Morphology of galaxies in the Hubble Deep Field North and South

Deep high-resolution images of the sky have opened the door to the quantitative approach of studying the morphological structure of distant galaxies. The recent release of the Hubble Deep Field South images have come to add to this rich database of high-redshift galaxies and, in the context of this conference on galaxy evolution, we present the preliminary results we have obtained from our quantitative morphological analysis of the galaxies in the F814W image of the Hubble Deep Field South and F606W image of the Hubble Deep Field North. Our structural parameters are based on a two-component surface brightness made up of a Sersic profile and an exponential profile and obtained from the drizzled F606W HDF-N and F814W HDF-S images, complementary to our existing database of morphological properties of the F814W HDF-N. Our PSF-convolved bulge/disk surface-brightness model fts permit us to distinguish between disk- and bulge-dominated systems. The observed distributions derived from the HDF-S data show that only 10% of the galaxies, as viewed through the F814W filter, are bulge-dominated, a number similar to the 9% found in the F814W HDF-N galaxies down to m(F814W)(AB) = 26.0. The morphology of galaxies can appear strikingly dissimilar at different observed wavelengths (and likewise at different redshifts when observed in the same passband). To begin quantifying this difference, we compare the quantitative parameters derived from the F606W and F814W images of the HDF-N. We discuss combining our observed structural parameters with existing photometric and spectroscopic redshift catalogs to convert them to physical quantities and characterize the evolution of galaxies in terms of their colors, sizes and magnitudes.