Surface brightness and effective radius for elliptical galaxies

Abstract

Seeing convolved two-dimensional de Vaucouleurs profiles have been fitted to digital images of the brightest elliptical galaxies in two nearby groups of galaxies and three clusters of galaxies with redshifts in the range 0.06 to 0.15. The digital images were created by scanning electronographic plates obtained by the use of several versions of the RGO electronographic camera. The linear relation between effective surface brightness ..mu../sub e/ and the logarithm of the effective radius r/sub e/, first discovered by Kormendy to be valid for nearby elliptical galaxies, is found to be equally valid for the largest and brightest galaxies in rich clusters of galaxies. The apparent universal nature of that relation indicates that the same type of processes might have been involved during the formation of all ellipticals from cD galaxies in clusters to fainter ellipticals in small groups. It is suggested that the (I/sub e/,r/sub e/) relation is not changed by the expected dynamical evolution of the brightest galaxies in clusters. If the cosmic nature of the (I/sub e/,r/sub e/) relation is confirmed by future observations, we suggest using the vertical position of that relation, derived from the brightest elliptical galaxies in rich clusters, as a new cosmological test, whichmore » should be independent of dynamical evolution.« less