The CSO PKS 1718-649 In Gamma-Rays With Fermi-LAT

We report the detection (> 5sigma ) with Fermi-LAT of gamma-ray emission from the nearby (z = 0.014) radio galaxy, PKS 1718-649. This is the first detection in gamma-rays of a bona fide Compact Symmetric Object, a class of sources that are thought to represent the first stage in the evolution of extragalactic radio sources. A detection in the gamma-ray band is a clear indication of a non-thermal high-energy component and provides us with important insights on the physical conditions of expanding young radio sources. The symmetric radio morphology indicates that the source is seen at a large inclination angle and disfavors a contribution of the jet boosted emission. The steep gamma-ray spectrum and steady faint emission are consistent with the scenario of isotropic gamma-ray emission from the compact (<2pc) radio lobes, as proposed by models of expanding young radio sources. We discuss this interpretation and the perspectives for the detection of other young sources in gamma-rays.