Volume 415, Number 1, February III 2004
|Page(s)||47 - 54|
|Published online||03 February 2004|
The origin of optical emission from super-Eddington accreting Active Galactic Nuclei: The case of Ton S 180
LUTh/Observatoire de Paris-Meudon et CNRS UMR 8102, Place Jules Janssen, 92195 Meudon Cedex, France e-mail: Toshihiro.Kawaguchi@obspm.fr; Arnaud.Pierens@obspm.fr; Jean-Marc.Hure@obspm.fr
2 Postdoctoral Fellow of the Japan Society for the Promotion of Science
3 Université Paris 7 Denis Diderot, 2 place Jussieu, 75251 Paris Cedex 05, France
Corresponding author: T. Kawaguchi, Toshihiro.Kawaguchi@obspm.fr
Accepted: 17 October 2003
Self-gravitating accretion discs have only been studied in a few nearby objects using maser spots at the parsec-scale. We find a new spectral window for observing the self-gravitating accretion disc in super-Eddington accreting Active Galactic Nuclei (AGNs). This window is determined by calculating the outermost radius () of a non self-gravitating disc and the corresponding emission wavelength () as a function of various disc parameters. We find that reaches ~ for , when (where α, , and are, respectively, the viscosity parameter, gas accretion rate onto the central black hole (BH), the BH mass and the Eddington luminosity). Moreover, is as small as ~ for , which is the smallest α case in this study. Therefore, the window for observing the self-gravitating part of an AGN accretion disc is from ~m to . Incidentally, can be less than the photon trapping radius for . Namely, a self-gravitating, optically-thick, advection-dominated accretion disc is expected to appear in the extremely high accretion rate regime. Next, we demonstrate that the Mid-Infrared to X-ray spectrum of a bright, well-studied Narrow-Line Seyfert 1 galaxy, Ton S 180, is indeed well fitted by the spectrum arising from the following three components: an inner slim disc (with a corona), an outer, self-gravitating non-Keplerian disc and a dusty torus. The total mass, BH mass plus the entire disc mass, is found to be about . If the surface density varies with radius r in proportion to r-0.6, the total mass is consistent with the central mass estimated by Hβ and [O III] widths.
Key words: accretion, accretion disks / radiation mechanisms: thermal / galaxies: active / galaxies: individual: Ton S 180 / galaxies: nuclei / galaxies: Seyfert
© ESO, 2004
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