AN UPPER LIMIT TO THE INFRARED BACKGROUND FROM OBSERVATIONS OF TEV GAMMA-RAYS

An upper bound to the energy density of infrared background radiation is derived from considering the effect of gamma-gamma interactions on the observed TeV gamma-ray spectrum of the active galaxy Markarian 421 . This upper bound proves to be the most restrictive for the wavelengt h range of 10-12 mu m. These constraints are presently limited by the uncertainty of extrapolating the source spectrum from 5 to 500 GeV. Ob servations in the regime less than 100 GeV would significantly improve these limits, allowing for a wide range of IR production models to be constrained.