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In this work, we study the extended viscous dark energy models in the context of matter perturbations. To do this, we assume an alternative interpretation of the flat Friedmann-Lema^itre-Robertson-Walker Universe, through the nonadditive entropy and the viscous dark energy. We implement the relativistic equations to obtain the growth of matter fluctuations for a smooth version of dark energy. As result, we show that the matter density contrast evolves similarly to the $Lambda$CDM model in high redshift; in late time, it is slightly different from the standard model. Using the latest geometrical and growth rate observational data, we carry out a Bayesian analysis to constrain parameters and compare models. We see that our viscous models are compatible with cosmological probes, and the $Lambda$CDM recovered with a $1sigma$ confidence level. The viscous dark energy models relieve the tension of $H_0$ in $2 sim 3 sigma$. Yet, by involving the $sigma_8$ tension, some models can alleviate it. In the model selection framework, the data discards the extended viscous dark energy models.
We study how the cosmological constraints from growth data are improved by including the measurements of bias from Dark Energy Survey (DES). In particular, we utilize the biasing properties of the DES Luminous Red Galaxies (LRGs) and the growth data
We assume cold dark matter to possess a small bulk-viscous pressure which typically attenuates the growth of inhomogeneities. Explicit calculations, based on Eckarts theory of dissipative processes, reveal that for viscous cold dark matter the usual
We derive for the first time the growth index of matter perturbations of the FLRW flat cosmological models in which the vacuum energy depends on redshift. A particularly well motivated model of this type is the so-called quantum field vacuum, in whic
We show that in clustering dark energy models the growth index of linear matter perturbations, $gamma$, can be much lower than in $Lambda$CDM or smooth quintessence models and present a strong variation with redshift. We find that the impact of dark
The rate of structure formation in the Universe is different in homogeneous and clustered dark energy models. The degree of dark energy clustering depends on the magnitude of its effective sound speed $c^{2}_{rm eff}$ and for $c_{rm eff}=0$ dark ener