SIMBAD references

1999ApJ...522..157R - Astrophys. J., 522, 157-164 (1999/September-1)

The distribution of absorbing column densities among Seyfert 2 galaxies.

RISALITI G., MAIOLINO R. and SALVATI M.

Abstract (from CDS):

We use hard X-ray data for an ``optimal'' sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local universe. Of all Seyfert 2 galaxies in the sample, 75% are heavily obscured (NH>1023 cm–2), and about half are Compton thick (NH>1024 cm–2). Intermediate type 1.8-1.9 Seyfert galaxies are characterized by an average NH much lower than ``strict'' Seyfert 2 galaxies. No correlation is found between NH and the intrinsic luminosity of the nuclear source. This NH distribution has important consequences for the synthesis of the cosmic X-ray background. In addition, the large fraction of Compton-thick objects implies that most of the obscuring gas is located within a radius of a few 10 pc from the nucleus.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Galaxies: Nuclei - Galaxies: Seyfert - X-Rays: Galaxies

CDS comments: t.1 : IRS 07145 and 11215 are IRAS 07145-2914 and IRAS 11215-2806

Simbad objects: 95

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