If X-rays observed from any extragalactic radio jets are due to inverse
Compton scattering on the cosmic microwave background (CMB) radiation, then
such a source will be detectable with the same surface brightness anywhere in
the more distant universe. Chandra observations imply that such systems do
exist, and will therefore serve as Cosmic Beacons out to the redshift at which
they form.Comment: Proceedings of the conference "Lighthouses of the Universe: