dr Yuri Shtanov, Bogolyubov Institute for Theoretical Physics, Kiev

Statistical anisotropy in the inflationary universe

Cosmological inflation remains to be a unique theory of generation of plausible initial conditions in the early universe. In particular, it generates the quasiclassical perturbations with power spectrum determined by the fundamental principles of quantum field theory. After the end of inflationary epoch, such perturbations serve as primeval seeds for the formation of large-scale structure (galaxies and galactic clusters) in the universe. In this talk, we pay attention to the fact that the quasiclassical perturbations permanently generated at early stages of inflation break homogeneity and isotropy of the cosmological background. The evolution of the small-scale quantum vacuum modes then proceeds on this inhomogeneous background. As a result, the power spectrum of primordial perturbations develops statistical anisotropy, which can manifest itself in the observable large-scale structure and cosmic microwave background. The effect is predicted to have almost scale-invariant form dominated by a quadrupole and may serve as a non-trivial test of the inflationary scenario. Theoretical expectation of the magnitude of this statistical anisotropy depends on the assumptions about the physics in the trans-Planckian region of wavenumbers. Part of the talk will be devoted to the discussion of this trans-Planckian issue in cosmology.