The Millennium Galaxy Catalogue: Exploring the Color-Concentration Bimodality via Bulge-Disk Decomposition
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).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2009
- DOI:
- 10.1088/0004-637X/699/1/105
- arXiv:
- arXiv:0904.3096
- Bibcode:
- 2009ApJ...699..105C
- Keywords:
-
- galaxies: evolution;
- galaxies: formation;
- galaxies: fundamental parameters;
- Astrophysics - Cosmology and Extragalactic Astrophysics;
- Astrophysics - Galaxy Astrophysics
- E-Print:
- 14 pages, 8 figures, accepted for publication in ApJ (18 April 2009). High resolution version available at http://www-star.st-and.ac.uk/~ec60/mgc.pdf