The contribution of untriggered GRBs to the -ray background can be estimated in a number of ways, but all depend on modeling, or inferring from observations, the typical high-energy GRB spectra. For the optimistic case that the TeV flux made by a GRB is 10 &215; greater than the MeV flux, then the superpositions of GRB emissions are found to make 10% of the -ray background after cascading from high energies into the GeV band . If one instead relies on observations of EGRET spark-chamber GRBs that show that the fluence in the EGRET band is only 10% of the fluence in the BATSE band, then GRBs are found to give very little ( 1%) contribution to the -ray background . This neglects the contributions of short, hard GRBs and low luminosity GRBs, but since these have small fluences and all-sky rates, they are unlikely to make a significant contribution to the -ray background.
It hardly needs to be mentioned that GLAST observations of the high-energy emission from GRBs will provide crucial information to determine the share of the background -ray intensity provided by GRBs.