Sunyaev-Zeldovich effect from hydrodynamical simulations: Maps and low order statistics

Abstract

We use moving mesh hydrodynamical simulations to make maps of the Sunyaev-Zeldovich effect. We present these maps for several cosmological models and explore their lowest moments. We find that the first moment, the mean Compton y parameter, is typically between $1\ensuremath{-}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ for cluster abundance normalized models, the lower value corresponding to the high density models, and scales as ${\ensuremath{\sigma}}_{8}^{3\ensuremath{-}4}.$ Power spectra at $l\ensuremath{\sim}1000$ have an amplitude between 1 and $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ in the Rayleigh-Jeans regime, with a similar depedendence on the background cosmology. The amplitude of the power spectrum strongly depends on the power spectrum normalization and scales as ${\ensuremath{\sigma}}_{8}^{6\ensuremath{-}9}.$ On smaller scales $(lg1000)$ the spectrum is dominated by halos below ${10}^{13}{M}_{\ensuremath{\bigodot}}$ and so is sensitive to the thermal history of galactic halo gas. On larger scales $(ll1000)$ the power spectrum is less sensitive to nongravitational energy injection, but becomes very noisy, with large field to field variations in the power spectrum caused by rare bright sources in the maps, which dominate the spectrum over the large scale structure correlations. The cross-correlation power spectrum with weak lensing or projected galaxy distribution is significant and the cross-correlation coefficient is around 0.5 over a wide range of scales. A comparison with Press-Schechter predictions gives very good agreement for all statistics, indicating that there is no significant contribution to SZ from nonvirialized structures. The one point distribution function shows clear deviations from Gaussianity and can be well approximated as log-normal on small scales.