The discovery challenges existing concepts of the acceleration processes close to black holes and how radiation is absorbed in space, and indicates that the universe is not as opaque as previously thought. Last year Mrk421 rewarded patient observers with the most explosive gamma display ever, with a flux ten times higher than that of the much closer Crab Nebula, the strongest known steady gamma source in the sky. Weekes suggested that the anticipated effect of two sources of attenuation, dust near the AGN and the amorphous population of infrared photons in intergalactic space, may have been overestimated. These cosmic particles are accelerated by a process derived from the enormous gravity of a black hole to energies in excess of those attained by man-made particle accelerators.
Theoretical astrophysicists have yet to explain the processes involved.
Even more difficult to explain is how the gamma rays, once produced, can escape from the jet without interacting with lower energy photos and degrading in energy as a result. Once clear of the galaxy, the gamma rays must traverse vast regions of intergalactic space, where they could be absorbed by interacting with infrared radiation from galaxies formed in the early universe. However, the recent observations suggest that the density of infrared photons is much less than previously predicted. We had believed there were more low-energy photons out there to absorb the gamma rays, but so many are getting through to us from such a large distance that it appears there's much less interaction taking place. A reduced number of such photons thus has direct implications for current theories of the history of the universe, particularly for galaxy formation.