Impact of dark energy perturbations on the growth index

• Autor(a) principal: Batista, Ronaldo Carlotto
• Data de Publicação: 2014
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/30833
• topic: Dark energy equation

We show that in clustering dark energy models the growth index of linear matter perturbations, γ, can be much lower than in Λ CDM or smooth quintessence models and presents a strong variation with redshift. We find that the impact of dark energy perturbations on γ 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 < γ ( z ) < 0.48 at 0 < z < 3. We also show that the constant γ parametrization for the growth rate, f = d   ln δ m / d lna = Ω γ m, is a few percent inaccurate for such models and that a redshift-dependent parametrization for γ 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 f ( R ) and clustering dark energy models can present similar values for γ