A complete sample of GHz-peaked-spectrum radio sources and its radio properties

We dene a complete sample of thirty-three GHz-Peaked-Spectrum (GPS) radio sources based on their spectral properties. We present measurements of the radio spectra and polarization of the complete sample and a list of additional GPS sources which fail one or more criteria to be included in the complete sample. The majority of the data have been obtained from quasi-simultaneous multi-frequency observations at the Very Large Array (VLA) during 3 observing sessions. Low frequency data from the Westerbork Synthesis Radio Telescope (WSRT) and from the literature have been com- bined with the VLA data in order to better dene the spectral shape. The objects presented here show a rather wide range of spectral indices at high and low frequencies, including a few cases where the spectral index below the turnover is close to the theoretical value of 2.5 typical of self-absorbed incoherent synchrotron emission. Faint and diuse ex- tended emission is found in about 10% of the sources. In the majority of the GPS sources, the fractional po- larization is found to be very low, consistent with the residual instrumental polarization of 0.3% 1 .