The intrinsic bispectrum of the Cosmic Microwave Background [PhD thesis]

Understand

The CMB bispectrum is a potential window on exciting new physics, as it is sensitive to the non-Gaussian features in the primordial fluctuations, the same fluctuations that evolved into today's planets, stars and galaxies.

• However, this invaluable information is potentially screened, as not all of the observed non-Gaussianity is of primordial origin.
• Indeed, a bispectrum arises even for perfectly Gaussian initial conditions due to non-linear dynamics, such as CMB photons scattering off free electrons and propagating in an inhomogeneous Universe.
• In this thesis, I introduce the reader to this intrinsic bispectrum in a pedagogic way, building up from the standard model of cosmology and from cosmological perturbation theory, the tool cosmologists use to unravel the history of the cosmos.