Brightest Members of Clusters of Galaxies

Abstract

THE work of Humason, Mayall and Sandage¹ and the more recent work of Sandage^2–5 and Peterson⁶ show that the dispersion in the absolute magnitude of the first brightest galaxies in rich clusters of galaxies is only 0.3 magnitude. Peebles⁷ suggested that this small dispersion is simply the consequence of the cluster luminosity function and compared the distribution predicted by the statistical theory with the observations of Humason, Mayall and Sandage¹. I have shown⁸ how the distributions predicted by the statistical theory vary with the richness of the cluster of galaxies and has compared the predicted distributions with the observations of Humason, Mayall and Sandage¹, and with his own observations⁶. But Peach⁹ considered that the statistical theory is inadequate when he compared the distributions calculated from the statistical theory with new data of Sandage.