Authors: Alister W. Graham, P. Erwin, I. Trujillo
Abstract: We investigate the nuclear and global structure of elliptical galaxies, and the apparent disparity between the Nuker and Sersic light-profile models. We show that the so-called "power-law" galaxies in fact have Sersic R1/n profiles over their entire observed radial range. Consequently, only three (Sersic-profile) parameters are required to simultaneously describe both the inner (HST-resolved) and outer profiles of low-luminosity (M > -20.5 B-mag) elliptical galaxies. We also find that "core galaxies" have Sersic profiles with a (partially evacuated) single power-law core. We have developed a modified (5-parameter) Sersic profile with a power-law core to model the complete radial extent of luminous galaxies with cores. In addition to quantifying the global stellar distribution in these systems, we have derived new estimates of their core radii and other central properties. Comparison of the central stellar deficits with the galaxies' black holes suggests that the number of (dissipationless) major mergers that have produced luminous elliptical galaxies is around 1-2, rather than 8--10, which agrees nicely with theory and implies that the galactic merger history of the Universe is roughly an order of magnitude less violent than previous observational analyses had suggested.