The Millennium Galaxy Catalogue: the space density and surface-brightness distribution(s) of galaxies
Abstract
We recover the joint and individual space density and surface-brightness distribution(s) of galaxies from the Millennium Galaxy Catalogue (MGC). The MGC is a local survey spanning 30.9 deg2 and probing approximately 1-2 mag arcsec-2 deeper than either the Two-Degree Field Galaxy Redshift Survey (2dFGRS) or the Sloan Digital Sky Survey (SDSS). The MGC contains 10095 galaxies to BMGC < 20 mag with 96 per cent spectroscopic completeness. For each galaxy we derive individual K-corrections and seeing-corrected sizes. We implement a joint luminosity-surface-brightness step-wise maximum-likelihood method to recover the bivariate brightness distribution (BBD) inclusive of most selection effects. Integrating the BBD over surface brightness we recover the following Schechter function parameters: φ*= (0.0177 +/- 0.0015)h3Mpc-3, M*BMGC- 5 log h= (-19.60 +/- 0.04) mag and α=-1.13 +/- 0.02. Compared to the 2dFGRS we find a consistent M* value but a slightly flatter faint-end slope and a higher normalization, resulting in a final luminosity density jbJ= (1.99 +/- 0.17) × 108hLsolarMpc-3- marginally higher than, but consistent with, the earlier 2dFGRS, ESP, and SDSS z= 0.1 results. The MGC is inconsistent with the SDSS z= 0.0 result (+3σ) if one adopts the derived SDSS evolution.
The MGC surface-brightness distribution is a well-bounded Gaussian at the M* point with φ*= (3.5 +/- 0.1) × 10-2h3Mpc-3, μe*= (21.90 +/- 0.01) mag arcsec-2 and σln Re= 0.35 +/- 0.01. The characteristic surface brightness for luminous systems is invariant to MBMGC- 5 log h~-19 mag faintwards of which it moves to lower surface brightness. The surface-brightness distribution also broadens (σln Re~ 0.5 - 0.7) towards lower luminosities. The luminosity dependence of σln Re provides a new constraint for both the theoretical development and numerical simulations, which typically predict a mass-independent σlnRe~ 0.56 +/- 0.04. Higher resolution (FWHM << 1 arcsec) and deeper (μlim>> 26 mag arcsec-2 in the B-band) observations of the local Universe are now essential to probe to lower luminosity and lower surface-brightness levels.- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2005
- DOI:
- 10.1111/j.1365-2966.2005.08990.x
- arXiv:
- arXiv:astro-ph/0503228
- Bibcode:
- 2005MNRAS.360...81D
- Keywords:
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- astronomical data bases: miscellaneous;
- galaxies: evolution;
- galaxies: formation;
- galaxies: fundamental parameters;
- galaxies: general;
- galaxies: luminosity function;
- mass function;
- Astrophysics
- E-Print:
- Accepted for publication in MNRAS, 26 pages with 21 figures (some degraded). A full pdf version, along with MGC data release, is available from the MGC website at, http://www.eso.org/~jliske/mgc