J/A+A/578/A134 Compact early-type galaxies in SDSS (Saulder+, 2015)
Dozens of compact and high velocity-dispersion, early-type galaxies in
Sloan Digital Sky Survey.
Saulder C., van den Bosch R.C.E., Mieske S.
<Astron. Astrophys., 578, A134-134 (2015)>
=2015A&A...578A.134S 2015A&A...578A.134S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Morphology ; Velocity dispersion
Keywords: galaxies: elliptical and lenticular, cD - surveys -
galaxies: fundamental parameters - galaxies: peculiar
Abstract:
Passive galaxies at high redshift are much smaller than equally
massive early types today. If this size evolution is caused by
stochastic merging processes, then a small fraction of the compact
galaxies should persist until today. Up to now it has not been
possible to systematically identify the existence of such objects in
Sloan Digital Sky Survey (SDSS). We aim at finding potential survivors
of these compact galaxies in SDSS, as targets for more detailed
follow-up observations. From the virial theorem, it is expected that
for a given mass, compact galaxies have stellar velocity dispersion
higher than the mean owing to their smaller sizes. Therefore velocity
dispersion, coupled with size (or mass), is an appropriate method of
selecting relics, independent of the stellar population properties.
Based on these considerations, we designed a set of criteria the use
the distribution of early-type galaxies from SDSS on the
log10(R0)-log10(σ0) plane to find the most extreme
objects on it. We thus selected compact massive galaxy candidates by
restricting them to high velocity dispersions σ0>323.2km/s and
small sizes R0<2.18kpc. We find 76 galaxies at 0.05<z<0.2, which
have properties that are similar to the typical quiescent galaxies at
high redshift. We discuss how these galaxies relate to average
present-day early-type galaxies. We study how well these galaxies fit
on well-known local universe relations of early-type galaxies, such as
the fundamental plane, the red sequence, or mass-size relations. As
expected from the selection criteria, the candidates are located in an
extreme corner of the mass-size plane. However, they do not extend as
deeply into the so-called zone of exclusion as some of the red nuggets
found at high redshift, since they are a factor 2-3 less massive on a
given intrinsic scale size. Several of our candidates are close to the
size resolution limit of SDSS, but are not so small that they are
classified as point sources. We find that our candidates are
systematically offset on a scaling relation compared to the average
early-type galaxies, but still within the general range of other
early-type galaxies. Furthermore, our candidates are similar to the
mass-size range expected for passive evolution of the red nuggets from
their high redshift to the present. The 76 selected candidates form an
appropriate set of objects for further follow-up observations. They do
not constitute a separate population of peculiar galaxies, but form
the extreme tail of a continuous distribution of early-type galaxies.
We argue that selecting a high-velocity dispersion is the best way to
find analogues of compact high redshift galaxies in the local
universe.
Description:
As the baseline sample of our search for b19 analogues, we made broad
use of the Sloan Digital Sky Surveys (SDSS) and especially of its
tenth (Ahn et al., 2014ApJS..211...17A 2014ApJS..211...17A) and seventh (Abazajian et al.,
2009ApJS..182..543A 2009ApJS..182..543A) data releases (DR10 and DR7). Furthermore, we
used GalaxyZoo (Lintott et al., 2008MNRAS.389.1179L 2008MNRAS.389.1179L, 2011, Cat.
J/MNRAS/410/166) for our galaxy classifications, the refits of SDSS
DR7 using Sersic profiles done by Simard et al. (2011, Cat.
J/ApJS/196/11), and the stellar masses from Mendel et al. (2014, Cat.
J/ApJS/210/3), which is itself based on the previous work of Simard et
al. (2011, Cat. J/ApJS/196/11). For comparison, we also used the list
of 63 compact massive galaxies from Taylor et al. (2010, Cat.
J/ApJ/720/723), which is based on SDSS DR7 as well as a list of 29
compact massive galaxies from Trujillo et al. (2009ApJ...692L.118T 2009ApJ...692L.118T),
which is based on the NYU Value-Added Galaxy Catalog (Blanton et al.,
2005AJ....129.2562B 2005AJ....129.2562B) and covers a sub-sample of SDSS.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 86 76 List of the basic parameters of our candidate
galaxies
table3.dat 107 76 List of the derived parameters based on the
de Vaucouleurs fits from SDSS for our candidate
galaxies
tableb1.dat 89 86 List of the basic parameters of our alternative
candidate galaxies using the Sersic fit parameters
of Simard et al. (2011, Cat. J/ApJS/196/11)
instead of the de Vaucouleurs fit parameters used
for our main candidate sample
tableb2.dat 95 86 List of the derived parameters based on the Sersic
fits from Simard et al. (2011, Cat. J/ApJS/196/11)
for our alternative candidate galaxies
tablec1.dat 36 187 Cross-match list of all IDs of all galaxies
used in this investigation
tablec2.dat 85 60 List of the basic parameters of all galaxies in
our basic sample that are also parts of the
galaxies provided in Taylor et al.
