Imprints of Primordial Non-Gaussianities in X-ray and SZ Signals from Galaxy Clusters

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 dark-matter-only simulations starting from initial conditions with different levels of non-Gaussianity: fNL = 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 Sunyaev-Zel'dovich signals. Our analysis allows us to estimate the differences in 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 fNL 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 σ8. 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 fNL. 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 with fNL = +/-100.