The Millennium Galaxy Catalogue: bulge–disc decomposition of 10 095 nearby galaxies

We have modelled the light distribution in 10095 galaxies from the Millennium Galaxy Catalogue (MGC), providing publically available structural catalogues for a large, rep- resentative sample of galaxies in the local Universe. Three different models were used: (1) a single Sersic function for the whole galaxy, (2) a bulge-disc decomposition model using a de Vaucouleurs (R 1/4 ) bulge plus exponential disc, (3) a bulge-disc decomposi- tion model using a Sersic (R 1/n ) bulge plus exponential disc. Repeat observations for � 700 galaxies demonstrate that stable measurements can be obtained for object com- ponents with a half-light radius comparable to, or larger than, the seeing half-width at half maximum. We show that with careful quality control, robust measurements can be obtained for large samples such as the MGC. We use the catalogues to show that the galaxy colour bimodality is due to the two-component nature of galaxies (i.e. bulges and discs) and not to two distinct galaxy populations. We conclude that under- standing galaxy evolution demands the routine bulge-disc decomposition of the giant galaxy population at all redshifts.

[1]  R. Nichol,et al.  Quantifying the Bimodal Color-Magnitude Distribution of Galaxies , 2003, astro-ph/0309710.

[2]  P. Tenjes,et al.  Surface photometry and structure of high redshift disk galaxies in the HDF-S NICMOS field , 2005, astro-ph/0512165.

[3]  S. Driver,et al.  The Millennium Galaxy Catalogue : morphological classification and bimodality in the colour-concentration plane , 2006, astro-ph/0602240.

[4]  L. Ho,et al.  Detailed structural decomposition of galaxy images , 2002, astro-ph/0204182.

[5]  K. Freeman.  On the disks of spiral and SO Galaxies , 1970 .

[6]  P. Norberg,et al.  The Millennium Galaxy Catalogue: the photometric accuracy, completeness and contamination of the 2dFGRS and SDSS-EDR/DR1 data sets , 2003, astro-ph/0312317.

[7]  The Evolution of Disk Galaxies in the GOODS-South Field: Number Densities and Size Distribution* , 2004, astro-ph/0401483.

[8]  S.Cole,et al.  The 2dF Galaxy Redshift Survey: spectra and redshifts , 2001, astro-ph/0106498.

[9]  The Peculiar Motions of Early-type Galaxies in Two Distant Regions. IV. The Photometric Fitting Procedure , 1996, astro-ph/9609089.

[10]  Christopher J. Conselice,et al.  The Relationship between Stellar Light Distributions of Galaxies and Their Formation Histories , 2003 .

[11]  J. Liske,et al.  The Millennium Galaxy Catalogue: 16 ⩽ BMGC < 24 galaxy counts and the calibration of the local galaxy luminosity function , 2002 .

[12]  S. Driver,et al.  The Millennium Galaxy Catalogue: the space density and surface-brightness distribution(s) of galaxies , 2005, astro-ph/0503228.

[13]  B. Poggianti.  K and evolutionary corrections from uv to ir , 1996, astro-ph/9608029.

[14]  The 2dF Galaxy Redshift Survey: galaxy luminosity functions per spectral type , 2001, astro-ph/0107197.

[15]  W. W. Morgan.  PRELIMINARY CLASSIFICATION OF THE FORMS OF GALAXIES ACCORDING TO THEIR STELLAR POPULATION. II , 1958 .

[16]  Bhasker K. Moorthy,et al.  The First Data Release of the Sloan Digital Sky Survey , 2003, astro-ph/0305492.

[17]  A. Graham,et al.  A Morphological Type Dependence in the μ0-log h Plane of Spiral Galaxy Disks , 2001, astro-ph/0103405.

[18]  A. Naim,et al.  Automated morphological classification of APM galaxies by supervised artificial neural networks , 1995, astro-ph/9503001.

[19]  A. Graham,et al.  HST Photometry of Dwarf Elliptical Galaxies in Coma, and an Explanation for the Alleged Structural Dichotomy between Dwarf and Bright Elliptical Galaxies , 2003, astro-ph/0303391.

[20]  T. Lauer,et al.  Brightest Cluster Galaxy Profile Shapes , 1996, astro-ph/9603006.

[21]  A. Naim,et al.  Neural computation as a tool for galaxy classification: methods and examples , 1995, astro-ph/9508012.

[22]  A K-band central disc surface brightness correlation with scalelength for early-type disc galaxies, and the inclination correction , 2001, astro-ph/0104111.

[23]  R. Bouwens,et al.  The DEEP Groth Strip Survey. VIII. The Evolution of Luminous Field Bulges at Redshift z ∼ 1 , 2004, astro-ph/0412004.

