Forecasts on the dark energy anisotropic stress for the esa euclid survey

The cosmological constant Λ seems to be a not satisfactory explanation of the late-time accelerated expansion of the Universe, for which a number of experimental evidences exist; therefore, it has become necessary in the last years to consider alternative models of dark energy, meant as cause of the accelerated expansion. In the study of dark energy models, it is important to understand which quantities can be determined starting from observational data, without assuming any hypothesis on the cosmological model; such quantities have been determined in Amendola, Kunz et al., 2012. In the same paper it has been further shown that it is possible to estabilish a relation between the model-independent parameters and the anisotropic stress η, which can be also expressed as a combination of the functions appearing in the most general Lagrangian for the scalar-tensor theories, the Horndeski Lagrangian. In the present thesis, the Fisher matrix formalism is used to perform a forecast on the constraints that will be possible to make on the anisotropic stress η in the future, starting from the estimated uncertainties for the galaxy clustering and weak lensing measurements which will be performed by the European Space Agency Euclid mission, to be launched in 2020. Further, constraints coming from supernovae-Ia observations are considered. The forecast is performed for two cases in which (a) η is considered as depending from redshift only and (b) η is constant and equal to one, as in the ΛCDM model.

Editorial reorganization of an alphabetically ordered collection of short stories: analysis of problems and hypothesis of possible solutions

This paper aims to show, analyze and solve the problems related to the translation of the book with meaning-bond alphabetically ordered chapter titles La vita non è in ordine alfabetico, by the Italian writer Andrea Bajani. The procedure is inevitable for a possible translation of the book, and it is necessary to have a preliminary pattern to follow. After translating the whole book, not only is a revision fundamental, but a restructure and reorganization of the collection may be required, hence, what this thesis offers is a scheme to start from, together with an analysis of the possible problems that may arise, and a useful method to find a solution.