Date: February 1st 2018
Speaker: Sandrine Codis (IAP)
Title: Intrinsic alignments : theoretical and numerical insights
In this talk, I will show how both dark matter and hydrodynamical simulations predict that the morphology of galaxies is correlated with the cosmic web. This large-scale coherence of galaxy shapes could possibly induce some non-negligible level of contamination for future cosmic shear experiments. Because this effect is very sensitive to the small scale baryonic physics, it is difficult to use dark matter-only simulations as the sole resource to predict and control intrinsic alignments. I will show how state-of-the-art hydrodynamical simulations like Horizon-AGN can be used to shed light on the level of intrinsic alignment we should expect for future weak lensing measurements. On the theoretical side, I will describe an analytical Lagrangian model that reproduces qualitatively the correlations between the intrinsic angular momentum of galaxies and the cosmic filaments. The key ingredient is to take into account the anisotropy of the cosmic web in the standard theory of spin acquisition by tidal torquing.