A new generation of galaxy surveys is at our doorstep. By mapping billions of galaxies over the sky, they will deliver precision constraints on the cosmological model. The significant gains in constraining power are accompanied by the need to develop more accurate models of the large-scale structure. Several physical effects will come into play that could be neglected or simplified in previous analyses. I will discuss the constraining power of upcoming surveys, focusing mostly on Rubin Observatory, and the modelling challenges they face.
Amongst the physical effects that need to be modelled, I will focus mostly on the “intrinsic alignments” of galaxies: alignments between their shapes that are likely to arise from tidal interactions between them. I will introduce a new modelling strategy based on the effective-field-theory description of intrinsic alignments and I will show tests of its robustness against numerical simulations. Finally, I will highlight new opportunities that will arise from modelling and constraining intrinsic alignments.