›The intrinsic non-Gaussianity of the Cosmic Microwave Background
The non-Gaussianity of the Cosmic Microwave Background (CMB) is a powerful probe of the early Universe since it can be related to the physics that took place soon after the Big Bang. In particular, the detection of a non-vanishing CMB bispectrum by the Planck satellite would rule out the simplest models of cosmic inflation, opening to the exciting possibility of multi-field physics in the early Universe. However, we do not expect all of the observed non-Gaussianity to be of primordial origin. Non-linear evolution will also generate some degree of non-Gaussianity that will contaminate the primordial signal. We estimate this intrinsic CMB non-Gaussianity by using a new, efficient code for solving the second-order Einstein-Boltzmann equations. The full calculation involves contributions from recombination and less tractable contributions from terms integrated along the line of sight. When including all physical effects but lensing and time-delay, we find the bias on the primordial non-Gaussianity to be below the expected sensitivity of the Planck satellite.