Relativistic jets in narrow-line Seyfert 1 galaxies. New discoveries and open questions
1 INAF - Istituto di Radioastronomia, Via Gobetti 101, I-40129 Bologna, Italy
2 U.S. Naval Research Laboratory, Code 7653, 4555 Overlook Ave. SW, Washington, DC 20375-5352, USA
3 KTH, Department of Physics, and the Oskar Klein Centre, AlbaNova, SE-106 91 Stockholm, Sweden
a e-mail: firstname.lastname@example.org
Published online: 9 December 2013
Before the launch of the Fermi satellite only two classes of AGNs were known to produce relativistic jets and thus emit up to the γ-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first four years of observations by the Large Area Telescope on board Fermi confirmed that these two are the most numerous classes of identified sources in the extragalactic γ-ray sky, but the discovery of γ-ray emission from 5 radio-loud narrow-line Seyfert 1 galaxies revealed the presence of a possible emerging third class of AGNs with relativistic jets. Considering that narrow-line Seyfert 1 galaxies seem to be typically hosted in spiral galaxy, this finding poses intriguing questions about the nature of these objects, the onset of production of relativistic jets, and the cosmological evolution of radio-loud AGN. Here, we discuss the radio-to-γ-rays properties of the γ-ray emitting narrow-line Seyfert 1 galaxies, also in comparison with the blazar scenario.
© Owned by the authors, published by EDP Sciences, 2013
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