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Paper: Luminous Infrared Galaxies: Optical Morphology and Photometry, Molecular Gas Masses, and Starburst/AGN Activity versus Infrared Luminosity
Volume: 320, The Neutral ISM in Starburst Galaxies
Page: 230
Authors: Sanders, D.; Ishida, C.
Abstract: Optical (BVI) imaging and photometry have been obtained for a statistically complete sample of 56 luminous infrared galaxies with log Lir/LSolar = 11.12 − 11.99, selected from the all-sky IRAS Revised Bright Galaxy Sample (629 objects with 60 μm flux > 5.24 Jy). These new data add strong support to the theory that strong interactions/mergers of ∼ L* molecular gas-rich spirals are the trigger for the enormous infrared luminosities. Nearly all objects with log Lir/LSolar > 11.5 appear to be in a late stage of merging with a median premerger timescale of ∼3 × 108 yrs. Additional data for our complete sample (optical spectra, CO emission, near-infrared imaging) confirm that as the infrared luminosity increases the mean projected separation of the two nuclei decreases, the nuclear concentration of molecular gas and dust increases, and the fraction of Seyfert-type spectra increases. The ultimate fate of these luminous infrared systems is briefly discussed.
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