An XMM-Newton observation of Ton S180: Constraints on the continuum emission in ultrasoft Seyfert galaxies

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dc.creatorVaughan, S.
dc.creatorBoller, Th.
dc.creatorFabian, A. C.
dc.creatorBallantyne, D. R.
dc.creatorBrandt, W. N.
dc.creatorTrumper, J.
dc.date2002-07-30
dc.date.accessioned2026-07-07T10:47:27Z
dc.date.available2026-07-07T10:47:27Z
dc.descriptionWe present an XMM-Newton observation of the bright, narrow-line, ultrasoft Seyfert 1 galaxy Ton S180. The 0.3-10 keV X-ray spectrum is steep and curved, showing a steep slope above 2.5 keV (Gamma ~ 2.3) and a smooth, featureless excess of emission at lower energies. The spectrum can be adequately parameterised 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 ionised accretion disc, inverse-Compton scattering of soft disc photons by thermal electrons, and Comptonisation by electrons with a hybrid thermal/non-thermal distribution. We emphasise 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.
dc.description9 pages, accepted for publication in MNRAS
dc.identifierhttps://arxiv.org/abs/astro-ph/0207650
dc.identifierhttp://arxiv.org/abs/astro-ph/0207650
dc.identifierMon.Not.Roy.Astron.Soc.337:247,2002
dc.identifierdoi:10.1046/j.1365-8711.2002.05908.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/183539
dc.subjectAstrophysics
dc.titleAn XMM-Newton observation of Ton S180: Constraints on the continuum emission in ultrasoft Seyfert galaxies
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