J/ApJS/147/1 Classification of nearby galaxies (Conselice+, 2003)
The relationship between stellar light distributions of galaxies and
their formation histories.
Conselice C.J.
<Astrophys. J. Suppl. Ser. 147, 1 (2003)>
=2003ApJS..147....1C 2003ApJS..147....1C
ADC_Keywords: Galaxies, nearby ; Morphology
Keywords: galaxies: evolution - galaxies: formation - galaxies: structure
Abstract:
A major problem in extragalactic astronomy is the inability to
distinguish in a robust, physical, and model-independent way how
galaxy populations are physically related to each other and to their
formation histories. A similar, but distinct, and also long-standing
question is whether the structural appearances of galaxies, as seen
through their stellar light distributions, contain enough physical
information to offer this classification. We argue through the use of
240 images of nearby galaxies that three model-independent parameters
measured on a single galaxy image reveal its major ongoing and past
formation modes and can be used as a robust classification system.
These parameters quantitatively measure: the concentration (C),
asymmetry (A), and clumpiness (S) of a galaxy's stellar light
distribution. When combined into a three-dimensional "CAS" volume all
major classes of galaxies in various phases of evolution are cleanly
distinguished. We argue that these three parameters correlate with
important modes of galaxy evolution: star formation and major merging
activity. This is argued through the strong correlation of Hα
equivalent width and broadband colors with the clumpiness parameter S,
the uniquely large asymmetries of 66 galaxies undergoing mergers, and
the correlation of bulge to total light ratios, and stellar masses,
with the concentration index. As an obvious goal is to use this system
at high redshifts to trace evolution, we demonstrate that these
parameters can be measured, within a reasonable and quantifiable
uncertainty with available data out to z∼3 using the Hubble Space
Telescope GOODS ACS and Hubble Deep Field images.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 113 Nearby Normal Galaxies from the Frei Sample,
1996AJ....111..174F 1996AJ....111..174F
table2.dat 64 5 Starburst Galaxies
table3.dat 64 19 Dwarf Ellipticals from Conselice et al.,
2003AJ....125...66C 2003AJ....125...66C
table4.dat 51 37 Dwarf Irregulars from Van Zee, 2000AJ....119.2757V 2000AJ....119.2757V
table5.dat 60 66 IRAS Infrared Galaxies
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Byte-by-byte Description of file: table1.dat table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Galaxy name
14- 19 A6 --- MType Hubble type
22- 26 F5.1 mag BMAG Absolute B magnitude
28- 31 F4.2 --- C(R) Concentration of stellar light from R data (1)
33- 37 F5.2 --- A(R) Asymmetric distribution from R data
39- 42 F4.2 --- e_A(R) rms uncertainty on A(R)
44- 48 F5.2 --- AG(R) Global asymmetry from R data
50- 53 F4.2 --- e_AG(R) rms uncertainty on AG(R)
55- 59 F5.2 --- S(R) Clumpiness from R data (G1)
61- 64 F4.2 --- e_S(R) rms uncertainty on S(R)
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Note (1): Typically, errors on the concentration index are ±0.1
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Galaxy name
15- 18 F4.2 --- C(B) Concentration of stellar light from B data (1)
20- 24 F5.2 --- A(B) Asymmetric distribution from B data
26- 29 F4.2 --- e_A(B) rms uncertainty on A(B)
31- 35 F5.2 --- AG(B) Global asymmetry from B data
37- 40 F4.2 --- e_AG(B) rms uncertainty on AG(B)
42- 46 F5.2 --- S(B) Clumpiness from B data (G1)
48- 51 F4.2 --- e_S(B) rms uncertainty on S(B)
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Note (1): Typically, errors on the concentration index are ±0.1
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [CGW2003] Sequential number
4- 7 A4 --- --- [IRAS]
8 A1 --- F [F] for IRAS Faint sources (Cat. II/156)
9- 18 A10 --- IRAS IRAS name
19 A1 --- n_IRAS [d] Note on IRAS (1)
20- 24 F5.3 --- z Redshift
26- 29 F4.2 --- C(I-V) Concentration of stellar light from I or V
data (2) (3)
31- 35 F5.2 --- A(I-V) Asymmetric distribution from I or V data (2)
37- 40 F4.2 --- e_A(I-V) rms uncertainty on A(B)
42- 45 F4.2 --- AG(I-V) Global asymmetry from I or V data (2)
47- 50 F4.2 --- e_AG(I-V) rms uncertainty on AG(B)
52- 55 F4.2 --- S(I-V) Clumpiness from I or V data (2) (G1)
57- 60 F4.2 --- e_S(I-V) rms uncertainty on S(B)
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Note (1): Individual note:
d: IRAS 07381+3215, because of its lower than average surface brightness,
had its parameters measured within the 3xr(η=0.5) radius.
Note (2): For objects 1-43, the parameters listed are measured in the
F814W (I) filter and for objects 44-66 the F606W (V) filter was used
Note (3): Typically, errors on the concentration index are ±0.1
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Global Notes:
Note (G1):
The "clumpiness" is defined as the ratio of the amount of light
contained in high-frequency structures to the total amount of light
in the galaxy. For ellipticals this ratio should be, and generally is,
near zero.
History:
From electronic version of the journal
* 11-Jun-2005: The 'F' was added for IRAS Faint sources in table5
(End) James Marcout, Patricia Bauer [CDS] 31-Jul-2003