München 2019 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 3: Cosmology I

GR 3.2: Talk

Tuesday, March 19, 2019, 11:45–12:00, HS 4

A semiclassical path to cosmic large-scale structure — •Cora Uhlemann — Centre for Theoretical Cosmology, University of Cambridge, UK — Fitzwilliam College, University of Cambridge, UK

We chart a path towards solving for the nonlinear gravitational dynamics of cold dark matter by relying on a semiclassical description using the propagator. The evolution of the propagator is given by a Schroedinger equation, where the small parameter acts as a softening scale that regulates singularities at shell-crossing, where particle trajectories cross. The leading-order propagator, called free propagator, is the semiclassical equivalent of the Zeldovich approximation, where particles move along straight trajectories. At next-to-leading order, we solve for the propagator perturbatively and obtain the displacement and velocity fields in the classical limit. We show that our perturbative results respect the underlying Hamiltonian structure and complement our analysis with illustrative numerical examples showing that the propagator solutions closely resemble Lagrangian Perturbation Theory. Finally, we demonstrate the generation of vorticity, which is a non-trivial multi-stream phenomenon that arises naturally as a conserved topological charge in our propagator method.