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Abstract: We present the results from a survey of 57 low-redshift Abell galaxy clustersto study the radial dependence of the luminosity function LF. The dynamicalradius of each cluster, r200, was estimated from the photometric measurement ofcluster richness, Bgc. The shape of the LFs are found to correlate with radiussuch that the faint-end slope, alpha, is generally steeper on the clusteroutskirts. The sum of two Schechter functions provides a more adequate fit tothe composite LFs than a single Schechter function. LFs based on the selectionof red and blue galaxies are bimodal in appearance. The red LFs are generallyflat for -22 < M Rc < -18, with a radius-dependent steepening of alpha for M Rc> -18. The blue LFs contain a larger contribution from faint galaxies than thered LFs. The blue LFs have a rising faint-end component alpha ~ -1.7 for M Rc> -21, with a weaker dependence on radius than the red LFs. The dispersion ofM* was determined to be 0.31 mag, which is comparable to the median measurementuncertainty of 0.38 mag. This suggests that the bright-end of the LF isuniversal in shape at the 0.3 mag level. We find that M* is not correlated withcluster richness when using a common dynamical radius. Also, we find that M* isweakly correlated with BM-type such that later BM-type clusters have a brighterM*. A correlation between M* and radius was found for the red and blue galaxiessuch that M* fades towards the cluster center.

Author: Wayne A. Barkhouse 1, H. K. C. Yee 2, Omar López-Cruz 3 1 Department of Astronomy, University of Illinois, 2 Department of Astro


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