| Description: | This summer I worked on VLBI data on local analogs of high redshift Lyman Break galaxies for a project initiated by Roderik Overzier (Max Plank Institute for Astrophysics). Lyman Break galaxies are believed to correspond to an important phase in galaxy formation and evolution. Observations of such objects could help probe the relationship between star formation and active galactic nuclei (AGN). However, it is difficult to observe low-luminosity AGN at such a high redshift, so instead we studied a sample of relatively nearby starforming galaxies that have similar properties. The sources were observed with the European VLBI Network (EVN), to look for compact emission showing evidence of massive black holes in the nuclei of these galaxies. Most of the targets were undetected on milliarcsecond scales, indicating that their radio emission is dominantly coming from extended starforming regions. There were two sources detected with high significance in the EVN data, J015028+130858 and J092159+450912. The former was clearly resolved. The latter one appeared more compact, and the data could be fitted with either a circular Gaussian or a point source model, but simulations of the data showed that it was significantly resolved as well. These two sources thus most likely posess very compact nuclear starbursts and hide no massive AGN. The implication for the SKA is that similar sources at much higher redshifts may be misinterpreted as low-luminosity AGN based on their compact structure.
The black and white image of the galaxy J092159+450912 was taken by the Huble Space Telescope. The colour image is a dirty map of the field taken by the EVN on 2008 June 6 at 1.7 GHz.
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