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Luminous infrared galaxies in the local universe : global properties, nuclear activity, and the starburst--agn connection

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Item Summary

Title: Luminous infrared galaxies in the local universe : global properties, nuclear activity, and the starburst--agn connection
Authors: U, Vivian
Keywords: luminous infrared galaxies
global properties
nuclear activity
Starburst-Agn Connection
Issue Date: Dec 2012
Publisher: [Honolulu] : [University of Hawaii at Manoa], [December 2012]
Abstract: We present the kinematic and energetic properties of the local luminous and ultraluminous galaxies through a multiwavelength study of the global photometry and a high resolution near-infrared and submillimeter investigation of the inner few-kiloparsec region. Global spectral energy distributions (SEDs) have been constructed using uniform photometry extracted with common aperture masks, enabling derivation of physical properties such as infrared luminosities and stellar masses as a whole. Using a modified blackbody fit to the mid-infrared to submillimeter SED, infrared luminosities LIR [8 −1000μm] have been recomputed and shown to be ∼0.02 dex systematically lower than those determined previously from the four IRAS bands. The mean dust temperature for the sample is 33.2 ± 6.2 K; the mean dust mass is Mdust = 2 × 107M⊙. The mean stellar mass is M⋆ = 6×1010M⊙, consistent with that for high-z objects with similar luminosities. Using different AGN indicators, ∼60% of the ULIRGs (and 25% of the LIRGs) are classified as an AGN.
A basic understanding of the global properties of the local (U)LIRGs prompt detailed investigations on the physical processes associated with nuclear energetic activity. We have undertaken a high-resolution observing campaign using Keck's near-infrared integral-field spectrograph with adaptive optics and the Submillimeter Array to study gas and stellar morphology and kinematics in the nuclei of these infrared-luminous galaxy mergers. At least one nucleus in each of the merger systems is found to host a nuclear molecular disk ≥ 200 pc in size. Black hole masses range from ∼ 3 × 108M⊙ to 1 × 109M⊙, and often fall close to or above the well-known scaling relations that correlates black holes and their host galaxies' bulges. The cold CO gas that fuels nuclear activity is found to reside in compact gas disks 1 − 2.5 kpc in size, with masses MH2 ∼ 109−10M⊙. Through general surveys and specific case studies of NGC 6240 and Mrk 273, we demonstrate the value of high-resolution near-infrared and submillimeter observations in disentangling the physical conditions at the heart of (U)LIRGs.
Description: Ph.D. University of Hawaii at Manoa 2012.
Includes bibliographical references.
URI/DOI: http://hdl.handle.net/10125/100799
Appears in Collections:Ph.D. - Astronomy



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