view Abstract Citations (27) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Gamma-Ray Burst Rate at High Photon Energies Mannheim, Karl ; Hartmann, Dieter ; Funk, Burkhardt Abstract Some gamma-ray burst (GRB) spectra exhibit high-energy tails with the highest photon energy detected at 18 GeV. The spectral slope of the high- energy tails is sufficiently flat in νFnu_ to consider the possibility of their detection at still higher energies. We calculate how many bursts can reasonably be expected above a given energy threshold for a cosmological distribution of bursts satisfying the observed apparent brightness distribution. The crucial point is that the gamma-ray absorption by pair production in the intergalactic diffuse radiation field eliminates bursts from beyond the gamma-ray horizon τgammaγ_ ~ 1 thus drastically reducing the number of bursts at high energies. Our results are consistent with the nondetection of bursts by current experiments in the 100 GeV to 100 TeV energy range. For the earthbound detector array MILAGRO, we predict a maximal GRB rate of ~10 events per year. The Whipple Observatory can detect, under favorable conditions, ~1 event per year. The event rate for the HEGRA array is ~0.01 per year. Detection of significantly higher rates of bursts would severely challenge cosmological burst scenarios. Publication: The Astrophysical Journal Pub Date: August 1996 DOI: 10.1086/177629 arXiv: arXiv:astro-ph/9605108 Bibcode: 1996ApJ...467..532M Keywords: COSMOLOGY: DIFFUSE RADIATION; GAMMA RAYS: BURSTS; GALAXIES: INTERGALACTIC MEDIUM; Astrophysics E-Print: 9 pages latex, postscript figures included full text sources arXiv | ADS | data products SIMBAD (1)