Spectral line investigation of Active Galactic Nuclei at Belgrade Observatory

The spectral line shape investigations of the Active Galactic Nuclei are carried out at the Belgrade Observatory since 1994. Initially the researches were only theoretical, the object of them having been the effects of the gravity field on the spectral line shapes. Subsequently these researches were extended to include the analysis of the observed emission spectral lines. On the basis of this analysis of the observed spectral lines the modelling was undertaken of the emission regions of the Active Galactic Nuclei. Special attention was paid to the investigation of time variations of these emission lines which point to the existence of two broad line emission regions in these objects.