MERLIN+VLA Images of two Hubble Flanking Field Objects

18 days of MERLIN data at 20 cm together with 30 hours of VLA data have been combined to make maps of the Hubble Deep Field and Flanking Fields with a noise level of ~3.5 microJy per beam. These maps are the most sensitive ever made at 20 cm wavelength. The main aim of this study is to see whether starbursts or AGN dominate the ultra--weak radio source population. The present results suggest that while the majority of the sources detected at 20cm have characteristics consistent with starbursts (steep spectra, extended on kpc-scales, shapes often consistent with optical shape of host galaxy) a significant minority are clearly AGN (recognisable morphologies or flat spectra). Typically the AGN are identified with elliptical galaxies at z~1 while the putative starbursts are associated with disk systems in the redshift range 0.5 to 1.
Muxlow et al. (Manchester) and Richards et al. (NRAO)