Search for GeV gamma-ray emission from clusters of galaxies studied by TeV telescopes

Abstract

A cluster of galaxies is a huge system bounded by gravitation, and cosmic rays are thought to be confined in the system, thus it should contain much non-thermal components. Many theories predict significant gamma-ray emission that could be detectable by state-of-the-art gamma-ray telescopes. Some clusters have already been studied by using Fermi gamma-ray space telescope in the GeV band and Cherenkov telescopes in the TeV band, but most clusters are not studied in both energy bands. Here I present results on GeV gamma-ray emission from clusters of galaxies which have been given upper limits by Cherenkov telescopes using Fermi archival data.