J/ApJ/835/104 SAMI Galaxy Survey: rotators classification (van de Sande+, 2017)
The SAMI Galaxy Survey: revisiting Galaxy classification through high-order
stellar kinematics.
van de Sande J., Bland-Hawthorn J., Fogarty L.M.R., Cortese L.,
D'Eugenio F., Croom S.M., Scott N., Allen J.T., Brough S., Bryant J.J.,
Cecil G., Colless M., Couch W.J., Davies R., Elahi P.J., Foster C.,
Goldstein G., Goodwin M., Groves B., Ho I.-T., Jeong H., Jones D.H.,
Konstantopoulos I.S., Lawrence J.S., Leslie S.K., Lopez-Sanchez A.R.,
McDermid R.M., McElroy R., Medling A.M., Oh S., Owers M.S., Richards S.N.,
Schaefer A.L., Sharp R., Sweet S.M., Taranu D., Tonini C., Walcher C.J.,
Yi S.K.
<Astrophys. J., 835, 104-104 (2017)>
=2017ApJ...835..104V 2017ApJ...835..104V (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Surveys ; Redshifts ; Morphology
Keywords: cosmology: observations; galaxies: evolution; galaxies: formation;
galaxies: kinematics and dynamics; galaxies: stellar content;
galaxies: structure
Abstract:
Recent cosmological hydrodynamical simulations suggest that integral
field spectroscopy can connect the high-order stellar kinematic
moments h3 (∼skewness) and h4 (∼kurtosis) in galaxies to their
cosmological assembly history. Here, we assess these results by
measuring the stellar kinematics on a sample of 315 galaxies, without
a morphological selection, using two-dimensional integral field data
from the SAMI Galaxy Survey. Proxies for the spin parameter
(λRe) and ellipticity (εe) are used to separate
fast and slow rotators; there exists a good correspondence to regular
and non-regular rotators, respectively, as also seen in earlier
studies. We confirm that regular rotators show a strong h3 versus
V/σ anti-correlation, whereas quasi-regular and non-regular
rotators show a more vertical relation in h3 and V/σ.
Motivated by recent cosmological simulations, we develop an
alternative approach to kinematically classify galaxies from their
individual h3 versus V/σ signatures. Within the SAMI Galaxy
Survey, we identify five classes of high-order stellar kinematic
signatures using Gaussian mixture models. Class 1 corresponds to slow
rotators, whereas Classes 2-5 correspond to fast rotators. We find
that galaxies with similar λRe-εe values can show
distinctly different h3-V/σ signatures. Class 5 objects are
previously unidentified fast rotators that show a weak h3 versus
V/σ anti-correlation. From simulations, these objects are
predicted to be disk-less galaxies formed by gas-poor mergers. From
morphological examination, however, there is evidence for large
stellar disks. Instead, Class 5 objects are more likely disturbed
galaxies, have counter-rotating bulges, or bars in edge-on galaxies.
Finally, we interpret the strong anti-correlation in h3 versus
V/σ as evidence for disks in most fast rotators, suggesting a
dearth of gas-poor mergers among fast rotators.
Description:
The SAMI instrument and Galaxy Survey is described in detail in Croom+
(2012MNRAS.421..872C 2012MNRAS.421..872C) and Bryant+ (2015MNRAS.447.2857B 2015MNRAS.447.2857B). SAMI is a
multi-object integral field spectrograph on the 3.9m Anglo Australian
Telescope (AAT). For the SAMI Galaxy Survey, the 580V grating is used
in the blue arm of the spectrograph, which results in a resolution of
R∼1700 with wavelength coverage of 3700-5700Å. In the red arm, the
higher resolution grating 1000R is used, which gives an R∼4500 over
the range 6300-7400Å.
We use 24 unsaturated, unblended CuAr arc lines in the blue arm, and
12 lines in the red arm, from 16 frames between 2013 March 05 and 2015
August 17, for all 819 fibers.
