TEV GAMMA-RAYS FROM 3C-279 - A POSSIBLE PROBE OF ORIGIN AND INTERGALACTIC INFRARED RADIATION-FIELDS

The gamma-ray spectrum of 3C 279 during 1991 June exhibited a near perfect power law between 50 MeV and over 5 GeV with a differential spectral index of -(2.02 +/- 0.07). If extrapolated, the gamma-ray spectrum of 3C 279 should be easily detectable with first generation air Cerenkov detectors operating above approximately 0.3 TeV, provided there is no intergalactic absorption. However, by using model-dependent lower and upper limits for the extra-galactic infrared background radiation field, we predict a sharp cutoff of the 3C 279 spectrum between approximately 0.1 and approximately 1 TeV. The sensitivity of present air Cerenkov detectors is good enough to measure such a cutoff, which would provide the first opportunity to obtain a measurement of, or at least a severe constraint on the extragalactic background infrared radiation field.