Direct construction of the galaxy luminosity function as a function of redshift

A novel method is proposed for investigating the evolution of the galaxy luminosity function using the results of faint galaxy redshift surveys. The luminosity function is calculated at a number of redshifts using the Phi(G) estimator of Felten (1976), and the errors on the luminosity function are estimated employing the spatial correlation function. While the standard method merely gives a yes/no decision about whether a particular model is an adequate fit to the data, the result of applying the new method is an immediate pictorial impression, as well as a direct quantitative measure, of both the strength and type of evolution and of the limitations of the data. This method is applied to three recent redshift surveys. There is strong evidence that the amplitude of the luminosity function increases by a large factor (about 3) in the redshift range 0-0.4. No evidence for any change in the shape of the luminosity function was found