Speaker: Marco Bruni
Location: Texas Symposium, Dallas
While early Universe and horizon scales perturbations are investigated with relativistic perturbation theory, non-linear structure formation in cosmology is traditionally studied with Newtonian N-body simulations. In view of new large scale galaxy surveys that will provide data with an unprecedented accuracy, it seems timely to go beyond the Newtonian approximation, unifying the study of the very large scales and the non-linear scales in a single theoretical framework. To this end I will describe a sort of post-Newtonian formalism adapted to cosmology, dubbed post-Friedmann approach, illustrating the first practical applications. It turns out that – at leading order – the power spectrum of the frame dragging vector potential can be extracted from purely Newtonian simulations. Similarly, the difference between the two scalar potential, known as “slip” in cosmology, can also be computed, sourced at leading order by purely Newtonian non-linear terms. I will also discuss the relevance of relativistic corrections to the initial conditions in Newtonian simulations that arise at second order in perturbation theory.