NGC 3147: a 'true' type 2 Seyfert galaxy without the broad-line region |
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| Authors: | S Bianchi A Corral F Panessa X Barcons G Matt L Bassani F J Carrera E Jiménez-Bailón |
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| Institution: | Dipartimento di Fisica, Universitàdegli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy;Instituto de Física de Cantabria (CSIC-UC), 39005 Santander, Spain;INAF-IASF, Via P. Gobetti 101, 40129 Bologna, Italy;Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, 04510 Mexico DF, Mexico;LAEFF Apd. 78 Villanueva de la Cañada, 28691 Madrid, Spain |
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| Abstract: | We report on simultaneous optical and X-ray observations of the Seyfert galaxy, NGC 3147. The XMM–Newton spectrum shows that the source is unabsorbed in the X-rays ( N H < 5 × 1020 cm−2) . On the other hand, no broad lines are present in the optical spectrum. The origin of this optical/X-rays misclassification (with respect to the Unification Model) cannot be attributed to variability, since the observations in the two bands are simultaneous. Moreover, a Compton-thick nature of the object can be rejected on the basis of the low-equivalent width of the iron Kα line (≃130 eV) and the large ratio between the 2–10 keV and the O iii ] fluxes. It seems therefore inescapable to conclude that NGC 3147 intrinsically lacks the Broad-Line Region, making it the first 'true' type 2 Seyfert galaxy. |
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| Keywords: | galaxies: active galaxies: Seyfert X-rays: individual: NGC 3147 |
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