Estudo da interação no setor escuro através do parâmetro de hubble

Abstract

A possible approach to the cosmological coincidence problem is to allow dark matter and dark energy to interact with each other also nongravitationally. Two general classes of interaction were considered in this thesis, characterized by a constant interaction parameter ( or 􀀀). Their ability to address the coincidence problem was appraised and was shown that some models are capable to alleviate the problem. It is estimated the average accuracy required to distinguish interacting cosmological models from the conventional CDM scenario using the cosmic expansion rate H(z) data. The analysis is performed at two levels: through Monte Carlo simulations based on an interaction model, in which H(z) samples with different accuracies are generated, and through a semianalytic method that calculates the error propagation of the parameters or 􀀀 as a function of the error in H(z). It is shown that the semianalytical approach agrees with simulations and that to detect an interaction using H(z) data only, these must reach an accuracy better than 1% if the parameter is of the order of recent determinations (10􀀀2). This means that, among the planned surveys, the Wide Field Infrared Survey Telescope has the best chance to detect an interaction, though at a low significance level. To determine more precisely the existence of an interaction it would be needed to combine the expansion data with other type of observation