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

Sheean Jolicoeur; Roy Maartens; Simthembile Dlamini

doi:10.1140/epjc/s10052-023-11482-2

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 320
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

Sheean Jolicoeur¹^a, Roy Maartens¹^,2^,3 and Simthembile Dlamini¹

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

^a jolicoeursheean@gmail.com

Received: 17 January 2023
Accepted: 6 April 2023
Published online: 24 April 2023

Abstract

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 $f_{NL}$ $f_{\textrm{NL}}$ , 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 $σ (f_{NL}) \sim 4$ $\sigma (f_{\textrm{NL}}) \sim 4$ .

© The Author(s) 2023

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.