[en] We report results from multi-epoch X-ray observations of the Seyfert 1.5 galaxy ESO 362-G18 performed between 2005 November and 2010 June. ESO 362-G18 generally exhibits the typical X-ray spectrum of type 1 active galactic nuclei. A disc-reflection component accounts for broad residuals in the iron K band and above 10 keV, as well as for a significant soft excess. From our best-fitting reflection model, we measure a black hole spin a ≥ 0.92 at the 99.99 per cent confidence level. ESO 362-G18 is also (typically) mildly absorbed by a column of neutral gas. The absorber is variable and one observation, performed ˜2 months after a typical mildly absorbed one, is heavily absorbed by a cold column density of ˜ 3-4 × 10[SUP]23[/SUP] cm[SUP]-2[/SUP], nearly two orders of magnitude higher than that during any other observation. UV variability between the heavily absorbed observation and the others suggests that the absorber can be identified with a dusty, clumpy torus. The absorption variability time-scale enables us to locate the X-ray-emitting region within the innermost ˜50 gravitational radii. Such result holds not only for the X-ray continuum, but also for the soft excess.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Agis-Gonzalez, Beatriz ; Centro de Astrobiología (CSIC-INTA), Dep. de Astrofíica, Villanueva de la Cañada, E-28692, Madrid, Spain
Miniutti, G.; Centro de Astrobiologia (CSIC-INTA), Dep. de Astrofisica ; ESA, PO Box 78, E-28691 Villanueva de la Cañada, Madrid, Spain
Kara, E.; Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
Fabian, A. C.; Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
Sanfrutos, M.; Centro de Astrobiologia (CSIC-INTA), Dep. de Astrofisica ; ESA, PO Box 78, E-28691 Villanueva de la Cañada, Madrid, Spain
Risaliti, G.; Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138, USA ; INAF - Osservatorio Astronomico di Arcetri, L.go E. Fermi 5, I-50125 Firenze, Italy
Bianchi, S.; Dipartimento di Matematica e Fisica, Università degli Studi di Roma Tre, via della Vasca Navale 84, I-00146 Roma, Italy
Strotjohann, N. L.; Physikalisches Institut, Universität Bonn, Nussallee 12, D-53115 Bonn, Germany
Saxton, R. D.; XMM SOC, ESA, PO Box 78, E-28691 Villanueva de la Cañada, Madrid, Spain
Parker, M. L.; Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK)
Language :
English
Title :
Black hole spin and size of the X-ray-emitting region(s) in the Seyfert 1.5 galaxy ESO 362-G18