Squeezing information from radio surveys to probe the primordial Universe

TL;DR

This paper proposes a new correlation statistic for radio surveys that enhances constraints on primordial non-Gaussianity, surpassing current methods and forecasts, by effectively combining different telescope modes to analyze large-scale structure.

Contribution

It introduces a novel correlation statistic and a fusion technique for radio telescope modes to improve measurements of the squeezed bispectrum and primordial non-Gaussianity.

Findings

Constraints on $f_{NL}^{loc}$ can reach $\sigma ext{(}f_{NL}^{loc} ext{)} \

The method outperforms Planck and Euclid in measuring primordial non-Gaussianity.

A small subset of triangles suffices for high-precision constraints.

Abstract

A major goal of cosmology is to understand the nature of the field(s) which drove primordial Inflation. Through future observations, the statistics of large-scale structure will allow us to probe primordial non-Gaussianity of the curvature perturbation at the end of Inflation. We show how a new correlation statistic can significantly improve these constraints over conventional methods. Next-generation radio telescope arrays are under construction which will map the density field of neutral hydrogen to high redshifts. These telescopes can operate as an interferometer, able to probe small scales, or as a collection of single dishes, combining signals to map the large scales. We show how to fuse these these operating modes in order to measure the squeezed bispectrum with higher precision and greater economy. This leads to constraints on primordial non-Gaussianity that will improve on measurements by Planck, and out-perform other surveys such as Euclid. We forecast that $\sigma(f_{\mathrm{NL}}^{\mathrm{loc}})\sim 3$, achieved by using a small subset, $\mathcal{O}(10^2-10^3)$, of the total number of accessible triangles. The proposed method can be used for any signal that peaks in squeezed configurations.