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AGN: Quasars

AGN: Quasars. By: Jay Hooper. Outline. Types of AGN Components of AGN Differences between AGN General Overview. Types of AGN. AGN – Active Galactic Nuclei Quasars QUA si- S tell A r R adio source Blazars Seyfert Type 1 Type 2

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AGN: Quasars

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  1. AGN: Quasars By: Jay Hooper

  2. Outline • Types of AGN • Components of AGN • Differences between AGN • General Overview

  3. 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

  4. 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 1000’s 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

  5. 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.

  6. 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

  7. 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!

  8. 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.

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

  10. General Overview Distances are computed by their apparent red-shifts, with the farthest recorded z=5.5 corresponding to about 14 billion ly • This is roughly a time period when the universe was 1/10 its present age

  11. 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.

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

  13. 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

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