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 (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) and employ the selection criteria of Damjanov et al. (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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
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)
Note (1): The internal kinematics and stellar population errors are formally computed statistical errors and do not include possible systematic uncertainties.
Byte-by-byte Description of file: table2.dat
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)
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.
History: From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 18-Apr-2017
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