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ID: 5724.0, MPI für extraterrestrische Physik / High Energy Astrophysics at MPE
An XMM-Newton observation of Ton S180: constraints on the continuum emission in ultrasoft Seyfert galaxies
Authors:Vaughan, S.; Boller, T.; Fabian, A. C.; Ballantyne, D. R.; Brandt, W. N.; Trümper, J.
Date of Publication (YYYY-MM-DD):2002-11-21
Title of Journal:Monthly Notices of the Royal Astronomical Society
Journal Abbrev.:Mon. Not. R. Astron. Soc.
Issue / Number:1
Start Page:247
End Page:255
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:We present an XMM-Newton observation of the bright, narrow- line, ultrasoft type 1 Seyfert galaxy Ton S180. The 0.3-10 keV X-ray spectrum is steep and curved, showing a steep slope above 2.5 keV (Gamma similar to 2.3) and a smooth, featureless excess of emission at lower energies. The spectrum can be adequately parametrized using a simple double power-law model. The source is strongly variable over the course of the observation but shows only weak spectral variability, with the fractional variability amplitude remaining approximately constant over more than a decade in energy. The curved continuum shape and weak spectral variability are discussed in terms of various physical models for the soft X-ray excess emission, including reflection off the surface of an ionized accretion disc, inverse Compton scattering of soft disc photons by thermal electrons, and Comptonization by electrons with a hybrid thermal/non-thermal distribution. We emphasize the possibility that the strong soft excess may be produced by dissipation of accretion energy in the hot, upper atmosphere of the putative accretion disc.
Free Keywords:galaxies : active; galaxies : individual : Ton S180; galaxies : Seyfert; X-rays : galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für extraterrestrische Physik
External Affiliations:Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA,; England; Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England; Max Planck Inst Extraterr Phys, D-85748 Garching, Germany; Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
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