Observed properties of jets in young radio galaxies

Compact Symmetric Objects (CSOs) are a recently discovered class of radio galaxy thought to be quite young (age similar to 1000 years). These compact (size < 1 kpc) radio sources are morphologically similar to classical double radio galaxies with lobes, hot-spots, jets, and cores, but they inhabit a much denser environment. This dense environment can give rise to free-free and HI absorption of components, and in some cases may impact the shape of the source. VLBI studies can reveal the growth of the source, and motions in the jet. In a few cases, bidirectional motions are observed on either side of the core. I will review the properties of CSOs, paying particular attention to VLBA observations of jet motions and deflections. (C) 2003 Published by Elsevier B.V.