A radio perspective on star-formation in distant galaxies

Determination of the epoch dependent star-formation rate of field galaxies is one of the principal goals of modern observational cosmology. Deep radio surveys, sensitive to starbursts out to z similar to 1-2, may hold the key to understanding the evolution of the starburst phenomenon unhindered by the effects of dust. Using deep, high resolution radio observations of the Hubble Deep Field, we show that the mu Jy radio emission from field galaxies at z similar to 0.4 - 1 is primarily starburst in origin. In addition, we have discovered a population of optically faint, possibly obscured systems that are candidate high-z protogalaxies. At least one of these radio sources is identified with a sub-mm detection.