Journal Article

B2 0954+25A: a typical <i>Fermi</i> blazar or a γ -ray loud Narrow Line Seyfert 1?

G. Calderone, G. Ghisellini, M. Colpi and M. Dotti

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 424, issue 4, pages 3081-3093
Published in print August 2012 | ISSN: 0035-8711
Published online August 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21456.x
B2 0954+25A: a typical Fermi blazar or a γ -ray loud Narrow Line Seyfert 1?

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Abstract

B2 0954+25A, detected by the Fermi satellite, is a blazar with interesting observational properties: it has been observed to transit from a jet-dominated to a disc-dominated state; its radio spectrum appears flat at all observing frequencies (down to 74 MHz); optically, the Hβ; line profile is asymmetric. The flatness of the radio spectrum suggests that the isotropic emission from radio lobes is very weak, despite the large size of its jet (≳500 kpc). Its broad-band spectral energy distribution is surprisingly similar to that of the prototypical γ-ray, radio-loud, type 1 narrow-line Seyfert (γ-NLS1) galaxy PMN J0948+0022. In this work, we revisit the mass estimates of B2 0954+25A considering only the symmetric component of the Hβ; line and find (1–3) × 108 M. In light of our composite analysis, we propose to classify the source as a transition object between the classes of flat spectrum radio quasars and γ-NLS1 galaxies. A comparison with two members of each class (3C 273 and PMN J0948+0022) is discussed.

Keywords: galaxies: jets; quasars: individual: B2 0954+25A

Journal Article.  9452 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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