(2010, Cat. J/ApJ/720/723)
tablec3.dat 106 60 List of the derived parameters of all galaxies
in our basic sample that are also parts of the
galaxies provided in Taylor et al.
(2010, cat J/ApJ/720/723)
tablec4.dat 89 23 List of the basic parameters of all galaxies in
our basic sample that are also parts of the
galaxies provided in Trujillo et al.
(2009ApJ...692L.118T 2009ApJ...692L.118T)
tablec5.dat 111 23 List of the derived parameters of all galaxies
in our basic sample that are also parts of the
galaxies provided in Trujillo et al.
(2009ApJ...692L.118T 2009ApJ...692L.118T)
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See also:
J/ApJ/720/723 : Compact galaxies in the local universe (Taylor+, 2010)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID Internal ID (G1)
4- 22 I19 --- SDSS SDSS DR10 ID
24- 31 F8.4 deg RAdeg Right ascension (J2000)
34- 41 F8.4 deg DEdeg Declination (J2000)
43- 48 F6.4 --- z Redshift already corrected for our motion
relative to the CMB
50- 54 F5.2 mag rmag Observed apparent SDSS r magnitude (G2)
56- 59 F4.2 mag e_rmag rms uncertainty on rmag
61- 64 F4.2 arcsec aSDSS Angular semi-major axis (G2)
66- 69 F4.2 arcsec e_aSDSS rms uncertainty on aSDSS
71- 73 I3 km/s sigmaSDSS Central velocity dispersion (G2)
75- 76 I2 km/s e_sigmaSDSS ? rms uncertainty on sigmaSDSS
78- 81 F4.2 --- b/a Axis ratio b/a (G2)
83- 86 F4.2 --- LETG GalaxyZoo probability ETG of the galaxy
being classified as an early type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID Internal ID (G1)
4- 7 F4.2 kpc Rr Scale radius Rr of the galaxies measured
in the SDSS r band
9- 12 F4.2 kpc e_Rr rms uncertainty on Rr
14- 16 I3 km/s sigma0 Corrected central velocity dispersion
18- 19 I2 km/s e_sigma0 rms uncertainty on sigma0
21- 25 F5.2 mag/arcsec2 mur Surface brightness measured in the
SDSS rband
27- 30 F4.2 mag/arcsec2 e_mur rms uncertainty on mur
32- 37 F6.2 mag rMAG Absolute magnitude in r band
39- 42 F4.2 mag e_rMAG rms uncertainty on rMAG
44- 47 F4.2 mag gMAG-rMAG g-r colour index
49- 52 F4.2 mag e_gMAG-rMAG rms uncertainty on gMAG-rMAG
54- 59 F6.2 mag zMAG Absolute magnitude in z band
61- 64 F4.2 mag e_zMAG rms uncertainty on zMAG
66- 70 F5.2 [Msun] logMdyn logarithm of the dynamical mass
72- 75 F4.2 [Msun] e_logMdyn rms uncertainty on log10(Mdyn)
77- 81 F5.2 [Msun] logM* logarithm of the stellar mass
83- 86 F4.2 [Msun] e_logM* rms uncertainty on log10(M*)
88- 92 F5.2 [Msun/Lsun] gammadyn Dynamical mass-to-light ratio
(in solar units M☉/L☉,r)
94- 97 F4.2 [Msun/Lsun] e_gammadyn rms uncertainty on γdyn
99-102 F4.2 [Msun/Lsun] gamma* Stellar mass-to-light ratio
(in solar units M☉/L☉,r)
104-107 F4.2 [Msun/Lsun] e_gamma* rms uncertainty on γdyn
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID Internal ID (G1)
4- 22 I19 --- SDSS SDSS DR10 ID
24- 31 F8.4 deg RAdeg Right ascension (J2000)
33- 39 F7.4 deg DEdeg Declination (J2000)
41- 46 F6.4 --- z Redshift already corrected for our motion
relative to the CMB
48- 52 F5.2 mag rmag Observed apparent SDSS r magnitude (G2)
54- 57 F4.2 mag e_rmag rms uncertainty on rmag
59- 62 F4.2 arcsec aSDSS Angular semi-major axis (G2)
