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Title: Investigating powerful jets in radio-loud narrow-line Seyfert 1s

Here, we report results on multiband observations from radio to γ-rays of the two radio-loud narrow-line Seyfert 1 (NLSy1) galaxies PKS 2004-447 and J1548+3511. Furthermore, both sources show a core–jet structure on parsec scale, while they are unresolved at the arcsecond scale. The high core dominance and the high variability brightness temperature make these NLSy1 galaxies good γ-ray source candidates. Fermi-Large Area Telescope detected γ-ray emission only from PKS 2004-447, with a γ-ray luminosity comparable to that observed in blazars. There was no γ-ray emission observed for J1548+3511. Both sources are variable in X-rays. J1548+3511 shows a hardening of the spectrum during high activity states, while PKS 2004-447 has no spectral variability. A spectral steepening likely related to the soft excess is hinted below 2 keV for J1548+3511, while the X-ray spectra of PKS 2004-447 collected by XMM–Newton in 2012 are described by a single power law without significant soft excess. No additional absorption above the Galactic column density or the presence of an Fe line is detected in the X-ray spectra of both sources.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [2] ;  [3] ;  [3]
  1. National Inst. for Astrophysics (INAF), Firenze (Italy). Inst. of Radio Astronomy
  2. National Inst. for Astrophysics (INAF), Firenze (Italy). Inst. of Radio Astronomy; Univ. of Bologna (Italy). Dept. of Physics and Astronomy
  3. KTH Royal Inst. of Technology, Stockholm (Sweden). Dept. of Physics and Oskar Klein Centre
  4. US Naval Research Lab., Washington, DC (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 453; Journal Issue: 4; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; galaxies: Seyfert; gamma-rays: general; radio continuum: general
OSTI Identifier:
1354919