An axisymmetric, nonstationary model of the central engine in an active galactic nucleus. II - Accretion disk electrodynamics

1989 ◽  
Vol 347 ◽  
pp. 684 ◽  
Author(s):  
Seok Jae Park ◽  
Ethan T. Vishniac
Keyword(s):  
Accretion Disk ◽  
Active Galactic Nucleus ◽  
Nonstationary Model ◽  
Central Engine

Radio continuum of galaxies with H2O megamaser disks

2017 ◽  
Vol 13 (S336) ◽  
pp. 139-140
Author(s):  
F. Kamali ◽  
C. Henkel ◽  
A. Brunthaler ◽  
C. M. V. Impellizzeri ◽  
K. M. Menten ◽  
...  
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Active Galactic Nucleus ◽  
Position Angle ◽  
Radio Continuum ◽  
Supermassive Black Hole ◽  
5 Ghz

AbstractIn our attempt to investigate the basic active galactic nucleus (AGN) paradigm requiring a centrally located supermassive black hole (SMBH), a close to Keplerian accretion disk and a jet perpendicular to its plane, we have searched for radio continuum in galaxies with H2O megamasers in their disks. We observed 18 such galaxies with the Very Large Baseline Array in C band (5 GHz, ~2 mas resolution) and we detected 5 galaxies at 8 σ or higher levels. For those sources for which the maser data is available, the positions of masers and those of the 5 GHz radio continuum sources coincide within the uncertainties, and the radio continuum is perpendicular to the maser disk’s orientation within the position angle uncertainties.

scholarly journals PROBING THE ACCRETION DISK AND CENTRAL ENGINE STRUCTURE OF NGC 4258 WITHSUZAKUANDXMM-NEWTONOBSERVATIONS

2009 ◽  
Vol 691 (2) ◽  
pp. 1159-1167 ◽  
Author(s):  
Christopher S. Reynolds ◽  
Michael A. Nowak ◽  
Sera Markoff ◽  
Jack Tueller ◽  
Joern Wilms ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Central Engine

scholarly journals Particle Acceleration in Extragalactic Jets and Implications for the High-Energy Emission from Blazars

1994 ◽  
Vol 159 ◽  
pp. 29-32
Author(s):  
R. Schlickeiser ◽  
C. D. Dermer
Keyword(s):  
Compton Scattering ◽  
Accretion Disk ◽  
High Energy ◽  
Relativistic Electrons ◽  
Spectral Evolution ◽  
Inverse Compton Scattering ◽  
Central Engine ◽  
Inverse Compton ◽  
Γ Rays ◽  
Γ Ray

We demonstrate that the prevalence of superluminal sources in the sample of γ-ray blazars and the peak of their luminosity spectra at γ-ray energies can be readily explained if the γ-rays result from the inverse Compton scattering of the accretion disk radiation by relativistic electrons in outflowing plasam jets. Compton scattering of external radiation by nonthermal particles in blazar jets is dominated by accretion disk photons rather than scattered radiation to distances of ∼ 0.01–0.1 pc from the central engine for standard parameters. The size of the γ-ray photosphere and the spectral evolution of the relativistic electron spectra constrain the location of the acceleration and emission sites in these objects.

scholarly journals Relativistic Neutrons in Active Galactic Nuclei

1989 ◽  
Vol 134 ◽  
pp. 215-216
Author(s):  
Marek Sikora ◽  
Bronisław Rudak ◽  
Mitchell Begelman
Keyword(s):  
Active Galactic Nuclei ◽  
Electron Energy ◽  
Active Galactic Nucleus ◽  
Galactic Nuclei ◽  
Substantial Fraction ◽  
Proton Proton ◽  
Proton Collisions ◽  
Central Engine ◽  
Proton Proton Collisions

A substantial fraction of the radiation from an active galactic nucleus (AGN) is apparently nonthermal in origin, and is probably produced by ultrarelativistic electrons. How much energy goes into relativistic protons is uncertain, but it is likely to be comparable to the electron energy or larger. Indeed, several authors (Sikora et al. 1987; Kazanas and Ellison 1986; Zdziarski 1986) have shown that proton-photon and proton-proton collisions can be efficient sources of relativistic pairs in the central engine of an AGN. Thus it is not necessary for electrons to be accelerated directly in AGNs, provided that protons are accelerated with high enough efficiency.

scholarly journals Status of Agn Unification Models

1995 ◽  
Vol 10 ◽  
pp. 551-557 ◽  
Author(s):  
P.D. Barthel
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Near Infrared ◽  
Spherical Body ◽  
Rapid Variability ◽  
Radio Jets ◽  
Central Engine ◽  
Relativistic Beaming ◽  
Superluminal Motion ◽  
Dust Distribution

Unification of Active Galactic Nuclei is obviously multidimensional. Dimensions include the mass and angular momentum of the postulated central black hole, the mass accretion rate through the accretion disk surrounding the black hole, and the orientation of this central engine plus associated dust with respect to the line of sight (e.g., Blandford 1990). As for orientation related unification, considerable progress has been made over the past decade. This review will deal with this geometric unification.Mechanisms in AGN include:1.relativistic beaming in radio jets (as manifested by rapid variability from radio to ϒ-rays, superluminal motion, synchrotron self-Compton2.emission by an optically thick, non-spherical body (e.g., hot accretion disk);3.external collimation and shadowing by an anisotropic dust distribution (as manifested by the existence of hidden continua, observed through polarization or photon deficit in extended emission line regions, and hidden broad line regions, observed through polarization or in the less opaque near infrared part of the spectrum).These anisotropic mechanisms introduce selection biases, they lead to incorrect inferred luminosities and make us overestimate the AGN diversity. They furthermore imply unification at some level.

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