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arXiv · 1712.01128

Dynamics of expansion of the Universe in model with the additional coupling between dark energy and dark matter

R. Neomenko·B. Novosyadlyj·O. Sergijenko
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Abstract

We study the dynamics of expansion of the homogeneous isotropic Universe and the evolution of its components in the model with nonminimally coupled dynamical dark energy. Dark energy, like the other components of the Universe, is described by the perfect fluid approximation with the equation of state (EoS) $p_ {de}=w\rho_{de}$, where the EoS parameter $w$ depends on time and is parameterized via the squared adiabatic sound speed $c_{ a}^2$ which is assumed to be constant. On basis of the general covariant conservation equations for the interacting dark energy and dark matter and Einstein equations in Friedmann-Lemaitre-Robertson-Walker metric we analyze the evolution of energy densities of the hidden components and the dynamics of expansion of the Universe with two types of interaction: proportional to the sum of densities of the hidden components and proportional to their product. For the first interaction the analytical expressions for the densities of dark energy and dark matter were obtained and analyzed in detail. For the second one the evolution of densities of hidden components of the Universe was analyzed on basis of the numerical solutions of their energy-momentum conservation equations. For certain values of the parameters of these models the energy densities of dark components become negative. So to ensure that the densities are always positive we put constraints on the interaction parameter for both models.

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R. Neomenko, B. Novosyadlyj, O. Sergijenko. 2017-12-01. Dynamics of expansion of the Universe in model with the additional coupling between dark energy and dark matter. https://arxiv.org/abs/1712.01128

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