Publication Date:
2014-02-20
Description:
We report on radio-to--ray observations during 2011 May–September of PMN J0948+0022, the first narrow-line Seyfert 1 (NLSy1) galaxy detected in -rays by Fermi -Large Area Telescope. Strong variability was observed in -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 -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.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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