Direct imaging of Seyfert galaxies in emission lines and high resolution radio mapping often show their narrow line regions and linear (double or jet-like) radio sources to be aligned on the hundreds of parsecs scale. This relationship is unlikely to reflect ionization of the thermal gas by the expanding radio components or by their relativistic electrons. The most likely explanation, which is also favored by optical polarization measurements, is that ionizing photons escape preferentially along the rotation axis of the same inner (≲ pc scale) disk as collimates the radio jet. Such a bipolar form may be the most common morphology of the narrow line region. Differences of radio properties between Seyfert type 1's and 2's may be at least partially related to aspect effects. The north east radio lobe of NGC 1068 shows a limb-brightened, conical structure with the magnetic field running parallel to the edge of the cone. This source is modelled in terms of a radiative bow shock wave being driven into the interstellar medium of the galaxy by the radio ejecta. If the pre-shock density is as high as 400 cm−3, as suggested by CO measurements, the shock velocity is found to be ≃ 75 km s−1 and the jet velocity ≃ 4000 km s−1, the latter being close to the emission line widths. The narrow line region in this galaxy is morphologically and kinematically associated with the jet.

Jets, and more general kinds of directed flow, are increasingly seen as important aspects of the activity of galactic nuclei. Their frequent presence, on scales from parsecs to megaparsecs, in radio galaxies implicates jets in the production of radio lobes, and instances have been found of jets apparently “frustrated” and disrupted in gas-rich galactic disks. Jet-like emission is occasionally found on small scales around Seyfert nuclei, with some observations suggesting links to nuclei at yet lower levels of (radiative) activity.

The fraction of Seyfert galaxies containing linear radio sources is quite substantial and may be more than 50% (Ulvestad and Wilson 1984). About 20 of the well resolved Seyfert galaxies show double or triple structure on the arcsec scale. In this respect these objects are very reminiscent of the classical radio galaxies, but they are typically smaller than these by several orders of magnitude, both with regard to power ∼ 1039–1041 erg/s and linear extent kpc (Wilson, this volume). They are basically confined in the wider nuclear environment. The central small scale () radio sources in Seyfert galaxies are very weak, mJy at 6 cm wavelength, and have therefore hardly been observed with VLBI (see, e.g. Preuss 1984).

Active Galactic Nuclei and quasars are characterized at radio wavelengths by a high surface brightness, a flat spectrum, variations in intensity on time scales of a few days to a few years, and by large internal motions which probably reflect Doppler beaming from a synchrotron source which is moving with relativistic velocity away from the central energy source and toward the observer. The observations do not support interpretations based on simple ballistic models where the observed motion and core strength depends only on the geometric orientation of a relativistic beam, but appear to require significant dispersion in intrinsic properties as well as complex dynamics.

A complete sample of 13 flat spectrum radio sources is investigated over a wide range of frequencies and spatial resolutions. SSC-calculations lead to the prediction of bulk relativistic motion in all sources. So far 6 out of 7 sources observed with sufficient dynamic range by means of VLBI show evidence for apparent superluminal motion.

The quasar 3C454.3 has a “core-jet” structure, on scales ranging from 50 kpc to 100 pc. VLBI observations made during the last 5 years show that the structural variations within the core region are very different from those seen in the “classical” superluminal sources. After a period of very rapid expansion (apparent velocity va ≥ 30c), the brightest features in the core region showed little relative motion (va < 3c), although at least one weak, more distant component appears to have separated from the others with va ~ 19c. The most likely interpretation of the stationary features involves stationary shocks excited by a relativistic flow.

The structure of the quasar 3C 345 has been studied at 18 and 49 cm wavelengths by VLBI method. The structure has a nucleus and a jet, which changes direction with distance from the nucleus. The continuum emission of the nucleus and the jet regions correspond to a source with a large optical depth, the cut frequence goes down with increasing distance from nucleus.

The analysis of the optical variability of 3C 345 along with the apparent superluminal motions in the milliarcsecond jet suggests a connection between these forms of activity.

The optical variability of the quasar 3C 345 is presented including our 18-year photographic observations and all published data by 1984. The extrapolated moments of ejection of milliarcsecond jet components from nucleus coincide with the initial phases of the “slow” optical flares. The prediction about the arising of a new radiocomponent based on such treatment was confirmed later on. Some evidence of similar connection for the N-galaxy 3C 120 is given.

It has been discovered in recent years that some extragalactic objects have apparent superluminal motions in their milliarcsecond jets. It is obvious that independently of the concrete physical interpretation of this phenomenon it represents an evidence of nuclear activity. Consequently this phenomenon may be connected with the variability of the optical continuum source. The object most suitable for studying such a relationship is the quasar 3C 345. This superluminal object is the best-observed both by VLBI technique and by several optical monitoring programs which revealed very high degree of its optical variability ( in the B-band).

