Weak Lensing halo detection by Euclid

It has been widely shown that weak lensing surveys can be used for detecting dark matter concentrations. Here we use the aperture mass method to predict the detectability and number density of cluster-sized halos from a weak lensing survey as expected from the future space-based Euclid mission. The method bases on the image distortion of back- ground galaxies caused by the gravitational potential of intervening dark matter distribution. Preliminary results on the expected number density of halos with a given signal-to-noise ratio are presented for different cosmologies, showing how halo number counts can be a useful probe to discriminate among different cosmological models.