Multitracer technique for galaxy bispectrum - An application to constraints on non-local primordial non-Gaussianities -

TL;DR

This paper investigates how galaxy bispectra combined with multitracer techniques can improve constraints on primordial non-Gaussianities, potentially surpassing current cosmic microwave background limits.

Contribution

It demonstrates that multitracer analysis of galaxy bispectra can significantly reduce cosmic variance and tighten constraints on non-local primordial non-Gaussianities.

Findings

Multitracer technique reduces cosmic variance noise.

Future galaxy surveys can constrain non-Gaussianity parameters better than current CMB limits.

Constraints on non-local primordial non-Gaussianities will be more stringent.

Abstract

We explore the use of galaxy bispectra with multitracer technique as a possible probe of primordial non-Gaussianities. We forecast future constraints on non-linearity parameters, $f_{\rm NL}^{\rm eq}$ and $f_{\rm NL}^{\rm orth}$, which respectively characterize the equilateral- and orthogonal-types primordial bispectra, and show that the multitracer analysis would be effective with reducing the cosmic-variance noise if the number density of galaxies is high enough. We find that the measurement of galaxy bispectrum by future galaxy surveys can reach the constraints on the non-local type primordial non-Gaussianities to the level severer than current one which has been obtained by cosmic microwave background observations.