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

Abstract

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 comparison with 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 faintend slope. For the whole sample we find M* 19X7 (for V 1Y H 0 100 km s 1 Mpc 1 Y a 1X3Y f* 0X017X For class 1 ('early-type') we find M* 19X6Y a 0X7, while for class 5 ('late-type') we find M* 19X0Y a 1X7. The derived 2dF luminosity functions agree well with other recent luminosity function estimates.