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F.W. Stecker, S.T. Scully (NASA Goddard Space Flight Center)
It has been suggested cosmological \gamma-ray bursts (GRBs) can produce the observed flux of cosmic rays at the highest energies in the 100-300 EeV range. However, recent observations indicate that the redshift distribution of \gamma-ray bursts most likely follows the redshift distribution of the average star formation rate in the universe, a rate which was much higher in at redshifts of 1.5 to 2 than it is today. We show that, as a consequence, energy losses suffered by ultrahigh energy cosmic rays caused by meson producing interactions with photons of the 2.7K cosmic background radiation would have a profound effect on both the flux and energy spectrum of the cosmic rays putatively produced by GRBs which would be observed at the Earth during the present epoch. The cosmic rays with energies above 10 EeV which we predict would have a much lower flux than that observed, particularly those above 60 EeV.