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Paper: The brightest galaxies in clusters
Volume: 10, Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium
Page: 209
Authors: Bhavsar, Suketu P.
Abstract: It has been shown, using extreme value theory, that first-ranked galaxies in rich clusters cannot all be statistical, the tail end of a luminosity function. The distribution of their absolute magnitudes requires that at least a fraction of them belong to a separate class of objects. This conforms with the popular (but debated) view that some of the brightest galaxies in clusters (e.g. the cD galaxies) are formed by a 'special' process. A statistical analysis of the magnitudes of the brightest galaxies, under the general assumption that they consist of both special and normal galaxies, leads to the following 'most probable' situation. About 73 percent of the Abell richness 0 and 1 clusters have a special galaxy. The luminosities of these special galaxies have a Gaussian distribution with a dispersion of 0.3 mag. Their metric magnitudes are on average 0.5 mag brighter than the average magnitudes of the brightest normal galaxies. Statistical analysis does not rule out the possibility that all first-ranked galaxies in rich clusters are special.
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