Primordial non-Gaussianities in the Intergalactic Medium

TL;DR

This paper uses high-resolution hydrodynamical simulations to study how primordial non-Gaussianities affect the statistical properties of the Lyman-alpha forest in the high-redshift intergalactic medium, revealing detectable deviations from Gaussian models.

Contribution

It provides the first detailed analysis of non-Gaussian effects on Lyman-alpha flux statistics using high-resolution simulations, highlighting potential observational signatures.

Findings

Flux probability distribution function shows >20% differences at z>3 for f_NL=±100.

Flux bispectrum deviations up to 20% at large scales and z~4 for f_NL=±100.

Detection of non-Gaussianities is challenging but potentially feasible with future data.

Abstract

We present results from the first high-resolution hydrodynamical simulations of non-Gaussian cosmological models. We focus on the statistical properties of the transmitted Lyman-alpha flux in the high redshift intergalactic medium. Imprints of non-Gaussianity are present and are larger at high redshifts. Differences larger than 20 % at z>3 in the flux probability distribution function for high transmissivity regions (voids) are expected for values of the non linearity parameter f_NL=\pm 100 when compared to a standard LCDM cosmology with f_NL=0. We investigate also the one-dimensional flux bispectrum: at the largest scales (corresponding to tens of Mpc) we expect deviations in the flux bispectrum up to 20% at z~4 (for f_NL=\pm 100), significantly larger than deviations of ~ 3% in the flux power spectrum. We briefly discuss possible systematic errors that can contaminate the signal. Although challenging, a detection of non-Gaussianities in the interesting regime of scales and redshifts probed by the Lyman-alpha forest, could be possible with future data sets.