PowerPoint

1. 23 May 2008
Elitzur, M.
Dept. of Physics & Astronomy
Univ. of Kentucky
1Adam Szewciw

2. SMBH ~10^6 –
10^9 solar
masses
Accretion Disk
Collimated Jets
Torus
Adam Szewciw
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3. “Donut”
Composition
• Gas clouds
• Dust particles
 ISM composition
(Si, Mg, Al, C, O)
 Clumpy
 Optically thick
Location
• Sublimation radius
(~10 – 30 pc)
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4. Radio-loud – large (kpc) jets
Radio-quiet (80-90% of AGNs)
• Type I Seyfert
 X-ray – visible
 Infrared bump
• Type II Seyfert
 Only infrared
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5. Are there really two
types?
“Hot disk”
emissions in
UV/visible – power
law
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6. Basic idea: Type I
and Type II AGNs
are the same
• Classification
depends on viewing
angle
“Central engine”
• SMBH & Accretion
disk
• Emit x-rays, visible
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7. Central engine emits radiation
Torus absorbs x-rays, visible
• Reemits as infrared
Nucleus obscured if rays encounter clouds
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8. Simple model:
“smooth density”
Obscuration by
torus
Relevant
parameters:
• Viewing angle
• Angular width
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9. Insert clumpiness
• Probability
dependent viewing
• Relevant
parameters:
 Number density
 Angular width
• Angular profile:
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10.  Moshe, E. The Toroidal Obscuration of Active Galactic
Nuclei. 23 May 2008, Elsevier.
 Krawczynski, H. & Treister, E. Active Galactic Nuclei –
the Physics of Individual Sources and the Cosmic History
of Formation and Evolution. 17 Jan. 2013.
 Pierre Auger Observatory. www.auger.org
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