The large-scale structure from non-Gaussian primordial perturbations

TL;DR

This study investigates how primordial non-Gaussianity affects large-scale cosmic structures by analyzing simulated data, revealing subtle scale-dependent deviations in polyspectra that are mostly consistent with current CMB constraints.

Contribution

It introduces a novel approach by characterizing primordial non-Gaussianity through initial density fluctuations' probability density functions rather than bispectrum forms.

Findings

Initial non-Gaussianity has minimal impact on the first three polyspectra.

Some models show scale-dependent deviations in bispectrum and trispectrum at percent level.

Most models align with CMB constraints on trispectrum.

Abstract

The late-time effect of primordial non-Gaussianity offers a window into the physics of inflation and the very early Universe. In this work we study the consequences of a particular class of primordial non-Gaussianity that is fully characterized by initial density fluctuations drawn from a non-Gaussian probability density function, rather than by construction of a particular form for the primordial bispectrum. We numerically generate multiple realisations of cosmological structure and use the late-time matter power spectrum, bispectrum and trispectrum to determine the effect of these modified initial conditions. We show that the initial non-Gaussianity has only a small imprint on the first three polyspectra, when compared to a standard Gaussian cosmology. Furthermore, some of our models present an interesting scale-dependent deviation from the Gaussian case in the bispectrum and trispectrum, although the signal is at most at the percent level. The majority of our models are consistent with CMB constraints on the trispectrum, while the others are only marginally excluded. Finally, we discuss further possible extensions of our study.