The first gamma-ray outburst of a narrow-line Seyfert 1 galaxy: the case of PMNJ0948+0022 in 2010 July
We report on a multiwavelength campaign for the radio-loud narrow-line Seyfert 1 (NLS1) galaxy PMN J0948+0022 (z= 0.5846) performed in 2010 July–September and triggered by a high-energy γ-ray outburst observed by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. The peak flux in the 0.1–100 GeV energy band exceeded, for the first time in this type of source, the value of ~10^(−6) photon cm^(−2) s^(−1), corresponding to an observed luminosity of ~10^(48) erg s^(−1). Although the source was too close to the Sun position to organize a densely sampled follow-up, it was possible to gather some multiwavelength data that confirmed the state of high activity across the sampled electromagnetic spectrum. The comparison of the spectral energy distribution of the NLS1 PMN J0948+0022 with that of a typical blazar – such as 3C 273 – shows that the power emitted at γ-rays is extreme.
Additional Information© 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS. Accepted 2010 December 20. Received 2010 December 3; in original form 2010 October 21. Article first published online: 8 Mar. 2011. 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. This work has been partially supported by PRIN-MiUR 2007 and ASI Grant I/088/06/0. The OVRO 40-m monitoring programme is supported in part by NASA (NNX08AW31G) and the NSF (AST-0808050). This work is based on observations with the 100-m telescope of the Max-Planck-Institut für Radioastronomie (MPIfR) at Effelsberg. IN is member of the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Universities of Bonn and Cologne. The Fermi LAT Collaboration acknowledges support from a number of agencies and institutes for both development and the operation of the LAT as well as scientific data analysis. These include NASA and DOE in the United States, CEA/Irfu and IN2P3/CNRS in France, ASI and INFN in Italy, MEXT, KEK and JAXA in Japan, and the K. A.Wallenberg Foundation, the Swedish Research Council and the National Space Board in Sweden. Additional support from INAF in Italy and CNES in France for science analysis during the operations phase is also gratefully acknowledged. This research has made use of data from the MOJAVE data base that is maintained by the MOJAVE team (Lister et al. 2009). The MOJAVE project is supported under NSF grant AST-0807860 and NASA Fermi grant NNX08AV67G. RATAN-600 observations were supported in part by the Russian Foundation for Basic Research grant 08-02-00545. YYK was supported in part by the return fellowship of Alexander von Humboldt Foundation.
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