Prof. Oliver Hahn

The accuracy of predictions of non-linear structure formation required in the era of precision cosmology is unprecedented. These predictions rely on both computer simulations and perturbative calculations. At their interface, initial conditions for cosmological simulations have to bridge the gap between the multi-physics highly-accurate, but linear, modelling of the evolution of perturbations in the Universe after inflation, and the deeply non-linear but physically simpler regime of late-time cosmic structure formation. Inaccuracies in the initial conditions for cosmological N-body simulations could thus easily be the largest source of systematic error in predicting the non-linear large-scale structure, which is a sensitive cosmological probe of the late-time Universe. After giving an introduction on how cosmological simulations are set up, I will present our new results and techniques on very accurate and economic N-body simulations, the limits of perturbation theory, and new semi-numerical techniques borrowing from quantum dynamics.