Open AccessThe Millennium Galaxy Catalogue: the space density and surface‐brightness distribution(s) of galaxies
Author(s) -
Driver S. P.,
Liske J.,
Cross N. J. G.,
De Propris R.,
Allen P. D.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.08990.x
Subject(s) - physics , astrophysics , field galaxy , surface brightness , galaxy , redshift survey , sky , astronomy , brightness , luminosity , luminosity function , redshift , absolute magnitude
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 deg 2 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 10 095 galaxies to B MGC < 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) h 3 Mpc −3 , M * B MGC− 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 j b J= (1.99 ± 0.17) × 10 8 h L ⊙ Mpc −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 −2 h 3 Mpc −3 , μ e *= (21.90 ± 0.01) mag arcsec −2 and σ ln R e= 0.35 ± 0.01 . The characteristic surface brightness for luminous systems is invariant to M B MGC− 5 log h ≈−19 mag faintwards of which it moves to lower surface brightness. The surface‐brightness distribution also broadens (σ ln R e≈ 0.5 − 0.7) towards lower luminosities. The luminosity dependence of σ ln R e provides a new constraint for both the theoretical development and numerical simulations, which typically predict a mass‐independent σ ln R e≈ 0.56 ± 0.04 . Higher resolution (FWHM ≪ 1 arcsec) and deeper ( μ lim ≫ 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.