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The extragalactic background light (EBL) is the radiation accumulated throughthe history of the Universe in the wavelength range from the ultraviolet to thefar infrared. Local foregrounds make the direct measurement of the diffuse EBLnotoriously difficult, while robust lower limits have been obtained by addingup the contributions of all the discrete sources resolved in deep infrared andoptical galaxy observations. Gamma-ray astronomy has emerged in the past fewyears as a powerful tool for the study of the EBL: very-high-energy (VHE)photons traversing cosmological distances can interact with EBL photons toproduce e$^+$e$^-$ pairs, resulting in an energy-dependent depletion of thegamma-ray flux of distant sources that can be used to set constraints on theEBL density. The study of the EBL is one of the key scientific programscurrently carried out by the MAGIC collaboration. We present here the resultsof the analysis of 32 VHE spectra of 12 blazars in the redshift range 0.03 -0.94, obtained with over 300 hours of observations with the MAGIC telescopesbetween 2010 and 2016. A combined likelihood maximization approach is used toevaluate the density and spectrum of the EBL most consistent with the MAGICobservations. The results are compatible with state-of-the-art EBL models, andconstrain the EBL density to be roughly within $\simeq 20\%$ of the nominalvalue in such models. The study reveals no anomalies in gamma-ray propagationin the large optical depth regime - contrary to some claims based onmeta-analyses of published VHE spectra.

Measurement of the EBL through a combined likelihood analysis of gamma-ray observations of blazars with the MAGIC telescopes