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

Abstract

Surveys of the matter distribution contain ‘fossil’ information on possible non-Gaussianity that is generated in the primordialUniverse. 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 21cm intensity mapping survey, like the upcoming SKAO survey.