Imprints of primordial non-Gaussianities in X-ray and SZ signals from galaxy clusters

TL;DR

This study investigates how primordial non-Gaussianities influence galaxy cluster signals in X-ray and SZ observations, finding small effects compared to current uncertainties but potential for future constraints at high redshift.

Contribution

It provides the first detailed analysis of non-Gaussianity effects on cluster counts and signals using cosmological simulations with varying f_NL values.

Findings

Primordial non-Gaussianity effects are small compared to current cosmological uncertainties.

Future surveys at z>1 can significantly constrain f_NL.

SPT survey could detect ~1000 clusters at z>1 with a 15-20% difference for f_NL=±100.

Abstract

Several inflationary models predict the possibility that the primordial perturbations of the density field may contain a degree of non-Gaussianity which would influence the subsequent evolution of cosmic structures at large scales. In order to study their impact, we use a set of three cosmological DM-only simulations starting from initial conditions with different levels of non-Gaussianity: f_NL=0,+/-100. More specifically, we focus on the distribution of galaxy clusters at different redshifts and, using suitable scaling relations, we determine their X-ray and SZ signals. Our analysis allows us to estimate the differences in the logN-logS and logN-logY due to the different initial conditions and to predict the cluster counts at different redshifts expected for future surveys (eROSITA and SPT). We also use a second set of simulations assuming a different cosmological scenario to estimate how the dependence on f_NL is degenerate with respect to other parameters. Our results indicate that the effects introduced by a realistic amount of primordial non-Gaussianity are small when compared to the ones connected with current uncertainties in cosmological parameters, particularly with sigma_8. However, if future surveys will be associated with optical follow-up campaigns to determine the cluster redshift, an analysis of the samples at z>1 can provide significant constraints on f_NL. In particular we predict that the SPT cluster survey will be able to detect ~1000 clusters at z>1 for the Gaussian case, with a difference of 15-20 per cent associated to f_NL=+/-100.