The four known molecular absorption line systems at redshifts z=0.25–0.89 are discussed. Two of the systems originate in the galaxy hosting the ‘background’ AGN, while in two cases the absorption occurs in truely intervening galaxies. Indirect evidence for the existence of very small scale structure in the molecular ISM is presented. A new absorption line at z=0.89 towards PKS1830–211 opens up ...

The model I recently proposed for the structure of quasars unifies all the emission, absorption and reflection phenomenology of quasars and AGN, and so is heavily overconstrained and readily tested. Here I concentrate on how the model has performed against tests since publication with many of the tests being reported at this meeting. I then begin to explore how these and future tests can discri...

Dust plays an essential role in the unification theory of active galactic nuclei (AGNs). This review summarizes our current understanding of the extinction and infrared emission properties of the circumnuclear dust in AGNs as well as the inferred dust composition and size distribution.

Using the Green function method, binding effects on produced η-mesons in the two-stage reaction γ + A → N + η + (A − 1) → N + (πN) + (A − 2) are studied. The energy spectrum of the correlated πN pairs which arise from decays of η’s inside the nucleus is strongly affected by an attractive η-nucleus optical potential. Its resonant behavior gives a clear signal of formating intermediate η-mesic nu...

I review here some of the main observational features in microquasars and AGNs as sources of high-energy γ-rays as well as some of the current models that try to explain the emission in the γ-ray domain.

In this review I present observational results of active galactic nuclei that my colleagues and I have recently obtained. I discuss their significance in terms of unification schemes and evolutionary scenarios.

The main characteristics of the average spectrum of radio quiet AGN in the UV and X-ray range are reviewed, and the emission mechanisms are discussed in the framework of accretion disk models, in particular the “irradiated cold relativistic disk”. It is shown that some problems arise in confronting the predictions of the model to the observations. We propose an alternative model in terms of a h...

We discuss CO spectral line data of a volume-limited sample of 23 nearby (z < 0.03) low luminosity radio galaxies, selected from the B2 catalogue. We investigate whether the CO properties of our sample are correlated with the properties of the host galaxy, and in particular with the dust component. We find strong evidences for a physical link between the dust disks probed by HST in the galaxy c...

Some recent results on the physical and statistical properties of nearby and distant AGN are presented. I first discuss the properties of “elusive” AGNs, i.e. obscured AGNs which do not show a Seyfert-like spectrum in the optical. Then I present preliminary results from a detailed study of the contribution of obscured AGNs and of their host galaxies to the infrared cosmic background. Finally I ...