A Walk through AGN Country—For the Somewhat Initiated

Key issues in AGN and galaxy formation are discussed. Very successful Unified Models explain much of the variety of AGN with orientation effects; the ingredients are shadowing by a dusty “torus” and relativistic beaming. A spinoff result is described which is important for the formation of massive e...

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Bibliographic Details
Published in:Galaxies 2023-10, Vol.11 (5), p.102
Main Author: Antonucci, Robert R. J.
Format: Article
Language:English
Subjects:
Accretion disks
Active galactic nuclei
active galaxies
Astronomical models
astrophysics
astrophysics of galaxies
Critical thinking
Deposition
Dust
Dust emission
Elliptical galaxies
Emission
Emissions
Galactic evolution
Quasars
Radio galaxies
Star & galaxy formation
Stars & galaxies
Toruses
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Summary:Key issues in AGN and galaxy formation are discussed. Very successful Unified Models explain much of the variety of AGN with orientation effects; the ingredients are shadowing by a dusty “torus” and relativistic beaming. A spinoff result is described which is important for the formation of massive elliptical galaxies, the most spectacular and unequivocal AGN feedback phenomenon known. This is the so-called “alignment effect” in powerful radio galaxies at z∼>1. One of them is a BAL radio galaxy! Next, I explain a very robust derivation of the reddening law for nuclear dust, which reveals a dearth of small grains on parsec scales. Then, the quasistatic thin accretion disk model, thought by many to explain the energetically dominant optical/UV continuum, is thoroughly debunked. Much of this was known when the model was proposed 35 years ago. A new argument is provided that trivially falsifies a huge superset of such models. I then show that it is possible to see the central engine spectrum with the atomic and dust emission surgically removed! Few have noticed this breakthrough work. Finally, the far IR dust emission in Cygnus A is 10% polarized; to date, high nuclear dust polarization has been seen in all radio loud objects and no radio quiet ones.
ISSN:2075-4434
2075-4434
DOI:10.3390/galaxies11050102