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Paper: AGN-Obscuring Starbursts
Volume: 249, The Central Kiloparsec of Starbursts and AGN: the La Palma Connection
Page: 418
Authors: Levenson, N. A.; Cid Fernandes, R.; Weaver, K. A.; Heckman, T. M.; Storchi-Bergmann, T.
Abstract: X-ray observations demonstrate that Seyfert 2 galaxies containing circumnuclear starbursts are significantly more absorbed than ``pure'' Seyfert 2s without starbursts. The starbursts themselves contribute to the obscuration. In some cases, a ``torus'' or other material very close to the active nucleus is also present, and these examples fit within unified models that attribute observational differences between Seyfert 1 and Seyfert 2 galaxies to viewing geometry. In other cases, however, the starburst alone accounts for the obscuration. The orientation of the nuclear region is genuinely face-on, although the starburst conceals the broad optical emission lines that would otherwise classify these galaxies as Seyfert 1s. In extreme cases, only the starburst, not the active nucleus, may be detectable at optical wavelengths, but the central engine remains the primary source of X-rays. While optical surveys would not identify the active nuclei that make these ``X-ray-loud composite galaxies'' significant X-ray sources, such galaxies may in fact be important contributors to the cosmic X-ray background.
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