ABSTRACT Partridge The galaxies and clusters now visible in the Universe grew from small perturbations in density present at very early times, corresponding to redshifts >1000. Many details of this evolutionary process are poorly understood. In particular, we have only rudimentary (but rapidly improving) understanding of the formation of cosmic structure in the first 5 billion years after the recombination of the primeval plasma, that is in the large range of redshifts 1-1000. Refined radio-wavelength searches for various classes of fluctuations in the cosmic microwave background radiation (CBR) will tell us more about the early phases of structure formation, at the high end of this crucial redshift interval. Optical, IR and radio observations of galaxies or galaxy fragments at z = 1-3 are already providing important clues to the final stages of galaxy formation (e.g., the onset of star formation). Searches for CBR fluctuations and radio wavelength observations of high redshift galaxies will be carried out. The goal of the research is to help bridge the gap in our understanding of cosmic evolution during the epoch corresponding to redshifts (z) = 1-1000. A study of the Hubble Deep Field at radio wavelengths will be carried out. The Hubble Deep Field (HDF) is a small but typical region of the sky selected by astronomers for intensive study at all wavelengths, beginning with a very deep Space Telescope exposure late last year. The aim is to use observations across the electromagnetic spectrum to move our understanding of galaxy evolution forward. Our radio observations will be carried out at the Very Large Array at 8.4 and 1.4 GHz and with angular resolution from 10" down to 0.4" (close to the Space Telescope resolution). Among the scientific goals of our observations are: --measuring radio spectra and morphologies to determine the nature of the radio emission (synchrotron from supernova activity? active galactic nuclei?) --refining counts of radio source s at low flux densities --examining the correlation of radio and optical luminosities --improving limits on fluctuations in the CBR on angular scales 6"-80" --searching for the microwave signals produced by clusters or protoclusters of galaxies at z > 1. Several related projects will parallel these efforts, including further work on foreground sources of noise which interfere with searches for CBR fluctuations, planning for a European space mission to map the CBR, and near infrared observations of both high redshift galaxies already observed at the VLA and of the 2-4 micron cosmic microwave background. A postdoctoral associate will assist in some or all of these projects. The position is intended, however, to provide the postdoc with further experience and training in both teaching and research. In addition to his or her research involvement, the postdoc would design and teach one course per year at Haverford, under the close supervision and mentoring of members of our department. Undergraduate students will be involved in various aspects of the research.
