Upper Limit on Gamma-Ray Flux above 10[TSUP]19[/TSUP] [CLC]e[/CLC]V Estimated by the Akeno Giant Air Shower Array Experiment
Citations Over TimeTop 10% of 2002 papers
Abstract
The origin of the highest energy cosmic rays (≥1020 eV) is not well understood. Interesting models called "top-down" scenarios have been proposed to explain the origin. The γ-ray flux in ultra-high-energy cosmic rays is a key parameter for giving constraints on such models. To study the properties of γ-ray showers, we carry out simulation studies that take into account both the Landau-Pomeranchuk-Migdal effect and electromagnetic interactions in the geomagnetic field. Based on an analysis of muons in air showers observed by the Akeno Giant Air Shower Array, the upper limits on the γ-ray flux are estimated to be 28% above 1019 eV and 67% above 1019.5 eV in the observed air showers at a confidence level of 95%. Above 1020 eV, the primary composition is in agreement with an extrapolation from lower energies, and there is no indication that the observed events are mostly γ-ray showers. These results provide observational constraints for origin models up to the highest energies.
Related Papers
- → Ultrahigh energy gamma rays in the geomagnetic field and atmosphere(2003)24 cited
- → An investigation on the phase angle of radio signals from cosmic ray air showers(2017)1 cited
- → Muon content in air showers between 10 PeV and 1 EeV determined from measurements with KASCADE-Grande(2019)1 cited
- → Study of muons in extensive air showers from ultra-high energy cosmic rays measured with the Telescope Array experiment(2019)
- → Highlights from gamma-ray observation by the Tibet ASgamma experiment.(2021)