The self-regulated evolution of dwarf galaxies

A model of the interstellar medium (ISM) is developed that takes into account its multiphase structure, in particular the existence of a system of cold clouds embedded in a hot intercloud medium. The model considers star formation, kinetic energy input into the cloud system from stars, and kinetic energy loss through cloud-cloud collisions. These processes result in a characteristic equilibrium state of the ISM with properties that are in good agreement with observations. Analytical solutions for the global equilibrium states of dwarf galaxies are derived for simplified scenarios. First results of three-dimensional numerical simulations are presented. The serf-regulated evolution within a confining dark halo leads to a model galaxy characterized by exponential density profiles for the gaseous and stellar components, as observed in dwarf galaxies. No significant mass loss of cold gas occurs. The characteristic global properties of the simulated galaxies are in excellent agreement with the observations.