The Sunyaev-Zel'dovich effects from a cosmological hydrodynamical simulation: large-scale properties and correlation with the soft X-ray signal

Using the results of a cosmological hydrodynamical simulation of the concordance Lambda cold dark matter model, we study the global properties of the Sunyaev-Zel'dovich (SZ) effects, both considering the thermal (tSZ) and the kinetic (kSZ) component. The simulation follows gravitation and gas dynamics and includes also several physical processes that affect the baryonic component, like a simple reionization scenario, radiative cooling, star formation and supernova feedback. Starting from the outputs of the simulation we create mock maps of the SZ signals due to the large structures of the Universe integrated in the range 0 <= z <= 6. We predict that the Compton y-parameter has an average value of (1.19 +/- 0.32) x 10(-6) and is lognormally distributed in the sky; half of the whole signal comes from z < 1 and about 10 per cent from z > 2. The Doppler b-parameter shows approximately a normal distribution with vanishing mean value and an s.d. of 1.6 x 10(-6), with a significant contribution from high-redshift (z > 3) gas. We find that the tSZ effect is expected to dominate the primary cosmic microwave background anisotropies for l greater than or similar to 3000 in the Rayleigh-Jeans limit, while interestingly the kSZ effect dominates at all frequencies at very high multipoles (l greater than or similar to 7 x 10(4)). We also analyse the cross-correlation between the two SZ effects and the soft (0.5-2 keV) X-ray emission from the intergalactic medium and we obtain a strong correlation between the three signals, especially between X-ray emission and tSZ effect (r(l) similar or equal to 0.8-0.9) at all angular scales.