Quasi-simultaneous multi-frequency observations of inverted-spectrum GPS candidate sources

Abstract

Context. Gigahertz-Peaked Spectrum (GPS) sources are likely the precursors of local radio galaxies. Existing GPS source samples are small (<200). Aims. We aim to extend the available sample of the Gigahertz-Peaked Spectrum (GPS) and High Frequency Peaker (HFP) sources in order to study their nature with greater detail and higher statistical significance. Methods. A sample of 214 radio sources, which were extracted from the SPECFIND catalog and show an inverted radio spectrum, were observed quasi-simultaneously at 4.85, 10.45, and 32 GHz with the 100-m Effelsberg radio telescope. Using the VLBA calibrator survey (VCS) we have investigated the parsec-scale morphology of the sources. Results. About 45% of the sources in our sample are classified as GPS or HFP candidates. We add 65 new GPS/HFP candidates to existing samples. We confirm the expected tendency that HFP are more compact on a milliarcsecond scale than the classical GPS sources, which peak at lower frequencies. Conclusions. The data mining of the SPECFIND database represents a promising tool for the discovery of new GPS/HFP sources.