X iv : a st ro - p h / 98 03 05 9 v 1 6 M ar 1 99 8 On the role of shock waves in galaxy cluster evolution

Received ; accepted – 2 – ABSTRACT Numerical simulations of galaxy clusters including two species – baryonic gas and dark matter particles – are presented. Cold Dark Matter spectrum, Gaussian statistics and flat universe are assumed. The dark matter component is evolved numerically by means of a standard particle mesh method. The evolution of the baryonic component has been studied numerically by using a multidimensional (3D) hydrodynamical code based on modern high resolution shock capturing techniques. These techniques are specially designed for treating accurately complex flows in which shocks appear and interact. With this picture, the role of shock waves in the formation and evolution of rich galaxy clusters is analyzed. Our results display two well differenced morphologies of the shocked baryonic matter: filamentary at early epochs and quasi-spherical at low redshifts. Subject headings: cosmology: theory—hydrodynamics—large-scale structure of the universe —methods:numerical—shock waves – 3 –