Session B16 - Neutrino and Gamma Ray Astrophysics.
MIXED session, Saturday morning, April 29
202C, Convention Center
The spectral density of the Extragalactic Background Light (EBL) (0.1-100 \mum) contains extensive information on the early history of the Universe: cosmology, galaxy and star formation, metal and dust production, and the rate of re-processing of starlight to infrared wavelengths by the dust. In spite of great interest, EBL has so far escaped direct detection due to strong backgrounds from interplanetary dust scattering and emission, stars and galactic foregrounds, and interstellar dust emission. In the late sixties Gould and Schréder pointed out that observations of extragalactic photons in the region 0.1 to 100 TeV can be used for indirect detection of EBL because the two photons are coupled via pair production. Recent detections of AGN which indeed emit such energetic photons provide the data necessary to utilize this technique. We will review recent experimental results and uncertainties associated with theoretical predictions of EBL as well as the contribution and potential of the ground based \gamma-ray observatories, such as Whipple and VERITAS, to measure the EBL field.