GOODS-HERSCHEL AND CANDELS: THE MORPHOLOGIES OF ULTRALUMINOUS INFRARED GALAXIES AT z ∼ 2

By J. Kartaltepe, Mark Dickinson, D. M. Alexander, Eric F. Bell, T. Dahlén, D. Elbaz, S. Faber, J. Lotz, D. H. Mcintosh, T. Wiklind and 33 more. 2011

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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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/198978972faf686aaffea37f4a60876057ca821e

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Citations in the corpus

Dusty Star Forming Galaxies at High Redshift (2014, background): “Observations suggest that main sequence galaxies at higher redshifts (z ∼ 2) undergo a higher fraction of mergers and interactions than their z ∼ 0 counterparts (e.g. Lotz et al., 2008; Kartaltepe et al., 2010, 2012).”
UNLEASHING POSITIVE FEEDBACK: LINKING THE RATES OF STAR FORMATION, SUPERMASSIVE BLACK HOLE ACCRETION, AND OUTFLOWS IN DISTANT GALAXIES (2013, background): “…important for the most extreme star formation rates observed at high redshift, and are important locally in accounting for ULIRGs, they are likely subdominant at high redshift both in triggering the bulk of star formation (Kartaltepe et al. 2012) and in triggering AGNs (Treister et al. 2012).”
Cosmic X-ray surveys of distant active galaxies (2015, background): “…luminous AGNs are preferentially triggered by major mergers, as also found for the most powerful star-forming galaxies (e.g., Treister et al 2012; Kartaltepe et al 2012), which could indicate that major mergers are required to drive sufficient quantities of gas into the central regions of…”
THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES THE REST-FRAME FAR-INFRARED EMISSION OF SUB-MILLIMETER GALAXIES (2014, background): “…and/or irregular morphologies (Chen et al. 2014), and the low Sérsic index n measured for the population is consistent with merging systems (Kartaltepe et al. 2012); dynamical studies of resolved Hα emission from SMGs find strong evidence of kinematically distinct multiple components…”
The Evolution of Galaxy Structure Over Cosmic Time (2014, background): “Kartaltepe et al. (2012) find that a sample of ULIRGs selected from the CANDELS fields are more likely than a field galaxy sample to be involved in galaxy interactions and mergers (72+5−7% vs. 32±3%).”
REGULARITY UNDERLYING COMPLEXITY: A REDSHIFT-INDEPENDENT DESCRIPTION OF THE CONTINUOUS VARIATION OF GALAXY-SCALE MOLECULAR GAS PROPERTIES IN THE MASS-STAR FORMATION RATE PLANE (2013, unknown): “…to pure luminosity-selection are required for obtaining a census of bursty SF activity at high redshift, e.g., based on their position in the SFR versus M⋆ plane (e.g., Rodighiero et al. 2011, Whitaker et al. 2012) or based on their morphology (e.g., Kartaltepe et al. 2012, Kaviraj et al. 2013).”
Morphologies of z ∼ 0.7 AGN host galaxies in CANDELS: no trend of merger incidence with AGN luminosity (2014, background): “Bluer bands are also inspected to facilitate the classification (Kartaltepe et al. 2012, 2014).”
BLACK HOLE VARIABILITY AND THE STAR FORMATION–ACTIVE GALACTIC NUCLEUS CONNECTION: DO ALL STAR-FORMING GALAXIES HOST AN ACTIVE GALACTIC NUCLEUS? (2013, methodology): “We adopt the relationship between fmerge and LIR obtained using deep Hubble Space Telescope rest-frame optical imaging of luminous star-forming galaxies (Kartaltepe et al. 2012).”
A CANDELS–3D-HST SYNERGY: RESOLVED STAR FORMATION PATTERNS AT 0.7 < z < 1.5 (2013, background): “…initial subsets of the CANDELS legacy data set, several works have 2 contrasted monochromatic structural measurements to galaxy-integrated stellar population properties (Wuyts et al. 2011b; Szomoru et al. 2011; Bell et al. 2012; Wang et al. 2012; Kartaltepe et al. 2012; Bruce et al. 2012).”
THE KMOS3D SURVEY: DESIGN, FIRST RESULTS, AND THE EVOLUTION OF GALAXY KINEMATICS FROM 0.7 ⩽ z ⩽ 2.7 (2014, background): “…parameters (e.g. Sérsic indices; 8 Wisnioski et al. Wuyts et al. 2011a; Law et al. 2012b; van der Wel et al. 2014b) or visual classifications (e.g. Kartaltepe et al. 2012; Hung et al. 2013), which yield similar findings of a MS dominated by disk galaxies with the majority of mergers lying above…”
The Herschel census of infrared SEDs through cosmic time (2013, background): “Moreover, Zamojski et al. (2011) and Kartaltepe et al. (2012) find more than 70 per cent of ULIRGs up to z ∼ 2 to be mergers.”
SMOOTH(ER) STELLAR MASS MAPS IN CANDELS: CONSTRAINTS ON THE LONGEVITY OF CLUMPS IN HIGH-REDSHIFT STAR-FORMING GALAXIES (2012, methodology): “We mention in passing that object ID12328 serves as the prototype of 6 a merging system in the CANDELS visual classification effort (e.g., Kocevski et al. 2012; Kartaltepe et al. 2012).”