter-dark energy interactions, unifying various cosmological scenarios and analyzing associated perturbation dynamics.

Contribution

It introduces a novel interaction-based mechanism for cosmic acceleration, unifying different models and exploring non-adiabatic perturbations resulting from fluctuating interaction rates.

Findings

Interaction-driven transition to acceleration

Unified framework encompassing LCDM and Chaplygin gas

Non-adiabatic perturbation dynamics from fluctuating interactions

Abstract

Interactions between dark matter and dark energy with a given equation of state are known to modify the cosmic dynamics. On the other hand, the strength of these interactions is subject to strong observational constraints. Here we discuss a model in which the transition from decelerated to accelerated expansion of the Universe arises as a pure interaction phenomenon. Various cosmological scenarios that describe a present stage of accelerated expansion, like the LCDM model or a (generalized) Chaplygin gas, follow as special cases for different interaction rates. This unifying view on the homogeneous and isotropic background level is accompanied by a non-adiabatic perturbation dynamics which can be seen as a consequence of a fluctuating interaction rate.