2010A&A...519L...6N

We search for persistent extragalactic sources of γ-rays with energies above 100GeV with the Fermi telescope. We construct a systematic survey of the extragalactic γ-ray sky at energies above 100GeV. Such a survey has not been done before by the ground-based Cherenkov γ-ray telescopes, which have, contrary to Fermi, a narrow field of view. We study a map of arrival directions of the highest energy photons detected by Fermi at Galactic latitudes |b|>10° and search for significant point-source-like excesses above the diffuse Galactic and extragalactic γ-ray backgrounds. We identify eight significant point-source-like excesses in this map. Seven of the eight sources are known TeV blazars. The previously unknown source is identified with the galaxy IC310, which is situated in Perseus cluster of galaxies. The source is detected with a significance 6σ above 30GeV. We identify two possible scenarii for γ-ray emission from this source. One possibility is that emission originates from the base of relativistic outflow from the active nucleus, as in the BL Lacs and FRI type radio galaxies. Otherwise γ-ray photons could be produced at the bow shock that is formed as a result of the fast motion of the galaxy through the intracluster medium. The two models could be distinguished through studying of the γ-ray signal variability.