TY - JOUR
T1 - Color separation of galaxy types in the Sloan Digital Sky Survey imaging data
AU - Strateva, Iskra
AU - Ivezić, Željko
AU - Knapp, Gillian R.
AU - Narayanan, Vijay K.
AU - Strauss, Michael A.
AU - Gunn, James E.
AU - Lupton, Robert H.
AU - Schlegel, David
AU - Bahcall, Neta A.
AU - Brinkmann, Jon
AU - Brunner, Robert J.
AU - Budavári, Tamás
AU - Csabai, István
AU - Castander, Francisco Javier
AU - Doi, Mamoru
AU - Fukugita, Masataka
AU - Gyory, Zsuzsanna
AU - Hamabe, Masaru
AU - Hennessy, Greg
AU - Ichikawa, Takashi
AU - Kunszt, Peter Z.
AU - Lamb, Don Q.
AU - McKay, Timothy A.
AU - Okamura, Sadanori
AU - Racusin, Judith
AU - Sekiguchi, Maki
AU - Schneider, Donald P.
AU - Shimasaku, Kazuhiro
AU - York, Donald
PY - 2001/10
Y1 - 2001/10
N2 - We study the optical colors of 147,920 galaxies brighter than g* = 21, observed in five bands by the Sloan Digital Sky Survey (SDSS) over ∼100 deg2 of high Galactic latitude sky along the celestial equator. The distribution of galaxies in the g*-r* versus u*-g* color-color diagram is strongly bimodal, with an optimal color separator of u*-r* = 2.22. We use visual morphology and spectral classification of subsamples of 287 and 500 galaxies, respectively, to show that the two peaks correspond roughly to early- (E, S0, and Sa) and late-type (Sb, Sc, and Irr) galaxies, as expected from their different stellar populations. We also find that the colors of galaxies are correlated with their radial profiles, as measured by the concentration index and by the likelihoods of exponential and de Vaucouleurs' profile fits. While it is well known that late-type galaxies are bluer than early-type galaxies, this is the first detection of a local minimum in their color distribution. In all SDSS bands, the counts versus apparent magnitude relations for the two color types are significantly different and demonstrate that the fraction of blue galaxies increases toward the faint end.
AB - We study the optical colors of 147,920 galaxies brighter than g* = 21, observed in five bands by the Sloan Digital Sky Survey (SDSS) over ∼100 deg2 of high Galactic latitude sky along the celestial equator. The distribution of galaxies in the g*-r* versus u*-g* color-color diagram is strongly bimodal, with an optimal color separator of u*-r* = 2.22. We use visual morphology and spectral classification of subsamples of 287 and 500 galaxies, respectively, to show that the two peaks correspond roughly to early- (E, S0, and Sa) and late-type (Sb, Sc, and Irr) galaxies, as expected from their different stellar populations. We also find that the colors of galaxies are correlated with their radial profiles, as measured by the concentration index and by the likelihoods of exponential and de Vaucouleurs' profile fits. While it is well known that late-type galaxies are bluer than early-type galaxies, this is the first detection of a local minimum in their color distribution. In all SDSS bands, the counts versus apparent magnitude relations for the two color types are significantly different and demonstrate that the fraction of blue galaxies increases toward the faint end.
KW - Galaxies: fundamental parameters
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U2 - 10.1086/323301
DO - 10.1086/323301
M3 - Article
AN - SCOPUS:18044362115
SN - 0004-6256
VL - 122
SP - 1861
EP - 1874
JO - Astronomical Journal
JF - Astronomical Journal
IS - 4
ER -