Properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies^⋆

¹ INAF–Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy
e-mail: luigi.foschini@brera.inaf.it
² Dipartimento di Fisica e Astronomia, Università di Padova, vicolo dell’Osservatorio 3, 35122 Padova, Italy
³ Department of Astronomy and Center for Cosmology and AstroParticle Physics, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁵ Department of Astronomy and Physics, Saint Mary’s University, Halifax, Canada
⁶ Space Science Center, Morehead State University, 235 Martindale Dr., Morehead, KY 40351, USA
⁷ Swift Mission Operation Center, 2582 Gateway Dr., State College, PA 16801, USA
⁸ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
⁹ Aalto University Department of Radio Science and Engineering, PO Box 13000, 00076 Aalto, Finland
¹⁰ Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany
¹¹ Astro Space Center of the Lebedev Physical Institute, 117997 Moscow, Russia
¹² Department of Physics, Purdue University, West Lafayette, IN 47907, USA
¹³ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica, 90146 Palermo, Italy
¹⁴ Institut de Radio Astronomie Millimétrique, Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain
¹⁵ ITPA, Universität Würzburg, Campus Hubland Nord, Emil-Fischer-Str. 31, 97074 Würzburg, Germany
¹⁶ Mesoamerican Centre for Theoretical Physics (MCTP), Universidad Autónoma de Chiapas (UNACH), Carretera Emiliano Zapata Km. 4, Real del Bosque (Teràn), 29050 Tuxtla Gutiérrez, Chiapas, Mexico
¹⁷ Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, 34127 Trieste, Italy

Received: 12 September 2014
Accepted: 11 November 2014

Abstract

We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse data from radio frequencies to X-rays, and supplement these with information available from online catalogues and the literature in order to cover the full electromagnetic spectrum. This is the largest known multiwavelength survey for this type of source. We detected 90% of the sources in X-rays and found 17% at γ rays. Extreme variability at high energies was also found, down to timescales as short as hours. In some sources, dramatic spectral and flux changes suggest interplay between a relativistic jet and the accretion disk. The estimated masses of the central black holes are in the range ~10⁶⁻⁸ M_⊙, lower than those of blazars, while the accretion luminosities span a range from ~0.01 to ~0.49 times the Eddington limit, with an outlier at 0.003, similar to those of quasars. The distribution of the calculated jet power spans a range from ~10^42.6 to ~10^45.6 erg s^-1, generally lower than quasars and BL Lac objects, but partially overlapping with the latter. Once normalised by the mass of the central black holes, the jet power of the three types of active galactic nuclei are consistent with each other, indicating that the jets are similar and the observational differences are due to scaling factors. Despite the observational differences, the central engine of RLNLS1s is apparently quite similar to that of blazars. The historical difficulties in finding radio-loud narrow-line Seyfert 1 galaxies might be due to their low power and to intermittent jetactivity.