The Millennium Galaxy Catalogue : morphological classification and bimodality in the colour-concentration plane

By S. Driver, P. Allen, Alister W. Graham, Ewan Cameron, J. Liske, S. Ellis, N. Cross, R. Propris, Steve Phillipps, W. Couch. 2006

204 citations recorded by the source corpus.

Using 10095 galaxies (B < 20 mag) from the Millennium Galaxy Catalogue, we derive B-band luminosity distributions and selected bivariate brightness distributions for the galaxy population subdivided by eyeball morphology; Sersic index (n); two-degree Field Galaxy Redshift Survey (2dFGRS) η parameter; rest-(u - r) colour (global and core); MGC continuum shape; half-light radius; (extrapolated) central surface brightness; and inferred stellar mass-to-light ratio. All subdivisions extract highly correlated subsets of the galaxy population which consistently point towards two overlapping distributions: an old, red, inert, predominantly luminous, high central-surface brightness subset; and a young, blue, star forming, intermediate surface brightness subset. A clear bimodality in the observed distribution is seen in both the rest-(u - r) colour and log (n) distributions. Whilst the former bimodality was well established from Sloan Digital Sky Survey data, we show here that the rest-(u - r) colour bimodality becomes more pronounced when using the core colour as opposed to global colour. The two populations are extremely well separated in the colour-log(n) plane. Using our sample of 3314 (B < 19 mag) eyeball classified galaxies, we show that the bulge-dominated, early-type galaxies populate one peak and the bulge-less, late-type galaxies occupy the second. The early- and mid-type spirals sprawl across and between the peaks. This constitutes extremely strong evidence that the fundamental way to divide the luminous galaxy population (M BMGC -5 log h < -16 mag, i.e. dwarfs not included) is into bulges (old red, inert, high concentration) and discs (young, blue, star forming, low concentration) and that the galaxy bimodality reflects the two-component nature of galaxies and not two distinct galaxy classes. We argue that these two components require two independent formation mechanisms/processes and advocate early bulge formation through initial collapse and ongoing disc formation through splashback, infall and merging/accretion. We calculate the B-band luminosity densities and stellar mass densities within each subdivision and estimate that the z ≈ 0 stellar mass content in spheroids, bulges and discs is 35 ± 2, 18 ± 7 and 47 ± 7 per cent, respectively.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9ea2de5dcedb51ee3ab899f25e6c8e55e84281f2

