EBL studies with ground-based VHE γ-ray detectors: Current status and potential of next-generation instruments

The diffuse meta-galactic radiation field at ultraviolet-to-infrared wavelengths—commonly labeled extragalactic background light (EBL)—contains the integrated emission history of the Universe. Difficult to access via direct observations, indirect constraints on its density can be derived through observations of very-high–energy (VHE; E > 100 GeV) gamma rays from distant sources: the VHE photons are attenuated via pair production with the low-energy photons from the EBL, leaving a distinct imprint in the VHE spectra measured on Earth. Discoveries made with current-generation VHE observatories like H.E.S.S., MAGIC and VERITAS enabled strong constraints on the density of the EBL, especially in the near infrared. Here, the constrains on the EBL density from such ground-based VHE observations will be briefly reviewed and the potential of the next-generation instruments to improve on these limits will be discussed