[24]  Gerard de Vaucouleurs,et al.  Rechereches sur les nebuleuses extragalactiques , 1948 .

[25]  S. Bergh.  A new classification system for galaxies. , 1976 .

[26]  Canada-France Redshift Survey: Hubble Space Telescope Imaging of High-Redshift Field Galaxies , 1995, astro-ph/9507028.

[27]  Stephen C. Odewahn,et al.  Automated Morphological Classification in Deep Hubble Space Telescope UBVI Fields: Rapidly and Passively Evolving Faint Galaxy Populations , 1996 .

[28]  G. Vaucouleurs.  Classification and Morphology of External Galaxies , 1959 .

[29]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[30]  On the Shape of the Light Profiles of Early Type Galaxies - Part Two - the - Diagram , 1993, astro-ph/9309013.

[31]  Mamoru Doi,et al.  Morphological classification of galaxies using simple photometric parameters , 1993 .

[32]  The Broadband Optical Properties of Galaxies with Redshifts 0.02 < z < 0.22 , 2002, astro-ph/0209479.

[33]  I. Trujillo,et al.  Quantitative Morphology of Galaxies in the Core of the Coma Cluster , 2004 .

[34]  The Magnitude-Size Relation of Galaxies out to z ~ 1 , 1999, astro-ph/9902147.

[35]  Simon P. Driver,et al.  A Concise Reference to (Projected) Sérsic R 1/n Quantities, Including Concentration, Profile Slopes, Petrosian Indices, and Kron Magnitudes , 2005, Publications of the Astronomical Society of Australia.

[36]  C. Baugh,et al.  Hierarchical galaxy formation , 2000, astro-ph/0007281.

[37]  R. D. Jong.  Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. ?;?? II. A two-dimensional method to determine bulge and disk parameters , 1996, astro-ph/9601002.

[38]  A. Naim,et al.  A Comparative study of morphological classifications of APM galaxies , 1995 .

[39]  R. Saglia,et al.  Structural properties of discs and bulges of early-type galaxies , 2004, astro-ph/0410121.

[40]  O. Lahav,et al.  Galaxies, Human Eyes, and Artificial Neural Networks , 1994, Science.

[41]  Ignacio Trujillo,et al.  Quantitative morphological analysis of the Hubble Deep Field North and Hubble Deep Field South – I. Early- and late-type luminosity–size relations of galaxies out to z∼ 1 , 2004 .

[42]  N. Caon,et al.  Galaxy Light Concentration. I. Index Stability and the Connection with Galaxy Structure, Dynamics, and Supermassive Black Holes , 2001, astro-ph/0110159.

[43]  B. Tinsley,et al.  Evolution of galaxies and stellar populations , 1977 .

[44]  John Kormendy,et al.  Brightness distributions in compact and normal galaxies. II. Structure parameters of the spheroidal component. , 1977 .

[45]  M. Capaccioli.  Photometry of early-type galaxies and the r 1/4 law. , 1989 .

[46]  Karl Glazebrook,et al.  The morphologies of distant galaxies. II. Classifications from the Hubble Space Telescope medium deep survey , 1996 .

[47]  Chien Y. Peng,et al.  GEMS: The Surface Brightness and Surface Mass Density Evolution of Disk Galaxies , 2005 .

[48]  N. Vogt,et al.  The DEEP Groth Strip Survey. II. Hubble Space Telescope Structural Parameters of Galaxies in the Groth Strip , 2002, astro-ph/0205025.

[49]  R. Sanders,et al.  Exponential bulges in late-type spirals : an improved description of the light distribution. , 1994 .

[50]  Jose Luis. Sersic,et al.  Atlas de Galaxias Australes , 1968 .

[51]  D. Christlein,et al.  Disentangling Morphology, Star Formation, Stellar Mass, and Environment in Galaxy Evolution , 2004, astro-ph/0411359.

[52]  W. W. Morgan.  Some Characteristics of Galaxies. , 1962 .

[53]  J. Aguerri,et al.  Structural Parameters of Dwarf Galaxies in the Coma Cluster: On the Origin of dS0 Galaxies , 2005, astro-ph/0504549.

[54]  B. Elmegreen,et al.  Optical Tracers of Spiral Wave Resonances in Galaxies: II. Hidden Three-Arm Spirals in a Sample of 18 Galaxies , 1991 .

[55]  S. dos Anjos,et al.  BUDDA: A New Two-dimensional Bulge/Disk Decomposition Code for Detailed Structural Analysis of Galaxies , 2004, astro-ph/0404103.

[56]  STRUCTURE OF DISK-DOMINATED GALAXIES. I. BULGE/DISK PARAMETERS, SIMULATIONS, AND SECULAR EVOLUTION , 2002, astro-ph/0208404.