Inflationary perturbations in anisotropic backgrounds and their imprint on the CMB

摘要: We extend the standard theory of cosmological perturbations to homogeneous but anisotropic universes. present an exhaustive computation for case a Bianchi I model, with residual isotropy between two spatial dimensions, which is undergoing complete isotropization at onset inflation; we also show how can be further extended more general backgrounds. In presence single inflaton field, there are three physical (precisely as in isotropic case), obtained (i) by removing gauge and nondynamical degrees freedom, (ii) finding combinations remaining modes terms quadratic action canonical. The perturbations, later regime become scalar mode tensor polarizations (gravitational wave), coupled each other already linearized level during phase. This generates nonvanishing correlations different CMB anisotropies, particularly relevant large scales (and, potentially, related scale anomalies WMAP data). As example, compute spectrum this geometry, assuming that slow roll For simple set-up, fixing initial conditions appears difficult than case, additional assumptions seem needed provide predictions anisotropies.