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Published July 10, 2009 | Published
Journal Article Open

Fermi/Large Area Telescope Discovery of Gamma-Ray Emission from a Relativistic Jet in the Narrow-Line Quasar PMN J0948+0022

Abdo, A. A.
Ackermann, M.
Ajello, M. ORCID icon
Axelsson, M.
Baldini, L.
Ballet, J.
Barbiellini, G.
Bastieri, D.
Battelino, M.
Baughman, B. M.
Bechtol, K.
Bellazzini, R.
Bloom, E. D.
Bonamente, E.
Borgland, A. W.
Bregeon, J.
Brez, A.
Brigida, M.
Bruel, P.
Caliandro, G. A.
Cameron, R. A.
Caraveo, P. A.
Casadjian, J. M
Cavazzuti, E.
Cecchi, C.
Chekhtman, A.
Cheung, C. C.
Chiang, J.
Ciprini, S.
Claus, R.
Cohen-Tanugi, J.
Collmar, W.
Conrad, J
Costamante, L.
Dermer, C. D.
De Angelis, A.
De Palma, F.
Digel, S. W.
Do Couto e Silva, E.
Drell, P. S.
Dubois, R.
Dumora, D.
Farnier, C.
Favuzzi, C.
Focke, W. B.
Foschini, L.
Frailis, M.
Fuhrmann, L.
Fukazawa, Y.
Funk, S.
Fusco, P.
Gargano, F.
Gehrels, N.
Germani, S.
Giebels, B.
Giglietto, N.
Giordano, F.
Giroletti, M.
Glanzman, T.
Grenier, I. A.
Grondin, M. -H.
Grove, J. E.
Guillemot, L.
Guiriec, S.
Hanabata, Y.
Harding, A. K. ORCID icon
Hartman, R. C.
Hayashida, M.
Hays, E.
Hughes, R. E.
Jóhannesson, G.
Johnson, A. S.
Johnson, W. N.
Kamae, T.
Katagiri, H
Kataoka, F.
Kerr, M.
Knödlseder, J.
Kuehn, F.
Kuss, M.
Lande, J.
Latronico, L.
Lemoine-Goumard, M.
Longo, F.
Loparco, F.
Lott, B.
Lovellette, M. N.
Lubrano, P.
Madejski, G. M.
Makeev, A.
Max-Moerbeck, W. ORCID icon
Mazziotta, M. N.
McConville, W.
McEnery, J. E.
Meurer, C.
Michelson, P. F.
Mitthumsiri, W.
Mizuno, T.
Monte, C.
Monzani, M. E.
Morselli, A.
Moskalenko, I. V.
Murgia, S.
Nolan, P. L.
Norris, J. P.
Nuss, E.
Ohsugi, T.
Omodei, N.
Orlando, E.
Ormes, J. F.
Paneque, D.
Panetta, J. H.
Parent, D.
Pavlidou, V.
Pearson, T. J. ORCID icon
Pepe, M.
Pesce-Rollins, M.
Piron, F.
Porter, T. A.
Rainò, S.
Rando, R.
Razzano, M.
Readhead, A. ORCID icon
Reimer, A.
Reimer, O.
Reposeur, T.
Richards, J. L.
Ritz, S.
Rodriguez, A. Y.
Romani, R. W. ORCID icon
Ryde, F.
Sadrozinski, H. F. -W.
Sambruna, R.
Sanchez, D.
Sander, A.
Saz Parkinson, P. M.
Scargle, J. D.
Schalk, T. L.
Sgrò, C.
Smith, D. A.
Spandre, G.
Spinelli, P.
Starck, J.-L.
Stevenson, M.
Strickman, M. S.
Suson, D. J.
Tagliaferri, G.
Takahashi, H.
Tanaka, T.
Thayer, J. G.
Thompson, D. J.
Tibaldo, L.
Tibolla, O.
Torres, D. F. ORCID icon
Tosti, G.
Tramacere, A.
Uchiyama, Y.
Usher, T. L.
Vilchez, N.
Vitale, V.
Waite, A. P.
Winer, B. L.
Wood, K. S. ORCID icon
Ylinen, Y.
Zensus, J. A.
Ziegler, M.
Fermi Collaboration
LAT Collaboration


We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy γ-ray emission from the peculiar quasar PMN J0948+0022 (z = 0.5846). The optical spectrum of this object exhibits rather narrow Hβ (FWHM(Hβ) ~1500 km s^–1), weak forbidden lines, and is therefore classified as a narrow-line type I quasar. This class of objects is thought to have relatively small black hole mass and to accrete at a high Eddington ratio. The radio loudness and variability of the compact radio core indicate the presence of a relativistic jet. Quasi-simultaneous radio/optical/X-ray and γ-ray observations are presented. Both radio and γ-ray emissions (observed over five months) are strongly variable. The simultaneous optical and X-ray data from Swift show a blue continuum attributed to the accretion disk and a hard X-ray spectrum attributed to the jet. The resulting broadband spectral energy distribution (SED) and, in particular, the γ-ray spectrum measured by Fermi are similar to those of more powerful Flat-Spectrum Radio Quasars (FSRQs). A comparison of the radio and γ-ray characteristics of PMN J0948+0022 with the other blazars detected by LAT shows that this source has a relatively low radio and γ-ray power with respect to other FSRQs. The physical parameters obtained from modeling the SED also fall at the low power end of the FSRQ parameter region discussed in Celotti & Ghisellini. We suggest that the similarity of the SED of PMN J0948+0022 to that of more massive and more powerful quasars can be understood in a scenario in which the SED properties depend on the Eddington ratio rather than on the absolute power.

Additional Information

© 2009 American Astronomical Society. Received 2009 March 6. Accepted 2009 April 30. Published 2009 June 17. The Fermi/LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase from the following agencies is also gratefully acknowledged: the Istituto Nazionale di Astrofisica in Italy and the K. A. Wallenberg Foundation in Sweden for providing a grant in support of a Royal Swedish Academy of Sciences Research fellowship for J.C. This research is partly based on observations with the 100 m telescope of the Max-Planck-Institut für Radioastronomie (MPIfR) at Effelsberg. The monitoring program at the OVRO is supported by NASA award NNX08AW31G and NSF award AST-0808050. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has made use of data obtained from the High Energy Astrophysics Science Archive Research Center (HEASARC), provided by NASA's Goddard Space Flight Center.

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