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2009 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 699, no 2, 976-984 p.Article in journal (Refereed) Published
Abstract [en]

We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy. gamma-ray emission from the peculiar quasar PMN J0948+0022 (z = 0.5846). The optical spectrum of this object exhibits rather narrow H beta (FWHM(H beta) similar to 1500 km s(-1)), weak forbidden lines, and is therefore classified as a narrow-line type I quasar. This class of objects is thought to have relatively small black hole mass and to accrete at a high Eddington ratio. The radio loudness and variability of the compact radio core indicate the presence of a relativistic jet. Quasi-simultaneous radio/optical/X-ray and gamma-ray observations are presented. Both radio and gamma-ray emissions (observed over five months) are strongly variable. The simultaneous optical and X-ray data from Swift show a blue continuum attributed to the accretion disk and a hard X-ray spectrum attributed to the jet. The resulting broadband spectral energy distribution (SED) and, in particular, the gamma-ray spectrum measured by Fermi are similar to those of more powerful Flat-Spectrum Radio Quasars (FSRQs). A comparison of the radio and gamma-ray characteristics of PMN J0948+0022 with the other blazars detected by LAT shows that this source has a relatively low radio and gamma-ray power with respect to other FSRQs. The physical parameters obtained from modeling the SED also fall at the low power end of the FSRQ parameter region discussed in Celotti & Ghisellini. We suggest that the similarity of the SED of PMN J0948+0022 to that of more massive and more powerful quasars can be understood in a scenario in which the SED properties depend on the Eddington ratio rather than on the absolute power.

Place, publisher, year, edition, pages
2009. Vol. 699, no 2, 976-984 p.
Keyword [en]
galaxies: active, gamma rays: observations, quasars: individual (PMN, J0948+0022), seyfert 1 galaxies, spectral energy-distributions, inverse-compton, catastrophe, active galactic nuclei, black-hole mass, radio-loud, blazar unification, ghz sources, sky survey, radiation
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:kth:diva-18549DOI: 10.1088/0004-637x/699/2/976ISI: 000267401500008ScopusID: 2-s2.0-68149178185OAI: diva2:336596

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2016-04-21Bibliographically approved

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Axelsson, M.Ryde, FelixBattelino, MilanConrad, JanYlinen, Tomi
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