“Ballistic” models are now put in doubt on the strength of the observed properties of “superluminal” components, and preference is given to “screen” models. It is suggested that active nuclei are supermassive systems, such as SS-433, with two precessing relativistic plasma jets, which flow from opposite directions into the same precession cone. In this case “superluminal” components can manifest themselves as displacements of the interaction between these jets and inhomogeneities in the circum-nuclear medium (clouds). Thus, due to isotropic production of relativistic particles in the interaction area and/or magnetic field distortions, bursts of emission may be observed not only along flows, as would be the case for BL Lacertae objects, but also at appreciable angular distances from the jets. Moreover, one may understand the observed one-sidedness of VLBI-jets on parsec scales and the symmetrical VLA-structures on kiloparsec scales as a result of random cloud hits by the precessing flows. We suggest that the observed repetition of active cycles of different objects may be caused by several cloud hits by the precessing flows of a complex multibeam structure once every 50–100 years.

An explanation of observed phenomena in AGN is proposed on the basis of the hypothesis about the ejection of compact formations from a “central object” which emits relativistic electrons. In particular, the possible causes of the discrete structure of jets, appearance of “superluminal” velocities and superfast variations of radiation from nuclei in X-ray and optical regions are considered.

This paper reports the results of a programme of multifrequency observations of a sample of Blazars concentrating particularly on the millimetre through infrared region. Our observations have demonstrated the need for a new model to explain the spectral behaviour of a major flare in 3C273. This also provides a good description of the variability exhibited by Blazars. We have also shown that the radio through mid-IR synchrotron spectrum of 3C273 is a separate component from the optical/IR.

At the Astronomical Observatory of Leningrad State University two observational programs of investigation of lacertids - photographic photometry and photoelectric polarimetry - are in progress for many years. Some results for OJ 287 and BL Lac are of interest: (1) existence of preferable direction of polarization, (2) correlations between the brightness and polarization parameters, and (3) high degree of polarization (~50%) of individual sources responsible for variability.

This paper presents a progress report on a major extension of the Einstein Observatory Medium Sensitivity Survey (MSS). The results obtained from the survey are briefly summarized, particular emphasis is given to the Active Galactic Nuclei (AGN) and BL Lac objects of the MSS. The basic properties of these classes of extragalactic objects are presented and discussed.

For six published high resolution QSO spectra a correlation analysis of unidentified absorption lines is performed. The two-point correlation functions typically show some quasiperiodic structure. The results allow for the interpretation that absorbing clouds lie in sheetlike structures as predicted by the pancake theory.

The problem of the origin of celestial bodies - stars, galaxies and their clusters - is discussed proceeding from the concept of superheavy strongly interacting elementary particles termed superhadrons.

Starting from generalized Regge law the universal relationship between mass and intrinsic angular momentum of cosmic objects has been established. Expressions are obtained for parameters of stars and Universe via fundamental constants. The prediction of the global rotation of the Universe is discussed and the problems of cosmic magnetic fields and energy problem in active galaxies are considered.

In this review, I will deal principally with the optical morphology of these three types of object, and attempt to outline similarities and essential differences. By this, I mean to include studies of the types of host galaxy, nuclear and galaxy luminosities and colours, interactions with other galaxies, and the general associations with other galaxies. Where relevant, I will refer to morphology at other wavelengths (generally radio), spectroscopy, and UV or X-ray properties. However, I expect these areas to be covered much more fully by other reviews and papers in this volume.

Images of 16 PQ quasars with z < 0.2 were obtained using the CCD camera at the 2.3 m telescope of Steward Observatory. It is found that about 35% of the quasars have one or more close companions (at r ≤ 100 kpc). The data also suggest that the companion galaxies are almost always redder than the nebulous components of the quasars. This is consistent with previous findings by other investigators that companion galaxies of quasars do not have high level of activity.

Results from a spectroscopic survey of groups around Seyfert galaxies and of an appropriate control sample are reported. The groups are ≲1 Mpc across. A nuclear spectroscopic “activity class” is assigned to each group member. The active types show a peaked distribution around the Seyfert galaxy and are confined to a critical radius ~300 kpc while the nonactive members are uniformly distributed over the whole extent of the groups. These results are briefly discussed.

Multiple nucleus Markarian Galaxies may owe their origin to merging processes among galaxies. They may therefore be key objects for our understanding of galaxy evolution and the origin of nuclear activity. From morphological and multi-spectral data we show that these objects are in an unusually high state of dynamical and nuclear activity (starbursts, Seyfert activity) as would be expected from advanced stages of galaxy mergers.

The possibility that quasars are activated by interactions between galaxies has received considerable attention following the discovery of extended emission surrounding many low and moderate redshift quasars, and the distored morphological appearances of some of these extensions. We have obtained high resolution narrow-band optical images of the field of the low-redshift quasar MR2251-178 which reveal, in addition to nebulosity closely associated with the quasar, diffuse line-emitting regions separated by up to 100 kpc from the nucleus but kinematically associated with it. We attribute these regions to density perturbations of the gaseous envelope or disc now known to rotate about this quasar, caused by a tidal interaction between the quasar and a nearby active galaxy in the same cluster. Limits of between 2–4 × 108 years can be placed on the time elapsed since this interaction.