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arXiv · 1909.10336

Unphysical properties in a class of interacting dark energy models

R. von Marttens·H. A. Borges·S. Carneiro·J. S. Alcaniz·W. Zimdahl
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Abstract

Models with non-gravitational interactions between the dark matter and dark energy components are an alternative to the standard cosmological scenario. These models are characterized by an interaction term, and a frequently used parameterization is $Q = 3\xi H \rho_{x}$, where $H$ is the Hubble parameter and $\rho_{x}$ is the dark energy density. Although current observations support such a model for negative values of the interaction parameter $\xi$, we show here that this interval of values of $\xi$ leads the model to predict a violation of the Weak Energy Condition (WEC) for the dark matter density, regardless of the value of the equation-of-state parameter of the dark energy component. This violation is accompanied by unphysical instabilities of matter perturbations.

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R. von Marttens, H. A. Borges, S. Carneiro, J. S. Alcaniz, W. Zimdahl. 2019-09-20. Unphysical properties in a class of interacting dark energy models. https://doi.org/10.1140/epjc%2Fs10052-020-08682-5

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