Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-02-10
Mon.Not.Roy.Astron.Soc.368:414-434,2006
Astronomy and Astrophysics
Astrophysics
Accepted for publication in MNRAS, 23 pages, 17 figures. Comments welcome. MGC website is at: http://www.eso.org/~jliske/mgc/
Scientific paper
10.1111/j.1365-2966.2006.10126.x
Using 10 095 galaxies (B < 20 mag) from the Millennium Galaxy Catalogue, we derive B-band luminosity distributions and selected bivariate brightness distributions for the galaxy population. All subdivisions extract highly correlated sub-sets of the galaxy population which consistently point towards two overlapping distributions. A clear bimodality in the observed distribution is seen in both the rest-(u-r) colour and log(n) distributions. 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 3 314 (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 is into bulges and discs 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 per cent, 18 +/- 7 and 47 +/- 7 per cent respectively. [Abridged]
Allen Paul D.
Cameron Ewan
Couch Warrick J.
Cross Nicholas J. G.
de Propris Roberto
No associations
LandOfFree
The Millennium Galaxy Catalogue: morphological classification and bimodality in the colour-concentration plane does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Millennium Galaxy Catalogue: morphological classification and bimodality in the colour-concentration plane, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Millennium Galaxy Catalogue: morphological classification and bimodality in the colour-concentration plane will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-599785