Dust obscuration studies along quasar sight-lines using simulated galaxies

We use the results of a set of three-dimensional SPH-treecode simulations which model the formation and early evolution of disc galaxies, including the generation of heavy elements by star formation, to investigate the effects of dust absorption in quasar absorption-line systems. Using a simple prescription for the production of dust, we have compared the column density, zinc abundance and optical depth properties of our models with the known properties of damped Lyman α (DLA) systems. We find that a significant fraction of our model galaxy discs have a higher column density than any observed DLA system. We are also able to show that such parts of the disc tend to be optically thick, implying that any background quasar would be obscured through much of the disc. This would produce the selection effect against the denser absorption systems thought to be present in observations.