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Bardeen Petterson effect and the disk structure of the seyfert galaxy ngc 1068

Grant number: 07/02760-1
Support type:Regular Research Grants - Publications - Scientific article
Duration: June 01, 2007 - October 31, 2007
Field of knowledge:Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
Principal Investigator:Anderson Caproni
Grantee:Anderson Caproni
Home Institution: Centro de Ciências Exatas e Tecnológicas. Universidade Cruzeiro do Sul (UNICSUL). São Paulo , SP, Brazil

Abstract

VLBA high spatial resolution observations of the disk structure of the active galactic nucleus (AGN) NGC 1068 have recently revealed that the kinematics and geometry of this AGN is well characterized by an outer disk of H2O maser emission having a compact milliarcsecond-(parsec) scale structure, which is encircling a thin rotating inner disk surrounding a about 10to7 Mo compact mass, likely a black hole. A curious feature in this source is the occurrence of a misalignment between the inner and outer parts of the disk, with the galaxys radio jet being orthogonal to the inner disk. We interpret this peculiar configuration as due to the Bardeen-Petterson effect, a general relativistic effect that warps an initially inclined (to the black hole equator) viscous disk and drives the angular momentum vector of its inner part into alignment with the rotating black hole spin. We estimate the timescale for both angular momentato get aligned as a function of the spin parameter of the Kerr black hole. We also reproduce the shape of the parsec andkiloparsec-scale jets, assuming a model in which the jet is precessing with a period and aperture angle that decrease exponentially with time, as expected from the Bardeen-Petterson effect. (AU)