A turn-over in the galaxy luminosity function of the Coma cluster core?

Our previous study of the faint end (R less than or equal to 21.5) of the g alaxy luminosity function (GLF) was based on spectroscopic data in a Small region near the Coma cluster center. In this previous study Adami ct al. (1 998) suggested, with moderate statistical significance, that the number of galaxies actually belonging to the cluster was much smaller than expected. This led us to increase our spectroscopic sample. Here, we have improved th e statistical significance of the results of the Coma GLF faint end study ( R less than or equal to 22.5) by using a sample of 88 redshifts. This inclu des both new spectroscopic data and a literature compilation. The relatively small number of faint galaxies belonging to Coma that was su ggested by Adami ct al. (1998) and Seeker et al. (1998) has been confirmed with these new observations. We also confirm that the color-magnitude relat ion is not well suited for finding the galaxies inside the Coma cluster cor e, close to the center at magnitudes fainter than R similar to 19. We show that there is an enhancement in the Coma line of sight of field galaxies co mpared to classical field counts. This can be explained by the contribution of groups and of a distant,z similar to 0.5 cluster along the line of sigh t. The result is that the Coma GLF appears to turn-over or at least to become Rat for the faint galaxies. We suggest that this is due to environmental ef fects.