Sergio del Campo, Júlio. C. Fabris, Ramón Herrera, Winfried Zimdahl
We assume the cosmological dark sector to consist of pressureless matter and holographic dark energy with a cutoff length proportional to the Ricci scale. The requirement of separate energy-momentum conservation of the components is shown to establish a relation between the matter fraction and the (necessarily time-dependent) equation-of-state parameter of the dark energy. Singling out intrinsically adiabatic pressure perturbations of the dark-energy component, the matter perturbations are found as linear combinations of the total energy-density perturbations of the cosmic medium and the relative (non-adiabatic) perturbations of the components. The resulting background dynamics is consistent with observations from supernovae of type Ia, baryonic acoustic oscillations and the differential age of old objects. For a physically interesting parameter space the perturbation quantities show a stable behavior. On smaller scales the model predicts oscillations in the dark sector which potentially should be testable by weak gravitational lensing and by their impact on the anisotropy spectrum of the cosmic microwave background.
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http://arxiv.org/abs/1303.3436
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