Q0906+6930: The Highest-Redshift Blazar
  We report the discovery of a radio-loud flat-spectrum QSO at z=5.47 with properties similar to those of the EGRET gamma-ray blazars. This source is the brightest radio QSO at z>5, with a pc-scale radio jet and a black hole mass estimate >10^{10}M_\odot. It appears to be the most distant blazar discovered to date. High energy observations of this source can provide powerful probes of the background radiation in the early universe. 
Roger W. Romani, David Sowards-Emmerd, Lincoln Greenhill and Peter   Michelson