The survey has four volume-limited galaxy samples derived from cuts in
stellar mass in the Galaxy and Mass Assembly (GAMA) G09, G12, and G15
regions (Driver+ 2011, J/MNRAS/413/971).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 85 315 Compilation of all measured quantities
table3.dat 36 315 Log-likehood estimates and high-order classification
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See also:
J/MNRAS/371/703 : MILES library of empirical spectra (Sanchez-Blazquez+, 2006)
J/MNRAS/404/1639 : MILES base models & new line index system (Vazdekis+, 2010)
J/MNRAS/413/813 : ATLAS3D project. I. (Cappellari+, 2011)
J/MNRAS/416/1680 : ATLAS3D project. VII. (Cappellari+, 2011)
J/MNRAS/413/971 : Galaxy And Mass Assembly (GAMA) DR1 (Driver+, 2011)
J/MNRAS/414/888 : ATLAS3D project. III. (Emsellem+, 2011)
J/A+A/556/A55 : Multi-color photom. of star-forming galaxies (Ilbert+, 2013)
J/ApJ/777/18 : Stellar mass functions of galaxies to z=4 (Muzzin+, 2013)
J/ApJ/771/85 : Dynamical masses of z∼2 quiescent gal. (van de Sande+, 2013)
J/MNRAS/446/1567 : SAMI Galaxy Survey: Early Data Release (Allen+, 2015)
J/MNRAS/454/2050 : SAMI Pilot Survey (Fogarty+, 2015)
J/MNRAS/452/2087 : Galaxy And Mass Assembly (GAMA): DR2 (Liske+, 2015)
J/A+A/591/A143 : NGC 3115 MUSE images (Guerou+, 2016)
J/MNRAS/456/1299 : SAMI Galaxy Survey: gas streaming (Cecil+, 2016)
http://sami-survey.org/ : SAMI Galaxy Survey website
http://www.gama-survey.org/ : Galaxy And Mass Assembly (GAMA) home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- ID [8487/9403801368] Catalog ID (CATID) (G1)
12- 17 F6.4 --- zsp [0.01/0.09] Spectroscopic redshift
19- 23 F5.2 [Msun] logM* [10/11.6] Log stellar mass
25- 28 F4.2 mag g-i [0.7/1.4] g-i color index
30- 35 F6.3 kpc Re [0.8/15.8] Effective semi-major axis
37- 41 F5.3 --- ell Ellipticity
43- 47 F5.3 --- rmaxSig [0.3/3.6] Maximum aperture radius velocity
dispersion, normalised by Re
49- 53 F5.3 --- rmaxh3 [0.1/1.5] Maximum aperture radius h3,
normalised by Re
55- 61 F7.3 --- lamRe [0.03/0.7]?=-99 Spin parameter proxy
within one Re
63- 67 F5.3 --- e_lamRe [0.002/0.02]?=0 Error on lamRe
69- 76 F8.4 --- <k5k1Re> [0.007/2]?=-99 Mean kinemetry k5/k1 value
within one Re
78- 85 F8.4 --- e_<k5k1Re> [0.002/612]?=0 Error on <k5k1Re>
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- ID [8487/9403801368] Catalog ID (CATID) (G1)
12- 15 F4.2 --- Sigamaj [0.03/1] Best-fit standard deviation along
major axis of high-order data (σmajor)
17- 21 F5.3 --- Sigmbmin [0.02/0.07] Best-fit standard deviation along
minor axis of high-order data (σminor)
23- 28 F6.2 --- phi [-45/5] Best-fit angle Φ of high-order data
30- 34 F5.2 --- Corr [-1/0.4] Pearson correlation coefficient
of high-order data
36 I1 --- Cl [1/5] High-order stellar kinematic class (1)
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Note (1): Class as follows:
1 = galaxies mostly found on the red sequence and dominate at the high-mass
end (M*>1011M☉); the range of V/σ is very narrow as
compared to the range of h4, with no trend, similar to the h3 signatures
(slow rotators; 52 occurrences).
2 = galaxies with a lower mean stellar masses than Class 1, but the bulk
resides on the red sequence; broader spread in V/σ as compared
to Class 1 (97 occurrences).
3 = heart-shape clear for regular rotator (64 occurrences)
4 = heart-shape clear for regular rotator (57 occurrences)
5 = galaxies which have a large range in both color and stellar mass;
rounder distribution in h4 and V/σ (45 occurrences).
See text for further explanations.
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Global Notes:
Note (G1): The galaxies with ID≥9008500007 are from a catalog produced by
Dr Matt Owers. General Information on these targets are available in
Owers et al. 2017, but unfortunately the catalogs from those papers are not
publicly available yet. They will be made available as part of an
upcoming SAMI Data Release.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Aug-2017