J/ApJS/268/34 Morphology of COSMOS -UltraVISTA -DASH galaxies (Dai+, 2023)
The classification of galaxy morphology in the COSMOS-DASH field: a
combination-based machine-learning clustering model.
Dai Y., Xu J., Song J., Fang G., Zhou C., Ba S., Gu Y., Lin Z., Kong X.
<Astrophys. J. Suppl. Ser., 268, 34 (2023)>
=2023ApJS..268...34D 2023ApJS..268...34D
ADC_Keywords: Galaxy catalogs; Morphology; Photometry, infrared; Redshifts;
Galaxies, radius
Keywords: Galaxy structure ; Astrostatistics techniques ;
Astronomy data analysis
Abstract:
By applying our previously developed two-step scheme for galaxy
morphology classification, we present a catalog of galaxy morphology
for H-band-selected massive galaxies in the COSMOS-DASH field, which
includes 17292 galaxies with stellar mass M*>1010M☉ at
0.5<z<2.5. The classification scheme is designed to provide a complete
morphology classification for galaxies via a combination of two
machine-learning steps. We first use an unsupervised machine-learning
method (i.e., bagging-based multiclustering) to cluster galaxies into
five categories: spherical (SPH), early-type disk, late-type disk,
irregular (IRR), and unclassified. About 48% of the galaxies
(8258/17292) are successfully clustered during this step. For the
remaining sample, we adopt a supervised machine-learning method (i.e.,
GoogLeNet) to classify them, during which galaxies that are well
classified in the previous step are taken as our training set.
Consequently, we obtain a morphology classification result for the
full sample. The t-SNE test shows that galaxies in our sample can be
well aggregated. We also measure the parametric and nonparametric
morphologies of these galaxies. We find that the Sersic index
increases from IRR to SPH and the effective radius decreases from IRR
to SPH, consistent with the corresponding definitions. Galaxies from
different categories are separately distributed in the G-M20 space.
Such consistencies with other characteristic descriptions of galaxy
morphology demonstrate the reliability of our classification result,
ensuring that it can be used as a basic catalog for further galaxy
studies.
Description:
With the Drift and shift (DASH) technique, Mowla+ (2019ApJ...880...57M 2019ApJ...880...57M)
present a wide-field NIR survey of the COSMOS field, which is also
named COSMOS-DASH. It is taken with 57 DASH orbits in the F160W filter
of WFC3 and covers an area of 0.49deg2 (0.7deg2 when combined with
archival data). See Section 2.1.
To obtain stellar mass and other physical parameters of galaxies, we
select our sample from the UltraVista Ks-selected catalog
(Muzzin+ 2013, J/ApJS/206/8), which is based on an early release of
the NIR data (UltraVista Data Release 1). See Section 2.2.
We adopt the UltraVISTA/Ks selected catalogs and HST/F160W images from
the COSMOS-DASH survey. We study the massive galaxies with
M*>1010M☉ at 0.5<z<2.5, which are bright enough to derive
reliable morphologies. Finally, 17292 galaxies are selected in our
final sample. See Section 2.3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 65 17292 The fully classified catalog
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See also:
II/373 : The fourth UltraVISTA data release (DR4) (Moneti+, 2019)
J/ApJ/588/218 : i*g* photometry of SDSS EDR galaxies (Abraham+, 2003)
J/AJ/126/1183 : Major galaxy mergers at z≲3 (Conselice+, 2003)
J/AJ/128/163 : Galaxy morphological classification (Lotz+, 2004)
J/ApJ/735/86 : NEWFIRM MBS: photometric catalogs (Whitaker+, 2011)
J/A+A/544/A156 : UltraVISTA Catalogue Release DR1 (McCracken+, 2012)
J/ApJS/206/8 : COSMOS/UltraVISTA Ks-selected catalogs v4.1 (Muzzin+, 2013)
J/MNRAS/440/843 : SIM2D parameters of SDSS-DR7 galaxies (Omand+, 2014)
J/A+A/631/A38 : Local galaxies dust properties (Lianou+, 2019)
J/ApJ/925/34 : The COSMOS-DASH morphological catalog (Cutler+, 2022)
http://archive.stsci.edu/hlsp/cosmos-dash : COSMOS-DASH on MAST
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [1/17292] Sequential number identifier
7- 15 F9.5 deg RAdeg [149.43/150.7] Right ascension (J2000)
17- 23 F7.5 deg DEdeg [1.6/2.9] Declination (J2000)
25- 29 F5.2 mag Hmag [16.93/23.5] Magnitude in H band
31- 34 F4.2 --- zphot [0.5/3] Photomeric redshift
36- 40 F5.2 [Msun] logMs [10/12] Logarithmic of stellar mass
42- 47 F6.2 kpc re [0.2/322] Effective radius
49- 52 F4.2 --- n [0.2/8] Sersic index
54- 57 F4.2 --- G [0.33/0.85]? Gini coefficient, Equation 1
59- 63 F5.2 --- M20 [-2.4/-0.3]? Normalized second-order moment of
the brightest 20% of the galaxy flux;
Equation 3 in Section 4.3.2.
65- 65 I1 --- MType [0/4]? Label of Morphology Type in our result (1)
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Note (1): Label of Morphology Type in our result as follows:
0 = spherical (SPH; 5335 occurrences)
1 = early-type disk (ETD; 3132 occurrences)
2 = late-type disk (LTD; 2837 occurrences)
3 = irregular disk (IRR; 1693 occurrences)
4 = unclassified (UNC; 4295 occurrences)
See Section 3.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Dec-2023