Kinematics of elliptical galaxies with a diffuse dust component

Observations show that early-type galaxies contain a considerable amount of interstellar dust, most of which is believed to exist as a diffusely distributed component. We construct a four-parameter elliptical galaxy model in order to investigate the effects of such a smooth absorbing component on the projection of kinematic quantities, such as the line profiles and their moments. We investigate the dependence of these effects on the optical depth and on the dust geometry. Our calculations show that both the amplitude and the morphology of these quantities can be significantly affected. The effects of dust should therefore be taken into consideration when interpreting photometric and kinematic properties, and in correlations that utilize these quantities.