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Paper: Buried AGNs in LINER Ultraluminous Infrared Galaxies
Volume: 320, The Neutral ISM in Starburst Galaxies
Page: 266
Authors: Imanishi, M.
Abstract: We report on ground-based infrared 2.8−4.1 μm slit spectra of the nuclei of ultraluminous infrared galaxies (ULIRGs) classified optically as LINERs. Strong absorption features by ice-covered dust grains at 3.05 μm and/or by bare dust grains at 3.4 μm are detected. Based on the absorption optical depths of these features, it is quantitatively demonstrated that the buried energy sources in the majority of the observed ULIRGs are not spatially mixed with nuclear dust and molecular gas, as is expected for a typical starburst, but are very compact and more centrally-concentrated than the nuclear dust and molecular gas. This geometrical requirement is best explained by a buried AGN, and in these ULIRGs, the dereddened AGN luminosities can be comparable to the infrared luminosities.
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