Quasars, extremely violent and luminous galaxies, are thought to form when a massive black hole in
a galaxy core consumes large amounts of material (10 to1000 solar masses per year). The continuous part of the spectrum is
synchrotron radiation produced by high-speed electrons in a strong magnetic field (i.e., not "thermal" radiation
as for stars). The broad emission lines arise from a thin gas that is strongly heated as it falls toward the black hole. Quasars are so
far from us that the entire spectrum is greatly red-shifted. Features normally be seen in the UV are shifted into the visible region, a fact
which confused their identification when first discovered.
Spectrum of Quasar