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GOODS-Herschel and CANDELS : the morphologies of ultraluminous infrared galaxies at z ∼ 2

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Abstract
Using deep 100 and 160 mu m observations in GOODS-South from GOODS-Herschel, combined with high-resolution HST/WFC3 near-infrared imaging from CANDELS, we present the first detailed morphological analysis of a complete, far-infrared (FIR) selected sample of 52 ultraluminous infrared galaxies (ULIRGs; L-IR > 10(12) L-circle dot) at z similar to 2. We also make use of a comparison sample of galaxies with lower IR luminosities but with the same redshift and H-band magnitude distribution. Our visual classifications of these two samples indicate that the fractions of objects with disk and spheroid morphologies are roughly the same but that there are significantly more mergers, interactions, and irregular galaxies among the ULIRGs (72(-7)(+5)% versus 32 +/- 3%). The combination of disk and irregular/interacting morphologies suggests that early-stage interactions, minor mergers, and disk instabilities could play an important role in ULIRGs at z similar to 2. We compare these fractions with those of a z similar to 1 sample selected from GOODS-H and COSMOS across a wide luminosity range and find that the fraction of disks decreases systematically with LIR while the fraction of mergers and interactions increases, as has been observed locally. At comparable luminosities, the fraction of ULIRGs with various morphological classifications is similar at z similar to 2 and z similar to 1, though there are slightly fewer mergers and slightly more disks at higher redshift. We investigate the position of the z similar to 2 ULIRGs, along with 70 z similar to 2 LIRGs, on the specific star formation rate versus redshift plane, and find 52 systems to be starbursts (i.e., they lie more than a factor of three above the main-sequence relation). We find that many of these systems are clear interactions and mergers (similar to 50%) compared to only 24% of systems on the main sequence relation. If irregular disks are included as potential minor mergers, then we find that up to similar to 73% of starbursts are involved in a merger or interaction at some level. Although the final coalescence of a major merger may not be required for the high luminosities of ULIRGs at z similar to 2 as is the case locally, the large fraction (50%-73%) of interactions at all stages and potential minor mergers suggests that these processes contribute significantly to the high star formation rates of ULIRGs at z similar to 2.
Keywords
ORIGINS DEEP SURVEY, REDSHIFT SUBMILLIMETER GALAXIES, STAR-FORMING, GALAXIES, SPACE-TELESCOPE MORPHOLOGIES, SPECTRAL ENERGY-DISTRIBUTION, EXTRAGALACTIC LEGACY SURVEY, DUST-OBSCURED GALAXIES, EXTENDED GROTH, STRIP, OPTICAL SPECTROSCOPY, MASSIVE GALAXIES, galaxies: active, galaxies: evolution, galaxies: starburst, infrared: galaxies

