Next Contents Previous


Radio sources in the Hubble Deep Field and surrounding region are identified with a variety of galaxy counterparts, mostly spiral and irregular galaxies in small groups, but including a few late type systems. Redshifts of HDF radio sources are comparable to those of radio galaxies identified with much stronger radio source samples, but the microjansky radio sources are much less luminous. Many of the galaxies with microjansky radio emission have also been detected by ISO at 6.7 or 15 microns. Measurements of the radio luminosity, morphology, variability, and spectral index suggest an emission mechanism which is powered in part by AGN and in part by starforming activity. Our estimates of star forming rates estimated from the observed radio emission of HDF galaxies is typically within a factor of two of that given by Rowan-Robinson (1997) from ISO observations at 6.7 microns. One radio source appears to have no optical counterpart in the HDF and may be an I dropout galaxy at a redshift greater than six.

The results reported here are based on work done in collaboration with E. Fomalont, R. Windhorst, and B. Partridge. A more detailed account will be given by Richards et al. (1998). Optical magnitudes and redshifts quoted in this paper are taken from data made available by J. Cohen et al. (1996), C. Steidel, L. Moustakas et al., (1997), A. Phillips et al. (1997), L. Cowie, (1997) and others. We are grateful to these colleagues for making the follow-up ground based optical data available. Part of this work was supported by NASA through grant AR-06337.02-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-2655. EAR acknowledges support of a Sigma Xi Grant-in-Aid-of-Research. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.