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THE MILLENNIUM GALAXY CATALOGUE: EXPLORING THE COLOR-CONCENTRATION BIMODALITY VIA BULGE-DISK DECOMPOSITION

2009; IOP Publishing; Volume: 699; Issue: 1 Linguagem: Inglês

10.1088/0004-637x/699/1/105

1538-4357

Ewan Cameron, Simon P. Driver, Alister W. Graham, J. Liske,

Impact of Light on Environment and Health

We investigate the origin of the galaxy color–concentration bimodality at the bright end of the luminosity function (MB − 5log h70 < −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 h70 M☉ 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 h70 M☉ 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 h370 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 〈(u − r)bulge − (u − r)disk〉 = 0.22 ± 0.02 mag).