Using VO tools to investigate distant radio starbursts hosting obscured AGN in the HDF(N) region

Context. A 10-arcmin region around the Hubble Deep Field (North) contains 92 radio sources brighter than 40 µJy which are wellresolved by MERLIN+VLA at 0. 2−2 �� resolution (average size ∼1 �� ). 55 of these have Chandra X-ray counterparts in the 2-Ms CDF(N) field including at least 17 with a hard X-ray photon index and high luminosity characteristic of a type-II (obscured) AGN. More than 70% of the radio sources have been classified as starbursts or AGN using radio morphologies, spectral indices and comparisons with optical appearance and rest-frame MIR emission. On this basis, starbursts outnumber radio AGN 3:1. Aims. We investigate the possibility that very luminous radio and X-ray emission originates from different phenomena in the same high-redshift galaxies. Methods. This study extends the Virtual Observatory (VO) methods previously used to identify X-ray-selected obscured type-II AGN, to examine the relationship between radio and X-ray emission. We describe a VO cut-out server for MERLIN+VLA 1.4-GHz radio images in the HDF(N) region.