64- 67 F4.2 arcsec e_aSDSS rms uncertainty on aSDSS
69- 71 I3 km/s sigmaSDSS Central velocity dispersion (G2)
73- 74 I2 km/s e_sigmaSDSS ? rms uncertainty on sigmaSDSS
76- 79 F4.2 --- nS Sersic index
81- 84 F4.2 --- e_nS rms uncertainty on nS
86- 89 F4.2 --- LETG GalaxyZoo probability of the galaxy being
classified as an early-type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- IDS Sersic ID
4- 7 F4.2 kpc Rr Scale radius of the galaxy measured
in the SDSS r band
9- 12 F4.2 kpc e_Rr rms uncertainty on Rr
14- 16 I3 km/s sigma0 Corrected central velocity dispersion
18- 19 I2 km/s e_sigma0 rms uncertainty on sigma0
21- 25 F5.2 mag/arcsec2 mur Surface brightness measured
in the SDSS r band
27- 30 F4.2 mag/arcsec2 e_mur rms uncertainty on mur
32- 37 F6.2 mag rMAG Absolute magnitude in r band
39- 42 F4.2 mag e_rMAG rms uncertainty on rMAG
44- 47 F4.2 mag gMAG-rMAG g-r colour index
49- 52 F4.2 mag e_gMAG-rMAG rms uncertainty on gMAG-rMAG
54- 58 F5.2 [Msun] logMdyn logarithm of the dynamical mass
60- 63 F4.2 [Msun] e_logMdyn rms uncertainty on logMdyn
65- 69 F5.2 [Msun] logM* logarithm of the stellar mass M*
71- 74 F4.2 [Msun] e_logM* rms uncertainty on logM*
76- 80 F5.2 [Msun/Lsun] gammadyn Dynamical mass-to-light ratio
82- 85 F4.2 [Msun/Lsun] e_gammadyn rms uncertainty on GammaDyn
87- 90 F4.2 [Msun/Lsun] gamma* Stellar mass-to-light ratio
92- 95 F4.2 [Msun/Lsun] e_gamma* rms uncertainty on Gamma*
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- SDSS SDSS DR10 ID
21- 22 I2 --- ID ?=- Internal ID
24- 25 I2 --- IDS ?=- Sersic ID (G3)
27- 28 I2 --- IDT ?=- Taylor et al. (2010, Cat. J/ApJ/720/723) ID
30- 36 I7 --- IDNY ?=- Trujillo et al. (2009ApJ...692L.118T 2009ApJ...692L.118T) ID
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- IDT Taylor et al. (2010, Cat. J/ApJ/720/723) ID
4- 22 I19 --- SDSS SDSS DR10 ID
24- 31 F8.4 deg RAdeg Right ascension (J2000)
33- 40 F8.4 deg DEdeg Declination (J2000)
42- 47 F6.4 --- z Redshift already corrected for our motion
relative to the CMB.
49- 53 F5.2 mag rmag Observed apparent SDSS r magnitude (G2)
55- 58 F4.2 mag e_rmag rms uncertainty on rmag
60- 63 F4.2 arcsec aSDSS Angular semi-major axis (G2)
65- 68 F4.2 arcsec e_aSDSS rms uncertainty on aSDSS
70- 72 I3 km/s sigmaSDSS Central velocity dispersion (G2)
74- 75 I2 km/s e_sigmaSDSS ? rms uncertainty on sigmaSDSS
77- 80 F4.2 --- b/a Axis ratio b/a (G2)
82- 85 F4.2 --- LETG GalaxyZoo probability ETG of the galaxy
being classified as an early type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- IDT Taylor et al. (2010, J/ApJ/720/723) ID
4- 7 F4.2 kpc Rr Scale radius of the galaxy measured
in the SDSS r band
9- 12 F4.2 kpc e_Rr rms uncertainty on Rr
14- 16 I3 km/s sigma0 Corrected central velocity dispersion
18- 19 I2 km/s e_sigma0 rms uncertainty on sigma0
21- 25 F5.2 mag/arcsec2 mur Surface brightness measured
in the SDSS r band
27- 30 F4.2 mag/arcsec2 e_mur rms uncertainty on mur
32- 37 F6.2 mag rMAG Absolute magnitude in r band
39- 42 F4.2 mag e_rMAG rms uncertainty on rMAG
44- 47 F4.2 mag gMAG-rMAG g-r colour index
49- 52 F4.2 mag e_gMAG-rMAG rms uncertainty on gMAG-rMAG
54- 59 F6.2 mag zMAG Absolute magnitude in z band
