THE ESO SLICE PROJECT (ESP) GALAXY REDSHIFT SURVEY. II. THE LUMINOSITY FUNCTION AND MEAN GALAXY DENSITY

The ESO Slice Project (ESP) is a galaxy redshift survey we have recently completed as an ESO Key-Project over about 23 square degrees, in a region near the South Galactic Pole. The survey is nearly complete to the limiting magnitude bJ =1 9 :4 and consists of 3342 galaxies with reliable redshift determination. TheESPsurveyisintermediatebetweenshallow,wideangle samples and very deep, one-dimensional pencil beams: span- ning a volume of 5 10 4 h 3 Mpc 3 at the sensitivity peak (z 0:1), it provides an accurate determination of the \local" luminosity function and the mean galaxy density. We nd that, although a Schechter function (with = 1:22, M bJ = 19:61 +5logh and =0 :020 h 3 Mpc 3 )i s an acceptable representation of the luminosity function over the entire range of magnitudes (MbJ 12:4 +5logh ), our data suggest the presence of a steepening of the luminosity function for MbJ 17 +5logh . Such a steepening at the faint end of the luminosity function, well tted by a power law with slope 1 :6, is almost completely due to galaxies with emis- sion lines: in fact, dividing our galaxies into two samples, i.e. galaxies with and without emission lines, we nd signicant differences in their luminosity functions. In particular, galax- ies with emission lines show a signicantly steeper slope and a fainter M.