discovery of gamma - ray emission from a relativistic jet in the narrow - line Seyfert 1 quasar

We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope of high-energy gamma-ray emission from the peculiar quasar PMN J0948+0022 (z = 0.585± 0.001). Contrary to the expectations, the optical spectrum of this quasar shows only narrow lines [FWHM(Hβ) ∼ 1500 km/s] and the typical characteristics of narrow-line Seyfert 1 type galaxies. However, the strong radio emission and the flat spectrum suggest the presence of a relativistic jet, which can now be confirmed by the detection of MeV-GeV photons. PMN J0948+0022 is therefore the first radio-loud narrowline Seyfert 1 quasar to be detected at gamma-rays and the third type of γ−ray emitting AGN, after blazars and radiogalaxies.