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Chicago
Kartaltepe, Jeyhan S, Mark Dickinson, David M Alexander, Eric F Bell, Tomas Dahlen, David Elbaz, SM Faber, et al. 2012. “GOODS-Herschel and CANDELS : the Morphologies of Ultraluminous Infrared Galaxies at z ∼ 2.” Astrophysical Journal 757 (1).
APA
Kartaltepe, J. S., Dickinson, M., Alexander, D. M., Bell, E. F., Dahlen, T., Elbaz, D., Faber, S., et al. (2012). GOODS-Herschel and CANDELS : the morphologies of ultraluminous infrared galaxies at z ∼ 2. ASTROPHYSICAL JOURNAL, 757(1).
Vancouver
1.
Kartaltepe JS, Dickinson M, Alexander DM, Bell EF, Dahlen T, Elbaz D, et al. GOODS-Herschel and CANDELS : the morphologies of ultraluminous infrared galaxies at z ∼ 2. ASTROPHYSICAL JOURNAL. 2012;757(1).
MLA
Kartaltepe, Jeyhan S, Mark Dickinson, David M Alexander, et al. “GOODS-Herschel and CANDELS : the Morphologies of Ultraluminous Infrared Galaxies at z ∼ 2.” ASTROPHYSICAL JOURNAL 757.1 (2012): n. pag. Print.
@article{8573769,
  abstract     = {Using deep 100 and 160 mu m observations in GOODS-South from GOODS-Herschel, combined with high-resolution HST/WFC3 near-infrared imaging from CANDELS, we present the first detailed morphological analysis of a complete, far-infrared (FIR) selected sample of 52 ultraluminous infrared galaxies (ULIRGs; L-IR > 10(12) L-circle dot) at z similar to 2. We also make use of a comparison sample of galaxies with lower IR luminosities but with the same redshift and H-band magnitude distribution. Our visual classifications of these two samples indicate that the fractions of objects with disk and spheroid morphologies are roughly the same but that there are significantly more mergers, interactions, and irregular galaxies among the ULIRGs (72(-7)(+5)% versus 32 +/- 3%). The combination of disk and irregular/interacting morphologies suggests that early-stage interactions, minor mergers, and disk instabilities could play an important role in ULIRGs at z similar to 2. We compare these fractions with those of a z similar to 1 sample selected from GOODS-H and COSMOS across a wide luminosity range and find that the fraction of disks decreases systematically with LIR while the fraction of mergers and interactions increases, as has been observed locally. At comparable luminosities, the fraction of ULIRGs with various morphological classifications is similar at z similar to 2 and z similar to 1, though there are slightly fewer mergers and slightly more disks at higher redshift. We investigate the position of the z similar to 2 ULIRGs, along with 70 z similar to 2 LIRGs, on the specific star formation rate versus redshift plane, and find 52 systems to be starbursts (i.e., they lie more than a factor of three above the main-sequence relation). We find that many of these systems are clear interactions and mergers (similar to 50%) compared to only 24% of systems on the main sequence relation. If irregular disks are included as potential minor mergers, then we find that up to similar to 73% of starbursts are involved in a merger or interaction at some level. Although the final coalescence of a major merger may not be required for the high luminosities of ULIRGs at z similar to 2 as is the case locally, the large fraction (50%-73%) of interactions at all stages and potential minor mergers suggests that these processes contribute significantly to the high star formation rates of ULIRGs at z similar to 2.},
  articleno    = {23},
  author       = {Kartaltepe, Jeyhan S and Dickinson, Mark and Alexander, David M and Bell, Eric F and Dahlen, Tomas and Elbaz, David and Faber, SM and Lotz, Jennifer and McIntosh, Daniel H and Wiklind, Tommy and Altieri, Bruno and Aussel, Herve and Bethermin, Matthieu and Bournaud, Frederic and Charmandaris, Vassilis and Conselice, Christopher J and Cooray, Asantha and Dannerbauer, Helmut and Dave, Romeel and Dunlop, James and Dekel, Avishai and Ferguson, Henry C and Grogin, Norman A and Hwang, Ho Seong and Ivison, Rob and Kocevski, Dale and Koekemoer, Anton and Koo, David C and Lai, Kamson and Leiton, Roger and Lucas, Ray A and Lutz, Dieter and Magdis, Georgios and Magnelli, Benjamin and Morrison, Glenn and Mozena, Mark and Mullaney, James and Newman, Jeffrey Allen and Pope, Alexandra and Popesso, Paola and van der Wel, Arjen and Weiner, Benjamin and Wuyts, Stijn},
  issn         = {0004-637X},
  journal      = {ASTROPHYSICAL JOURNAL},
  keywords     = {ORIGINS DEEP SURVEY,REDSHIFT SUBMILLIMETER GALAXIES,STAR-FORMING,GALAXIES,SPACE-TELESCOPE MORPHOLOGIES,SPECTRAL ENERGY-DISTRIBUTION,EXTRAGALACTIC LEGACY SURVEY,DUST-OBSCURED GALAXIES,EXTENDED GROTH,STRIP,OPTICAL SPECTROSCOPY,MASSIVE GALAXIES,galaxies: active,galaxies: evolution,galaxies: starburst,infrared: galaxies},
  language     = {eng},
  number       = {1},
  pages        = {16},
  title        = {GOODS-Herschel and CANDELS : the morphologies of ultraluminous infrared galaxies at z ∼ 2},
  url          = {http://dx.doi.org/10.1088/0004-637X/757/1/23},
  volume       = {757},
  year         = {2012},
}

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