The 2dF Galaxy Redshift Survey: spectral types and luminosity functions

We describe the 2dF Galaxy Redshift Survey (2dFGRS), and the current status of the observations. In this exploratory paper, we apply a Principal Component Analysis to a preliminary sample of 5869 galaxy spectra and use the two most significant components to split the sample into five spectral classes. These classes are defined by considering visual classifications of a subset of the 2dF spectra, and also by comparing to high quality spectra of local galaxies. We calculate a luminosity function for each of the different classes and find that later-type galaxies have a fainter characteristic magnitude, and a steeper faint-end slope. For the whole sample we find M ⋆ = 19.7 (for =1,H0=100kms 1 Mpc 1 ), � = 1.3, � ⋆ = 0.017. For class 1 (‘early-type’) we find M ⋆ = 19.6, � = 0.7, while for class 5 (‘late-type’) we find M ⋆ = 19.0, � = 1.7. The derived 2dF luminosity functions agree well with other recent luminosity function estimates.