AGN:%20Quasars

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AGN Quasars

• By
• Jay Hooper

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Outline

• Types of AGN
• Components of AGN
• Differences between AGN
• General Overview

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Types of AGN

• AGN Active Galactic Nuclei
• Quasars
• QUAsi-StellAr Radio source
• Blazars
• Seyfert
• Type 1
• Type 2
• Are thought to be the same
  objects viewed in different
  orientations

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Components of AGN

• Supermassive black hole 108 - 109 solar masses
• Broad-line region dense clouds of ionized and
  heated gas, by ultraviolet and x-ray photons,
  rotating a velocities of 1000s of km/s
• Accretion disk Matter ripped apart by tidal
  forces spiraling inward. Approx. consumption of
  one solar mass of matter per year is required to
  power a quasar

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• Torus doughnut-shaped region of molecular gas
  and dust which is heated by the central source,
  emitting infrared light, but which obscures the
  central black hole, disk and broad-line region
  from observers viewing the quasar edge-on.
• Narrow-line region cone-shaped region of
  illuminated clouds
• Jets Oppositely-directed streams of plasma
  thought to be discharged due to the winding up of
  magnetic fields in an accretion disk that forms
  around a massive black hole converting
  gravitational and rotational energy into bulk
  outflows at high speeds perpendicular to the
  disk.

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Differences between AGN

• Quasars
• A clear view of the central engine source.
• High-energy gamma-rays. Usually 100 MeV or more,
  even up to the GeV range
• Produces more light and energy comparable to
  10-1000 galaxies,in a region as big as our solar
  system

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• Blazars
• believed to be a quasar which has one of its
  relativistic jets pointed directly toward the
  Earth. Therefore not as luminous as quasars.
• Same energy levels as a quasar, but have been
  recorded in the TeV range!

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• Seyfert two types divided by their spectral
  emission features. Emitters of low energy
  gamma-rays on the order of 100KeV. Produce on the
  order of .1 to 10 times the light and energy of
  our galaxy
• Type 1
• Has a hydrogen emission feature with very large
  widths. Due to tilted jet angle.

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• Type 2
• Has a hydrogen emission feature with much
  narrower widths. AGN viewed edge on.

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General Overview

• Distances are computed by their apparent
  red-shifts, with the farthest recorded z5.5
  corresponding to about 14 billion ly
• This is roughly a time period when the universe
  was 1/10 its present age

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• Give off radiation in the form of all wavelengths
• Only about 10 are strong radio sources. The rest
  are radio quiet.
• Size of source determined by time in variation of
  intensity
• if an object varies significantly in brightness
  over a period of a week, it cannot be larger than
  a light-week in size.

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• Superluminal motion up to 10c.
• bursts of synchrotron plasma shot out almost, but
  not quite, toward us at near speeds of c.

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References

• http//skyandtelescope.com/news/article_964_1.asp
• http//imagine.gsfc.nasa.gov/docs/science/know_l1/
  active_galaxies.html
• http//www.cv.nrao.edu/abridle/dragnparts.htm
• http//cassfos02.ucsd.edu/public/tutorial/AGN.html