Extensão do modelo LambdaCDM, baseada na teoria escalar-tensorial da gravitação.

Abstract

Cosmological measurements of both the expansion history H(z) and growth history fs8 have matured, and the two together provide an important test of cosmological scalar-tensor theory, in particular the Brans-Dicke type which provides an extension to the ?CDM model. We construct an explicit analytic expression (through an ansatz) as a modification of the Hubble rate of the ?CDM model, in which it is given in terms of a constant parameter m, which quantifies the differences between the background dynamics of the scalar-tensor theories and general relativity, thus performing a statistical analysis SNIa, H(z) and BAO to find the minimum fitting of the constant parameter. To complete our system, we introduce equations of fluid dynamical perturbations, the extension of the ?CDM in what regards develops an effective fluid approach for the matter growth function. We quantify the impact of deviations from standard background, of anisotropic stress and of non-vanishing perturbations of effective dark energy component on the matter growth rate function fs8 and confront the results with redshift-space distortion (RSD) measurements.