Observations and modeling of a clumpy galaxy at<i>z</i> = 1.6

Bournaud, F.; Daddi, E.; Elmegreen, Bruce G.; Elmegreen, D. M.; Nesvadba, N. P. H.; Vanzella, E.; Matteo, P. Di; Tiran, L. Le; Lehnert, M. D.; Elbaz, D.

doi:10.1051/0004-6361:20079250

Cited by 126 publications

(204 citation statements)

References 70 publications

(67 reference statements)

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“…Real observed galaxies that have publicly available kinematic classification are plotted as large points with error bars: in black for kinematically confirmed disks and in green for the known merger. The sample of observed galaxies with kinematic information is composed by the subset SINS galaxies with kinemetry classification in the GOODS-S area and by the clumpy disk in the study of Bournaud et al (2008) (see Section 6.3 for details.) Right: as on the left panel, but now the color-coding provides the level of contamination from isolated disks (i.e., the fraction of disk snapshots over all snapshots) in any given area of the M 20,MASS and A MASS .…”

Section: Quantitative Definition Of Mergersmentioning

confidence: 99%

“…Classification A kinematic classifications into rotationally supported disk or merger is currently available for some z > 1 galaxies (e.g., Epinat et al 2009;Bournaud et al 2008;Förster Schreiber et al 2009) which can thus be used to further validate the calibration of the classification in the M 20,MASS versus A MASS plane obtained from the MI-RAGE simulations. For this test we consider galaxies with a similar optical+NIR wavelength coverage as our HUDF sample.…”

Section: Validation On Real Galaxies With Kinematicmentioning

confidence: 99%

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A PHYSICAL APPROACH TO THE IDENTIFICATION OF HIGH-ZMERGERS: MORPHOLOGICAL CLASSIFICATION IN THE STELLAR MASS DOMAIN

Cibinel

Floc’h

Perret

et al. 2015

ApJ

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At z 1, the distinction between merging and "normal" star-forming galaxies based on single band morphology is often hampered by the presence of large clumps which result in a disturbed, merger-like appearance even in rotationally supported disks. In this paper we discuss how a classification based on canonical, non-parametric structural indices measured on resolved stellar mass maps, rather than on single-band images, reduces the misclassification of clumpy but not merging galaxies. We calibrate the mass-based selection of mergers using the MIRAGE hydrodynamical numerical simulations of isolated and merging galaxies which span a stellar mass range of 10 9.8 -10 10.6 M ⊙ and merger ratios between 1:1-1:6.3. These simulations are processed to reproduce the typical depth and spatial resolution of observed Hubble Ultra Deep Field (HUDF) data. We test our approach on a sample of real z ≃ 2 galaxies with kinematic classification into disks or mergers and on ∼100 galaxies in the HUDF field with photometric/spectroscopic redshift between 1.5 z 3 and M > 10 9.4 M ⊙ . We find that a combination of the asymmetry A MASS and M 20,MASS indices measured on the stellar mass maps can efficiently identify real (major) mergers with 20% contamination from clumpy disks in the merger sample. This mass-based classification cannot be reproduced in star-forming galaxies by H−band measurements alone, which instead result in a contamination from clumpy galaxies that can be as high as 50%. Moreover, we find that the mass-based classification always results in a lower contamination from clumpy galaxies than an H−band classification, regardless of the depth of the imaging used (e.g.,

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Section: Quantitative Definition Of Mergersmentioning

confidence: 99%

Section: Validation On Real Galaxies With Kinematicmentioning

confidence: 99%

A PHYSICAL APPROACH TO THE IDENTIFICATION OF HIGH-ZMERGERS: MORPHOLOGICAL CLASSIFICATION IN THE STELLAR MASS DOMAIN

Cibinel

Floc’h

Perret

et al. 2015

ApJ

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“…The merging timescale would be around 1.2 Gyr. Although a large and unique rotating disk consituted by large clumps as seen in Bournaud et al (2008) cannot be excluded (leading to V max /σ 0 = 2.3), fitting the brightest component alone gives better results in terms of χ 2 , suggesting and signal to noise ratio (bottom) maps, Hα velocity field (top) and associated errors (bottom), Hα velocity dispersion map and associated errors (bottom) obtained from Gaussian fits to the SINFONI data cubes after smoothing spatially with a two-dimensional Gaussian of FWHM = 2 pixels. Except for the instrumental spectral PSF, no correction has been applied to compute the velocity dispersion map.…”

Section: Vvds220596913mentioning

confidence: 99%

“…Fast turbulent speeds in the gaseous component imply the formation of massive clumps. Gas-rich primordial disks may evolve through a clumpy phase into bright early-type disk galaxies with a massive exponential disk, a classical bulge and possibly a central black hole (Noguchi 1999;Immeli et al 2004a,b;Elmegreen et al 2005;Bournaud et al 2007Bournaud et al , 2008. These massive clumps are suggested from NACO high resolution deep imaging and Hα maps from adaptive optics SINFONI observations in two galaxies of the SINS sample ).…”