61- 64 F4.2 mag e_zMAG rms uncertainty on zMAG
66- 70 F5.2 [Msun] logMdyn logarithm of the dynamical mass
72- 75 F4.2 [Msun] e_logMdyn rms uncertainty on logMdyn
77- 81 F5.2 [Msun] logM* logarithm of the stellar mass M*
83- 86 F4.2 [Msun] e_logM* rms uncertainty on logM*
88- 91 F4.2 [Msun/Lsun] gammadyn Dynamical mass-to-light ratio
(in solar units M☉/L☉,r)
93- 96 F4.2 [Msun/Lsun] e_gammadyn rms uncertainty on GammaDyn
98-101 F4.2 [Msun/Lsun] gamma* Stellar mass-to-light ratio
(in solar units M☉/L☉,r)
103-106 F4.2 [Msun/Lsun] e_gamma* rms uncertainty on Gamma*
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 --- IDNY Trujillo et al. (2009ApJ...692L.118T 2009ApJ...692L.118T) ID
9- 27 I19 --- SDSS SDSS DR10 ID
29- 36 F8.4 deg RAdeg Right ascension (J2000)
38- 44 F7.4 deg DEdeg Declination (J2000)
46- 51 F6.4 --- z Redshift already corrected for our motion
relative to the CMB
53- 57 F5.2 mag rmag Observed apparent SDSS r magnitude (G2)
59- 62 F4.2 mag e_rmag rms uncertainty on rmag
64- 67 F4.2 arcsec aSDSS Angular semi-major axis (G2)
69- 72 F4.2 arcsec e_aSDSS rms uncertainty on aSDSS
74- 76 I3 km/s sigmaSDSS Central velocity dispersion (G2)
78- 79 I2 km/s e_sigmaSDSS ? rms uncertainty on sigmaSDSS
81- 84 F4.2 --- b/a Axis ratio b/a (G2)
86- 89 F4.2 --- LETG GalaxyZoo probability ETG of the galaxy
being classified as an early type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 --- IDNY Trujillo et al. (2009ApJ...692L.118T 2009ApJ...692L.118T) ID
9- 12 F4.2 kpc Rr Scale radius of the galaxy measured
in the SDSS r band
14- 17 F4.2 kpc e_Rr rms uncertainty on Rr
19- 21 I3 km/s sigma0 Corrected central velocity dispersion
23- 24 I2 km/s e_sigma0 rms uncertainty on sigma0
26- 30 F5.2 mag/arcsec2 mur Surface brightness measured
in the SDSS r band
32- 35 F4.2 mag/arcsec2 e_mur rms uncertainty on mur
37- 42 F6.2 mag rMAG Absolute magnitude in r band
44- 47 F4.2 mag e_rMAG rms uncertainty on rMAG
49- 52 F4.2 mag gMAG-rMAG g-r colour index
54- 57 F4.2 mag e_gMAG-rMAG rms uncertainty on gMAG-rMAG
59- 64 F6.2 mag zMAG Absolute magnitude in z band
66- 69 F4.2 mag e_zMAG rms uncertainty on zMAG
71- 75 F5.2 [Msun] logMdyn logarithm of the dynamical mass
77- 80 F4.2 [Msun] e_logMdyn rms uncertainty on logMdyn
82- 86 F5.2 [Msun] logM* logarithm of the stellar mass M*
88- 91 F4.2 [Msun] e_logM* rms uncertainty on logM*
93- 96 F4.2 [Msun/Lsun] gammadyn Dynamical mass-to-light ratio
98-101 F4.2 [Msun/Lsun] e_gammadyn rms uncertainty on gammadyn
103-106 F4.2 [Msun/Lsun] gamma* Stellar mass-to-light ratio
108-111 F4.2 [Msun/Lsun] e_gamma* rms uncertainty on gamma*
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Global notes:
Note (G1): Internal IDs, which are used to identify the galaxies. The numbering
is essentially random and only based on the order the galaxies were drawn
from the basic sample. The galaxy b19 has the internal ID 2.
Note (G2): observed uncorrected refitted SDSS parameters.
Note (G3): Sersic IDs of the alternative sample based on the parameters from
Simard et al. (2011, Cat. J/ApJS/196/11) provided in Appendix B.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Nov-2015