The three types of "Exotic Galaxies" we will be focusing on in this class are Radio, Seyfert and Quasars.  These galaxies are also known as AGN(Active Galactic Nuclei) because of their extremely active cores.  At the core of these galaxies are supermassive black holes, with a typical mass of 10⁸ solar masses, which supply the gravitational energy source required to fuel the immense activity of the core.
 
Radio Galaxies

Active galactic nuclei that produces radio lobes, which are the dominant feature of the galaxy, that span a distance thousands of times greater than the galaxy itself.  These radio lobes,typically two) are on opposite ends of the galaxy eminating from the jet stream of particles flowing out of the accretion disk around the black hole.  The jet stream is traveling nearly the speed of light creating the condition necessary for producing synchrotron radiation which is responsible for the intense radio emissions.

Seyfert Galaxies

Active galactic nuclei at the center of a spiral galaxy with an extremely luminous core and jets similar to that of a radio galaxy.

Quasars(Quasi-stellar objects)

The most luminous object in the Universe given its compact size.  They are also amongst the most distant objects in the Universe, which leads to the conclusion that their existence was more prominent in the Early Universe than it is today. An upper limit on the scale of these objects can be determined by measuring the time between variations the object's brightness based on the condition that an object cannot be larger than the distance it takes light to travel across its diameter.  The typical variation in brightness for a Quasar is a week, which implies that the object cannot be larger than a light week across because if it were any bigger, the variation in light should have taken more time to communicate with another part of the Quasar.

Gravitational Lenses

Much like the Sun is a able to bend the light from a star that is viewed near the solar surface, galaxies can also act as "lens" to bend the light that reach us from distant objects.  A large galaxy is able to warp or curve the space around its vicinity to create a curved path for light to travel.  Very distant objects that are directly behind the large galaxy when viewed from the Earth are most likely to be lensed because the angle of light bending is less for objects at a greater distance.  Therefore, Quasars behind large galaxies are the most common objects astronomers observe this effect.  Depending on the alignment of the lens, multiple lensed objects may appear and sometimes even rings of light.