Primordial Non-Gaussianity Estimation using 21 cm Tomography from the Epoch of Reionization

TL;DR

This paper evaluates the potential of 21cm tomography during the epoch of reionization to measure primordial non-Gaussianity, showing that upcoming radio telescopes could significantly improve constraints on inflation models.

Contribution

It reassesses the detectability of primordial non-Gaussianity using 21cm power spectrum measurements, providing updated sensitivity forecasts for SKA and Omniscope.

Findings

SKA can achieve Δf_NL ~ 3, comparable to Planck limits.

Omniscope can detect Δf_NL ~ 0.2, surpassing current constraints.

Revised methods significantly improve previous estimates.

Abstract

Measuring the small primordial nonGaussianity (PNG) predicted by cosmic inflation theories may help diagnose them. The detectability of PNG by its imprint on the 21cm power spectrum from the epoch of reionization is reassessed here in terms of $f_{NL}$, the local nonlinearity parameter. We find that an optimum, multi-frequency observation by SKA can achieve $\Delta f_{NL} \sim 3$ (comparable to recent Planck CMB limits), while a cosmic-variance-limited array of this size like Omniscope can even detect $\Delta f_{NL} \sim 0.2$. This substantially revises the methods and results of previous work.