Constraining primordial non-Gaussianity by combining next-generation galaxy and 21 cm intensity mapping surveys

Sheean Jolicoeur*, Roy Maartens, Simthembile Dlamini

*Corresponding author for this work

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Surveys of the matter distribution contain ‘fossil’ information on possible non-Gaussianity that is generated in the primordial Universe. This primordial signal survives only on the largest scales where cosmic variance is strongest. By combining different surveys in a multi-tracer approach, we can suppress the cosmic variance and significantly improve the precision on the level of primordial non-Gaussianity. We consider a combination of an optical galaxy survey, like the recently initiated DESI survey, together with a new and very different type of survey, a 21 cm intensity mapping survey, like the upcoming SKAO survey. A Fisher forecast of the precision on the local primordial non-Gaussianity parameter fNL, shows that this multi-tracer combination, together with non-overlap single-tracer information, can deliver precision comparable to that from the CMB. Taking account of the largest systematic, i.e. foreground contamination in intensity mapping, we find that σ(fNL) ∼ 4.

Original languageEnglish
Article number320
Number of pages10
JournalEuropean Physical Journal C
Issue number4
Publication statusPublished - 24 Apr 2023

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