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: 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 Sunyaev―Zel'dovich signals. Our analysis allows us to estimate the differences in log N― log S and log N―log Y 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 σ 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 with f NL = ±100.