Mergers and binary systems of SMBH in the contexts of nuclear activity and galaxy evolution

The dynamic evolution of binary systems of supermassive black holes (SMBH) may be a key factor affecting a large fraction of the observed properties of active galactic nuclei (AGN) and galaxy evolution. Different classes of AGN can be related in general to four evolutionary stages in a binary SMBH: 1) early merger stage; 2) wide pair stage; 3) close pair stage; and 4) pre-coalescence stage. This scheme can explain a variety of properties of AGN: radio and optical luminosity differences between different classes of AGN, long-term and short-term variability, quasi-periodic nuclear flares, recurrent formation of relativistic outflows in AGN and their apparent morphology and kinematics.Comment: 2 pages, no figures; to be published in Proceedings of the Conference "Growing Black Holes", Garching, Germany June 21-25, 2004, edited by A.Merloni, S.Nayakshin, R.Sunyaev (Springer-Verlag series of ESO Astrophysic

A Multi-Frequency Study of 3C309.1

Here we summarize our results from a detailed multi-frequency study of the QSO 3C309.1 based on the Very Long Baseline Array (VLBA) observations made in mid 1998. From our images, we find a curved jet extending up to 100 milliarcseconds (mas) to the east at low frequencies with two main components, A and B. A preliminary astrometric analysis (Ros and Lobanov 2001) provides a determination of the core position at different frequencies by phase-referencing to a nearby radio source, QSO S5 1448+76. The changes of the core position with frequency suggest high opacity close to the core caused by synchrotron self-absorption. Due to the large astrometric uncertainties we cannot draw any conclusions about the values of the opacity gradients at high frequencies. We believe that a detailed analysis of the frequency depedence of the core position will reveal the profile of the matter distribution in the broad line region, as was initially suggested by Lobanov (1998).Comment: To be published in the volume "Highlights of Spanish Astrophysics (III), Proceedings of the 5th Scientific Meeting of the Spanish Astronomical Society" of the Astrophysics and Space Science Library (Kluwer), J. Gallego, J. Zamorano, N. Cardiel (eds.), 1 page, 1 figure, no abstract, needs kapproc.st