Abstract

The intrinsic correlations of galaxy shapes are a recognised contaminant to weak gravitational lensing measurements. Luminous red galaxies have been observed to point radially towards each other, likely as a consequence of the action of the tidal field of the large-scale structure on their shapes and orientations; blue, disc-like galaxies show no detectable alignment from current observations. If these intrinsic alignments are not accounted for, cosmological constraints from weak gravitational lensing could be severely biased. I will describe the exploration of the intrinsic alignment signal in the Horizon-AGN cosmological hydrodynamical simulation, in preparation for future weak lensing surveys. In particular, I will describe the different contributions to intrinsic alignments, their redshift evolution and the relative galaxy-dark matter halo alignment. On the other hand, I will turn the question around and explore whether there is useful cosmological information to be extracted from intrinsic alignments with future surveys. For this last part, I will focus on anisotropic models of inflation which leave a lasting imprint on the tidal field of the large-scale structure, and the shapes of galaxies.