J/ApJ/793/39 Spectroscopic properties of BOSS compact galaxies (Damjanov+, 2014)
The number density of quiescent compact galaxies at intermediate redshift.
Damjanov I., Hwang H.S., Geller M.J., Chilingarian I.
<Astrophys. J., 793, 39 (2014)>
=2014ApJ...793...39D 2014ApJ...793...39D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; Redshifts ; Velocity dispersion ; Abundances ;
Morphology
Keywords: galaxies: evolution - galaxies: fundamental parameters -
galaxies: stellar content - galaxies: structure
Abstract:
Massive compact systems at 0.2<z<0.6 are the missing link between
the predominantly compact population of massive quiescent galaxies at
high redshift and their analogs and relics in the local volume. The
evolution in number density of these extreme objects over cosmic time
is the crucial constraining factor for the models of massive galaxy
assembly. We select a large sample of ∼200 intermediate-redshift
massive compacts from the Baryon Oscillation Spectroscopic Survey
(BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey
photometric sources with spectroscopic signatures of evolved
redshifted galaxies. A subset of our targets have publicly available
high-resolution ground-based images that we use to augment the
dynamical and stellar population properties of these systems by their
structural parameters. We confirm that all BOSS compact candidates are
as compact as their high-redshift massive counterparts and less than
half the size of similarly massive systems at z∼0. We use the
completeness-corrected numbers of BOSS compacts to compute lower
limits on their number densities in narrow redshift bins spanning the
range of our sample. The abundance of extremely dense quiescent
galaxies at 0.2<z<0.6 is in excellent agreement with the number
densities of these systems at high redshift. Our lower limits support
the models of massive galaxy assembly through a series of minor
mergers over the redshift range 0<z<2.
Description:
We use the BOSS DR10 data set (Ahn et al. 2014ApJS..211...17A 2014ApJS..211...17A) and
employ the selection criteria of Damjanov et al. (2013ApJ...775L..48D 2013ApJ...775L..48D)
to select compact galaxy candidates in the redshift range 0.2<z<0.6.
We search for stellar-like objects with spectroscopic redshifts in the
redshift range of interest (22288 sources) and exclude all
spectroscopically confirmed quasars (14108 sources) and actively
star-forming galaxies (by requiring the equivalent width of the
[OII]λλ3726, 3729 emission line to be EW [OII]<5Å;
7299 sources excluded). In addition, we inspect every pre-selected
spectrum to identify a 4000Å break and several absorption features
including the Balmer series, Ca H+K, and G band. We also apply a cut
to the inferred dynamical mass at Mdyn=1010Msun to construct a
sample of compact quiescent systems as massive as high- and
low-redshift comparison samples (see Sections 4 and 5.3). The final
list of BOSS compact galaxy candidates at redshift 0.2<z<0.6 contains
198 objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 75 198 Spectroscopic Properties of Compact Galaxy
Candidates Selected from BOSS
table2.dat 88 14 Structural Properties of BOSS Compact Galaxies
at Intermediate Redshift with Existing CFHT
Imaging
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See also:
II/317 : The CFHTLS Survey (T0007 release) (Hudelot+ 2012)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/MNRAS/418/1055 : BOSS morphology of galaxies (Masters+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- SDSS SDSS object identification number
21- 25 F5.3 --- z Redshift
27- 34 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000)
36- 44 F9.6 deg DEdeg Declination in decimal degrees (J2000)
46- 48 I3 km/s sigma Velocity Dispersion
50- 51 I2 km/s e_sigma Error in sigma (1)
53 A1 --- l_Age [<] Limit flag on Age
55- 59 I5 Myr Age Galaxy Age of best-fit SSP model
61- 64 I4 Myr e_Age ? Error in Age (1)
66- 70 F5.2 --- [Z/H] Metallicity of best-fit SSP model
72- 75 F4.2 --- e_[Z/H] Error in [Z/H] (1)
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Note (1): The internal kinematics and stellar population errors are formally
computed statistical errors and do not include possible systematic
uncertainties.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- SDSS SDSS object identification number
21- 24 A4 --- --- [SDSS]
25- 43 A19 --- Name SDSS designation (JHHMMSS.ss+DDMMSS.s)
45- 49 F5.3 --- z Redshift
51 A1 --- l_Rec [<] Limit flag on Rec
52- 55 F4.2 kpc Rec Circularized half-light radius of
the single-profile model (1)
57- 60 F4.2 kpc e_Rec ? Error in Rec
62- 65 F4.2 --- n ? Sersic index of the single-profile model
67- 70 F4.2 --- e_n ? Error in n
72- 75 F4.2 --- b/a ? Axial ratio of the single-profile model
77- 80 F4.2 --- e_b/a ? Error in b/a
82- 83 A2 --- Filter [g'r'i'z'] CFHT MegaCam filter
85- 88 F4.2 kpc HWFM Half width at the half maximum of the
point-spread function (2)
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Note (1): Re,c=Re.sqrt(b/a), where Re is the half-light radius along
the major axis and b/a is the axial ratio.
Note (2): In units of kiloparsecs at the target's redshift, constructed by
combining a set of stars in the CFHT MegaCam image.
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History:
From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 18-Apr-2017