Non-gaussianity and probe combination for large scale structure observables

This talk is mostly designed to introduce myself as a new postdoc in the department, by describing my research interests and some of my latest results. I will start by introducing my work with CMB observables in the context of the Planck mission. I studied two foregrounds to the CMB, which both trace the large scale structure (LSS) : the thermal Sunyaev-Zel'dovich (tSZ) effect and the Cosmic Infrared Background (CIB). I was interested in modeling and measuring their non-Gaussianity (NG) for two reasons : first to extract more information from these signals, and in turn better constrain their models, and second to asses how much they can contaminate estimates of primordial NG. This serves in turn to constrain cosmological parameters (tSZ effect), star-formation physics (CIB) or inflation (primordial NG).
In the second part of the talk, I will present some of my latest results working for the Dark Energy Survey (DES) on cluster number counts and the galaxy clustering 2-point function.I will present the analytical tools needed to combine their constraints, namely modeling their joint covariance. I will show how this modelisation can be tackled with the halo model and a diagrammatic formalism. I will emphasize the importance of non-Gaussian terms, and thus the necessity of a fully non-linear model. I will then present analytical Fisher forecasts showing the interest of combining these two probes, and how they can work in synergy for some parameters.
I will conclude with prospects and avenues of research that may be of interest to the DPT group.