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Published March 11, 2014 | Submitted + Published
Journal Article Open

Multiwavelength observations of the γ-ray-emitting narrow-line Seyfert 1 PMN J0948+0022 in 2011


We report on radio-to-γ-ray observations during 2011 May–September of PMN J0948+0022, the first narrow-line Seyfert 1 (NLSy1) galaxy detected in γ-rays by Fermi-Large Area Telescope. Strong variability was observed in γ-rays, with two flaring periods peaking on 2011 June 20 and July 28. The variability observed in optical and near-infrared seems to have no counterpart in γ-rays. This different behaviour could be related to a bending and inhomogeneous jet or a turbulent extreme multicell scenario. The radio spectra showed a variability pattern typical of relativistic jets. The XMM spectrum shows that the emission from the jet dominates above ∼2 keV, while a soft X-ray excess is evident in the low-energy part of the X-ray spectrum. Models where the soft emission is partly produced by blurred reflection or Comptonization of the thermal disc emission provide good fits to the data. The X-ray spectral slope is similar to that found in radio-quiet NLSy1, suggesting that a standard accretion disc is present, as expected from the high accretion rate. Except for the soft X-ray excess, unusual in jet-dominated active galactic nuclei, PMN J0948+0022, shows all characteristics of the blazar class.

Additional Information

© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 December 19. Received 2013 November 27; in original form 2013 October 3. First published online: January 24, 2014. 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 is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Études Spatiales in France. We thank the Swift team for making these observations possible, the duty scientists and science planners. The OVRO 40m monitoring programme is supported in part by NASA grants NNX08AW31G and NNX11A043G, and NSF grants AST-0808050 and AST-1109911. This paper is partly based on observations with the 100m telescope of the MPIfR (Max-Planck-Institut f¨ur Radioastronomie) at Effelsberg and the Medicina telescope operated by INAF-Istituto di Radioastronomia. We acknowledge A. Orlati, S. Righini and the Enhanced Single-dish Control System Development Team. The CSS survey is funded by the National Aeronautics and Space Administration under grant no. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the US National Science Foundation under grants AST-0909182. This research has made use of observations obtained with the 2.1m telescope of the Observatorio Astrofisico Guillermo Haro (OAGH), in the state of Sonora, Mexico, operated by the INAOE, Mexico. OAGH acknowledges funding from the INAOE Astrophysics Department. The Metsähovi team acknowledges the support from the Academy of Finland to our observing projects (numbers 212 656, 210 338, 121 148 and others). This research made use of data from MOJAVE data base that is maintained by the MOJAVE team (Lister et al. 2009). This work is based on observations obtained with XMM–Newton, an ESA science mission with instrument and contributions directly funded by ESA Member States and the USA (NASA). JL acknowledges financial support from the Swedish National Space Board. FD thanks A. Breeveld and P. Roming for useful discussion about OM and UVOT cross-calibration. JL thanks Andy Fabian for useful discussion. We thank S. Cutini, S. Digel, D. Thompson and the anonymous referee for useful comments and suggestions.

Attached Files

Published - MNRAS-2014-D'Ammando-3521-34.pdf

Published - MNRAS-2014-D=0027Ammando-3521-34.pdf

Submitted - 1312.5522v1.pdf


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