NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-07-15 T15:29:53 PDT
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For refcode 2005A&A...442..185B:
Retrieve 27 NED objects in this reference.
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NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2005A&A...442..185B A search for changing-look AGN in the Grossan catalog S. Bianchi, M. Guainazzi, G. Matt, M. Chiaberge, K. Iwasawa, F. Fiore and R. Maiolino Received 9 May 2005 / Accepted 13 July 2005 We observed with XMM-Newton 4 objects selected from the Grossan (1992, Ph.D. Thesis) catalog, with the aim to search for new "changing-look" AGN. The sample includes all the sources which showed in subsequent observations a flux much lower than the one measured with HEAO A-1: NGC 7674, NGC 4968, IRAS 13218+0552 and NGC 1667. None of the sources was caught in a high flux state during the XMM-Newton observations, whose analysis reveal they are all likely Compton-thick objects. We suggest that, for all the sources, potential problems with the HEAO A-1 source identification and flux measurement prevent us from being certain that the HEAO A-1 data represent a putative "high" state for these objects. Nonetheless, based on the high flux state and Compton-thin spectrum of its GINGA observation, NGC 7674 represents probably the sixth known case of a "changing-look" Seyfert 2 galaxy. From the X-ray variability pattern, we can estimate a likely lower limit of a few parsec to the distance of the inner walls of the torus in this object. Remarkably, IRAS 13218+0552 was not detected by XMM-Newton, despite being currently classified as a Seyfert 1 with a large [OIII] flux. However, the original classification was likely to be affected by an extreme velocity outflow component in the emission lines. The object likely harbors an highly obscured AGN and should be re-classified as a type 2 source. Key words: galaxies: Seyfert, X-rays: galaxies, X-rays: individual: NGC 7674, X-rays: individual: IRAS 13218+0552
Retrieve 27 NED objects in this reference.
Please click here for ADS abstract

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