Constraining primordial non-Gaussianity by combining next-generation galaxy and 21 cm intensity mapping surveys
Date
2023Author
Sheean, Jolicoeur
Maartens, Roy
Jolicoeur, Sheean
Dlamini, Simthembile
Metadata
Show full item recordAbstract
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 21cm 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