Numerical approaches to star formation and SuperNovae energy feedback in simulations of galaxy clusters

Abstract

The goal of this work is to to investigate different numerical approaches and to introduce a new, physically-based sub-grid model for the ISM physics, including a treatment of star formation and Type II supernovae energy feedback (MUPPI, MUlti-Phase Particle Integrator). Our model follows the ISM physics using a system of ordinary differential equations, describing mass and energy flows among the different gas phases in the ISM inside each gas particle. The model also includes the treatment of SNe energy transfer from star-forming particles to their neighbours. We will show in this Thesis how this model is able to reproduce observed ISM properties, while also providing an effective thermal energy feedback and responding to variations in the local hydrodynamical properties of the gas, e.g. crossing of a spiral density wave in a galaxy disk. We believe the model we presented here will be particularly useful in cosmological simulations of formation and evolution of isolated galaxies and galaxy clusters. For this reason, the first application of the present Ph.D. work will therefore be to apply MUPPI to cosmological simulations, with the aim of determine how an improved treatment of star formation and feedback astrophysical processes impacts on many open issues, from the properties of simulated disk galaxies to the properties of cold baryons (galaxies and diffuse stellar component) in galaxy clusters, to the properties of the Intra-Cluster Medium in presence of an effective supernovae thermal feedback.