Search for Ultra--High-Energy Radiation from Gamma-Ray Bursts
Abstract
A recent class of models suggests that some gamma-ray bursters may produce ultra-high-energy (>~100 TeV) photons. Using data from the CYGNUS array, we have searched for evidence of emission of ultra-high-energy radiation coincident with gamma-ray bursts observed either by the third Interplanetary Network of satellites or by the BATSE instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for six bursts whose locations were accurately determined by the Network, or for any point in the sky within 2 σ of the BATSE location coordinates of 52 additional bursts. Flux upper limits depend greatly on the zenith angles of the bursts, but typical limits above 100 TeV are ~4 x 10^-10^ cm^-2^ s^-1^. The flux upper limits for three of the bursts imply that the observed spectrum softens between 2 MeV and ~100 TeV: If the production spectrum does not soften between these energies, the bursts must have a cosmological origin.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1994
- DOI:
- 10.1086/187325
- Bibcode:
- 1994ApJ...426L...1A
- Keywords:
-
- Astronomical Spectroscopy;
- Energy Spectra;
- Gamma Ray Astronomy;
- Gamma Ray Bursts;
- Photons;
- Spaceborne Astronomy;
- Gamma Ray Observatory;
- Probability Density Functions;
- Astronomy;
- GAMMA RAYS: BURSTS;
- GAMMA RAYS: OBSERVATIONS