Probing fundamental physics with the cosmic microwave background and large scale structures

par Anna Mangilli (IAP)

jeudi 21 nov. 2013, 11:00 → 12:00 Europe/Paris

Auditorium (Annecy-le-Vieux)

Despite the remarkable agreement between present data and the theoretical framework given by the standard cosmological $\Lambda$CDM model, we are still far from an exhaustive understanding of our Universe, starting from its early stages up to its late time history. The theoretical understanding of the mechanism that produced the primordial density perturbations, which are the seed of the anisotropies in the Cosmic Microwave Background (CMB) and of the large scale structure (LSS) of the Universe we observe today, is still an unsolved issue. Moreover, none of the "dark" components of the energetic balance of the Universe can find an explanation within the standard model of fundamental interactions. Obtaining a theoretical framework to understand the initial conditions for structure formation and determining the nature of dark matter and dark energy are indeed the biggest puzzles and challenges in modern physics. More and more precise observational probes allow for more stringent tests of the cosmological $\Lambda$CDM model, opening the quest for distinctive signatures of new physics and extensions beyond the standard picture. In these talk I will present how the CMB and LSS can be used for precision tests to prove and challenge the standard cosmological picture. The talk is divided in two parts. In the first one I will focus on CMB non-Gaussianity, I will explain why it is useful, I will show how it can be used to have insights not only in the physics of the very early universe but also in its late time evolution, probing both inflationary physics and dark energy. I will show how the CMB Planck satellite constrained for the first time CMB Non-Gaussianity with unprecedented precision and which are the theoretical implications. In the second part, I will talk about the nature of the primordial perturbations and how to investigate their properties with the CMB and LSS surveys. In particular I will show the implication of the extension beyond the standard $\Lambda$CDM picture allowing for both adiabatic and entropy primordial modes. Finally I will presents forecasts on how combining CMB data from Planck and from an Euclid-type LSS survey can improve the constraints of the nature of the primordial perturbations even in the most general cosmological models with no prior assumptions on the nature of dark energy and geometry of the Universe.

Slides LAPTH_Mangilli_2013.pdf