Obscuration and the various kinds of Seyfert galaxies

Two samples of Seyfert galaxies are used to investigate the classification of these galaxies. A complete X-ray selected sample of 16 active spirals is defined and the luminosities and axial ratio of the parent galaxy are given. The data suggest strongly that obscuration occurs in the broad emission line region, which has a flattened configuration parallel to that of the parent galaxy, and that obscuration is more likely for low luminosity objects. A larger, heterogeneous sample of 69 active galaxies is also considered. As many values as possible were collected for the soft and hard X-ray luminosities (HX), the luminosities at four other wavelengths, and the IR spectral index alpha. It is found that HX is the key parameter. There is direct evidence that the covering factor is a function of HX. Various IR correlations further suggest that the fraction of the luminosity radiated by dust grains is a smooth function of HX.