Effect of baryonic feedback on cosmic shear tomography.
Semboloni, Elisabetta (Leiden University/Leiden Observatory)

The deflection of light by large scale structure, i.e. cosmic shear, is a powerful cosmological proof.However, to date, the interpretation of cosmic shear measurements relies on models which have been developed and refined using dark matter only simulations. Using a set of hydrodynamical simulations, we explore the effect of various mechanisms such as, cooling, star formation, metal enrichment, Supernovae and AGN outflows on the weak lensing power spectrum. We show that the interpretation of two-point shear statistics for a space-based mission such as Euclid, using dark-matter only models can lead to a bias on the equation of state w_0 as high as 40%. We suggest a model which can be adjusted using scaling relations and account for real baryonic feedback. We show that this model is able to significantly reduce the bias on the cosmological parameters.