Section: Introductionmentioning

confidence: 99%

Integral field spectroscopy with SINFONI of VVDS galaxies

Épinat

Contini²,

Fèvre

et al. 2009

A&A

158

265

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Context. Identifying the main processes of galaxy assembly at high redshifts is still a major issue in understanding galaxy formation and evolution at early epochs in the history of the Universe. Aims. This work aims to provide a first insight into the dynamics and mass assembly of galaxies at redshifts 1.2 < z < 1.6, the early epoch just before the sharp decrease of the cosmic star formation rate. Methods. We use the near-infrared integral field spectrograph SINFONI on the ESO-VLT under 0.65 seeing to obtain spatially resolved spectroscopy on nine emission line galaxies with 1.2 ≤ z ≤ 1.6 from the VIMOS VLT Deep Survey. We derive the velocity fields and velocity dispersions on kpc scales using the Hα emission line. Results. Out of the nine star-forming galaxies, we find that galaxies are distributed in three groups: two galaxies can be well reproduced by a rotating disk, three systems can be classified as major mergers and four galaxies show disturbed dynamics and high velocity dispersion. We argue that there is evidence for hierarchical mass assembly from major merging, with most massive galaxies with M > 10 11 M subject to at least one major merger over a 3 Gyr period as well as for continuous accretion feeding strong star formation. Conclusions. These results point towards a galaxy formation and assembly scenario which involves several processes, possibly acting in parallel, with major mergers and continuous gas accretion playing a major role. Well controlled samples representative of the bulk of the galaxy population at this key cosmic time are necessary to make further progress.

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“…The discrepancies between morphological and kinematical results have increased the importance of kinematic studies because objects that are photometrically irregular in broadband HST images show "regular" kinematic maps (Bournaud et al 2008;van Starkenburg et al 2008;Puech 2010;Jones et al 2010;Förster Schreiber et al 2011;Genzel et al 2011). Thus, the aforementioned results emphasize the crucial role of spatially and spectrally resolved investigations of galaxies at different redshifts, such as those based on integral field spectroscopy (IFS), to map their morphology and kinematics.…”

Section: Introductionmentioning

confidence: 99%

Distinguishing disks from mergers: Tracing the kinematic asymmetries in local (U)LIRGs using kinemetry-based criteria

Bellocchi

Arribas

Colina

2016

A&A

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Context. The kinematic characterization of different galaxy populations is a key observational input for distinguishing between different galaxy evolutionary scenarios because it helps to determine the number ratio of rotating disks to mergers at different cosmic epochs. Local (ultra) luminous infrared galaxies ((U)LIRGs) cover similar range of star formation rates (SFR) as normal high redshift (high-z), star-forming galaxies (SFGs). Therefore, their study offer a unique opportunity to study at high linear resolution and signal-to-noise (S/N) extreme star forming events and compare these events with those observed at high-z. Aims. Our goal is to analyze in detail the kinematics of the ionized gas as traced by the Hα emission of a large sample of 38 local (z < 0.1) (U)LIRG systems (50 individual galaxies). In this study, we apply kinematic criteria, which are able to characterize the evolutionary status of these systems, allowing us to derive the disk and merger ratio in such local systems. Methods. We obtained Very Large Telescope (VLT) VIMOS optical integral field spectroscopy (IFS) data of a sample of 38 (U)LIRGs. These systems are morphologically classified in four groups according to their dynamical phases: isolated disk, paired disk, ongoing merger, and post-coalescence merger. The first two are referred as "disk", while the second two are referred to as "merger". The "unweighted" and "weighted" kinemetry-based methods are used to kinematically classify our galaxies in disk and merger. The total kinematic asymmetry value K tot has been used to quantify the global kinematic asymmetry degree of the observed and simulated systems. Results. From the kinemetry-based analysis we are able classify our local (U)LIRGs in three distinct kinematic groups according to their total kinematic asymmetry values (K tot ) as derived when using the weighted (unweighted) method: (1) 25 out of 50 galaxies are kinematically classified as disk with a K tot ≤ 0.16 (0.14); (2) 9 out of 50 galaxies are kinematically classified as merger with a K tot ≥ 0.94 (0.66); (3) 16 out of 50 galaxies lie in the "transition region", in which disks and mergers coexist, with 0.16 (0.14) < K tot < 0.94 (0.66). The K tot frontier value that better classifies the highest numbers of disks and mergers, in agreement with their morphology, is K tot = 0.19 (∼0.15): using this value the fractions of "well-classified disks" (I disk ) vs. "well classified mergers" (I merger ) are, respectively, ∼80% vs. ∼100%. The same results are obtained if we only consider the isolated disks as "true disks". When we apply our criteria to the high-z simulated systems, a lower total kinematic asymmetry frontier value (K tot ∼ 0.16 (∼0.14)) is derived with respect to that found locally. The loss of angular resolution smears out the kinematic features, thus making objects to appear more kinematically regular (disky) than actually they are.

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Observations and modeling of a clumpy galaxy atz = 1.6

Cited by 126 publications

References 70 publications

A PHYSICAL APPROACH TO THE IDENTIFICATION OF HIGH-ZMERGERS: MORPHOLOGICAL CLASSIFICATION IN THE STELLAR MASS DOMAIN

A PHYSICAL APPROACH TO THE IDENTIFICATION OF HIGH-ZMERGERS: MORPHOLOGICAL CLASSIFICATION IN THE STELLAR MASS DOMAIN

Integral field spectroscopy with SINFONI of VVDS galaxies

Distinguishing disks from mergers: Tracing the kinematic asymmetries in local (U)LIRGs using kinemetry-based criteria

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