千年星系表：通过膨胀盘分解探索颜色浓度双峰性
The Millennium Galaxy Catalogue: Exploring the Color-Concentration Bimodality via Bulge-Disc Decomposition
摘要：
我们研究了星系在光度函数亮端（M（B）- 5 log h <-18 mag）的色浓双峰性与星系的膨胀盘性质的关系。通过GIM 2D的2D表面亮度剖面模拟，我们将千年星系表中的星系群细分为单组分和双组分系统。我们发现单组分（椭圆和盘状）系统定义了星系色浓度分布的两个峰值（总恒星质量密度分别为0.7 +/- 0.1和1.3 +/- 0.1 x 10^8 h Msol Mpc^-3），而双组分系统对桥接星族和红色都有贡献，集中峰（恒星总质量密度分别为1.1 +/- 0.1和1.8 +/- 0.2 x 10^8 h Msun Mpc^-3）。此外，发光的、“无凸起的红色圆盘”和“无凸起的蓝色圆盘”（蓝色椭圆）是非常罕见的（体积密度分别为1.7 +/- 0.3和1.1 \pm 0.1 x 10^-4 h^3 Mpc^-3）。最后，在双组分群体中，我们证实了先前报道的凸起和椎间盘颜色之间的相关性（平均偏移仅<（u-r）_bulge-（u-r）_disc> = 0.22 +/- 0.02 mag）。
英文摘要：
We investigate the origin of the galaxy color-concentration bimodality at the bright-end of the luminosity function (M(B) - 5 log h < -18 mag) with regard to the bulge-disc nature of galaxies. Via (2D) 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 disc-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 x 10^8 h Msol 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 x 10^8 h Msun Mpc^-3 respectively). Moreover, luminous, `bulge-less, red discs' and `disc-less, blue bulges' (blue ellipticals) are exceptionally rare (with volume-densities of 1.7 +/- 0.3 and 1.1 \pm 0.1 x 10^-4 h^3 Mpc^-3 respectively). Finally, within the two-component population we confirm a previously-reported correlation between bulge and disc color (with a mean offset of only <(u-r)_bulge-(u-r)_disc> = 0.22 +/- 0.02 mag).
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