Broad-Band Spectra Study of 213 VSOP 5-GHz Survey Sources

We present a statistical and model study of 1−22 GHz spectra and 5-GHz interpolated data for 213 of 230 sources with declinations δ > −30°, selected for survey observations with the HALCA space radio telescope. The spectra of two subsamples were specially surveyed and monitored in 1997-2000 as a ground spectra support for the space VLBI survey in the framework of the VSOP Survey Programme. Every 1–22 GHz spectrum was measured with the RATAN-600 radio telescope at six wavelengths of 1.4, 2.7, 3.9, 7.7, 13, and 31 cm over a period of a few minutes (ten minutes or more near the pole). (25–30)% of the sources studied are outside of the VSOP selection criteria in 1997-2000 because of the variability of the VSOP sources, which were compiled from catalogs spanning a period between 1985 and 1996. About 60% of 186 VSOP/HALCA sources, monitored in 8 epochs, have amplitudes of variability greater than ± 10% at 5 GHz over the three-year period. 45 new strong of 660 additionally surveyed sources have been found and can be added to the HALCA sample. 26 of 45 sources are new for the full VSOP list. Almost all VSOP sources are suggested to have continuous jets at milliarcsecond scales. This conclusion is supported by an analysis of the individual spectra for 213 objects, their mean statistical shape in the local frame, and the long-term variable spectra for 25 objects. Model and statistical analyses suggest a common physical origin of the radio sources of various types in the studied samples and in the majority of VSOP survey sources.