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 $z \sim$ 1-2, may hold the key to understanding the evolution of the starburst phenonemon 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 $z\sim 0.4-1$ 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.