The Unification Model for active galactic nuclei posits that Seyfert 2s are intrinsically like Seyfert 1s, but that their broad-line regions (BLRs) are hidden from our view. A Seyfert 2 nucleus that truly lacked a BLR, instead of simply having it hidden, would be a so-called “true” Seyfert 2. No object has as yet been conclusively proven to be one. We present a detailed analysis of four of the ...

The unified model of Seyfert galaxies suggests that there are hidden broad-line regions (HBLRs) in Seyfert 2 galaxies (S2s). However, there is increasing evidence for the appearance of a subclass of S2s lacking of HBLR (non-HBLR S2s). An interesting issue arises as to relations of non-HBLR S2s with other types of Seyfert galaxies and whether or not they can be included in the unified model. We ...

In this third of a series of papers concerning active galaxies in the FIRST and Sloan Digital Sky Surveys, we analyze the spectroscopic and radio properties of a sample of narrow-line Active Galactic Nuclei (AGN), broad-line Seyfert I galaxies, and Quasars in the local universe in order to investigate the dependence of their activity on the mass, spin and accretion rates of the supermassive bla...

We have correlated a sample of 99 Seyfert 1 & 98 Seyfert 2 (Rafanelli et al., 1995) interacting galaxies with the survey and pointed ROSAT data and have detected 91 Seyferts 1 & 47 Seyfert 2s in the X-ray band. We have performed spectral and timing analysis of the X-ray detected sources, and we have examined the relation of the X-ray luminosity L X with the interaction strength Q.

In this review, rather than present and discuss in detail the first results obtained by BeppoSAX (see Boella et al. 1997 for an overall description of the mission) on Seyfert galaxies (these results are presented in detail elsewhere in this volume, see in particular the contributions by Perola, Comastri and Salvati), I will discuss current ideas on the X–ray emission of both type 1 and 2 object...

We have compared the X-ray–to–optical flux ratios (FX/Fopt) of absorbed active galactic nuclei (AGNs) in the Chandra Deep Field North (CDF-N) with those of nearby, optically classified Seyfert 2 galaxies. The comparison provides an opportunity to explore the extent to which the local population of absorbed AGNs can account for the properties of the distant, spectroscopically ambiguous sources t...

Before the launch of the Fermi satellite only two classes of AGNs were known to produce relativistic jets and thus emit up to the γ-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first four years of observations by the Large Area Telescope on board Fermi confirmed that these two are the most numerous classes of identified sources in the extragalactic...