Isophotal shapes of early-type galaxies to very faint levels
  We report on a study of the isophotal shapes of early-type galaxies, to very
faint levels reaching ~ 0.1% of the sky brightness. The galaxies are from the
Large Format Camera (LFC) fields obtained using the Palomar 5 m Hale telescope,
with integrated exposures ranging from 1 to 4 hours in the SDSS r, i and z
bands. The shapes of isophotes of early-type galaxies are important as they are
correlated with the physical properties of the galaxies and are influenced by
galaxy formation processes. In this paper we report on a sample of 132 E and SO
galaxies in one LFC field. We have redshifts for 53 of these, obtained using
AAOmega on the Anglo-Australian Telescope. The shapes of early-type galaxies
often vary with radius. We derive average values of isophotal shape parameters
in four different radial bins along the semi-major axis in each galaxy. We
obtain empirical fitting formulae for the probability distribution of the
sophotal parameters in each bin and investigate for possible correlations with
other global properties of the galaxies. Our main finding is that the isophotal
shapes of the inner regions are statistically different from those in the outer
regions. This suggests that the outer and inner parts of early-type galaxies
have evolved somewhat independently.
