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 QUAsi-StellAr Radio source Blazars Seyfert Type 1 Type 2 Are thought to be the same objects viewed in different orientations

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

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.

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

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!

Seyfert – two types divided by their spectral emission features 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.

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

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

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.

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

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