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Citations in the corpus

A LINK BETWEEN STAR FORMATION QUENCHING AND INNER STELLAR MASS DENSITY IN SLOAN DIGITAL SKY SURVEY CENTRAL GALAXIES (2013, background): “Indeed, a similar threshold has been found when examining the Sersic index (Sersic 1968), which quantifies the mass (more precisely, the light) distribution (Driver et al. 2006; Schiminovich et al. 2007; Bell 2008).”
Analysis of galaxy spectral energy distributions from far-UV to far-IR with CIGALE: studying a SINGS test sample (2009, result): “…found is consistent with the results of Kauffmann et al. (2003a, 2003b) for the SDSS and is reminiscent of the two basic galaxy populations “red sequence” (≥ 7 objects) and “blue cloud” (≥ 19 objects) discussed in, e.g., Strateva et al. (2001), Baldryet al. (2004), and Driver et al. (2006).”
The Millennium Galaxy Catalogue: bulge–disc decomposition of 10 095 nearby galaxies (2006, methodology): “That the majority of bulges identify with the red, high-n peak supports the conclusions of Driver et al. (2006) that the colour bimodality reported in the galaxy population is best explained by two fundamental components: bulges and discs, rather than two different galaxy populations.”
The SWIRE-VVDS-CFHTLS surveys: stellar mass assembly over the last 10 Gyr. Evidence for a major build up of the red sequence between z = 2 and z = 1 (2007, methodology): “We have used the results reported by Driver et al. (2006) based on the Millennium Galaxy Catalog (MGC) where they provide the LFs in B band and stellar mass density (ρ ) for a large variety of classification, based on morphology, colors, SED fitting and spectral classes (η parameter from 2dF:…”
BULGE n AND B/T IN HIGH-MASS GALAXIES: CONSTRAINTS ON THE ORIGIN OF BULGES IN HIERARCHICAL MODELS (2008, result): “This difference can be attributed to the fact that the Driver et al. (2006) study did not perform bulge-disk-bar fits and thus, their B/T ratios may be skewed to higher values.”
The fundamental properties of galaxies and a new galaxy classification system (2006, background): “More recently, Driver et al. (2006) argue that light concentration and colour are fundamental properties that separate galaxies into early and late types, which is again a two-dimensional projection of this new system.”
Bulge mass is king: the dominant role of the bulge in determining the fraction of passive galaxies in the Sloan Digital Sky Survey (2014, background): “This bimodality is also seen in terms of colour (e.g. Strateva et al. 2001, Baldry et al. 2004, Driver et al. 2006).”
The UV-Optical Galaxy Color-Magnitude Diagram. I. Basic Properties (2007, background): “…in the red peak tend to be predominantly morphologically early-type and high surface brightness galaxies, while those in the blue peak are dominated bymorphologically late-type galaxies with lower surface brightness (Strateva et al. 2001; Driver et al. 2006; Blanton et al. 2003b; Ball et al. 2006).”
X-ray coronae in simulations of disc galaxy formation (2010, methodology): “…(Efstathiou et al. 1982; Mo et al. 1998; Syer et al. 1999), enabling the model to reproduce the abundance of morphological types observed in the local Universe (e.g. Driver et al. 2006, 2007; Fukugita et al. 2007; Bernardi et al. 2010; Parry et al. 2009). c© 2009 RAS ar X iv :1 00 5.”
A Log-Quadratic Relation for Predicting Supermassive Black Hole Masses from the Host Bulge Sérsic Index (2006, methodology): “In Graham et al. 2007 we apply this quadratic relation to the MillenniumGalaxy Catalog (Liske et al. 2003; Cross et al. 2004; Driver et al. 2006), containing 10,095 galaxies—which have been modeled with a Sérsic bulge plus exponential disk (Allen et al. 2006)—to determine the local supermassive…”
The Millennium Galaxy Catalogue: the B-band attenuation of bulge and disc light and the implied cosmic dust and stellar mass densities (2007, methodology): “…of obtaining statistical distributions for the disc and bulge components (e.g. disc/bulge luminosity–size or luminosity–colour distributions, see Driver et al. 2006), samples uncorrected for galaxy inclination will have their intrinsic distributions broadened (and skewed, see in particular…”
Galaxy Zoo: Disentangling the Environmental Dependence of Morphology and Colour ⋆ (2008, background): “Galaxies may also experience major mergers, which transform late-type galaxies into early-type galaxies with a central bulge component (e.g., Driver et al. 2006, Drory & Fisher 2007).”
Galaxy and Mass Assembly (GAMA): survey diagnostics and core data release (2010, background): “Galaxies typically comprise bulge and/or disc components that exhibit distinct properties (dynamics, ages, metallicities, profiles, dust and gas content), indicating potentially distinct evolutionary paths (e.g. cold smooth and hot lumpy accretion; cf. Driver et al. 2006 or Cook et al. 2010).”
Galaxy bimodality versus stellar mass and environment (2006, methodology): “A more robust method of outlining the two sequences is to consider a joint distribution in colour and structure (Driver et al. 2006).”
Photometric scaling relations of lenticular and spiral galaxies (2010, background): “But it has also been suggested by Driver et al. (2006) that the global properties of bulge-disk systems might result from the mixing of a red bulge stellar population with a blue disk population, in varying degrees.”
PRIMUS: CONSTRAINTS ON STAR FORMATION QUENCHING AND GALAXY MERGING, AND THE EVOLUTION OF THE STELLAR MASS FUNCTION FROM z = 0–1 (2013, background): “By the current epoch, quiescent galaxies vastly outnumber star-forming galaxies above ∼ 3 × 1010 M⊙, and account for more than half of the total stellar mass in the local Universe (Bell et al. 2003; Baldry et al. 2004; Driver et al. 2006).”
Galaxy Zoo: a sample of blue early-type galaxies at low redshift (2009, background): “…on a colour-magnitude diagram (e.g. Baldry et al. 2004; Figure 1), where early-type galaxies typically appear to lie on a red sequence while spirals display bluer colours and seem to reside in a ‘blue cloud’ (Chester & Roberts 1964; Bower et al. 1992; Driver et al. 2006; Faber et al. 2007).”
A CATALOG OF DETAILED VISUAL MORPHOLOGICAL CLASSIFICATIONS FOR 14,034 GALAXIES IN THE SLOAN DIGITAL SKY SURVEY (2010, background): “Recent morphological catalogs by Fukugita et al. (2007) and Driver et al. (2006) do not provide the visual detail presented here.”