How Complex is the Obscuration in Active Galactic Nuclei? New Clues from the Suzaku Monitoring of the X-Ray Absorbers in NGC 7582

• Published in: The Astrophysical journal Vol. 695; no. 1; pp. 781 - 787
• Main Authors: Bianchi, Stefano, Piconcelli, Enrico, Chiaberge, Marco, Bailón, Elena Jiménez, Matt, Giorgio, Fiore, Fabrizio
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 10.04.2009; IOP
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Active galaxies; Seyfert galaxies; galaxies: Seyfert; galaxies: active; Active galaxy nuclei; Galaxy nuclei; X-rays: individual (NGC 7582)
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/695/1/781

We present the results of a Suzaku monitoring campaign of the Seyfert 2 galaxy, NGC 7582. The source is characterized by very rapid (on timescales even lower than a day) changes of the column density of an inner absorber, together with the presence of constant components arising as reprocessing from a Compton-thick material. The best-fitting scenario implies important modifications to the zeroth-order view of Unified Models. While the existence of a pc-scale torus is needed in order to produce a constant Compton reflection component and an iron Ka-emission line, in this Seyfert 2 galaxy this is not viewed along the line of sight. On the other hand, the absorption of the primary continuum is due to another material, much closer to the black hole, roughly at the distance of the broad-line region, which can produce the observed rapid spectral variability. On top of that, the constant presence of a 1022 cm-2 column density can be ascribed to the presence of a dust lane, extended on a galactic scale, as previously confirmed by Chandra. There is now mounting evidence that complexity in the obscuration of active galactic nuclei (AGNs) may be the rule rather than the exception. We therefore propose to modify the Unification Model, adding to the torus the presence of two further absorbers/emitters. Their combination along the line of sight can reproduce all the observed phenomenology.