We propose an alternative model for the powering of active galactic nuclei (AGN), based on the assumption that all AGN have experienced mergers. In our model (Kaburaki and Taniguchi 1996; Taniguchi and Kaburaki 1996), a close pair of super-massive black holes (the black hole grazer) orbit one another in a plane roughly perpendicular to the galactic center magnetic field. The orbital motion induces surface charges on the black holes which produce an electric field. This field is strong enough to cause pair creation so that the Roche lobe of the binary system is filled with pair plasmas. Rigid-body rotation of the Roche-lobe magnetosphere drives electrodynamically a powerful synchrotron jet emanating from the center of mass of the binary. Furthermore, a pair of equatorial jets flow from the outer Lagrangian points of the binary system. Although these jets are not so collimated, they interact with the accreting gas ring formed around the orbital plane of the binary, causing broad line regions or H2O maser emission regions (Taniguchi et al. 1996). In addition to the primary jet, two secondary jets are also driven by local accretion disks around the two black holes. The interaction among the primary and the secondary jets may explain detailed jet morphology observed by VLBI facilities.

Between 1984 and 1990 we conducted a survey at Palomar Observatory (Filippenko and Sargent 1985) to quantify the luminosity function of nearby active galactic nuclei (AGNs). The Hale 5 m telescope was used to obtain high-quality, moderate-resolution optical spectra of a nearly statistically complete sample of about 500 bright (BT ≤ 12.5 mag), northern (δ > 0°) galaxies (see Ho et al. 1995 for details). The survey has now been completed, and the first scientific results are reported in a series of papers by Ho et al. (1997a, b, c).

We address the following questions. Is it possible that the heavy elements observed in high redshift quasars are formed in the vicinity of the black hole? And in this case do quasars produce, mainly during their growing phase, the first heavy elements which enrich the intergalactic medium and the protogalaxies?

To study broad line region (BLR) size and kinematics spectral monitoring of NGC 3516, NGC 4151, NGC 5548, NGC 7469 and 3C390.3 has been performed with the 6 m telescope of the Special Astrophysical Observatory (N. Arkhyz- North Caucasus) in 1986–1996. The spectra are obtained in the Nasmyth focus using the TV scanner with a resolution of 3–4Å and S/N= 10–25 within 4000–5200ÅÅ (1986–94, 500 spectra), and in the prime focus with the spectrograph UAGS (a long-slit mode) + CCD (resolution 5–10Å) or multi-pupil field spectrograph (MPFS) + CCD (resolution 4Å) within 4000–7000ÅÅ and S/N=50–100 (1995–96, 270 spectra).

One of the fundamental components of any theory of Active Galactic Nuclei (AGNs) is an accretion disk surrounding a supermassive blackhole. While most theories predict the formation of such a disk, fewer say anything about the observational consequences of the disk. Those studies which have addressed the observational signatures of accretion disks have found that the Lyman edge at 912Å is a powerful diagnostic feature for the physical characteristics of the disk. One of the important consequences of such disks is a feature at the Lyman edge (912Å). Spectroscopic investigations have found scant evidence for Lyman edge features arising in an accretion disk (Koratkar, Kinney and Bohlin 1992). Proving the existence of radiating disks in even a few AGNs would be a major step in our understanding of the phenomenon.

The one of the possibilities concerning the cause of AGN jets is the super-Eddington luminocity around the Massive Black Hole. If the case of optically thick state is assumed, we can define the super-Eddington temperature in the optically thick case, from the following condition that where r∗ = 2c2r/GM. The creation of electron- positron pairs and the pahse change are expected to occur in the such temperature rage around 109K, where the radiation pressure is dominant in the lower temperature and the pair pressure be in the higher one.

It is widely believed that accretion onto a black hole is the origin of X- and γ-ray emission and jets emerging from AGNs. Since the X- and γ-rays are highly variable, the accretion is also expected to be variable. We investigate highly variable hydrodynamical accretion with numerical simulations.

We belive that Active Galactic Nucleis(AGNs) have one or a few black holes in the center and get the activity from the binding energy of the matter falling into the black hole or(and) the rotational energy of the black hole. Since the sources of their energy exist near the black hole, the energy have to be carried from the vincity of black hole to a distance by some ways. As one of the way, we study the propagation of the waves (ex. The case of the light waves, Hanni 1977, and of sound wave, Takahashi et al. 1990). We investigated the propagation of fast magnetoacoustic wave. We belive the collimation of jet are caused by magnetic field. Further more, we think that the waves can extract the rotational energy of the black hole. This process is the version of wave of Penrose process(Penrose 1968), and is called the super radiant scattering.

