Daniel Meerburg, University of Groningen

"The non-Gaussian Universe"

Abstract: Our understanding of the universe origin and evolution relies on extracting statistical information on the largest cosmological scales. Thus far, our modern view of cosmology is mostly derived on the assumption that the universe can be described by Gaussian statistical processes. If true, the main and only relevant observable then is the 2-point correlation function or its Fourier equivalent the power spectrum. While this simplified model of the universe has gotten us very far, it will not suffice if we want to make headway in the future. Both for the purpose of our modelling of the early universe, where primordial non-Gaussianities would allow us to extract critical information on the fundamental theories that lay at the foundation of our universe, as well as the late universe, where gravitational collapse naturally introduces non-Gaussianities, extracting and modelling non-Gaussian statistics will be paramount. In this talk I will discuss the power of non-Gaussian statistics in understanding our universe and explain the challenges that will have to overcome to be able to use these non-Gaussianities in cosmological inference. Through a few examples, I will show how we hope to find evidence for very small primordial signals using the cosmic microwave background, the stochastic gravitational wave background and large scale structure. In addition, I will show how late-time non-Gussianities, while a nuisance to the primordial signal, contain valuable cosmological and astrophysical information themselves.