TY - JOUR
T1 - GOODS-Herschel and candels
T2 - The morphologies of ultraluminous infrared galaxies at z ∼ 2
AU - Kartaltepe, Jeyhan S.
AU - Dickinson, Mark
AU - Alexander, David M.
AU - Bell, Eric F.
AU - Dahlen, Tomas
AU - Elbaz, David
AU - Faber, S. M.
AU - Lotz, Jennifer
AU - McIntosh, Daniel H.
AU - Wiklind, Tommy
AU - Altieri, Bruno
AU - Aussel, Herve
AU - Bethermin, Matthieu
AU - Bournaud, Frederic
AU - Charmandaris, Vassilis
AU - Conselice, Christopher J.
AU - Cooray, Asantha
AU - Dannerbauer, Helmut
AU - Dave, Romeel S
AU - Dunlop, James
AU - Dekel, Avishai
AU - Ferguson, Henry C.
AU - Grogin, Norman A.
AU - Hwang, Ho Seong
AU - Ivison, Rob
AU - Kocevski, Dale
AU - Koekemoer, Anton
AU - Koo, David C.
AU - Lai, Kamson
AU - Leiton, Roger
AU - Lucas, Ray A.
AU - Lutz, Dieter
AU - Magdis, Georgios
AU - Magnelli, Benjamin
AU - Morrison, Glenn
AU - Mozena, Mark
AU - Mullaney, James
AU - Newman, Jeffrey Allen
AU - Pope, Alexandra
AU - Popesso, Paola
AU - Van Der Wel, Arjen
AU - Weiner, Benjamin
AU - Wuyts, Stijn
PY - 2012/9/20
Y1 - 2012/9/20
N2 - Using deep 100 and 160 μm 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; LIR > 1012 L⊙) at z ∼ 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+5-7% 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 ∼ 2. We compare these fractions with those of a z ∼ 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 ∼ 2 and z ∼ 1, though there are slightly fewer mergers and slightly more disks at higher redshift. We investigate the position of the z ∼ 2 ULIRGs, along with 70 z ∼ 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 (∼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 ∼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 ∼ 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 ∼ 2.
AB - Using deep 100 and 160 μm 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; LIR > 1012 L⊙) at z ∼ 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+5-7% 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 ∼ 2. We compare these fractions with those of a z ∼ 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 ∼ 2 and z ∼ 1, though there are slightly fewer mergers and slightly more disks at higher redshift. We investigate the position of the z ∼ 2 ULIRGs, along with 70 z ∼ 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 (∼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 ∼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 ∼ 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 ∼ 2.
KW - galaxies: active
KW - galaxies: evolution
KW - galaxies: starburst
KW - infrared: galaxies
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UR - http://www.scopus.com/inward/citedby.url?scp=84866135970&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/757/1/23
DO - 10.1088/0004-637X/757/1/23
M3 - Article
AN - SCOPUS:84866135970
SN - 0004-637X
VL - 757
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 23
ER -