Hydrodynamical chemistry simulations of the Sunyaev–Zel'dovich effect and the impacts from primordial non-Gaussianities

Abstract

The impacts of Compton scattering of hot cosmic gas with the cosmic microwave background radiation (Sunyaev-Zel'dovich effect, SZ) are consistently quantified in Gaussian and non-Gaussian scenarios, by means of 3D numerical, N-body, hydrodynamic simulations, including cooling, star formation, stellar evolution and metal pollution (He, C, O, Si, Fe, S, Mg, etc.) from different stellar phases, according to proper yields for individual metal species and mass-dependent stellar lifetimes. Light cones are built through the simulation outputs and samples of one hundred maps for the resulting temperature fluctuations are derived for both Gaussian and non-Gaussian primordial perturbations. From them, we estimate the possible changes due to early non-Gaussianities on: SZ maps, probability distribution functions, angular power spectra and corresponding bispectra. We find that the different growth of structures in the different cases induces significant spectral distortions only in models with large non-Gaussian parameters, $f_{\rm NL}$. In general, the overall trends are covered by the non-linear, baryonic evolution, whose feedback mechanisms tend to randomize the gas behaviour and homogenize its statistical features, quite independently from the background matter distribution. Deviations due to non-Gaussianity are almost undistinguishable for $f_{\rm NL}\lesssim 100$, remaining always at few-per-cent level, within the error bars of the Gaussian scenario. Rather extreme models with $f_{\rm NL}\sim1000$ present more substantial deviations from the Gaussian case, overcoming baryon contaminations and showing discrepancies up to a factor of a few in the spectral properties.