Signature of primordial non-Gaussianity on the 21 cm power spectrum from dark ages

Abstract

We study the signature of primordial non-Gaussianity imprinted on the power spectrum of the 21 cm line differential brightness temperature during dark ages. Employing the perturbative treatment of gravitational clustering, we quantitatively estimate the effects of the non-Gaussian and one-loop corrections on the 21 cm power spectrum. The potential impact of the use of the 21 cm power spectrum for the constraint on local-type primordial non-Gaussianity is investigated based on the Fisher matrix analysis. Our results show that the 21 cm power spectrum for an array with a baseline of several tens of kilometers can constrain the primordial non-Gaussianity to a level severer than that from cosmic microwave background measurements, and its constraining power is stronger than that of the 21 cm bispectrum, while in the ultimate situation the 21 cm bispectrum eventually becomes more powerful.