Key points are not available for this paper at this time.
Context. The background radiation in the optical and the infrared cause energy loss in the propagation of high energy particles through space. In particular, TeV observations with Cherenkov telescopes of extragalactic sources are influenced by the opacity effects due to the interaction of the very high-energy source photons with the background light.
Franceschini et al. (Tue,) studied this question.