Simulations Of Galaxy Clusters With And Without Winds I. The Structure Of Clusters

We use gas dynamic simulations to explore the effects of galactic winds on the structure of the intracluster medium (ICM) in X–ray clusters. Two ensembles of 18 realizations, spanning a decade in temperature T , are evolved with and without galactic winds in an underlying standard CDM cosmology with Ω=1 and Ωb =0.1. Galaxies are identified as peaks in the initial, linear density field, and are assumed to lose half their initial mass over a Hubble time in winds with effective temperature Twind=8 keV. The extra wind energy raises the entropy of the gas above the level generated by gravitationally induced shocks. This leads to substantially lower central densities in the ensemble with winds compared to the ensemble lacking winds. The magnitude of this effect increases with decreasing mass or virial temperature, and results in a trend of shallower gas profiles at lower temperatures, consistent with observations. In contrast, we find the final temperature of the gas is relatively unaffected; a similar mass–temperature relation results with or without winds. The input wind energy, which is comparable to the thermal energy in low temperature systems, is effectively consumed as work to lift the gas in the dark matter dominated potential. [email protected] [email protected]