Chemical and Dynamical Evolution of Local Dwarf Galaxies
Gustavo Lanfranchi
Universidade Cruzeiro do Sul
Local dwarf galaxies are key objects in field of galactic evolution due to their proximity, to the fact that they could be associated to the small blocks that gave rise to larger galaxies, and to their particular features. Dwarf Spheroidal Galaxies, for instance, are known to be almost totally depleted of neutral gas in their central regions and are characterized by very particular abundance ratios patterns. The mechanisms responsible for the gas removal are not fully known: they could be driven by internal (galactic winds) or external (ram pressure, tidal stripping) agents, or by a combination of both. The observed pattern of the abundance ratios, on the other hand, seems to be related to the low star formation rate and to the gas lost. In this talk, I will discuss a scenario for the formation and evolution of these type of galaxy, based upon results obtained with hydrodynamical simulations and chemical evolution models compared to observations. The chemical evolution models offer an explanation for several chemical properties of the dwarf spheroidal galaxies, by considering a star formation with long episodes of activity with low intensity and the occurrence of an intense galactic wind when the thermal energy of the gas is equal or higher than the binding energy. The consistency of the gas removal is analysed in details with 3D hydrodynamical simulations, taking into account the results of the chemical evolution studies, the details of the dark matter halo, and different star formation histories.