High-energy astrophysics puzzle

Blazars are the brightest of active galactic nuclei, and many emit very high-energy gamma rays. New observations of a blazar known as PKS 1424+240 show that it is the most-distant known source of very high-energy gamma rays. But its emission spectrum appears highly unusual.

Fuente : http://www.eurekalert.org/pub_releases/2013-04/ci-…