Seminario

Il giorno 10 dicembre alle ore 11 presso la stanza 412, Michele Citran (APC, Paris, France) terra' un seminario di cosmologia dal titolo

Non-Gaussianity in Planck, LiteBIRD and component separation

Abstract

Non-Gaussianity in cosmology is the study of deviations from a Gaussian distribution in cosmological observables, commonly probed through the 3-point correlator, the bispectrum. Primordial non-Gaussianity (PNG), i.e. the bispectrum of the primordial fluctuations, provides a powerful means of constraining inflationary models. I will present how our analysis of the Planck Release 4 (PR4) data has yielded the most stringent constraints to date on scalar PNG, and how future missions such as LiteBIRD will further enhance these measurements by accessing the tensor sector.
I will then introduce a new formalism for the Spectral Matching Independent Component Analysis (SMICA) method that incorporates higher-order statistical information from foregrounds. This framework enables direct bispectrum estimation using frequency-channel maps, allowing simultaneous recovery of the bispectra of multiple components. By shifting non-Gaussianity estimation from the cleaned-map stage to the component-separation step, the method more effectively propagates and manages foreground uncertainties. This approach optimally combines the data by jointly accounting for both the power spectrum and bispectrum of all components—an improvement over standard analyses.