The oldest known one of these objects was formed during the universe's structure formation stage.  
Edwin Salpeter confirmed the discovery of the first of these objects to be identified.  Daily variation by at least one order of magnitude is demonstrated in the optically violent variable type of these objects. One of these appears as four distinct objects, called the (*) Einstein Cross. The oldest known one of these objects was formed during the universe's structure formation stage.  The first of these objects to be discovered was located in the constellation Virgo and was notable for its high redshift. These objects are powered by the gravitational accretion in supermassive black holes.  For 10 points, name these very bright and very distant radio sources.
Edwin Salpeter confirmed the discovery of the first of these objects to be identified.  
Quasars [or Quasi-Stellar Radio Sources; prompt on active galactic nuclei or AGN]