CONICET | Buscador de Institutos y Recursos Humanos

This is the forth of a series of papers on low X-ray luminosity galaxy clusters. Thesample comprises 45 galaxy clusters with X-ray luminosities fainter than 0.7 10 44 ergs −1 at redshifts lower than 0.2 in the regions of the Sloan Digital Sky Survey. Thesample of spectroscopic members of the galaxy clusters was obtained with the criteria:r p ≤ 1 Mpc and ∆V ≤ σ using our σ estimates containing 21 galaxy clusters withmore than 6 spectroscopic members. We have also defined a sample of photometricmembers with galaxies that satisfy r p ≤ 1 Mpc, and ∆V ≤ 6000 km s −1 including 45galaxy clusters with more than 6 cluster members. We have divided the redshift rangein three bins: z ≤ 0.065; 0.065 < z < 0.10; and z ≥ 0.10. We have stacked the galaxyclusters using the spectroscopic sub-sample and we have computed the best RS linearfit within 1σ dispersion. With the photometric sub-sample we have added more datato the RS obtaining the photometric 1σ dispersion relative to the spectroscopic RS fit.We have computed the luminosity function using the 1/V max method fitting it with aSchechter function. The obtained parameters for these galaxy clusters with low X-rayluminosities are remarkably similar to those for groups and poor galaxy clusters atthese lower redshifts.