Quantitative morphology of galaxies in the Hubble deep field

We measure quantitative structural parameters of galaxies in the Hubble dee p held (HDF) on the drizzled F814W images. Our structural parameters are ba sed on a two-component surface brightness made up of a Sersic profile and a n exponential profile. We compare our results to the visual classification of van den Bergh et al, and the C-A classification of Abraham et al. Our mo rphological analysis of the galaxies in the HDF indicates that the spheroid al galaxies, defined here as galaxies with a dominant bulge profile, make u p for only a small fraction, namely, 8%, of the galaxy population down to m (F814W)(AB) = 26.0. We show that the larger fraction of early-type systems in the van den Bergh sample is primarily due to the difference in classific ation of 40% of small, round galaxies with half-light radii less than 0." 3 1. Although these objects are visually classified as elliptical galaxies, w e find that they are disk dominated with bulge fractions less than 0.5. Giv en the existing large data set of HDF galaxies with measured spectroscopic redshifts, we are able to determine that the majority of distant galaxies ( z > 2) from this sample are disk dominated. Our analysis reveals a subset o f HDF galaxies that have profiles flatter than a pure exponential profile.