1994/11/07 by A. Biviano, Biviano, A., F. Durret +11
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9411025
7 pages, uuencoded postscript file (figures included) Accepted for publication on A&A
arxiv created 1994/11/07 · arxiv updated 2009/12/01
We have obtained new redshifts for 265 objects in the central 48~×~25~arcmin2 region of the Coma cluster. When supplemented with literature data, our redshift sample is 95~% complete up to a magnitude b26.5=18.0 (the magnitudes are taken from the photometric sample of Godwin et al. 1983). Using redshift-confirmed membership for 205 galaxies, and the location in the colour-magnitude diagram for another 91 galaxies, we have built a sample of cluster members which is complete up to b26.5=20.0. We show that the Coma cluster luminosity function cannot be adequately fitted by a single Schechter (1976) function, because of a dip in the magnitude distribution at b26.5∼17. The superposition of an Erlang (or a Gauss) and a Schechter function provides a significantly better fit. We compare the luminosity function of Coma to those of other clusters, and of the field. Luminosity functions for rich clusters look similar, with a maximum at Mb ≃ -19.5 + 5 × log h50, while the Virgo and the field luminosity functions show a nearly monotonic behaviour. These differences may be produced by physical processes related to the environment which affect the luminosities of a certain class of cluster galaxies.