Estimates of the cosmic gamma-ray flux at PeV to EeV energies from the EAS-MSU experiment data

الأصل · EN

Archival EAS-MSU data are searched for anomalous muonless events which may be caused by primary gamma rays with energies between 10¹5 eV and 10¹8 eV. We consider a refined sample of high-quality data and confirm the previously reported detection of a non-zero gamma-ray flux at 5x10¹6 eV with a similar flux value but at somewhat lower statistical significance, corresponding to the depletion of the sample. We present upper limits on the flux below and above these energies, including the first constraints in the range (10¹7-10¹8) eV never studied by any other experiment.