Impact of cooling and preheating on the Sunyaev-Zeldovich effect

We use hydrodynamical simulations to assess the impact of radiative cooling and "preheating" on predictions for the Sunyaev-Zeldovich (SZ) effect. Coo ling significantly reduces both the mean SZ signal and its angular power sp ectrum, while preheating can increase the mean distortion while leaving the angular power spectrum below that found in a simulation without heating or cooling. We study the relative contribution from high- and low-density gas , and we find that in the cooling model about 60% of the mean thermal disto rtion arises from low-overdensity gas. We find that halos dominate the ther mal SZ power spectrum in all models, while in the cooling simulation the ki netic SZ power spectrum originates predominantly in lower overdensity gas.