The rich cluster of galaxies ABCG 85 IV. Emission line galaxies, luminosity function and dynamical properties

This paper is the fourth of a series dealing with the cluster of galaxies A BCG 85. Using our two extensive photometric and spectroscopic catalogues (w ith 4232 and 551 galaxies respectively),we discuss here three topics derive d from optical data. First, we present the properties of emission line vers us non-emission line galaxies, showing that their spatial distributions som ewhat differ; emission line galaxies tend to be more concentrated in the so uth region where groups appear to be falling onto the main cluster in agree ment with the hypothesis (presented in our previous paper) that this infall may create a shock which can heat the X-ray emitting gas and also enhance star formation in galaxies. Then, we analyze the luminosity function in the R band, which shows the presence of a dip similar to that observed in othe r clusters at comparable absolute magnitudes: this result is interpreted as due to comparable distributions of spirals, ellipticals and dwarfs in thes e various clusters. Finally we present the dynamical analysis of the cluste r using parametric and non-parametric methods and compare the dynamical mas s profiles obtained from the X-ray and optical data.