Quijote PNG: The information content of the halo power spectrum and bispectrum

William R Coulton, Francisco Villaescusa-Navarro, Drew Jamieson, Marco Baldi, Gabriel Jung, Dionysios Karagiannis, Michele Liguori, Licia Verde, Benjamin D. Wandelt

Submitted on 30 June 2022


We investigate how much can be learnt about four types of primordial non-Gaussianity (PNG) from small-scale measurements of the halo field. Using the \textsc{quijote-png} simulations, we quantify the information content accessible with measurements of the halo power spectrum monopole and quadrupole, the matter power spectrum, the halo-matter cross spectrum and the halo bispectrum monopole. This analysis is the first to include small, non-linear scales, up to kmax=0.5h/Mpc, and to explore whether these scales can break degeneracies with cosmological and nuisance parameters making use of thousands of N-body simulations. For \emph{local} PNG, measurements of the scale dependent bias effect from the power spectrum using sample variance cancellation provide significantly tighter constraints than measurements of the halo bispectrum. In this case measurements of the small scales add minimal additional constraining power. In contrast, the information on \emph{equilateral} and \emph{orthogonal} PNG is primarily accessible through the bispectrum. For these shapes, small scale measurements increase the constraining power of the halo bispectrum by up to ×4, though the addition of scales beyond k0.3h/Mpc improves constraints largely through reducing degeneracies between PNG and the other parameters. These degeneracies are even more powerfully mitigated through combining power spectrum and bispectrum measurements. However even with combined measurements and small scale information, \emph{equilateral} non-Gaussianity remains highly degenerate with σ8 and our bias model.


Subject: Astrophysics - Cosmology and Nongalactic Astrophysics