Cosmology on Ultralarge Scales with Intensity Mapping of the Neutral Hydrogen 21 cm Emission: Limits on Primordial Non-Gaussianity

TL;DR

This paper discusses how large-scale 21 cm intensity mapping of neutral hydrogen can probe early Universe physics, especially primordial non-Gaussianity, potentially constraining inflation models with high precision.

Contribution

It proposes that HI intensity mapping at ultralarge scales can tightly constrain primordial non-Gaussianity, offering a new observational approach.

Findings

Potential to constrain f_NL with an error close to 1

Highlights the importance of ultralarge-scale measurements for early Universe physics

Suggests dedicated experiments could achieve these constraints

Abstract

The large-scale structure of the Universe supplies crucial information about the physical processes at play at early times. Unresolved maps of the intensity of 21 cm emission from neutral hydrogen HI at redshifts z~1-5 are the best hope of accessing the ultralarge-scale information, directly related to the early Universe. A purpose-built HI intensity experiment may be used to detect the large scale effects of primordial non-Gaussianity, placing stringent bounds on different models of inflation. We argue that it may be possible to place tight constraints on the non-Gaussianity parameter f_NL, with an error close to ~1.