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Abstract

Radio wavelengths offer a dust-unobscured window to the early universe. The aim of this thesis has been to characterize the star-forming properties of the high redshift radio galaxy population. We present a preliminary catalogue of the first 610MHz map of the COSMOS feld and find that the sample properties are consistent with predictions for the low frequency radio population. Furthermore, we compare radio and IR star formation rate (SFR) tracers on a large sample of starburst galaxies and find that locally calibrated infrared (IR) and 1.4 GHz radio continuum SFR tracers produce inconsistent results for the most active starbursts. These starbursts are rare locally, but become increasingly common in the early universe. The high redshift starburst population may to be more diffuse, and hence cooler, than local counterparts. In addition, the infrared-radio correlation, observed thus far to be linear and constant for a wide range of galaxies, may exhibit redshift or luminosity evolution. We conclude that a dedicated effort to better model the IR and radio spectral energy distributions of starbursts will be essential to accurately characterize the SFR density at higher redhifts than those considered by studies to date.