M87 - a misaligned synchrotron-proton blazar?

Abstract

The Fanaroff–Riley (FR) class 1 radio galaxy M87 is widely believed to be a misaligned blazar of BL Lac type. Its unresolved nuclear region is a strong non-thermal emitter of radio to X-ray photons that have been interpreted as synchrotron radiation. The recent detection of TeV-photons by the HEGRA-telescope array, if confirmed, would make it the first radio galaxy detected at TeV-energies. We discuss M87’s core emission in the context of the hadronic Synchrotron-Proton Blazar model. By modeling M87’s non-simultaneous spectral energy distribution we predict the peak power of the γ-ray component at 100 GeV at a flux level detectable for the new Cherenkov telescopes H.E.S.S., VERITAS and MAGIC. Thanks to M87’s proximity TeV photon absorption in the cosmic background radiation field is negligible. This offers for the first time the opportunity to directly trace the intrinsic high energy cutoff of a TeV-emitting blazar-like object.