Inflation produces an approximately Gaussian spectrum of scale-independent density perturbations. Deviations from scale independence and from Gaussianity are key indicators of the physical processes behind inflation and can reveal to us the physical nature of the field(s) responsible for this phase of the Universe. Primordial non-Gaussianity (pNG) is manifested both in the cosmic microwave background and in the matter distribution in the Universe. As a result of new planned survey instruments, galaxy maps may be able to constrain f_NL (the main parameter that controls non-Gaussianity) better than the Planck satellite has been able to do. It may be possible even to measure parameters which control the "shape'' of the non-Gaussianities, such as g_NL. The main difficulties are, of course, the proper control of large-scale systematics, which mix up with the signal we are trying to measure. We have three main goals in this project: (1) apply the tools already implemented by the student during her M. Sc. work to real data in order to check their functionality and to constraint pNG parameters; (2) introduce pNG in the multi-tracer code she already worked with and determine the level and form of the expected systematics (photometric redshifts, scale-dependent bias, etc.) for some of the recent galaxy surveys (e.g. J-PAS and PFS) such that we are able to recover the signal in the presence of these systematics and (3) develop the multi-tracer technique for the bispectrum and test if this improves the constraints on pNG parameters.
News published in Agência FAPESP Newsletter about the scholarship: