Speaker
Description
The presence of additional light fields during inflation can be robustly inferred (or ruled out), if signatures of primordial non-Gaussianity (PNG) of the local type are found (or not found) in upcoming cosmological surveys. In fact, upcoming measurements of the distribution of large-scale structures (LSS) in our Universe will have enough sensitivity to reach important theoretical thresholds distinguishing the single and multi-field regimes. This is only possible due to a well-known scale-dependent modulation in the distribution of biased tracers, such as galaxies, in comparison to the underlying matter field. Unfortunately, in this scale-dependent bias effect the amplitude of PNG is exactly degenerate with an unknown PNG bias coefficient, which hence needs to be independently estimated in order to produce a measurement of PNG from LSS observations. In this talk I show how the time evolution of tracer number counts can be used to estimate the PNG bias coefficient, using both N-body and Hydrodynamical simulations of LSS formation. I will argue that observational selection effects of specific surveys can be accounted for, and comment on applying this strategy to existing and upcoming datasets.