Quasar
From Slackerpedia Galactica
Vicious little dots, one of the many kinds of active galactic nuclei (AGN) observed in the universe. Quasars appear to be particularly bright and luminous due to the tremendous energies wrapped up in their jets.
As with other active galactic nuclei, quasars are believed to be galaxies with supermassive black holes at the center. When these black holes pull matter into themselves, some of it is shot out into space (at nearly the speed of light) in a jet. These relativistic particles can produce additional electromagnetic radiation by interacting with magnetic fields or even by bouncing off of other particles and photons. If the jet is pointed nearly along our line of sight, we see the AGN as a quasar. If we can see it vary in brightness in many different wavelengths, especially optical, it may be referred to as a blazar.
Because they are so bright, the light drowns out the host galaxy making quasars look like regular stars. In the early 1960's, astronomers figured out that through their red shifts that quasars exist at enormous distances so couldn't be the same as regular stars. They were renamed QSOs, for quasi-stellar object. But no one know exactly what they were. Eventually, some of them, most notably the famous object 3C 273, were found to be variable on timescales of weeks and months, meaning it could only be light-weeks or light-months in size. The discovery that something that small could be visible at such enormous distances not only changed our perception of how big the universe was, but also how energetic it could be. Only one thing could do that: a black hole. Finally, modern technology allowed us to image a few quasars and finally see the host galaxies around them.
