An Empirical Determination of the EBL and the Gamma-ray Opacity of the Universe

Understand

I present the results of a new approach to the intensity and photon density spectrum of the intergalactic background light as a function of redshift using observational data obtained in many different wavelength bands from local to deep galaxy surveys.

• This enables an empirical determination of both the EBL and its observationally based uncertainties.
• Using these results one can place 68% confidence upper and lower limits on the opacity of the universe to {\gamma}-rays, free of the theoretical assumptions that were needed for past calculations.
• I compare our results with measurements of the extragalactic background light, upper limits obtained from observations made by the Fermi Gamma-ray Space Telescope, and new observationally based results from Fermi and H.E.S.S.