OJ 287 is a blazar type active galaxy. The historical light curve shows outbursts occurring at quasi-regular intervals. These can be modeled by a secondary black hole interacting with the accretion disk of the primary black hole. We present results of wavelet analysis of the recent light curve of OJ 287, including the outbursts in 1994 and 1995.

We present X-ray observations of LINERs with ASCA. We detected a hard point-like source of X-ray luminosity of 1040–1041 erg s−1 at the nucleus. Their hard X-ray continuum is well represented by power-law of photon index ~ 1.8. The X-ray to Hα luminosity ratio LX/LHα is quite similar to Seyfert galaxies and strongly support the presence of low luminosity AGNs.

The hypothesis -raised and discussed in - that the source of AGN fueling can be, at least in elliptical galaxies, stars belonging to a dense stellar environment formed by globular clusters frictionally decayed and tidally destroyed by the gravitational field of central black hole (b.h.), is strongly supported in. The quantity of star mass swallowed by the b.h. and its time rate seem at all compatible with those needed to justify the intensity and time characteristics of galactic nuclei activity (see also).

Many large ellipticals were believed to have large, flat core, of which the radius is typically a few percents of the effective radius (e.g., Lauer, 1985). However, HST observations (e.g., Lauer et al., 1995) have revealed that they are not flat cores at all. The “cores” observed by HST are actually very shallow central density cusps (ρ ~ r−0.5~–1). Such a shallow cusp poses a serious problem to almost any scenario of the formation of ellipticals. If these ellipticals do not have central black holes (MBHs), we are faced with very strange structure with the velocity dispersion decreasing inward. Neither dissipationless/dissipational collapse nor merging have been able to make such a density distribution.

Nuclear activities in galaxies, such as nuclear starbursts or AGNs, are supposed to be induced by gas fueling into nuclear regions of galaxies. Non-axisymmetric gravitational potential caused by a stellar bar is a convincing mechanism for triggering gas fueling (Phinney 1994). However, numerical simulations have shown that the bar can not force the gas to accrete toward the galactic center beyond the inner Lindblad resonance (ILR). As a mechanism to overcome the ILR barrier, the double barred structure (Friedli & Martinet 1993), or the self-gravity of gas (Wada & Habe 1992, 1995; Elmegreen 1994) are proposed.

We investigated the dynamical reaction of the central region of galaxies to a falling massive black hole by N-body simulations. As the initial galaxy model, we used an isothermal King model and placed a massive black hole at around the half-mass radius of the galaxy. We found that the central core of the galaxy is destroyed by the heating due to the black hole and a very weak density cusp (ρ ∝ r−α, with α ∼ 0.5) is formed around the center. This result is consistent with recent observations of large elliptical galaxies by Hubble Space Telescope (Lauer et al. 1995; Byun et al. 1996; Gebhardt et al. 1996; Faber et al. 1996; Kormendy et al. 1996). The radius of the weak cusp region is large for large black hole mass. The velocity of the stars become tangentially anisotropic in the inner region, while in the outer region the stars have radially anisotropic velocity dispersion. Our result naturally explains the mechanism of the formation of the weak cusp found in the previous simulations of galaxy merging, and implies that the weak cusp observed in large elliptical galaxies may be formed by the heating process by sinking black holes during merging events.

“Low-luminosity” active galactic nuclei (LLAGNs) typically have ≳ mag, as opposed to −18 to −30 mag for luminous Seyfert 1 nuclei and QSOs. The physical origin of the class of emission-line nuclei known as low-ionization nuclear emission-line regions (LINERs; Heckman 1980) remains controversial. Based on the close resemblance of some LINERs to Seyfert nuclei, LINERs can arguably be considered another manifestation of the AGN phenomenon. An alternative view is that stellar processes account for LINER energy. The energetics alone do not provide a useful discrimator between the two possible mechanisms.

It is proposed that the Fanaroff and Riley division between class I and class II radio sources may be due to phenomena occurring in the coronae of magnetized accretion disks around black holes.

This symposium has revealed considerable new progress on nuclei of galaxies over the last three years. In this talk, I will try to point out the advances since the last meeting on exactly the same subject held three years ago at Ringberg Castle in Germany (see “The Nuclei of Normal Galaxies: Lessons from the Galactic Center”, ed. R. Genzel & A. Harris, Kluwer).