ﻻ يوجد ملخص باللغة العربية
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 energy perturbations on $gamma$ is enhanced if the dark energy equation of state has a large and rapid decay at low redshift. We study four different models with these features and show that we may have $0.33<gammaleft(zright)<0.48$ at $0<z<3$. We also show that the constant $gamma$ parametrization for the growth rate, $f=dlndelta_{m}/dln a=Omega_{m}^{gamma}$, is a few percent inaccurate for such models and that a redshift dependent parametrization for $gamma$ can provide about four times more accurate fits for $f$. We discuss the robustness of the growth index to distinguish between General Relativity with clustering dark energy and modified gravity models, finding that some $fleft(Rright)$ and clustering dark energy models can present similar values for $gamma$.
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
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
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
In this paper we study the evolution of cosmological perturbations in the presence of dynamical dark energy, and revisit the issue of dark energy perturbations. For a generally parameterized equation of state (EoS) such as w_D(z) = w_0+w_1frac{z}{1+z
We investigate the Tsallis holographic dark energy (THDE) models in the context of perturbations growth. We assume the description of dark energy by considering the holographic principle and the nonadditive entropy to carry out this. We implement the