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Astron. Astrophys. 336, 807-814 (1998)

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Anisotropic illumination in AGNs

The reflected component. Comparison to hard X-ray spectra from Seyfert Galaxies

J. Malzac 1, E. Jourdain 1, P.O. Petrucci 2 and G.Henri 2

1 C.E.S.R. (CNRS/UPS), 9, av. du Colonel Roche, B.P. 4346, F-31028 Toulouse Cedex 4, France
2 Laboratoire d'Astrophysique, Observatoire de Grenoble, B.P. 53X, F-38041 Grenoble Cedex, France

Received 18 February 1998 / Accepted 29 May 1998


We calculate the reflection component predicted by the anisotropic illumination model of Henri & Petrucci 1997. This component appears to be more important than for isotropic models. The overall X/[FORMULA] spectrum is found to be strongly angle-dependent. When the accretion disc is seen with a nearly edge-on orientation the reflection hump is weak, while a face-on viewing angle leads to a proeminent reflection hump with an equivalent reflection coefficient [FORMULA]. Such reflection dominated Seyfert 1s galaxies are not observed. By fitting observed X/[FORMULA] spectra, we derive inclination angle [FORMULA] for MCG 8-11-11 and [FORMULA] for IC 4329a and NGC 4151. Although the model succeed in reproducing individual observed spectra, it requires all the Seyfert 1s observed in the X-ray band to be seen with large inclination angles. Such a situation is highly improbable. On the other hand, we show that the ionisation of a fair part of the reflecting disk could represent an interesting improvement of the model, consistent with the data and relaxing the constraints on the high energy cut-off in Seyfert galaxies.

Key words: radiative transfer – X-rays: galaxies – galaxies: Seyfert – galaxies: individual: IC 4329a – galaxies: individual: MCG 8-11-11 – galaxies individual: NGC 4151

Send offprint requests to: J. Malzac, (malzac@cesr.cnes.fr)

© European Southern Observatory (ESO) 1998

Online publication: July 27, 1998