J/ApJ/720/723 Compact galaxies in the local universe (Taylor+, 2010)
On the dearth of compact, massive, red sequence galaxies in the local universe.
Taylor E.N., Franx M., Glazebrook K., Brinchmann J., van der Wel A.,
van Dokkum P.G.
<Astrophys. J., 720, 723-741 (2010)>
=2010ApJ...720..723T 2010ApJ...720..723T
ADC_Keywords: Galaxies, nearby ; Photometry, SDSS ; Velocity dispersion
Keywords: galaxies: evolution - galaxies: formation -
galaxies: fundamental parameters
Abstract:
We set out to test the claim that the recently identified population
of compact, massive, and quiescent galaxies at z∼2.3 must undergo
significant size evolution to match the properties of galaxies found
in the local universe. Using data from the Sloan Digital Sky Survey
(SDSS; Data Release 7), we have conducted a search for local red
sequence galaxies with sizes and masses comparable to those found at
z∼2.3. The SDSS spectroscopic target selection algorithm excludes high
surface brightness objects; we show that this makes incompleteness a
concern for such massive, compact galaxies, particularly for low
redshifts (z≲0.05). We have identified 63 M*>1010.7M☉
(∼5x1010M☉) red sequence galaxies at 0.066<zspec<0.12 which
are smaller than the median size-mass relation by a factor of 2 or
more. Consistent with expectations from the virial theorem, the median
offset from the mass-velocity dispersion relation for these galaxies
is 0.12 dex. We do not, however, find any galaxies with sizes and
masses comparable to those observed at z∼2.3, implying a decrease in
the comoving number density of these galaxies, at fixed size and mass,
by a factor of ≳5000. This result cannot be explained by
incompleteness: in the 0.066<z<0.12 interval, we estimate that the
SDSS spectroscopic sample should typically be ≳75% complete for
galaxies with the sizes and masses seen at high redshift, although for
the very smallest galaxies it may be as low as ∼20%. In order to
confirm that the absence of such compact massive galaxies in SDSS is
not produced by spectroscopic selection effects, we have also looked
for such galaxies in the basic SDSS photometric catalog, using
photometric redshifts. While we do find signs of a slight bias against
massive, compact galaxies, this analysis suggests that the SDSS
spectroscopic sample is missing at most a few objects in the regime we
consider.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 90 63 Properties of our compact galaxy candidates
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/MNRAS/398/1129 : Central galaxies in groups and clusters (Guo+, 2009)
J/MNRAS/382/109 : Massive galaxies in Extended Groth Strip (Trujillo+, 2007)
J/ApJS/166/526 : Compact extragalactic radio sources (Xu+, 2006)
J/A+A/330/423 : Early-type galaxies kinematics (Rampazzo+ 1998)
http://www.sdss.org/ : SDSS home page
http://www.ipac.caltech.edu/2mass/ : 2MASS home page at IPAC
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) (1)
11- 19 F9.5 deg DEdeg Declination in decimal degrees (J2000) (1)
21- 26 F6.4 --- z SDSS-DR7 spectroscopic redshift (1)
28- 32 F5.3 mag (u-r)o Observed SDSS (u-r) color index (1)
34- 38 F5.3 mag (u-r)c Rest-frame corrected SDSS (u-r) color index
40- 45 F6.3 [Msun] logM Log stellar mass (2)
47- 51 F5.3 arcsec Rdev Apparent De Vaucouleurs effective radius (1)
53- 56 F4.2 --- n Sersic index
58- 62 F5.3 arcsec Rser Apparent Sersic effective radius (3)
64- 68 F5.3 kpc Reff Physical De Vaucouleurs effective radius
70- 72 I3 km/s sigma Velocity dispersion (2)
74 A1 --- f_T [-] -: DR7 object that does not appear in DR4
76- 81 F6.3 Gyr T ? Luminosity-weighted age (4)
83 A1 --- f_Z [-] -: DR7 object that does not appear in DR4
85- 90 F6.3 [-] Z ? Mean metallicity (4)
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Note (1): From the default SDSS (York et al. 2000AJ....120.1579Y 2000AJ....120.1579Y; Strauss et al.
2002AJ....124.1810S 2002AJ....124.1810S) catalog for DR7 (Abazajian et al. 2009,
Cat. II/294), accessed via CAS (Thakar et al. 2008CSE....10...30T 2008CSE....10...30T).
Note (2): From the MPA-JHU catalog for DR7
(accessible via http://www.mpa-garching.mpg.de/SDSS/DR7/).
Note (3): From the NYU VAGC (Blanton et al. 2005AJ....129.2562B 2005AJ....129.2562B) for DR7.
Note (4): From the stellar age and metallicity catalog of Gallazzi et al.
(2005MNRAS.362...41G 2005MNRAS.362...41G) for DR4. Since these come from a DR4 catalog,
values are not available for all objects (see flag).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Jun-2012