Morphological evolution of X-ray clusters using hydrodynamical simulations

A large set of TREESPH simulations is used to test the global morphology of galaxy clusters and its evolution against X-ray data. A powerful method to investigate substructures in galaxy clusters are the power ratios introduced by Buote & Tsai. We consider three flat cosmological models: CDM, LCDM($\Omega_\Lambda = 0.7$) and CHDM($\Omega_h = 0.2$, 1 massive $\nu$), all normalized so to fit the observed number of clusters. For each model we built 40 clusters, using a TREESPH code, and performed a statistical comparison with a data sample including nearby clusters observed with ROSAT PSPC instrument. The comparison disfavors the LCDM model, as clusters appear too relaxed, while CDM and CHDM clusters, in which a higher degree of complexity occurs, seem to be closer to observations. A better fit of data can be expected for some different DM mix. If DM distributions are used instead of baryons, we find substructures more pronounced than in gas and models have a different score. Using hydrodynamical simulations is therefore essential to our aims.