Indications for a suppression of pair production at very high energies.

Manuel Meyer & Dieter Horns
The transparency of the universe for very high energy (VHE) photons is limited due to pair-production with low energy photons of the extra galactic background light (EBL) in the ultra-violet to infrared wavelength band. Here, we use 58 energy spectra from VHE emitting active galactic nuclei (AGN) from redshift 0.004 to 0.536 to search for signatures of deviations from the minimum expected opacity. A statistical study of the individual measurements reveals indications for an overcorrection...