Sept 5, 14:45 (30 mins) in A315   

Guido Pettinari (Portsmouth, UK)


Non-Gaussianity vs non-linear dynamics

The Cosmic Microwave Background (CMB) maps measured by the PLANCK experiment will allow us to test the physics of the primordial Universe with unprecedented accuracy. In particular, the detection of a deviation from Gaussianity in the CMB would rule out the simplest models of cosmic inflation. Unfortunately, several late-time mechanisms lead to non-Gaussian features in the CMB, thus inducing a bias on the estimation of the primordial signal. In our work, we focus on non-linear dynamics, whose contamination to the primordial non-Gaussianity has not been quantified unambigously in the literature. As non-linearities arise naturally in General Relativity, it is crucial that they are well-understood and hence removed from the data. In order to do so, we have written a second-order Boltzmann code to compute the CMB bispectrum, which involves the formidable task of solving the Boltzmann-Einstein system of equations at second order in perturbation theory. In this talk, I shall summarize the previous literature on the topic, highlight the differences with the first-order approach, describe the status of the project and present some preliminary results.