| The Millennium Galaxy Catalogue: exploring the color-concentration bimodality via bulge-disk decomposition (2009) | |||||||||||||||
Abstract | |||||||||||||||
| We investigate the origin of the galaxy color-concentration bimodality at the bright end of the luminosity function (MB – 5log h 70 < –18 mag) with regard to the bulge-disk nature of galaxies. Via (two-dimensional) surface brightness profile modeling with GIM2D, we subdivide the local galaxy population in the Millennium Galaxy Catalogue into one-component and two-component systems. We reveal that one-component (elliptical and disk-only) systems define the two peaks of the galaxy color-concentration distribution (with total stellar mass densities of (0.7 ± 0.1) and (1.3 ± 0.1) × 108 h 70 M sun Mpc–3, respectively), while two-component systems contribute to both a bridging population and the red, concentrated peak (with total stellar mass densities of (1.1 ± 0.1) and (1.8 ± 0.2) × 108 h 70 M sun Mpc–3, respectively). Moreover, luminous, "bulge-less, red disks", and "disk-less, blue bulges" (blue ellipticals) are exceptionally rare (with volume densities of (1.7 ± 0.3) and (1.1 ± 0.1) × 10–4 h 3 70 Mpc–3, respectively). Finally, within the two-component population we confirm a previously reported correlation between bulge and disk color (with a mean offset of only lang(u – r)bulge – (u – r)diskrang = 0.22 ± 0.02 mag). | |||||||||||||||
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