Low X-Ray Luminosity Galaxy Clusters. IV. SDSS galaxy clusters at z < 0.2

Abstract

This is the fourth of a series of papers on low X-ray luminosity galaxy clusters. The sample comprises 45 galaxy clusters with X-ray luminosities fainter than 0.7 × 1044 erg s.1 at redshifts lower than 0.2 in the regions of the Sloan Digital Sky Survey. The sample of spectroscopic members of the galaxy clusters was obtained with the criteria: Rp ≤ 1Mpc and δV ≤ σ using our σ estimates containing 21 galaxy clusters with more than six spectroscopic members. We have also defined a sample of photometric members with galaxies that satisfy rp ≤ 1Mpc, and δV ≤ 6000 km s -1 including 45 galaxy clusters with more than six cluster members.We have divided the redshift range in three bins: Z ≤ 0.065; 0.065 z 0.10; and z ≤ 0.10. We have stacked the galaxy clusters using the spectroscopic sub-sample and we have computed the best RS linear fit within 1 σ dispersion.With the photometric sub-sample we have added more data to the RS obtaining the photometric 1σ dispersion relative to the spectroscopic RS fit. We have computed the luminosity function using the 1/Vmax method fitting it with a Schechter function. The obtained parameters for these galaxy clusters with low X-ray luminosities are remarkably similar to those for groups and poor galaxy clusters at these lower redshifts.