Melbourne, J. and Ammons, M. and Wright, S. A. and Metevier, A. and Steinbring, E. and Max, C. and Koo, D. C. and Larkin, J. E. and Barczys, M. (2008) Triggered or self-regulated star formation within intermediate redshift luminous infrared galaxies. I. Morphologies and spectral energy distributions. Astronomical Journal, 135 (4). pp. 1207-1224. ISSN 0004-6256. http://resolver.caltech.edu/CaltechAUTHORS:20090410-141816524
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As part of the Center for Adaptive Optics (AO) Treasury Survey (CATS) we imaged a set of 15 intermediate redshift (z ~ 0.8) luminous infrared (IR) galaxies (LIRGs) with the Keck Laser Guide Star (LGS) AO facility. These galaxies were selected from the Great Observatories Origins Deep Survey (GOODS) southern field, allowing us to combine the high spatial resolution Hubble Space Telescope optical (B, V, i, and z-bands) images with our near-infrared (K'-band) images to study the LIRG morphologies and spatially resolved spectral energy distributions (SEDs). Two thirds of the LIRGs are disk galaxies, with only one third showing some evidence for interactions, minor, or major mergers. In contrast with local LIRG disks (which are primarily barred systems), only 10% of the LIRG disks in our sample contain a prominent bar. While the optical bands tend to show a significant point-like substructure, indicating distributed star formation, the AO K-band images tend to be smooth. They lack point-like structures to a K ~ 23.5 limit. This places an upper bound on the number of red super giants per blue knot at less than 4000. The SEDs of the LIRGs are consistent with distributed dusty star formation, as exhibited by optical to IR colors redder than allowed by old stellar populations alone. This effect is most pronounced in the galaxy cores, possibly indicating central star formation. We also observed a set of 11 intermediate redshift comparison galaxies, selected to be non-ellipticals with apparent K-band magnitudes comparable to the LIRGs. The "normal" (non-LIRG) systems tended to have lower optical luminosity, lower stellar mass, and more irregular morphology than the LIRGs. Half of the "normal" galaxies have SEDs consistent with intermediate aged stellar populations and minimal dust. The other half show evidence for some dusty star formation, usually concentrated in their cores. Our work suggests that the LIRG disk galaxies are similar to large disk systems today, undergoing self-regulated star formation, only at 10-20 times higher rates.
|Additional Information:||© 2008 The American Astronomical Society. Received 2007 August 29; accepted 2007 December 22; published 2008 March 4. We would like to thank Emeric Le Floc’h for contributing the 24 μm measurements of GOODS-S galaxies. This work has been supported in part by the NSF Science and Technology Center for Adaptive Optics, managed by the University of California (UC) at Santa Cruz under the cooperative agreement No. AST-9876783. It was also supported by the HST archival grant HST-AR-10965. The laser guide star adaptive optics system was funded by the W.M. Keck Foundation. The artificial laser guide star system was developed and integrated in a partnership between the Lawrence Livermore National Labs (LLNL) and the W.M. Keck Observatory. The laser was integrated at Keck with the help of Curtis Brown and Pamela Danforth. The NIRC2 near-infrared camera was developed by CalTech, UCLA and Keck (P.I. Keith Matthews). The data presented herein were obtained at the Keck Observatory, which is operated as a scientific partnership among the CalTech, UC and NASA. This work is supported in part under the auspices of the US Department of Energy, National Nuclear Security Administration and by the LLNL under contract W-7405-Eng-48. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this superb mountain.|
|Subject Keywords:||galaxies: spiral; galaxies: starburst; galaxies: stellar content; infrared: galaxies; instrumentation: adaptive optics|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||09 Jul 2009 23:44|
|Last Modified:||07 Jul 2015 17:41|
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