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Un modèle non-thermique de l'émission UV-X des galaxies de Seyfert : théories et contraintes observationnelles

Abstract : Whereas the observations of a high energy cut-off around one hundred ke V and the non detection of any annihilation lines in the spectra of Seyfert galaxies seem to favor thermal models, this work shows that non-thermal emission can also be an explanation of these phenomena. We develop a self-consistent non-thermal model of Seyfert galaxies continuum emission from UV to X ray. A high energy source, at rest at a given height above an accretion disk, is assumed to contain a non-thermal plasma scattering by Inverse Compton (IC) process the soft photons emitted as thermal radiation by the disk. The disk itself radiates only by reprocessing of the high energy radiation. This hot source is supposed to be the terminal shock of an aborted jet coming from the disk. Such a geometry is highly anisotropie which has a strong influence on IC process. The main characteristies of this model are deduced from the radiative balance between the disk and the hot source. Reflected components are included in order to fits obsevationnal data of different objects. Due to the anisotropy of the illumination, these components appear to be much more important than in standard isotropie illumination models, which leads to different conclusions for the inclination angles. Finally, we obtain a detailed study of the shock giving birth to the hot source, taking into account first and second order processes and radiative losses. These theoretical works are completed by the optical observations of a large sampIe of Seyfert galaxies in order to detect microvariabilities. We only obtain upper limits which constrain, in the scope of this non-thermal model, physical and geometrical parameters of the central regions of these Active Nuclei.
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Contributor : Pascale Talour <>
Submitted on : Monday, August 13, 2012 - 4:43:21 PM
Last modification on : Thursday, November 19, 2020 - 12:54:02 PM
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  • HAL Id : tel-00723762, version 1




Pierre-Olivier Petrucci. Un modèle non-thermique de l'émission UV-X des galaxies de Seyfert : théories et contraintes observationnelles. Astrophysique galactique [astro-ph.GA]. Université Joseph-Fourier - Grenoble I, 1998. Français. ⟨tel-00723762⟩



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