Three-dimensional simulations of the interstellar medium in dwarf galaxies - 1. Ram pressure stripping

We present three-dimensional hydrodynamic simulations of ram pressure stripping in dwarf galaxies. Analogous studies on this subject usually deal with much higher ram pressures, typical of galaxy clusters, or mild ram pressure due to the gas halo of the massive galactic companions. We extend over previous investigations by considering flattened, rotating dwarf galaxies subject to ram pressures typical of poor galaxy groups. We study the ram pressure effects as a function of several parameters such as galactic mass and velocity, ambient gas density and the angle between the galactic plane and the direction of motion. It turns out that this last parameter plays a role only when the gas pressure in the galactic centre is comparable to the ram pressure. Despite the low values of the ram pressure, some dwarf galaxies can be completely stripped after 1-2 Myr. This poses an interesting question on the aspect of the descents and, more in general, on the morphological evolution of dwarf galaxies. In cases in which the gas is not completely stripped, the propagation of possible galactic wind may be influenced by the disturbed distribution of the interstellar matter. We also consider the modification of the interstellar matter surface density induced by the ram pressure and find that the resulting compression may trigger star formation over long time-spans.