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

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.