Radio observations of GRB host galaxies.

We present 5.5 and 9.0 GHz observations of a sample of 17 GRB host galaxies at 0.5 < z < 1.4, using the radio continuum to explore their star formation properties in the context of the small but growing sample of galaxies with similar observations. Four sources are detected, one of those (GRB 100418A) likely due to lingering afterglow emission. We suggest that the previously reported radio afterglow of GRB 100621A may instead be due to host galaxy flux. We see no strong evidence for redshift evolution in the typical star formation rate of GRB hosts, but note that the fraction of ‘dark’ bursts with detections is higher than would be expected given constraints on the more typical long GRB population. We also determine the average radio-derived star formation rates of core collapse supernovae at comparable redshift, and show that these are still well below the limits obtained for GRB hosts, and show evidence for a rise in typical star formation rate with redshift in supernova hosts. [ABSTRACT FROM AUTHOR]