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Abstract

The content of this work is two-fold. In the first part we present a study on the contamination of the intrinsic alignments to weak lensing measurements in the future survey Euclid. On the grounds of the tidal torque theory, we have adopted from the literature two related prescriptions for modeling the intrinsic alignment signal and computed for both the resulting biases in the cosmological parameters.We find a slight discrepancy among the two models, which both significantly (up to > 3sigma) contaminate the estimates for Omega_m and sigma_8. The other parameters h, ns and w appear less affected. In the second part we present results based on an innovative statistical approach, the extreme value statistics. We investigate up to which level the primordial non-Gaussianities parameters fNL and gNL inherited by the bi- and trispectra of the weak lensing convergence can be constrained by the most extreme values of the convergence field.We find constraints of the order of 102 for fNL and 105 for gNL if individual extreme values are considered, therefore sadly showing only a relatively weak constraining power.