Publication Date:
2015-09-16
Description:
We report results on multiband observations from radio to -rays of the two radio-loud narrow-line Seyfert 1 (NLSy1) galaxies PKS 2004–447 and J1548+3511. 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 -ray source candidates. Fermi -Large Area Telescope detected -ray emission only from PKS 2004–447, with a -ray luminosity comparable to that observed in blazars. No -ray emission is 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.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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