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arXiv · astro-ph/0103077

Properties of the circumnuclear medium in Active Galactic Nuclei

R. Gilli·G. Risaliti·P. Severgnini·R. Maiolino·A. Marconi·M. Salvati
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Abstract

We propose a classification scheme for the circumnuclear medium of AGNs based on their location in the A_V - N_H plane (related to dust absorption and gas absorption, respectively). We present evidence that the A_V/N_H ratio is often lower than the Galactic value. This is shown by the broad line ratios of a sample of intermediate Seyferts, and by the optical/X-ray ratio of line selected (as opposed to color selected) AGNs. We point out the implications for the physical properties of the absorber. A complete classification would require a third axis, related to the density of the absorber and/or its distance from the AGN.

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R. Gilli, G. Risaliti, P. Severgnini, R. Maiolino, A. Marconi, M. Salvati. 2001-03-05. Properties of the circumnuclear medium in Active Galactic Nuclei. https://arxiv.org/abs/astro-ph/0103077

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