The self-regulated evolution of dwarf galaxies

A model of the interstellar medium (ISM) is developed that takes into accou nt its multiphase structure, in particular the existence of a system of col d clouds embedded in a hot intercloud medium. The model considers star form ation, kinetic energy input into the cloud system from stars, and kinetic e nergy loss through cloud-cloud collisions. These processes result in a char acteristic equilibrium state of the ISM with properties that are in good ag reement with observations. Analytical solutions for the global equilibrium states of dwarf galaxies are derived for simplified scenarios. First result s of three-dimensional numerical simulations are presented. The serf-regula ted evolution within a confining dark halo leads to a model galaxy characte rized by exponential density profiles for the gaseous and stellar component s, as observed in dwarf galaxies. No significant mass loss of cold gas occu rs. The characteristic global properties of the simulated galaxies are in e xcellent agreement with the observations.