Constraining primordial non-Gaussianity from large scale structure with the wavelet scattering transform

Abstract

We investigate the Wavelet Scattering Transform (WST) as a tool for the study of Primordial non-Gaussianity (PNG) in Large Scale Structure (LSS), and compare its performance with that achievable via a joint analysis with power spectrum and bispectrum (P+B). We consider the three main primordial bispectrum shapes — local, equilateral and orthogonal — and produce Fisher forecast for the corresponding f NL amplitude parameters, jointly with standard cosmological parameters. We analyze simulations from the publicly available Quijote and Quijote-png N-body suites, studying both the dark matter and halo fields. We find that the WST outperforms the power spectrum alone on all parameters, both on the f NL's and on cosmological ones. In particular, on f NL local for halos, the improvement is about 27%. When B is combined with P, halo constraints from WST are weaker for f NL local (at ∼ 15% level), but stronger for f NL equil (∼ 25%) and f NL ortho (∼ 28%). Our results show that WST, both alone and in combination with P+B, can improve the extraction of information on PNG from LSS data over the one attainable by a standard P+B analysis. Moreover, we identify a class of WST in which the origin of the extra information on PNG can be cleanly isolated.