An estimator for statistical anisotropy from the CMB bispectrum – Ema Dimstrogiovanni

Date: Tue. February 28th, 2012, 11:30 am-12:30 pm
Location: Rockefeller 221

Various data analysis of the Cosmic Microwave Background (CMB) radiation present anomalous features that can be interpreted as indications of statistical isotropy breaking. Some models of inflation involving vector fields predict statistical anisotropy in the correlation functions of primordial curvature perturbations. We employ a simplified vector field model and parametrize the bispectrum of curvature fluctuations in such a way that all the information about statistical anisotropy is encoded in some coefficients lambda_{LM} (representing the ratio of the anisotropic to the isotropic bispectrum amplitudes). We compute an optimal estimator for these coefficients and their Fisher error. We predict a sensitivity for an experiment like Planck to the anisotropic to isotropic amplitudes of about 10% if fNL is around 30. Our results are complementary to power spectrum analyses and particularly relevant for those models where statistical anisotropy is suppressed in the power spectrum and not negligible in the bispectrum. Download the slides –