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C. Conselice, M. A. Bershady (U. Wisconsin), M. Dickinson, H. C. Ferguson, A. S. Fruchter, C. Hanley, R. A. Lucas, J. Mack, P. Madau, M. Postman (STScI), A. Connolly, C. Papovich, A. Szalay (JHU), P. Eisenhardt (JPL), R. J. Elston (U. Florida), M. Giavalisco (OCIW), R. N. Hook (ST-ECF), S. A. Stanford (IGPP/LLNL), C. C. Steidel (Caltech)
We present a quantitative morphological study of high redshift galaxies using data from a complete NICMOS imaging survey of the Hubble Deep Field North. The NICMOS H(1.6\mu) and J(1.1\mu) images sample rest frame optical wavelengths for galaxies with z < 2.5. The high angular resolution of the NICMOS images allows us to directly compare quantitative morphological parameters of high redshift galaxies with those of nearby galaxies observed at similar rest-frame wavelengths. We classify the NICMOS-HDF galaxies to a limiting magnitude of I \approx 27 using asymmetry and rest-frame color. We also present methods for directly comparing asymmetries measured from the NICMOS images with those determined for a sample of ground-based images of nearby galaxies which span all morphological types.
We analyze the asymmetries of HDF galaxies as a function of wavelength, comparing the optical WFPC2 to the near-IR NICMOS images. We find that a large fraction of galaxies with peculiar WFPC2 morphologies remain asymmetric in the near-infrared NICMOS data. This suggests that the asymmetries are not simply the consequence of observing irregularly distributed star formation at blue/UV wavelengths, but instead reflect the truly irregular structural state of these galaxies, perhaps due to galaxy interactions or mergers.
The author(s) of this abstract have provided an email address for comments about the abstract: chris@astro.wisc.edu