On the 28th of January, the High Energy Stereoscopic System (H.E.S.S. the world’s largest ground-based gamma-ray observatory, located in Namibia) detected an orphan TeV gamma-ray flare in 3C279, not accompanied by flaring in the adjacent GeV gamma-ray regime. This is a gamma ray loud FSRQ (flat spectrum radio quasar) with a redshift of z = 0.538. Orphan flares
have to be caused by different processes than normal gamma ray flares, which are typically broad-band flares, characterized by variability across the entire electromagnetic spectrum. Specifically, the hadronic mirror model has been proposed to provide a consistent explanation of this flare.
The expected target photon densities have been calculated analytically using the cloud/mirror model starting from basic physical principles. This is compared to the density required to have the proton-gamma output approximately equal to the proton synchrotron radiation. The results are within one order of magnitude of each other. This is promising and shows that this model is feasible.