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

10+5 pages, 4 figures, "Minor corrections, main results unchanged. Version accepted by EPJC"

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Cited by in corpus (12)

• Learning to Concentrate: Multi-tracer Forecasts on Local Primordial Non-Gaussianity with Machine-Learned Bias
• Multi-tracer power spectra and bispectra: Formalism
• Pairwise kSZ signal extraction efficacy and optical depth estimation
• Radio-optical synergies at high redshift to constrain primordial non-Gaussianity
• Constraining primordial non-Gaussianity by combining photometric galaxy and 21cm intensity mapping surveys
• Multi-tracing the primordial Universe with future surveys
• Modes of the Dark Ages 21cm field accessible to a lunar radio interferometer
• Detecting Relativistic Doppler by Multi-Tracing a Single Galaxy Population
• Cosmic inflation in non-perturbative quantum gravity
• Constraining the growth rate on linear scales by combining SKAO and DESI surveys
• Unified Origin of Curvature Perturbation and Baryon Asymmetry of the Universe
• Primordial non-Gaussianity systematics from redshift mismatch with SPHEREx