https://doi.org/10.1140/epjc/s10052-023-11482-2
Regular Article - Theoretical Physics
Constraining primordial non-Gaussianity by combining next-generation galaxy and 21 cm intensity mapping surveys
1
Physics and Astronomy, University of the Western Cape, 7535, Cape Town, South Africa
2
Institute of Cosmology and Gravitation, University of Portsmouth, PO1 3FX, Portsmouth, UK
3
National Institute for Theoretical and Computational Sciences (NITheCS), 7535, Cape Town, South Africa
Received:
17
January
2023
Accepted:
6
April
2023
Published online:
24
April
2023
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 
, 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 
.
© The Author(s) 2023
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