The ACS Fornax Cluster Survey. IV. Deprojection of the Surface
  Brightness Profiles of Early-Type Galaxies in the Virgo and Fornax Clusters:
  Investigating the "Core/Power-Law Dichotomy"
  Although early observations with the Hubble Space Telescope (HST) pointed to
a sharp dichotomy among early-type galaxies in terms of the logarithmic slope
gamma' of their central surface brightness profiles, several studies in the
past few years have called this finding into question. In particular, recent
imaging surveys of 143 early-type galaxies belonging to the Virgo and Fornax
Clusters using the Advanced Camera for Surveys (ACS) on board HST have not
found a dichotomy in gamma', but instead a systematic progression from central
luminosity deficit to excess relative to the inward extrapolation of the
best-fitting global Sersic model. Given that earlier studies also found that
the dichotomy persisted when analyzing the deprojected density profile slopes,
we investigate the distribution of the three-dimensional luminosity density
profiles of the ACS Virgo and Fornax Cluster Survey galaxies. Having fitted the
surface brightness profiles with modified Sersic models, we then deproject the
galaxies using an Abel integral and measure the inner slopes gamma_3D of the
resulting luminosity density profiles at various fractions of the effective
radius R_e. We find no evidence of a dichotomy, but rather, a continuous
variation in the central luminosity profiles as a function of galaxy magnitude.
We introduce a parameter, Delta_3D, that measures the central deviation of the
deprojected luminosity profiles from the global Sersic fit, showing that this
parameter varies smoothly and systematically along the luminosity function.
