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J/ApJ/836/115   Double-component model fitting of elliptical gal.   (Oh+, 2017)

Testing the presence of multiple photometric components in nearby early-type galaxies using SDSS. Oh S., Greene J.E., Lackner C.N. <Astrophys. J., 836, 115-115 (2017)> =2017ApJ...836..115O (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; Photometry, SDSS ; Redshifts ; Morphology ; Models Keywords: galaxies: elliptical and lenticular, cD; galaxies: evolution Abstract: We investigate two-dimensional image decomposition of nearby, morphologically selected early-type galaxies (ETGs). We are motivated by recent observational evidence of significant size growth of quiescent galaxies and theoretical development advocating a two-phase formation scenario for ETGs. We find that a significant fraction of nearby ETGs show changes in isophotal shape that require multi-component models. The characteristic sizes of the inner and outer component are ∼3 and ∼15kpc. The inner component lies on the mass-size relation of ETGs at z∼0.25-0.75, while the outer component tends to be more elliptical and hints at a stochastic buildup process. We find real physical differences between single- and double-component ETGs, with double-component galaxies being younger and more metal-rich. The fraction of double-component ETGs increases with increasing σ and decreases in denser environments. We hypothesize that double-component systems were able to accrete gas and small galaxies until later times, boosting their central densities, building up their outer parts, and lowering their typical central ages. In contrast, the oldest galaxies, perhaps due to residing in richer environments, have no remaining hints of their last accretion episode. Description: We use the detailed visual morphology classification catalog of Nair & Abraham (2010, J/ApJS/186/427) to construct a sample of nearby elliptical galaxies in a range of mass and environment. The catalog is based on the SDSS DR4 main spectroscopic sample, and extends to z=0.1. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 138 838 Structural parameters of bestfit models
See also: V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015) J/AJ/101/1561 : Isophotometry of ellipticals in Abell clusters (Porter+ 1991) J/ApJS/142/1 : DEEP Groth Strip Survey. II. (Simard+, 2002) J/MNRAS/330/547 : Local galaxy ages and metallicities (Terlevich+, 2002) J/ApJS/182/216 : Surface photometry of Virgo ellipticals (Kormendy+, 2009) J/ApJS/186/427 : Detailed morphology of SDSS galaxies (Nair+, 2010) J/ApJ/720/723 : Compact galaxies in the local universe (Taylor+, 2010) J/ApJ/739/L44 : Structural data for gal. between 0.2<z<2.7 (Damjanov+, 2011) J/MNRAS/414/888 : ATLAS3D project. III. (Emsellem+, 2011) J/ApJS/203/24 : Structural parameters of gal. in CANDELS (van der Wel+, 2012) J/ApJ/775/106 : CANDELS passive and massive early-type gal. (Cassata+, 2013) J/ApJ/793/39 : Spectrosc. properties of BOSS compact gal. (Damjanov+, 2014) J/MNRAS/446/3943 : galaxies 2D phot. decompositions in SDSS-DR7 (Meert+, 2015) J/A+A/578/A134 : Compact early-type galaxies in SDSS (Saulder+, 2015) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 I4 --- ID [0/1132] Unique sample ID 6- 25 A20 --- Name SDSS name (JHHMMSS.ss+DDMMSS.ss) 27- 33 F7.3 deg RAdeg ? Right Ascension in decimal degrees (J2000) 35- 41 F7.3 deg DEdeg ? Declination in decimal degrees (J2000) 43- 47 F5.3 --- z [0.01/0.09] Spectroscopic redshift 49- 51 I3 km/s sigma [72/354] Velocity dispersion 53- 58 F6.2 mag rMag [-22.9/-18.4]? Absolute r magnitude 60- 63 F4.2 mag g-r [0.5/0.9]? Rest frame g-r color index 65- 68 F4.2 arcsec FWHM [0.7/2.1] FWHM of the PSF 70- 72 F3.1 --- nSer [1.4/9] Sersic index for Sersic model 74- 77 F4.2 --- eSer [0/0.6] Ellipticity for Sersic model 79- 83 F5.2 mag fSer [12/15.7] Flux for Sersic model 85- 89 F5.2 arcsec ReSer [1.6/94] Effective radius for Sersic model 91 I1 --- flag [0/2]? Flag on double component early-type galaxies (ETGs) (1) 93- 96 F4.2 --- edeV [0.01/0.6]? Ellipticity for deV component of deVExp model (2) 98-102 F5.1 deg padeV ? Position angle for deV component of deVExp model (2) 104-108 F5.2 arcsec RedeV [0.5/17.1]? Effective radius for deV component of deVExp model (2) 110-114 F5.2 mag fdeV [12.7/17]? Flux for deV component of deVExp model (2) 116-119 F4.2 --- eExp [0.01/0.8]? Ellipticity for Exp component of deVExp model (2) 121-125 F5.1 deg paExp ? Position angle for Exp component of deVExp model (2) 127-132 F6.2 arcsec ReExp [4/116]? Effective radius for Exp component of deVExp model (2) 134-138 F5.2 mag fExp [13.3/17]? Flux for Exp component of deVExp model (2)
Note (1): Flag as follows: 0 = single component; 1 = double component; 2 = double component with high confidence. See section 3.2 of the paper. Note (2): The two-component model (devExp) is a sum of a de Vaucouleurs and an exponential with Sersic indices of n=4 and n=1, respectively. The two components share a common center, but are allowed to have different PA and ellipticity. See section 3.1 for the fitting procedure.
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Sep-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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