Astrophysics - High Energy Astrophysical Phenomena
Astrophysics - Cosmology and Extragalactic Astrophysics
Beschreibung:
Very high energy (VHE, energy >~ 100 GeV) γ-rays undergo pairproduction with photons of the extragalactic background light (EBL).Thus, the intrinsic γ-ray flux of cosmological sources isattenuated and the Universe should be opaque to γ-rays above aredshift dependent energy. Recently, an indication has been found thatthe Universe is more transparent than predicted by a lower-limit EBLmodel. Here, this indication is confronted with additional VHE γ-ray spectra and different EBL models. Depending on the modelfor the opacity, the indication persist between a ~2.6σ and ~4.3σ confidence level.