A quasar is an AGN -- active galactic nuclei. It is a feeding super massive black hole. Material in the accretion disc moves at different speeds and can reach 80% the speed of light determined by its distance from the center of mass. Tremendous magnetic forces and friction are created heating the disc up to millions of degrees. Some of this material escapes through jets at the poles. It is these jets and the friction in the accretion disc that produce light that outshines entire galaxies.

Pretty sure it is these jets that create the gamma ray bursters and if one is pointed at your world, even billions of light years away, you are cooked. Im also pretty sure that SagA*, the SMB at the center of the Milky Way, has had an active phase like this in its past.