A study of young radio-loud AGN using space-VLBI
  Gigahertz Peaked Spectrum (GPS) sources form a key element in the study of the onset and evolution of radio-loud AGN, since they are most likely the young counterparts of extended radio sources. Here we discuss space-VLBI observations of GPS sources, which enable us to obtain unprecedented angular resolution at frequencies near their spectral turnovers. Observed peak brightness temperatures of Log[T]=10.5-11 Kelvin indicate that synchrotron self absorption is responsible for their spectral turnovers. This is in close agreement with previous size - spectral turnover statistics for GPS sources. The combination of these new space-VLBI observations with ground-based VLBI observations taken at an earlier epoch, confirm the young ages for the most compact GPS galaxies of several hundred years. 
Ignas Snellen (IoA Cambridge), Wolfgang Tschager (Leiden), Richard   Schilizzi (JIVE/Leiden), Huub Rottgering (Leiden), Geor...