Abstract
Here we use Voronoi tesselations to identify structures in hydrodynamical cosmological N-body simulations, that contain dark matter, gas and stars. This is an adaptive technique that allows accurate estimates of densities, and density gradients, for a non-structured distribution of points. We discuss how these estimates allow us to identify structures in the dark matter haloes, and in the stars, to identify galaxies, and how it is better than FOF or other sophisticated methods such as SubFind in some cases. The adaptive nature of the technique allow us to take large-scale gradients into account, allowing the identification of a galaxy on top of a background. The method resolves structures with multiple density profiles like spiral or irregular galaxies, and does not use any gravitational constraint to verify if structures are bound or virialized, so it is good for identifying evolving structures that are not necessarily in equilibrium.
